High Resolution Microclimate Study of Hollow Ridge Cave

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Electronic Theses, Treatises and Dissertations The Graduate School

2009 High Resolution Microclimate Study of Hollow Ridge Cave: Relationships Between Cave Meteorology, Air Chemistry, and Hydrology and the Impact on Speleothem Deposition Andrew Kowalczk

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COLLEGE OF ARTS AND SCIENCES

HIGH RESOLUTION MICROCLIMATE STUDY OF HOLLOW RIDGE

CAVE: RELATIONSHIPS BETWEEN CAVE METEOROLOGY, AIR

CHEMISTRY, AND HYDROLOGY AND THE IMPACT ON SPELEOTHEM

DEPOSITION

ANDREW KOWALCZK

A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science

Degree Awarded: Fall Semester, 2009

The members of the committee approve the thesis of Andrew Kowalczk defended on October 12, 2009.

______Philip N Froelich Professor Directing Thesis

______Yang Wang Committee Member

______Doron Nof Committee Member

______Tom Scott Committee Member

______Bill Burnett Committee Member

Approved:

______William Dewar, Chair, Oceanography

The Graduate School has verified and approved the above-named committee members.

ACKNOWLEDGEMENTS

The author would like to thank Nicole Tibbitts, Sammbuddha Misra, Ricky Peterson, Darrel Tremaine, Dr. Bill Burnett, Dr. Tom Scott, and Allen Mosler for editorial comments. The author would like to thank Darrel Tremaine, Craig Gaffka, Brian Kilgore, and Allen Mosler for assistance with field sampling. The author would like to thank Nicole Tibbitts, Sammbuddha Misra, Ricky Peterson, Natasha Dimova, Claire Langford, Dr. Michael Bizimus, Dr. Yang Wang, Dr. Yingfeng Xu, and Dr. Jeff Chanton for assistance in sample analyses and interpretation. The author would like to thank Dr. Philip Froelich for guidance, support, and funding throughout this project. Funding was provided by research (Oceanography) and teaching (FSU) assistantships. Project funding was provided by the Eppes Foundation. The author would like to acknowledge the Southeastern Cave Conservancy for permission to conduct research at the Hollow Ridge Cave Preserve.

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TABLE OF CONTENTS

List of Tables ...... vi List of Figures ...... viii List of Symbols ...... xii Abstract ...... xiii

1. Introduction to Research ...... 1

1.1. Purpose of Study ...... 1 1.2. Statement of Scientific Problem ...... 1 1.3. Overview of Thesis ...... 3

2. Background on Speleology ...... 5

2.1. Introduction to Speleology ...... 5 2.2. Speleogenesis and Karst Geology ...... 6 2.3. Speleothem Formation and Research...... 7 2.4. Cave Meteorology ...... 12 2.5. Summary ...... 15

3. Cave Air Ventilation and CO2 Outgassing by Radon-222 Modeling: How Fast do Caves Breathe? ...... 28

3.1. Abstract ...... 28 3.2. Introduction ...... 29 3.3. Site Description ...... 31 3.4. Methods...... 32 3.5. Results ...... 33 3.6. Discussion ...... 38 3.7. Conclusions ...... 42 3.8. Acknowledgements ...... 44

4. In situ Cave Monitoring at Hollow Ridge Cave ...... 56

4.1. Previous Studies ...... 56 4.2. Cave Monitoring Methods ...... 60 4.3. Cave Monitoring Results and Discussion ...... 67 4.4. Cave Monitoring Conclusions ...... 83

5. Speleothem Research ...... 125

5.1. Introduction ...... 125 5.2. Previous Research ...... 125

5.3. Methods...... 126 5.4. Results and Discussion ...... 129 5.5. Summary ...... 134

6. Summary of Thesis ...... 147

APPENDIX A ...... 150

APPENDIX B ...... 208

REFERENCES ...... 224

BIOGRAPHICAL SKETCH ...... 235

LIST OF TABLES

2.1: Summary of primary inorganic geochemical time-series in other drip water and speleothem climate studies...... 17

3.1: Average and Annual “Seasonal” Values for Time-Series Measurements ...... 45

3.2: Radon-222 Emission Rates (Φ222) ...... 46

4.1: Cave Monitoring Equipment ...... 86

4.2: RAD7 Portable 222Rn Detector Settings ...... 87

4.3: Radon-222 Emission Rates in Hollow Ridge Cave ...... 88

4.4: Radon-222 Emission Rates from Wall Flux Chambers ...... 89

18 4.5: Range of calcite-water and equilibrium  Ocalcite with temperature variations .. 90

4.6: Summary of Time Series Data at Hollow Ridge Cave ...... 91

A.1: Hollow Ridge Cave Time Series Data and Headers ...... 178

A.2: Hollow Ridge Cave CO2 Transect Data ...... 194

A.3: Hollow Ridge Cave 222Rn Transect Data ...... 196

A.4: Hollow Ridge Cave Drip and Sump Water Isotopes ...... 197

A.5: Hollow Ridge Cave 222Rn Intensive Data ...... 198

A.6: Recalculation of Φ222Rn during Flood Events ...... 207

B.1: Speleothem BC1, BC2, and BC3 U-series and Radiocarbon Dates ...... 208

B.2: Speleothem BC1 Stable Isotope Data ...... 209

B.3: Speleothem BC1 Trace Element Data ...... 215

B.4: Speleothem BC1 Color Spectrum Data and Headers ...... 216

B.5: Speleothem BC2 Stable Isotope Data ...... 217

B.6: Speleothem BC2 Trace Element Data ...... 219

B.7: Speleothem BC2 Color Spectrum Headers ...... 220

B.8: Speleothem BC3 Stable Isotope Data ...... 221

B.9: Speleothem BC3 Color Spectrum Headers ...... 223

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LIST OF FIGURES

1.1: Asian Monsoon Strength Evidenced in Chinese Speleothems ...... 4

2.1: Distribution of major cave and karst regions of the world ...... 18

2.2: Major cave and karst regions of the United States...... 19

2.3: Geologic Map of Florida ...... 20

2.4: Simplified Visual Representation of Karst Atmosphere Dynamics ...... 21

2.5: Typical ranges of oxygen and carbon isotopes in carbonate cave deposits and carbonate bedrock...... 23

2.6: Diagram of the processes involved in the 18O cycle ...... 24

2.7: Diagram of Solution Cave Formation and Speleothem Deposition ...... 25

2.8: Uranium-238 Decay Series ...... 26

2.9: Major processes involving the movement of air in caves and the exchange with the outside atmosphere...... 27

3.1: Simplified Visual Representation of Karst Atmosphere Dynamics ...... 47

3.2: Location of Hollow Ridge Cave ...... 48

3.3: Map of Hollow Ridge Cave ...... 49

3.4: Meteorological and Air Chemistry Time Series Inside and Outside of Hollow Ridge Cave ...... 51

3.5: Keeling plot of Hollow Ridge Cave and Obir Cave Air ...... 52

222 3.6: Weather Ventilation Events and Rn and CO2 ...... 53

3.7: Ventilation Rates, CO2 Import, and CO2 Outgassing June 2008 to March 2009 ...... 55

4.1: Location of Hollow Ridge Cave ...... 92

4.2: LIDAR Survey of Hollow Ridge Cave Vicinity ...... 93

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4.3: Map of Hollow Ridge Cave ...... 94

4.4: Map of Marianna, FL ...... 96

4.5: Generalized Upper Stratigraphy of the Marianna Area ...... 97

4.6: Rose Diagram of Hollow Ridge Cave Passages ...... 98

4.7: Instrumentation and Sample Collection Time-line at Hollow Ridge Cave ..... 99

4.8: Two Transects of 222Rn vs Distance at Hollow Ridge Cave...... 101

4.9: Three Transects of 222Rn vs Distance at Hollow Ridge Cave...... 102

4.10: Keeling plot of Hollow Ridge Cave and Obir Cave Air ...... 103

13 4.11: Cave Air [CO2] and  CO2 with distance from Entrance D ...... 104

13 4.12: Cave Air [CO2] and  CO2 over the study period ...... 105

4.13: Atmospheric Contribution to Cave Air CO2 ...... 106

4.14: Rainfall, Drip, and Sump Water 18O vs Time ...... 107

4.15: Drip, Sump, and Rainfall Samples Plotted on the GMWL ...... 108

4.16: Drip Rate vs Drip 18O ...... 109

4.17: Rainfall Amount vs 18O and D ...... 110

18 4.18: Mg/Ca ratios, Sea Surface Temperature, and  Oseawater from a northern Gulf of Mexico Sediment Core ...... 111

18 4.19: Theoretical  Ocalcite Precipitated from Drip Water in Hollow Ridge Cave . 112

4.20: Cumulative Rainfall and Drip Rates in the Ballroom ...... 113

4.21: Daily Rainfall and Drip Rates in the Ballroom...... 114

4.22: Barometric Pressure and Drip Rates in the Ballroom ...... 115

4.23: Meteorological and Aerochemical Time Series Inside and Outside of Hollow Ridge Cave ...... 116

4.24: Meteorological and Aerochemical Time Series Inside and Outside of Hollow Ridge Cave Over One Week...... 118

222 4.25: Cave Station 2 CO2 and Rn during Flood #1, February 2008 ...... 119

222 4.26: Cave Station 2 CO2 and Rn during Flood #2, December 2008 ...... 120

4.27: Hollow Ridge Cave 222Rn Intensive Map...... 121

4.28: Air Density Difference, Airflow Direction and Speed, and 222Rn During Intensive ...... 122

4.29: Turnover Rates of Air Exchange in Hollow Ridge Cave During Intensive .. 123

4.30: Ventilation Rates at Cave Stations 1 and 2 over the Study Period ...... 124

5.1: Map of Marianna, FL ...... 136

5.2: Map of Brooks Quarry Cave ...... 137

5.3: Typical Calibration Curves for Stable Isotope Analyses ...... 138

5.4: Uranium-series dates, true color photograph, red color spectrum, and isotopes from BC1...... 139

5.5: Age-Distance Scale of BC1 ...... 140

5.6: Trace Element, Isotope, and Color Scan Records of BC1 ...... 141

5.7: Photograph and CT scan of BC1 ...... 142

5.8: Radiocarbon dates, true color scan, red color spectrum, and isotopes from BC2 ...... 143

5.9: Isotope, Trace Element concentrations, and Color Photograph Records of the upper 1.1 cm of BC2 ...... 144

5.10: Radiocarbon dates, true color scan, red color spectrum, and isotopes from BC3 ...... 145

5.11: CT scan (left) and true color scan (right) of BC3 ...... 146

A.1: Wiring and Plumbing Diagram for MET Station ...... 170

A.2: Wiring Diagram for Cave Station 1 ...... 171

A.3: Plumbing Diagram for Cave Station 1 ...... 172

A.4: Wiring Diagram for Cave Station 2 ...... 173

A.5: Plumbing Diagram for Cave Station 2 ...... 174

A.6: Picture of MET Station at Hollow Ridge Cave ...... 175

A.7: Picture of Cave Station 1 ...... 176

A.8: Picture of Cave Station 2 ...... 177

LIST OF SYMBOLS

General Symbols: ka: kilo-annum (1000 years ago)

CO2: Carbon Dioxide 222Rn: Radon-222 13C: Ratio of Carbon-13 to Carbon-12 relative to a standard 18O: Ratio of Oxygen-18 to Oxygen-16 relative to a standard

SICACO3: Saturation Index of Calcium Carbonate in Water atm: Unit of atmospheric pressure A: Surface Area V: Volume ‰μ Parts per thousand, or permil. Notation to express13C and 18O values. ppm: Parts per Million. Can be expressed as a volume (ppmv)

Drip decay: A: Drip Rate at End of Model Period (30 drips hr-1) -1 A0: Initial Drip Rate at Beginning of Model Period (1000 drips hr ) -1 drip: Drip Loss Constant (hr )

Radon-222 and CO2 Modeling Symbols: -2 -1 Φ222Rn: Radon-222 Emission Rate from Cave Surfaces (dpm m hr ) -1 -1 222Rn: Radon-222 Decay Constant (hr ) (0.00756 hr ) -1 V: Cave Air Turnover Rate (hr ) (1/222)

222: Cave Air Turnover Time (hr) (1/ V)

ΦCO2: Emission Flux of CO2 from Cave Surfaces

ΨCO2: Consumption of CO2 in Cave (Limestone Dissolution, etc)

CO2: CO2 transport to the cave from the soil zone (as soil gas and drip degassed CO2)

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ABSTRACT

Long term, near continuous, in situ monitoring of cave meteorology, cave aerochemistry, and surface meteorology allows quantitative assessment of cave ventilation and the effect on

CO2 outgassing from cave systems. Because advances in mass spectrometry methods have lowered required sample sizes and increased accuracy for U-series age and carbonate stable isotope analyses, speleothems now have the potential to produce sub-annual paleoclimate records spanning tens of thousands of years (Dorale et al., 2002; Fairchild et al., 2006; Frappier et al., 2007; Lachniet, 2009). However, the need arises for long-term in situ monitoring of the cave environment to create multiple proxies that can be applied to speleothem geochemical records for more accurate interpretations of these records. Focusing on how the local precipitation signal transfers to the cave environment through the epikarst is essential to understanding how variations in precipitation affect drip water hydrochemistry, and ultimately the speleothems precipitated from these drip waters. However, an often overlooked subject is the role cave ventilation has on speleothem formation, and this research focuses on ventilation regimes and their affects on the CO2 cycle in the cave system. Cave meteorology, cave aerochemistry, and surface meteorology were measured from October 2007 to March 2009 at Hollow Ridge Cave, FL. Cave meteorology follows a similar, but greatly damped, pattern of temperature and barometric pressure as surface meteorology.

Continuous measurements of cave air radon-222 and CO2 indicate that ventilation primarily occurs via gravitational overturn. Strong seasonal patterns were observed in cave air radon-222 and CO2 concentrations, with decreased ventilation in the summer allowing concentrations to rise, while increased ventilation in winter keeps concentrations near outside atmospheric values.

A model developed to estimate CO2 outgassing indicates greater CO2 outgassing in the summer and fall than the winter, primarily due to increased CO2 transport to the cave environment from the soil zone, where rapid degradation of organics increases soil CO2 production. These results have been submitted and accepted in the form of a manuscript (Chapter 3) to Earth and Planetary Science Letters (Kowalczk and Froelich, 2009). Continuous records of drip rates in the cave suggest the thin overburden results in water residence times of approximately two weeks in the epikarst. However, this residence time is

xiii short enough to ensure complete mixing of infiltration waters because analyses of drip waters reveal little variation in their isotopic composition (< 0.3‰ 18O and < 8‰ D), while isotopic variations of up to 6‰ 18O are observed in local precipitation over similar periods. Also, the isotopic composition (18O and D) of aquifer water sampled from Hollow Ridge Cave is lighter than drip waters, indicating present rainfall is isotopically heavier than rainfall over the past 30 years, the average age of water in the North Florida Aquifer (Davis and Katz, 2007). Isotopic, trace element, computed tomography, color, and age analyses of three speleothems collected from Brooks Quarry Cave, FL indicate little variation in the 18O of precipitation from 70 ka to the present. However, poor chronology (radiocarbon dates) prevent comparison of isotopic, trace element, and color scan records from samples BC2 and BC3 to pollen records over the past 40 ka. Nevertheless, absolute U-series dating of sample BC1 suggest the approximate 3000 year isotopic record (69 Ka) may have recorded Dansgaard-Oeschger Event 19. The 13C records from these speleothems suggest either large shifts in the overlying vegetation composition (possibly from forest type to grassland/prairie type) or variations in cave ventilation processes that in turn affect drip water CO2 degassing processes. U-series dating of these samples will allow accurate comparison to pollen records from pond and lake sediment cores in north Florida, and will help construct a more accurate climate history of north Florida.

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CHAPTER 1

INTRODUCTION TO RESEARCH

1.1: Purpose of Study The ultimate purpose of the research conducted at Hollow Ridge Cave in Marianna, FL, is to gain insight on how local climate and cave meteorology affect modern calcite deposition. The majority of previous in situ cave monitoring programs focus on the transfer of the seasonal precipitation signal to speleothems (Asrat et al., 2008; Hu et al., 2008a). Long-term measurement of the variations in cave air CO2 concentrations have led to the development of models to estimate cave air CO2 concentrations based on temperature and soil productivity; however, air exchange has been largely ignored as having an influence on cave air CO2 concentrations (Baldini et al., 2008). In developing in situ monitoring stations to continuously measure cave 222 temperatures, CO2 concentrations, Rn concentrations, air flow, relative humidity, and barometric pressure, I aim to determine the effect cave meteorological processes have on the deposition of calcite. Two stations were deployed in Hollow Ridge Cave and one above the cave to monitor these parameters every half-hour from October 2007 to March 2009. This study is the 222 first of its kind to include continuous measurements of cave air CO2, Rn, and meteorological parameters for comparison to direct measurements of local climate. Also, supplementing these measurements are long-term measurements of cave air and drip water isotopes to determine ventilation and hydrologic processes occurring in the cave environment.

1.2: Statement of Scientific Problem Speleoclimatology, the study of paleoclimate records derived from speleothem calcite, is quickly becoming an important discipline in the paleoclimate field along with studies of tree rings, ice cores, and sediment cores. Speleothems are unique in that they can deposit annual laminations in highly stable environments (caves) and are safe from the erosional processes that plague sediment cores, ice cores, and tree rings over long (glacial/interglacial) periods (Fairchild et al., 2006). Speleothems can offer a global repository of paleoclimate records, carrying both regional and global climate signals in their isotope and trace element records (Genty et al., 2003). As such, many high fidelity speleothem records exist and offer a multitude of interpretations.

Speleothem records from multiple caves in southern China (Dongge, Hulu, Sanbao) provide a near continuous record of the Asian monsoon over the last 224 ka (Wang et al., 2001; Wang et al., 2005; Kelly et al., 2006; Wang et al., 2008). Direct comparison of speleothem 18O to summer insolation and ice core 18O records suggest these speleothems are viable recorders of Asian monsoon variability (Figure 1.1). High resolution U-series age analyses of these speleothems can also constrain the timing of global climate events found in ice cores and sediment cores (DO events, Heinrich events, etc). Speleothem records from Brazil suggest millennial scale climate changes (DO Events) affect the tropical hydrologic cycle, but that they are not as dominant as in the Northern Hemisphere (Cruz et al., 2005a). Variations in speleothem 18O from these regions are interpreted as being primarily driven by summer insolation, which drives atmospheric circulation and convective intensity over South America (Cruz et al., 2005a). Speleothem 18O records in Israel (Soreq and Peqiin Caves) neatly match the G. ruber 18O record from a Mediterranean sediment cores over the last 250 ka, suggesting these cave systems record a regional climate history and that there exists a robust link between the isotopic characteristics of the marine and land systems, via the 18O of seawater (Matthews et al., 2000; Bar-Matthews et al., 2003). Speleothem isotopic records can also offer insight the impact climate changes have on various cultures. Absolutely dated speleothem 18O records from Belize and India suggest the timing of major droughts was a major factor in the collapse of the Classic Maya civilization in Belize and lead to several of India‟s most devastating famines (Sinha et al., 2007; Webster et al., 2007). Interpretations of these records in ancient speleothems are well summarized in Fairchild et al. (2006); however, in-depth studies of modern cave conditions and their relations to modern speleothem deposition are rare. New research reveals cave and climate conditions affect the timing and rate of speleothem deposition (Spotl et al., 2005; Banner et al., 2007) and that thorough investigation of cave climate is essential for correct interpretations of speleothem climate signals (Banner et al., 2007; Mattey et al., 2008). In order to fully understand the complex processes involved in recording climate signals in speleothem calcite, speleothem paleoclimate scientists must look at the isotopic and trace element composition of speleothem formation waters and certain parameters of the cave environment.

1.3: Overview of Thesis This manuscript is divided into six chapters. The first chapter states the purpose of the study, describes the scientific problem addressed, and gives an overview of the thesis. Chapter 2 gives an introduction to the field of speleology and various cave studies starting with a description of speleology and then describing the various processes associated with cave development and the formation of speleothems. Interpretations of speleothem geochemical records and their uses are discussed, as are cave meteorological processes, including air 222 exchange, Rn, and CO2. Chapter 3 is the manuscript submitted and accepted to Earth and

Planetary Science Letters, discussing, in detail, ventilation modeling and CO2 exchange between the outside atmosphere and the cave. Chapter 4 describes research conducted in Hollow Ridge Cave. An introduction to previous research is followed by the methods, site description, results, and discussion of the in situ study of Hollow Ridge Cave. This includes near-continuous, time- series measurements of outside meteorology and cave meteorology. Results from grab sampling 222 of cave air Rn, cave air CO2, drip waters, and sump waters for isotopic compositions offer insight to ventilation and hydrologic processes inside and above the cave. Chapter 5 describes research conducted on three stalagmites collected from the Brooks Quarry Cave in Marianna, FL. Macro-sampling, micro-sampling, and analytical techniques are described for stable isotope, trace element, radiocarbon dating, U-series dating, CT scanning, RGB color scanning, and XRD mineralogical analyses, along with the results and conclusions derived from these three speleothems. Chapter 6 contains a summary of the thesis and future work to complement this study at Hollow Ridge Cave. The research agreement with the Southeastern Cave Conservancy, cave-monitoring power and wiring diagrams, pictures, cave-monitoring data (including time- series, transects, and intensives), and speleothem data are all contained in the appendices.

O record from from O record 18 δ O record from the the from O record 18 O records suggest the Monsoon strength suggest Asian of the O records is highly dependant 18  GISP2 ice core plotted over time. core Speleothem GISP2 ice upon summer insolation. H11 stands for Heinrich Event 11. The numbers insolation. Heinrich numbers upon summer 11. The for above Hulu caves the GISP2, Dongge, H11 stands Event and al. et Events Dansgaard-Oeschger 1through 24. Kelly (2006). from Figure represent Monsoon in The Asian Speleothems Evidenced Chinese speleothem 1.1 Asian Monsoon Strength Figure the and δ line) 25º σ (light grey insolation with summer at Donggecaves blue) (purple) and Hulu (dark

CHAPTER 2

BACKGROUND ON SPELEOLOGY

2.1: Introduction to Speleology Speleology, the science of caves, is a well-established cross-disciplinary field incorporating archaeology, biology, chemistry, geology, physics, meteorology, hydrology, scientific exploration, and cartography in the subterranean environment in order to better understand the processes involved in the formation (speleogenesis) and modification (speleomorphology) of cave systems. However, of greater interest to the paleoclimate field is the art of combining chemical, geological, and meteorological studies of caves with local climate studies to investigate the effects on the precipitation and preservation of speleothems (cave mineral deposits), which are capable of producing paleoclimate records spanning hundreds of thousands of years. It is imperative, therefore, to understand how speleothems form and how climate signals transfer through the cave environment to speleothems. Many high-quality speleothem records of long-term continental paleoclimate (e.g. Asian Monsoon) and short “events” (e.g. 8200-year cooling event) complement existing ice and sediment core climate records (McDermott et al., 2001; Wang et al., 2001; Cruz et al., 2005a; Brook et al., 2006; Hu et al., 2008b). Moreover, speleothems not only provide local repositories of regional climate variations, but also contain global climate variations in their isotope and trace element records. Interpretations of such records in ancient speleothems are well established and robust (Genty et al., 2003; McDermott, 2004; Fairchild et al., 2006; Lachniet, 2009). Nevertheless, few studies exist that connect present climate, cave climate, and modern speleothem calcite to interpretations of ancient speleothems. Links between modern calcite deposition and local temperature, rainfall, vegetation, drip water hydrochemical, and drip water isotopic cycles (proxy calibrations) may help to better interpret speleothem isotopic and trace element records. Because variations in speleothem geochemistry are acquired through variations in temperature, rainfall amount and source, drip-residence times, and changes in vegetation atop the epikarst, site-specific cave air and modern speleothem studies can help constrain interpretations of local geochemical records (McDermott, 2004; Treble et al., 2005a; Fairchild et al., 2006).

2.2: Speleogenesis and Karst Geology Speleogenesis, “the origin of caves”, is the study of the processes involved in underground cavity development (Palmer, 2007). Caves can be grouped into multiple categories (origin, host rock, shape, etc), however, this research focuses on caves developed in karst (solution caves). The three most common cave types are volcanic, glacier, and solution caves. Volcanic caves form when the outer surfaces of molten lava flows solidify. When liquid lava drains from inside the hard shell, a lava tube is created (Palmer, 2007). The island of Hawai‟i contains the most spectacular examples of these cave systems. Glacier caves form when melted water flows along fractures inside glacial ice, are enlarged as passages melt, and when meltwater carries glacial talus (rocks) through the passages (Fountain, 2005). Passages in glacier caves are typically enlarged in the warm summer months when warmer temperatures increase melt water volumes (Gulley, 2006). Solution caves form by the chemical dissolution of soluble bedrock (typically carbonates- limestone, dolomite, marble- but also gypsum and sandstone) as groundwater flows through pores and fissures (Palmer, 2007). Solution caves are the largest, most common type of cave, and as such hold the greatest interest to scientists because many solution caves contain information about local geologic and climate history (Fairchild et al., 2006; Palmer, 2007). Carbonate solution caves are of greatest interest to paleoclimate scientists because they house speleothems that can hold extensive, detailed paleoclimate records. Carbonate solution caves are most commonly developed in limestone bedrock, typically termed “karst” after the German name of a Slovenian plateau called Kras (Palmer, 2007). Karst, a limestone “rock mass in which cavity development is so extensive that there is little or no surface drainage of water,” is a geologic formation often containing paleoclimatic archives (Fairchild et al., 2006). Covering 10-15% of Earth‟s continental land mass, well-developed karst contains cave deposits with paleoclimatic records of global climatic events and cycles (Palmer, 2007). The global distribution of karst solution caves adds to the usefulness of searching these caves for paleoclimate archives because records from geographically separated locations can be compared to investigate the local effects of major global climate events (Figure 2.1). In the United States, karst caves can be found throughout much of the south-central, southeast, and eastern states (Figure 2.2) (Schmidt and Coe, 1988; Klimchouk et al., 2000; Palmer, 2007). The limestone platform of Florida and south Georgia, especially, offers a unique environment for the study of karst caves because of the proximity of multiple major universities (Florida State

University, University of Florida, University of South Florida) to a plethora of dry and submerged cave systems (Figure 2.3). Solution caves typically develop along existing cracks and fissures in the carbonate bedrock or along the boundary between the carbonate and a confining layer (shales, clay, granite, etc). Groundwater will flow along a preferential pathway (i.e. pre-existing fractures), dissolving limestone bedrock and enlarging cracks, fissures, and existing cavities. Over time, the dissolving action of groundwater creates extensive networks of interlinked conduits. Extensive discussion of cave development can be found in Klimchouk (2000).

2.3: Speleothem Formation and Research Speleothems are secondary mineral deposits formed in caves with many different chemical compositions and structures. This study focuses on the formation of carbonate speleothems in karst caves because these types of speleothems are most useful for paleoclimate records. Extensive discussion on all forms of speleothems can be found in Hill and Forti (1986). Five common forms of carbonate speleothems (soda straw stalactites, stalactites, stalagmites, flowstones, draperies), all deposited by dripping or flowing water, are found in most karst caves. Soda straw stalactites and stalactites form on the roof of the cave, while stalagmites form on the floor. Flowstones and draperies form on the walls and floors of caves. Soda straw stalactites are hollow, thin-walled tubes having a nearly uniform diameter of only a few millimeters their entire length and have been used to investigate calcite growth rates (Baskaran and Iliffe, 1993; Tanahara et al., 1998; Palmer, 2007). Soda straws form as dripping water flows through the interior hollow tube and deposits calcite on the terminal opening at the bottom of the formation. When the terminal opening of a soda straw fills in with calcite, a stalactite usually forms as the drip water follows a new path down the outside of the straw. As drip water flows down the outside of the stalactite, CO2 loss by degassing results in calcite precipitation, enlarging the outer walls of the formation. The base of the stalactite (at the ceiling) is the widest section of the stalactite, while the tip is the narrowest. Stalactite shape can be influenced by the rate of water flow and variations in calcite deposition (Short et al., 2005). Because of their growth dynamics and history, stalactites are not particularly useful for paleoclimate investigations. When drip waters fall off the tip of stalactites, calcite precipitates on the cave floor underneath the stalactite, forming a stalagmite. Stalagmite shape depends largely on the drip rate off the partner stalactite

7 and calcite deposition rates (Baldini, 2001; Self and Hill, 2003; Spotl et al., 2005; Collister and Mattey, 2008). Under high-flow drip locations, stalagmites are usually larger in size than partner stalactites because faster CO2 degassing occurs at the thin water film on the stalagmite. Also, prior CO2 degassing before the drops hit the stalagmite increases the calcite saturation index

(SICaCO3), and further CO2 degassing is more likely to precipitate calcite. The sequential deposition of calcite layers (speleothem varves; “sparves”) make stalagmites the preferred speleothem for paleoclimate investigations. As stalagmites and partner stalactites grow in size, they may merge to form a column, a continuous speleothem that reaches from floor to ceiling. Columns grow in diameter after the merge as water flows down the outer walls of the formation, and can create massive formations over 30 m high floor to ceiling (Palmer, 2007). Flowstones and draperies are deposited by water flowing down the ceiling and walls of caves. Draperies are narrow trails of calcite deposited on overhanging surfaces as water trickles down a preferential path along the cave wall (Palmer, 2007). Draperies extend outwards as more calcite deposits on the edges and can have a saw-like appearance created by the uniform spacing of the internal crystal structure (Hill and Forti, 1986; Palmer, 2007). Draperies are typically not useful for paleoclimate studies because of their irregular patterns of deposition. Flowstones deposit where water cascades in thin films down cave walls and floors, depositing calcite as CO2 degasses. Flowstones also contain sequential “sparves” and have produced paleoclimate records spanning over 500 ka in a single formation in a cave in σevada (the Devil‟s Hole flowstone record) (Coplen et al., 1994). Of these five common speleothem types, stalagmites and flowstones are the most popular for paleoclimate studies because they contain pronounced sequential layering and precipitate in more regular patterns than stalactites, columns, and draperies.

2.3.1: How carbonate speleothems precipitate. The formation of carbonate speleothems occurs via the dissolution of limestone bedrock and subsequent precipitation of secondary calcite. The enlargement of solution caves also occurs by this process. There are four steps involved in this process (Holland et al., 1964):

1) the oxidation of soil organics to produce high soil pCO2 - 2) hydration of CO2 to HCO3 in the soil zone 3) dissolution of limestone in the bedrock

4) precipitation of calcite via CO2 degassing from the cave

The chemical reactions (see Figure 2.4) in these steps are:

1) CH2O(s) + O2(g)  CO2(g) +H2O(aq) - + 2) CO2(g) +H2O(aq)  H2CO3(aq)  HCO3 (aq) + H (aq) - + 2+ - 3) HCO3 (aq) + H (aq) + CaCO3(s)  Ca (aq) + 2HCO3 (aq) 2+ - 4) Ca (aq) + 2HCO3 (aq)  CaCO3(s) + CO2(g) ↑ +H2O(aq)

These reactions drive changes in pCO2 between atmosphere (0.00038 atm), soil zone (~0.01 atm), and cave (~0.001 atm) (Klimchouk et al., 2000). Speleothem deposition is initiated by supersaturation of drip waters with respect to calcite, which occurs via two mechanisms: a)

CO2 degassing (dominant), and b) evaporation of drip waters (Hill and Forti, 1986). CO2 degassing is the dominant process driving speleothem deposition in most caves, where relative humidity is typically over 95% and thus evaporation is minimal. Calcite speleothems precipitated by CO2 degassing are commonly precipitated in isotopic equilibrium with formation waters. However, in arid and semi-arid regions speleothem deposition is primarily driven by evaporative processes (Hendy, 1971; Bar-Matthews et al., 1999; Bar-Matthews et al., 2003; Palmer, 2007).

Evaporation typically leads to forced CO2 degassing and precipitation of calcite where isotopes are kinetically fractionated. Climate proxies derived from carbonate speleothems are highly robust when speleothems are precipitated in isotopic equilibrium with formation waters (Fairchild et al., 2006; Lachniet, 2009).

2.3.2: Geochemical interpretations of stable isotopes and trace elements. Carbonate speleothems contain oxygen and carbon atoms in the crystalline structure of calcite, and therefore the ratios of oxygen and carbon isotopes can be used to investigate paleoclimate signals. The isotopic composition of flowstones and dripstones typically falls between -3 to -7‰ 18O (PDB) and +4 to -4‰ 13C (PDB) (Figure 2.5). In the karst system, oxygen is ultimately sourced from meteoric water and the dissolved limestone bedrock. Carbon is sourced from oxidized organic carbon in the soil zone, dissolved limestone bedrock, and atmospheric CO2 dissolved in meteoric waters (Baskaran and Krishnamurthy, 1993; Palmer, 2007). Fractionation constants for 18O and 13C are well known for the precipitation of calcite (Sharp, 2006).

2.3.2.1 Oxygen isotopes. The δ18O composition of speleothem calcite is determined by the isotopic composition of infiltration (percolation) waters and the temperature dependent fractionation between drip waters and calcite (Hendy, 1971). The isotopic composition of infiltration waters is derived from meteoric waters. Recognizing the various factors affecting the δ18τ composition of drip waters is essential for proper interpretations of speleothem δ18O records. Controls on variations in the δ18O composition of water in various phases of the hydrologic cycle are displayed in Figure 2.6 (Lachniet, 2009). Three main factors affect the δ18O signature of local precipitationμ 1) The δ18O signature of the vapor source region (ie. Ocean), 2) the „amount effect‟ (precipitation becomes more depleted in O with greater rainfall), and 3) Rayleigh Distillation (fractionation of δ18O and D during precipitation and evaporation). Global variations in the δ18O composition of seawater can be viewed as the determining factor behind the source effect (LeGrande and Schmidt, 2006; Lachniet, 2009), as water vapor sourced from subtropical waters will be heavier than temperate and polar waters. The amount effect, however, is not source dependent. There is an inverse relationship between rainfall δ18τ values and amount of rainfall (dδ18O/dP) in that increased rainfall will result in lighter δ18O as the heavier isotope preferentially rains out first (Lachniet, 2009). Rayleigh distillation results in the progressive depletion of δ18O and D as precipitation 16 18 and evaporation occur. Water containing oxygen-16 (H2 O) is lighter than oxygen-18 (H2 O), requiring less energy to move from the liquid to vapor phase, and is preferentially evaporated, 18 18 resulting in water vapor being depleted in O compared to its source water. Heavy water (H2 O) requires more energy to stay in the vapor phase, and will precipitate out before light water 16 (H2 O) during rainfall events. This process results in water vapor masses (and precipitation produced) becoming depleted in 18O as rainout progresses. Soil water δ18τ values are largely determined by the δ18O composition of local precipitation. Evapotranspiration may modify the signal of infiltrating meteoric waters, as increasing evapotranspiration will lead to heavier δ18O and D values in the residual solutions (Tang and Feng, 2001). Evapotranspiration may lead to surface water δ18O enrichment of up to 6.5‰, at a potential ET rate of 4 mm/day, and 2‰ at 1 mm/day in a Hawaiian transect (Hsieh et al., 1998). Infiltration rates also determine the δ18τ composition of cave drip waters. The δ18O composition of drip water depends on the rates of flow-through and overburden thickness (soil water residence time). Short epikarstic water residence times will result in drip waters having

10 similar isotopic signatures as recent local precipitation. However, long epikarstic water residence times will result in a well-mixed pool of infiltration water above the cave, and drip waters will reflect the isotopic signature of averaged annual precipitation. Geographical regions with distinct seasonal δ18O differences in precipitation should have this seasonal signal transferred to cave drip waters; however, long water residence times may filter this signal out (Fairchild et al., 2006). The δ18O of meteoric water is, therefore, translated to speleothem δ18O with little fractionation in the overburden (less than 2‰) and climate dynamics can be correlated to speleothem δ18O variations (Linge et al., 2001; Cruz et al., 2005b).

2.3.2.2 Carbon isotopes. The 13C signature of speleothems is derived from a combination of soil CO2, atmospheric CO2, the overlying limestone, and the kinetic fractionation associated with CO2 degassing from drip waters (Fairchild et al., 2006). The decomposition of organics in the soil zone increases soil CO2 concentrations up to 100,000 ppm in tropical regions, much higher than the 380 ppmv in the atmosphere today. Meteoric water contains dissolved 13 13 atmospheric CO2 ( C = -8‰) and picks up soil Cτ2 ( C = -12 to -28‰) as it percolates through the epikarst. The proportion of C3 (lighter 13C ≈ -28‰) to C4 (heavier 13C ≈ -12‰) vegetation will determine the isotopic composition of soil CO2 which transfers to percolation waters as CO2 is dissolved. Slightly acidic soil water (containing dissolved atmospheric and soil

CO2) percolates through the epikarst and dissolves the limestone bedrock which contributes another source of carbon to percolation waters. Even so, the δ13C of drip water will reflect the isotopic composition of soil CO2 because the total dissolved inorganic carbon derived from the soil zone is thought to be much greater than that derived from dissolved limestone (McDermott, 2004). When infiltration water (with atmosphere, soil, and limestone derived carbon) enters the cave air, CO2 degasses from the drip water until they reach calcite supersaturation. Subsequent degassing results in calcite precipitation. Fast degassing of CO2 results in kinetic fractionation of 13 12 13 C, as the lighter CO2 preferentially degasses first, leaving C enriched drip water (Fairchild et al., 2006). Speleothems are typically 10‰ heavier than the C3 and C4 plant signature due to isotopic fractionation during CO2 degassing (Dorale et al., 1992; McDermott, 2004). Studies of soil, limestone, drip, and cave air 13C and the interaction between each carbon reservoir in the cave system can help researchers better understand the processes involved in the formation of

13 speleothems. The processes and typical  C and CO2 values involved in the inorganic carbon cycle associated with caves are depicted in Figure 2.7.

2.3.2.3 Trace elements. The trace element composition of both drip waters and speleothems may contain additional climate signals and records of associated processes involved in the deposition of carbonate speleothems and can complement interpretations derived from the stable isotope composition of drip waters and speleothems. Correct interpretation of trace element records requires extensive knowledge of the local karst system and are likely site- specific although most trace element records in speleothems are indirectly linked to rainfall (Fairchild et al., 2006). When meteoric water percolates through the soil horizon and epikarst, trace elements are dissolved from clays, organics, salts, and carbonates. Drip water and speleothem trace element compositions have been interpreted to represent variations in groundwater residence time, prior calcite precipitation, speleothem growth rate, and soil chemistry (Fairchild et al., 2000; Baldini et al., 2002; Treble et al., 2003; Treble et al., 2005b; Johnson et al., 2006; Cruz et al., 2007). Ba/Ca and Sr/Ca ratios co-vary in most speleothems and are often interpreted as growth rate dependent (Treble et al., 2005b). Ba/Ca, Sr/Ca and U/Ca ratios, positively correlated with rainfall in a 20th century Australian speleothem, are inferred to be controlled by groundwater residence times and growth rates, which are controlled by precipitation amounts (Treble et al., 2003). Table 2.1 contains a summary of interpretations from drip water and speleothem trace element records. The interpretations of speleothem and drip water δ18τ, δ13C, and trace element ratios are site dependent and require extensive knowledge of the cave, soil, and local meteorological systems. Investigation of drip water chemistry is essential to correctly interpret variations in speleothem chemistry and may be useful as proxies for past rainfall, growth rates, groundwater residence times and soil chemistry (Spotl et al., 2005; Johnson et al., 2006).

2.4: Cave Meteorology Studies investigating both modern cave conditions and modern speleothem deposition are rare (Spotl et al., 2005; Banner et al., 2007; Baldini et al., 2008). Stalagmite growth rates, controlled partly by drip water CO2 degassing and, thus, cave air CO2 concentrations, are known to have intra-annual variability (Baldini et al., 2008). Variability in drip water CO2 degassing

12 rates affect the chemical composition of drip water, leading to seasonal variation in drip geochemistry which may be transferred to calcite (Spotl et al., 2005). By understanding the processes leading to diurnal and seasonal variability in cave air chemistry (ventilation and CO2 production) and how these effect speleothem deposition, interpretations of speleothem geochemical records can lead to enhanced interpretations of speleothem climate records (Banner et al., 2007; Baldini et al., 2008; Kowalczk et al., 2008).

2.4.1: Cave Aerochemsitry. Cave ventilation (air exchange with the outside atmosphere) has significant effects on cave meteorology, and more specifically, the composition of cave air. 222 The concentrations of Rn and CO2 gases in cave air depend upon the rates of introduction 222 222 ( Rn emission and CO2 transport from the soil zone), loss ( Rn decay and CO2 consumption), and air exchange. Physical air exchange rates can be quantitatively estimated by time-series measurements of 222Rn, while the carbonate system can be investigated by time-series measurements of CO2.

2.4.1.1: Radon-222. Limestone contains an average of 1.3-2.5 ppm 238U. Radon-222 gas is an intermediate daughter in a chain of radioactive decays that begins with 238U and ends with 206Pb (Figure 2.8) (Buecher, 1999). Radium-226 has a half-life of 1600 years, and 222Rn a half- life of 3.82 days. Radon-222 is ejected into the pore spaces by alpha recoil during 226Ra decay, and then emits into cave air (Burnett, 2007b). Because the surrounding limestone walls and drip waters emit 222Rn, it is found at higher concentrations in cave air than the outside atmosphere (Fernandez et al., 1986; Hakl et al., 1996; Hakl et al., 1997). Radon-222 is also a noble gas and, thus, a good tracer of air exchange in caves because it is chemically inert and has a half-life much longer than typical cave air turnover times. Because it is constantly emitted from the surrounding limestone, is chemically inert, and has a well-established half-life, Wilkening and Watkins (1976) developed 222Rn mass balance equations to estimate the air exchange rates between cave air and the outside atmosphere (discussed in detail in Chapter 3). In a general sense, cave chambers containing high 222Rn concentrations experience a low degree of air exchange, while chambers with low 222Rn concentrations generally experience faster air exchange, potentially up to tens of chamber volumes per hour (1000% volume exchange per hour). Radon-222 is generally found at higher concentrations further from the entrances;

13 however, isolated chambers in a cave system may have much higher 222Rn concentrations than adjacent, well-ventilated passages (Maddox, 1993; Cigna, 2005; Perrier et al., 2005). Figure 2.4 displays the processes associated with 222Rn balances in cave air.

222 2.4.1.2: CO2. Similar to Rn concentrations in caves, carbon dioxide concentrations in cave air are also generally higher than the outside free atmosphere. CO2 is found at higher concentrations that the outside atmosphere because CO2 from the soil zone is transported through the epikarst into cave, either via transport as dissolved CO2 in drip waters or in the gas phase through fissures and cracks present in the limestone bedrock. In temperate regions, the soil zone usually has CO2 concentrations ranging from 0.1 to 3.5 % (1000-35000 ppmv) although soil CO2 concentrations may be as high as 10% (100,000 ppmv) in tropical regions (Gillieson, 1996). The amount of CO2 transported via drip water relates to the calcite precipitation rate in the cave.

When drip waters enter lower pCO2 cave air, CO2 degasses. Drip water CO2 degassing rates are dependent upon the pCO2 difference between drip water and cave air. This difference depends on: 1) pCO2 of drip water where variations in soil pCO2 reflect seasonal growth, litter fall, and soil organic degradation; 2) drip rates which are a function of rainfall, percolation, evapotranspiration, and epikarst saturation; and 3) pCO2 of cave air which vary with cave air ventilation (White, 1988). Cave air CO2 is a balance between the transport of soil-derived high

CO2 from the epikarst and the influx of low CO2 air via ventilation. Meteoric waters inherit high pCO2 from organic decomposition and root respiration in the soil zone and then percolate through the epikarst and degas until reaching thermodynamic equilibrium when entering low pCO2 cave air (Figure 2.4). High pCO2 differences between drip water and cave air result in faster degassing and calcite deposition rates (Palmer, 2007).

2.4.2: Air exchange. Air exchange between the cave and outside free atmosphere can occur via a variety of processes (Figure 2.9), including gravitational exchange (density driven), barometric pressure differences, winds blowing into or across entrances (venturi effect), entrainment by flowing water, and convection driven by temperature differences in the bedrock in deep shafts (Palmer, 2007). According to the definition of Pflitsch and Piasecki (2003), cave passages can be classified according to their air movement and are classified as being dynamic (measureable physical air movement), transitional, or static (non-measureable physical air

14 movement). However, the use of 222Rn gas as a tracer of physical air movement indicates that a “static” classification is generally never obtained (Przylibski, 1999; Pflitsch and Piasecki, 2003). It must be noted that air exchange occurs both by „mass flow‟ (physical mass transport, advection, air movement, etc) and „mixing‟ (eddy diffusion, molecular diffusion). Mixing is 222 required to occur whenever gradients in air chemistry (cave air CO2 and Rn) are present. Furthermore, slight differences in air densities between the cave and outside atmosphere will create slow air currents (mass flow). Consequently, air exchange is considered to be the sum of mass flow and mixing processes. High-amplitude 222Rn variations over short periods (hours) have been observed where air movement is near the detection limits of most instrumentation suitable for the cave environment, indicating that continuous slow air movement is capable of transporting great quantities of cave air between chambers (Przylibski, 1999; Pflitsch and Piasecki, 2003; Perrier et al., 2005). The development of stratified bi-directional air currents during ventilation periods may have a significant effect on the formation of speleothems. During periods of gravitational overturn

(outside atmosphere air is denser than cave air), outside atmosphere air containing low CO2 concentrations may flow along the floor into cave systems, displacing the warmer, high CO2, cave air, which flows out of the cave along the ceiling. During this overturn, the CO2 gradient between drip waters and the cave air along the ceiling is low, resulting in slower CO2 degassing and calcite precipitation rates. However, a higher CO2 gradient is experienced along the floor of the cave, and faster CO2 degassing rates may lead to increased calcite precipitation rates. This is one reason why stalagmites are better paleorecorders than stalactites. This dual-layer exchange process is a contributing factor to why many stalagmites are observed to be much greater in size than stalactites in most cave systems.

2.5: Summary Speleology is a field combining methods and interpretations from many other long- established fields to develop a more complete understanding of the cave environment and the geochemical cycles recorded by speleothems. Fortunately, recent advances in mass spectrometry methods allow very accurate speleothem stable isotope analyses and U-series dating of samples (Fairchild et al., 2006; Wang et al., 2008; Lachniet, 2009). Paleoclimate records from speleothems now rival records from ice and sediment cores in temporal resolution, and further

15 advancement of sampling and mass spectrometry methods will likely lead to more accurate analyses. The length of speleothem paleoclimate records does not match that of marine sediment cores. Unfortunately, studies investigating modern cave meteorology and local climate to determine the direct effects on modern calcite deposition are rare (Spotl et al., 2005; Baldini et al., 2008; Hu et al., 2008a). It is imperative to investigate the direct effects local climate and cave processes have on the deposition of calcite, so modern proxies can be developed and applied to ancient speleothems to better interpretations of geochemical records.

Table 2.1: Summary of primary inorganic geochemical time-series in other drip water and speleothem climate studies. Drip Water References Speleothem References

Oxygen Residence time (Cobb et al., Variable (Hendy, 1971; isotopes in the epikarst; 2007; Onac et centennial to Cruz et al., Variable al., 2008) millenial 2005a) seasonal moisture moisture source source; temperature dependent fractionation

Carbon Variable CO2 (Hendy, 1971) Long term local (Genty et al., Isotopes degassing rates C3/C4 2003) result in kinetic vegetation fractionation changes

Ba/Ca Ratios Residence time (Baldini et al., Growth rate (Treble et al., in the epikarst 2002; Fairchild and layer 2005b) et al., 2006) thickness

Sr/Ca Ratio Prior calcite (Fairchild et al., Recharge rates (Treble et al., precipitation; 2000; Baldini et into the karstic 2005b; Cruz et residence time al., 2002) aquifer; growth al., 2007) in the epikarst rate

Mg/Ca Ratio Residence time (Fairchild et al., Recharge rates (Treble et al., in the epikarst; 2000; Baldini et into the karstic 2003; Treble et variable al., 2002; Spotl aquifer; prior al., 2005b; Cruz dissolution of et al., 2005) calcite et al., 2007) dolomite; prior precipitation calcite precipitation

U/Ca Ratio Vegetation (Treble et al., Growth rate (Treble et al., decay in the 2003) and layer 2005b) soil zone thickness

produced Regionsand paleoclimate karst that have exceptional and world. regions cave of the major 2.1: DistributionFigure of Brazil, Peninsula, eastern southern not limitedbut Borneo, China, include, studies the Yucatan to, southern Australia, are cave the Europe, and eastern Israel. (2007). Palmer isles,fold, the British France, from Spain, Appalachian Map

Figure 2.2: Major cave and karst regions of the United States. a) southeastern coastal plain (area involved of the (area plain southeasternUnitedand regions coastal in this study); cave a) karst States. 2.2: Major b)Figure marble plateaus; Interior Low Plateaus; Appalachian e) folded Mountains; Appalachian Mountains; c) d) Appalachian eastern in the belt Mountains; Plains; g) glaciated m) j) Black Guadalupe Plateau; h) southernHills; Plateau; Ozark lowlands; Great k) Colorado f) ranges; mountain lava TAGislands; r) flows; (Tennessee, Alabama, The Georgia) p) Alaskan western western n) q) Hawaii. d have highest cave e) (areas of the some in densities and region (2007). Palmer the world. from Map

Figure 2.3: Geologic Map of Florida. Map showing the bedrock Formations throughout Florida, highlighting the Marianna region in Jackson County (expanded view). The Formations in Jackson County are typically Eocene and Oligocene aged. Tallahassee (the state capital) and Florida State University are highlighted by the red four-point star. The city of Marianna is highlighted by the red oval, and Hollow Ridge Cave is highlighted by the green four-point star in the expanded view of Jackson County. Map drawn by Tom Scott of the Florida Geological Survey (Scott et al., 2001).

Simplified Visual Representation of Karst Air Dynamics. Caption Dynamics. of Karst Air page. on following Representation Simplified Visual :

2.4 Figure

Figure 2.4: Simplified Visual Representation of Karst Air Dynamics. 222 A conceptual cave showing the lithologic zones, chemical reactions, Rn and CO2 sources and 222 sinks, and Rn and CO2 mass balances associated with caves and cave ventilation. Meteoric water attains high CO2 in the soil zone and dissolves limestone during percolation. CO2 degasses from the drip water in lower pCO2 cave air, precipitating secondary calcite (speleothems). Radon-222 is constantly emitted (Φ222Rn) from the limestone surfaces and is transported via -1 fissures and drip water from the soil zone. Radon is lost through decay (radon = 0.00756 hr ) and export to the outside atmosphere. CO2 degasses from drip waters (ΦCO2 - precipitating secondary calcite), is transported via fissures and drip water from the soil zone, and is mixed into and out of the cave from the outside free atmosphere. It is also consumed by dissolution of calcite. Radon- 222 emission rates from cave surfaces are estimated by three methods represented in Table 2.2. When net air exchange is assumed to be zero, the volume of cave air exchanged (Vex) to the outside atmosphere is equal to the volume of outside atmosphere (Vex) mixed into the cave. Radon-222 and CO2 mass balance equations displayed in the upper right of the figure are used to 222 determine ventilation rates (via Rn) and calcite precipitation rates (via CO2) in results and discussion. The processes and chemical reactions involved in limestone dissolution and secondary calcite precipitation in various zones above and inside cave systems are shown in the middle of the figure. Three distinct zones are encountered: 1- the soil zone, where meteoric waters inherit high pCO2 and form weak carbonic acid; 2- the epikarst zone, where limestone dissolution occurs; and 3- cave air, where CO2 degassing results in secondary calcite precipitation. CO2 degasses from drip water and is transported in the gas phase from the soil zone through fissures. Radon- 222 is emitted from the limestone walls, ceiling, and floor and is transported from the soil zone through fissures and drip water. Radon-222 and CO2 are both exported from the cave to the outside atmosphere through air exchange (ventilation) as a volume of cave air is replaced with 222 222 lower Rn and CO2 outside atmosphere air. The symbols and terms in the Rn and CO2 mass balance equations are explained in the text.

Figure 2.5: Typical ranges of oxygen and carbon isotopes in carbonate cave deposits and carbonate bedrock. LS stands for limestone bedrock; DOL stands for dolomite bedrock. Line A represents the composition of initial calcite precipitation, while line B represents calcite precipitation initiated by evaporation. Figure redrawn from Figure 5.20 in Palmer (2007).

O cycle associated with cave drip waters and speleothem and drip waters speleothem with cave associated O cycle 18  Figure 2.6: Diagram of the involved in the processes 2.6: Diagram Figure (2009) Lachniet from deposition. Figure

2 C signatures (soil, limestone, and and (soil, limestone, C signatures 13 (atmosphere, soil, and cave air) and δ and soil,air) cave and (atmosphere,

2 view of speleogenesis and an overview of the influences on speleothem the influences pooling and of overview of speleogenesis depositionan seeping, by dripping,view flowing,

cave drip) (Palmer al. 1964, shown on the 2007, 2000, Hill are 1986 Holland et figure. 2006).Klimchouck Faichild cave leads to degassing and calcite deposition (step 4). Hollow Ridge Cave contains column, drapery, rimstone 4). containsflowstone, (step calcite column, deposition Hollow Ridge drapery, helectite, and Cave to degassing leads dam, stalactite pCO andstraw, The speleothems. stalagmite soda Figure 2.7 Diagram of Solution Deposition. 2.7 Diagram and Speleothem Formation Figure Cave A combined and condensating waters. Numbers 1-4 refer to the chemical steps involved in speleothem deposition. Meteoric waters inherit inherit waters. waters involved steps refersoil 1-4 deposition. condensating to the carbon Meteoric Numbers in speleothem and chemical with lower into cave a pCO steps Percolation then breathing acid- 3). 1,2), which readily dissolves (carbonic dioxide (step limestone 25

Figure 2.8: Uranium-238 Decay Series. Uranium-238 decays through a series of 13 daughters to stable 206Pb. Important in cave air and speleothem studies are 238U, 230Th, and 226Ra to 210Pb. Image courtesy of (http://home.clara.net/camplin/PRT/Tastrak/TNotes/Images/Chap6/Pic1.jpg).

outside atmosphere. the with the and in caves exchange air involving of processes the movement 2.9: Major Figure exchange gravitational by density Hollow cave Ridge exchange at processes for invoked are air two primary The between Figure cave and by and atmosphere, the outside the entrances. air differences winds blowing into or across (2007). Palmer from

CHAPTER 3

CAVE AIR VENTILATION AND CO2 OUTGASSING BY RADON-222 MODELING: HOW FAST DO CAVES BREATHE?

3.1: Abstract In general, the rate and timing of calcite precipitation is in part affected by variations in cave air CO2 concentrations. Knowledge of cave ventilation processes is required to quantify the effect variations in CO2 concentrations have on speleothem deposition rates and thus paleoclimate records. In this study we use radon-222 (222Rn) as a proxy of ventilation to estimate

CO2 outgassing from the cave to the atmosphere which can be used to infer relative speleothem deposition rates. Hollow Ridge Cave, a wild cave preserve in Marianna, Florida, is instrumented inside and out with multiple micro-meteorological sensor stations that record continuous physical and air chemistry time-series data. Our time series datasets indicate diurnal and seasonal 222 variations in cave air Rn and CO2 concentrations, punctuated by events that provide clues to 222 ventilation and drip water degassing mechanisms. Average cave air Rn and CO2 concentrations vary seasonally between winter (222Rn= 50 dpm L-1, where 1 dpm L-1= 60 Bq m-3; 222 -1 CO2= 360 ppmv) and summer ( Rn= 1400 dpm L ; CO2= 3900 ppmv), and large amplitude 222 -1 diurnal variations are witnessed during late summer and autumn ( Rn= 6 to 581 dpm L ; CO2= 360 to 2500 ppmv). We employ a simple first-order 222Rn mass balance model to estimate cave air exchange rates with the outside atmosphere. Ventilation occurs via density driven flow and winds across the entrances which create a „venturi‟ effect. The most rapid ventilation of those tested occurs 25 m inside the cave near the entrance (45 hr-1, 1.33 minute turnover time). Farther inside (175 m) exchange is slower and maximum ventilation rates are 3 hr-1 (22 minute turnover time). We estimate net CO2 flux from the epikarst to the cave atmosphere using a CO2 mass balance model 222 -2 -1 tuned with the Rn model. Net CO2 flux is highest in summer (72 mmol m day ) and lowest -2 -1 in late autumn and winter (12 mmol m day . Modeled ventilation and net CO2 fluxes are used to estimate net CO2 outgassing from the cave to the atmosphere. Average net CO2 outgassing is positive (net loss from the cave) and is highest in late summer and early autumn (about 4 mol hr- 1 -1 ) and lowest in winter (about 0.5 mol hr ). Modeling of ventilation, net CO2 flux from the

28 epikarst, and CO2 outgassing to the atmosphere from cave monitoring time-series can help better constrain paleoclimatic interpretations of speleothem geochemical records.

3.2: Introduction Many high quality speleothem records of long term continental paleoclimate (e.g. Asian Monsoon) and short “events” (e.g. 8200-year cooling event) now complement ice core and sediment core records (McDermott et al., 2001; Wang et al., 2001; Cruz et al., 2005a; Brook et al., 2006; Hu et al., 2008b). These cave deposits provide repositories of regional and global paleoclimate signals in their isotope and trace element records. Interpretations of such records in ancient speleothems are well established and robust (Genty et al., 2003; McDermott, 2004; Fairchild et al., 2006; Lachniet, 2009). Study of the complex relation between modern climate (local), cave atmosphere, and composition of the calcite deposited is needed to better understand geochemical records from ancient speleothems. Links between modern calcite deposition and local temperature, rainfall, vegetation and drip water hydrochemical and isotopic cycles (proxy calibration) will help to better interpret ancient speleothem geochemical records (Spotl et al., 2005; Johnson et al., 2006; Banner et al., 2007; Baldini et al., 2008; Kowalczk, 2009). Because variations in speleothem geochemistry are produced through changes in rainfall amount, rainfall source, drip water residence time, temperature, and vegetation atop the epikarst, site-specific cave atmosphere and speleothem studies can help constrain interpretations of local geochemical records (McDermott, 2004; Treble et al., 2005a; Fairchild et al., 2006). Studies of both modern cave conditions and speleothem deposition are rare and have primarily focused on relating drip water and air chemistry to hydrologic regimes (Spotl et al., 2005; Banner et al., 2007; Baldini et al., 2008; Collister and Mattey, 2008). Speleothem growth rates, controlled partly by drip water CO2 degassing rates and therefore cave air CO2 concentrations, are known to display intra-annual variability (Banner et al., 2007; Baldini et al.,

2008). Variability in drip water CO2 degassing rates affects the chemical composition of drip waters, leading to possible seasonal variation in drip water geochemistry which may be transferred to calcite (Spotl et al., 2005). Banner et al. (2007) were the first to directly quantify calcite deposition rates and the relationship to cave air CO2 concentrations. Understanding the processes (ventilation and CO2 flux from the epikarst) leading to diurnal and seasonal variability in cave air chemistry will lead to better comprehension of the effects on speleothem deposition

29 and improve interpretations of speleothem climate records (Banner et al., 2007; Baldini et al., 2008; Kowalczk et al., 2008). There are three zones encountered by infiltration waters as they percolate through the epikarst (Figure 3.1): 1) the soil zone, where meteoric waters inherit high pCO2 from organic decomposition and root respiration to form weak carbonic acid; 2) the epikarst zone, where limestone dissolution occurs; and 3) the cave zone, where CO2 degasses from drip water into void spaces to reach thermodynamic equilibrium with lower pCO2 cave air, leading to calcite precipitation once the drip water is saturated with dissolved calcite. CO2 is also transported in the gas phase from the soil zone through fissures. The net CO2 flux from the epikarst is the combination of drip water degassing and transport in the gas phase. Drip water CO2 degassing rates are dependent upon the pCO2 difference between drip water and cave atmosphere. This difference depends on: (1) pCO2 of drips - a function of soil pCO2, litter fall, and soil organic degradation; (2) drip rate - a function of rainfall, percolation rate, evapotranspiration in the overlying canopy, and epikarst saturation; and (3) pCO2 of cave air – a function of cave air ventilation and net CO2 flux (White, 1988). Large pCO2 differences between drip water and cave air results in faster degassing and higher calcite deposition rates (Palmer, 2007). Variations in cave air CO2 concentrations are a balance of the flux from the epikarst and exchange with the outside atmosphere. Site-specific time series investigations are necessary to decipher these relationships and further the understanding of climate effects on speleothem growth rates and isotopic compositions. Radon-222 gas is an intermediate daughter in a chain of radioactive decays that begins with 238U and ends with 206Pb (Buecher, 1999). Previous studies have found high 222Rn concentrations in cave air so this gaseous tracer can provide a useful proxy to investigate ventilation processes (Wilkening and Watkins, 1976; Perrier et al., 2005; Richon et al., 2005). Limestone contains an average 1.3-2.5 ppm 238U and thus 222Rn is naturally found in all limestone caves at concentrations higher than the outside atmosphere as a result of the constant emission of 222Rn from surfaces, fractures, and drip waters (Fernandez et al., 1986; Hakl et al., 1997). Moreover, 222Rn is a noble gas and thus a good tracer in cave air because it is chemically inert and has a half-life of 3.82 days, which is much longer than air turnover times in most caves (Fernandez et al., 1986; Perrier et al., 2005; Richon et al., 2005). Caves will display ventilation characteristics in 222Rn air chemistry unless turnover is slower than five mean lives of 222Rn

(approximately 1 month). Otherwise if cave air turnover is longer than one month, 222Rn will only display ingrowth and decay at secular equilibrium. Even so, 222Rn is the only natural tracer available in caves. Variations in 222Rn concentrations are a balance of the emission from cave surfaces and drip waters, decay in cave air, and exchange with the outside atmosphere. Radon- 222 mass balances were previously developed to estimate cave air exchange rates with the atmosphere (Wilkening and Watkins, 1976). However, these models have not previously been 222 applied to CO2 exchange; the main objective of this study is therefore to develope simple Rn and CO2 mass balances and then investigate CO2 outgassing by combining these mass balances.

Our over-arching hypothesis is that more vigorous cave ventilation and CO2 outgassing maintains in-cave CO2 concentrations at a lower level, which promotes more CO2 degassing from drip water, thereby increasing calcite precipitation rates.

3.3: Site Description Hollow Ridge Cave is located in Marianna, Jackson County, FL (30 46‟ 58.17” σ, 85 12‟ 13.15” W, 30 m a.s.l.), 105 km west of Tallahassee, the state capital (Figure 3.2). The mean annual temperature is 20° C. Average annual precipitation is 1480 mm. The Florida Caverns State Park is located 2 km north of Hollow Ridge Cave and contains two of the five longest caves in the state. The Chipola River flows through the heart of Marianna and Hollow Ridge Cave is located approximately 300 m from the river in a bluff at the edge of the eastern floodplain. The base level of the cave is approximately one meter above the edge of the floodplain and is subject to periodic flooding through its lower entrances. Figure 3.3 provides a complete plan view of the cave including field instrumentation used in this study. Hollow Ridge Cave has 1030 m of mapped passage developed in the flat-lying Bumpnose and Marianna limestone Formations (Oligocene) and 11 m total vertical relief (Puri, 1957; Puri and Vernon, 1964; Boyer, 1975). Hollow Ridge Cave is overlain by a thin soil veneer (average <0.5 m thick) composed of Plio-Pleistocene sands and clays with numerous limestone outcrops (Maddox, 1993). A portion of the ridge was previously used as a limestone quarry, located directly above the main entrance chamber. The interior of the cave seems undisturbed by the quarrying activities. An upland mixed pine and oak forest currently overlies the cave (White, 2006). Hollow Ridge Cave has four known natural entrances located in the southwest section of the cave that converge in the main entrance chamber (Figure 3.3). Entrances A, B, and C are

31 located on the ground level of the floodplain, and Entrance D is approximately 4 m above Entrances A, B, and C. The majority of passages are less than one meter above the floodplain, and are low (<1 m) and wide (>3 m), typical of local „water-table‟ type caves. There are two breakdown rooms (the Entrance Chamber, 3 m above the floodplain, and the Smith and Jones Room, less than 1 m above the floodplain) and a fissure passage (6 to 8 m above the floodplain) where vertical relief exceeds 8 m. Passage orientations are primarily in the 150-330° and 100- 280° directions. A low crawl from the Entrance Chamber leads to the Ballroom, a low and wide chamber with a mud floor up to 1.25 m thick. This section of the cave is typically wet, contains numerous active speleothems, and connects the southwest area (entrances) to the rest of the cave. A second low crawl leads to the Smith and Jones Room in the southeast section of the cave. This is the largest breakdown room and contains active speleothems and a permanent sump that turns into a spring when local aquifer levels are high. The fissure passage leads from the Smith and Jones room to the Signature Room, which is 7 to 9 m above the floodplain. The fissure passage and the Signature Room are formed in the upper Marianna Formation while lower passages are in the Bumpnose Formation.

3.4: Methods A meteorology station above the cave (Figure 3.3, MET Station) and two sensor stations within Hollow Ridge Cave (Figure 3.3, Cave Stations 1 and 2) continuously monitored surface meteorology, cave meteorology, and cave air chemistry (Table 3.1). Surface meteorology was compared to a weather station maintained at the Marianna Municipal Airport, 5 km NNE of Hollow Ridge Cave, to ensure site measurements were representative of local meteorology. All instruments and measurements, except the RAD7 portable 222Rn detectors (Durridge Inc.), were controlled by and logged every half hour to Campbell Scientific CR1000 dataloggers. The independent RAD7 portable 222Rn detectors were set to log hourly measurements on internal storage, and have a long term precision of ± 4%. Cave Station 1* was located approximately 100 m from Entrance D from October 31st, 2007 to February 16th, 2008. Cave Station 1* was destroyed in late February 2008, when the cave was inundated during flooding of the Chipola River. The station was re-deployed (herein referred to as „Cave Station 1‟) on June 18th, 2008 to the higher elevation Entrance Chamber (25 m from Entrance D). Cave Station 2 was deployed on

October 31, 2007, 175 m from Entrance D in the Signature Room, and was continuously operational. Grab sampling transects were collected bi-weekly to collect cave air from five locations (Figure 3.3, locations 1, 2, 3, 4, 5). Drip water (Figure 3.3, location 3) and sump water (Figure 3.3, location 5) grab samples were collected and analyzed for isotopic composition. Cave air samples were analyzed for CO2 concentration via LiCor Li820 CO2 gas analyzers (long term accuracy of ± 4% of measurement) and for inorganic 13C via direct injection by a Finnigan MAT Delta S Mass Spectrometer and HP 5890 Series II Gas Chromatograph (long term 13 reproducibility of ± 0.05‰  C). Radon-222 emission rates (Φ222) were estimated from two wall flux chamber measurements and two flooding events that inhibited ventilation (Table 3.2). Outside atmosphere and cave air densities were calculated using the barometric pressure

(P), universal gas constant (Rd ), and virtual temperature (Tv) (Equation 3.1). The virtual temperature is calculated using the air temperature (T), dew point (Td), and barometric pressure (P) (Equation 3.2). P air (3.1) Rd  Tv

5.7 Td .6 1110 2377. Td T (T  273.15 1()  .0( 379  )) (3.2) v P

The air density difference is calculated by subtracting the cave air density from the outside free atmosphere density (MET-cave). When outside air is denser than cave air density difference is positive. When cave air is denser than the outside atmosphere the density difference is negative.

3.5: Results 3.5.1. Cave Time Series Data 3.5.1.1. Atmosphere and Cave Meteorology. Observed meteorology at Hollow Ridge Cave over the study period is consistent with local long-term archives from Marianna, displaying typical seasonal weather patterns of North Florida (hot in summer, periodic strong cold fronts October to March). Temperature outside the cave averaged 18.3° C from November 1, 2007 to November 1, 2008, while temperature inside the cave averaged 19.6° C (Table 3.1). Ventilation regimes based on surface meteorology, cave meteorology, and cave air chemistry can be separated into three periods– Summer (May-July), Autumn (July through September), and

Winter (October to May), displayed in Figure 3.4 with outside rainfall, barometric pressure, 222 temperature, air density difference, as well as cave temperature, Rn, and CO2 concentrations. Cave meteorology lags and dampens variations in local outside atmosphere temperature and barometric pressure, suggesting local weather drives cave meteorology and ventilation, also observed in Austrian and Irish cave systems (Spotl et al., 2005; Baldini et al., 2008). Local weather drives ventilation in two ways. First, air density differences between cave air and outside atmosphere can create density-driven flows, resulting in air exchange between the cave and atmosphere. Because air density is influenced by temperature, the air density differences closely follow the temperature difference between the cave and atmosphere. Secondly, winds drive ventilation (venturi effect) via diurnal NW-N-NE barotropic winds that arise in the mid-morning and typically follow the ridge orientation (30°) at an average speed of 1-2 m s-1 through the forest canopy. Airflow at Entrance A has diurnal variability in both direction and magnitude that follows both the timing and magnitude of air density differences and barotropic winds. Similar observations have been noted in Japanese and Polish caves (Tanahara et al., 1997; Przylibski, 1999). Hollow Ridge Cave has both dynamic (continuous air movement) and static (stagnant air) sections (Pflitsch and Piasecki, 2003), but most passages exhibit dynamic characteristics. Temperatures at Cave Station 1* (100 m from the entrance) from Oct 31 2007 to Feb 16 2008 exhibited maximum diurnal changes of 0.1° C and a maximum seasonal change of 1.5° C (Figure 3.4). Cave Station 1 experienced increased atmospheric influence (greater diurnal and seasonal variation) in the Entrance Chamber (25 m from the entrance) from Jun 18 2008 to Feb 7 2009. Temperature at this site exhibited a 1.5 to 2° C diurnal variation imposed on a 5° C seasonal variation between summer and winter. Air flow rates of up to 1 m s-1 at Entrance A are recorded when outside air flows into the cave. Temperature at Cave Station 2 reflects seasonal atmosphere temperature variations with an annual range of 3.2° C and no detectable diurnal variation. The greater annual variability experienced in the Signature Room is likely due to thinner overlying epikarst which may have an increased response to annual temperature variations than thicker epikarst. Maximum and minimum cave temperatures at Station 2 are observed approximately two months after outside temperature extremes reflecting the lag effect of heating and cooling of the epikarst (Moore and Sullivan, 1981).

222 222 3.5.1.2. Cave Air Chemistry (CO2 and Rn). Cave air CO2 and Rn exhibit diurnal and seasonal variations at both stations, similar to cave studies in Texas (Banner et al., 2007), Austria (Spotl et al., 2005), England (Baldini et al., 2008), Poland (Przylibski, 1999), Japan 222 (Tanahara et al., 1997), and Hungary (Hakl et al., 1997). High overall Rn and CO2 concentrations typically occur during the warm summer periods; and low concentrations are typical of cold winter periods (Figure 3.4). CO2 concentrations in the Ballroom ranged from 300 to 1050 ppmv (Cave Station 1*) and in the Entrance Chamber ranged from 300 to 2300 ppmv

(Cave Station 1). Minimum CO2 concentrations (~300 ppmv) are assumed to represent daytime forest canopy air flowing into the cave plus condensation corrosion effects (lowering CO2 via limestone dissolution by water vapor) that combined will lower CO2 concentrations below mean atmosphere values (Bazzaz and Williams, 1991; Palmer, 2007). Diurnal variability up to 1900 ppmv during summer and autumn seasons (June to September) in the Entrance Chamber represents strong diurnal ventilation of low pCO2 outside air into the cave. Diurnal variability (1000 to 4000 ppmv) was previously observed in some Irish caves (Baldini et al., 2008).

CO2 concentrations at Cave Station 2 display larger seasonal but smaller diurnal variability than Cave Station 1 (Figure 3.4). Consistently low CO2 concentrations (500 ppmv) throughout the cold season end with a sharp transition (to over 4000 ppmv) at the start of the warm season as outside air becomes less dense than the cave air, and ventilation deep in the cave slows. High pCO2 conditions persist until early July, when concentrations decrease and fluctuate diurnally between 500 to 2000 ppmv throughout autumn. This trend lasts until late September when pCO2 falls to average winter concentrations of 500-1000 ppmv. Under normal (non-flood or heavy rain event conditions), high 222Rn concentrations occur in the warm season (summer) and low concentrations in the cold season (winter), consistent with increased ventilation in the 222 cold season. Diurnal variability in Rn in the summer and autumn is synchronous with CO2 at both cave stations, suggesting ventilation is a key component in controlling cave air pCO2 and 222Rn variations in the cave. A flooding event in February 2008 inhibited ventilation to the Signature Room (Cave Station 2) for a period of 6 days allowing 222Rn to increase from 100 dpm L-1 to 1020 dpm L-1, although these values were still increasing when ventilation resumed. CO2 concentrations display synchronous increase over the same period, from 750 ppmv to 1500 ppmv. A second flooding event (December 2008) displayed similar characteristics over a shorter interval (3 days). Radon-

-1 222 concentrations increased dramatically (60 to 1000 dpm L ) while CO2 concentrations display a slight increase (600 to 800 ppmv). Using the maximum instantaneous measured 222 222 increase in Rn, these two events allow estimates of the Rn emission rate (Φ222) from limestone surfaces, fissures, and drip water during non-normal conditions in the cave (see section

3.4.2). The chamber volume (Vchamber), surface area (Achamber), and measured instantaneous rate of increase (dC222/dt) are used to convert the concentration increase to an emission rate (Φ222):

dC222 Vchamber 222  (3.3) dt measured Achamber These flooding events are not normal conditions for the cave, and are preceded by intense rain events. The high rainfall before these events results in increased saturation of the epikarst and a dramatic increase in drip rates. When limestsone bearing 226Ra decays in a saturated system, the 222Rn atoms will recoil into the water phase rather than recoiling through air filled porosity into neighboring limestone grains (Menetrez and Mosley, 1996; Burnett, 2007a). As 226Ra decays, there is an increased likelihood that 222Rn atoms will recoil into the water phase during these complete saturation episodes, as opposed to recoiling into neighboring limestone grains. These two factors (increased drip rates, higher probability of 222Rn recoiling into the 222 water phase) result in increased transport of Rn and CO2 from the epikarst when compared to normal (non-saturated) conditions. Therefore, although these events are used to estimate the maximum 222Rn emission rates, they are calculated during “non-normal” conditions and therefore not used in our models.

3.5.2. Grab Sampling. Cave air grab samples were collected bi-weekly at five locations 13 13 for  CO2 and CO2 concentrations (Section 3.3). Samples having depleted  CO2 values (-

21.5‰) and high Cτ2 concentrations (4000 to 5000 ppmv) are typical of summer cave air farther 13 from the entrance (Figure 3.5). Conversely, less depleted  CO2 values (-12‰) with lower Cτ2 concentrations (500 to 600 ppmv) are typical of winter cave air closer to the entrance. The cave 13 air CO2 system is a simple two-endmember mixing system, with soil gas (lower  C, higher 13 CO2) as one endmember and outside atmosphere air (higher  C, lower CO2) as the other. 13 -1 Regression of  CO2 versus [CO2] (Keeling Plot- Figure 3.5) has a linear relationship similar to that found in atmospheric, soil, and snowpack CO2 (Keeling, 1958; Bowling et al., 2008). This 13 regression predicts a soil-gas end-member  CO2 of -22‰ and an atmospheric end-member

13 13  CO2 of -7‰. This relationship of  CO2 vs CO2 could be applied to our continuous CO2 13 time-series to convert it into modeled cave air  CO2, which could then be used to constrain the 13  C of precipitated calcite because cave air CO2 concentrations influence drip water CO2 degassing and calcite 13C should reflect the Keeling plot.

3.5.2. Ventilation. Air exchange rates in Hollow Ridge Cave are quantitatively estimated by continuous monitoring of cave air 222Rn activities (Wilkening and Watkins, 1976). 222 222 We propose a simple Rn mass balance model. Temporal variations (dC222/dt) in cave air Rn 222 concentrations (C222) are estimated by the balance of Rn emission (Φ222), radioactive decay -1 (222Rn = 0.00756 hr ), and air exchange with the outside atmosphere (v - turnover time) (Dueñas et al., 1999).

dC222 Achamber 1  222  222C222  (C222 C222atmos) (3.4) dt Vchamber  v where A and V are the surface area and volume of the cave chamber (a 9:1 surveyed surface area 222 to volume scale length is used at both stations) and C222-atmos is the Rn concentration of the outside air (measured less than 1 dpm L-1). When 222Rn emission, decay, and temporal variations are known, re-arrangement of

Equation (3.4) yields a solution for chamber air turnover times (v);

(C222  C222atmos)  v  (3.5) Achamber dC222 222  222C222  Vchamber dt -1 The reciprocal of chamber turnover time (v) is the turnover rate (v ), expressed in units of hr-1. Radon-222 emission rates in Hollow Ridge Cave were estimated by closed accumulation chambers (Ferry et al., 2001) and the greatest instantaneous rise during flooding events when the Signature Room was sealed (Table 3.2). The 222Rn emission rate of 3700 dpm m-2 hr-1 (in situ closed accumulation chamber method) is used in Equation (3.5) because we assume this is a representative 222Rn emission rate during normal (non flood) conditions, whereas the two higher 222Rn emission rates (4,444 and 20,000 dpm m-2 hr-1) are experienced in extreme flood conditions (Wilkening et al., 1972; Ferry et al., 2001). We assume the 9:1 area to volume scale length is constant for the entire cave system to simplify modeling at different points, although this is likely not the case. Radon-222 emission from cave surfaces and drip waters is also

37 assumed to be constant. This is also likely not the case and 222Rn emission rates are likely to vary with time and location. Hourly turnover rates at both cave stations are determined using Equation (3.5). Cave Station 1 had a faster maximum turnover rate (44.6 hr-1 = 1.33 minutes) than Cave Station 2 (2.76 hr-1 = 22 minutes). Both stations have similar temporal ventilation characteristics in the autumn (diurnal cycle between fast turnover and stagnation) and winter (continuous slow turnover lacking diurnal variability). However, in the summer Cave Station 2 stagnates while Cave Station 1 displays similar characteristics as in the autumn. Ventilation rates, averaged over 24-hours, are not significantly higher in the autumn (July-September) (~4 hr-1 = 15 minutes) or winter (October-April) (~2 hr-1 = 30 minutes) than the summer (May-June) (~1 hr-1 = 60 minutes). Cave Station 2 displays weak diurnal ventilation in all seasons except autumn. Autumn ventilation rates, averaged over 24-hour periods, (~ 0.6 hr-1 = 100 minutes) are higher than winter (0.25 hr-1 = 240 minutes) and summer (0.02 hr-1 = 3000 minutes).

3.6. Discussion 3.6.1. Ventilation Regimes. Three major ventilation regimes are identified at Hollow 222 222 Ridge Cave in the Rn and CO2 time-series using Rn mass balance (ventilation) modeling: 222 1) Continuous “winter” ventilation, which lowers cave air Rn and CO2 concentrations to near-atmospheric levels (October-May). Longitudinal gradients between Cave 222 Station 1 and Cave Station 2 in Rn and CO2 are at a minimum. 222 2) “Summer” stagnation, which allows build-up of cave air Rn and CO2 (May-June). 222 Longitudinal gradients in Rn and CO2 are at a maximum. 3) Diurnal variations in strong nighttime ventilation and daytime stagnation results in 222 high amplitude Rn and CO2 variations during “autumn” (July-September). Two mechanisms are proposed to drive ventilation in Hollow Ridge Cave under normal conditions: 1) density differences between the atmosphere and cave air, and 2) diurnal barotropic winds. During the winter, cold dense outside air cascading into the cave is the primary driver of 222 continuous ventilation, displacing the warmer, less dense air resulting in low Rn and CO2 concentrations. During the summer, cave air is cooler and denser than the warm outside air 222 resulting in cave air stagnation allowing Rn and CO2 concentrations to increase (Figure 3.4) (Tanahara et al., 1997). However, in autumn we believe diurnal variability in the air density

38 difference is responsible for the large range in ventilation rates. The complex architecture of Hollow Ridge Cave may cause the cave to have “ascending cave” characteristics (rising 222 passages) from July to September, when Rn and CO2 rise during the evening and peak early morning before sunrise as ventilation slows. Ventilation is typically faster during the autumn period (July to October), similar to findings in Ireland (Baldini et al., 2008). However, certain caves in Texas, New Mexico, Arizona, Spain, and Japan experience fastest ventilation in winter (Wilkening and Watkins, 1976; Fernandez et al., 1986; Tanahara et al., 1997; Buecher, 1999; Dueñas et al., 1999; Banner et al., 2007) and certain caves in Gibralter experience fastest ventilations in summer (Mattey et al., 2008). Two events are used to demonstrate major ventilation occurrences in the autumn and winter (Figure 3.6). In autumn, the wind shift (from east to south) during the passage of TS Faye (left panel) on August 23rd, 2008 resulted in strong ventilation of Hollow Ridge Cave via the “venturi effect”, producing low 222Rn concentrations and high ventilation rates roughly six hours after the shift. Positive air density differences (outside free atmosphere denser than cave) on a cold front passing January 16th, 2009 resulted in increased ventilation. However, drastic 222 variations in Rn and CO2 are not witnessed because winter cave air concentrations were already low. Hollow Ridge Cave architecture, having a typically flat lower level and multiple entrances at different heights, must have a significant role in the seasonality of air exchange. When atmosphere air is denser than cave air (night, winter), it flows into the cave along the lower passages and displaces the warmer, less dense cave air. This results in a lowering of the 222 222 Rn and CO2 concentrations. This flow pattern allows Rn and CO2 to build up during the day (Figure 3.6, left panel). When cave air is cooler (denser) than outside atmosphere (day, summer), 222 it will flow out of the cave and is replaced by lighter atmosphere (low Rn and CO2) air, 222 allowing Rn and CO2 to build up during the night (Figure 3.6, right panel). 222 Cave air chemistry ( Rn and CO2) is largely determined by the extent of ventilation. 222 Continuous ventilation (in winter) drives cave air Rn and CO2 down to near atmospheric levels, via fast turnover rates (maximum observed of 45 hr-1 and 3 hr-1 at Cave Stations 1 and 2, respectively) and short residence times (maximum observed 1.3 min and 22 min at Cave Stations 1 and 2, respectively) (Figure 3.6). Ventilation modeling indicates faster ventilation rates near cave entrances, supporting previous studies finding lower 222Rn concentrations closer to the

39 entrances (Figure 3.6) (Maddox, 1993). This spatial variation in ventilation is a primary factor in 222 the differences found in cave air CO2 and Rn concentrations from previous studies (Baldini et al., 2006a; Baldini et al., 2008). Decreased ventilation far from the entrance results in decreased pCO2 differences between cave air and drips, in turn decreasing CO2 degassing rates and calcite precipitation (Banner et al., 2007). Strong ventilation regimes lead to lower cave air CO2 concentrations (therefore stronger concentration gradients between drip waters and cave air) and higher degassing rates. This promotes enhanced calcite precipitation and ultimately faster speleothem growth.

3.6.2. Estimation of net CO2 Flux and CO2 Outsgassing. To quantify the effects that seasonal ventilation regimes have on calcite precipitation, it is important to quantify CO2 exchange between the cave and atmosphere on short (hourly to daily) and long (weekly to seasonally) timescales. Two factors determine CO2 exchange between the cave and atmosphere:

1) the net Cτ2 flux from the epikarst (ΔCO2), a function of CO2 transport from the epikarst

(ΦCO2) and consumption of CO2 by CaCO3 dissolution (ΨCO2) within the cave (ΔCO2 = ΦCO2 -

ΨCO2); and, 2) ventilation of the cave system with the outside atmosphere (v). Ventilation is determined by 222Rn modeling, discussed in Sections 3.4.2 and 3.5.1. Long term monitoring of 222 the CO2 and Rn concentrations in cave air allow for estimation of ΔCO2 and the subsequent exchange of CO2 between the cave and outside atmosphere – cave “breathing”. 222 A simple cave air CO2 mass balance developed (similar to the Rn mass balance) on temporal CO2 variations (dCCO2/dt) in cave air being a balance of net CO2 fluxes (ΔCO2) and the exchange with the atmosphere by ventilation (v). When the temporal variation in CO2, ventilation rates, and chamber surface area and volume are known, re-arrangement of the mass balance solves for ΔCO2:

V  (CCO cave CCO atmos) dCCO    chamber  2 2  2 (3.6) CO2      Achamber    222 dt 

Hollow Ridge Cave air is assumed to have three CO2 sources: (1) import from the outside atmosphere; (2) soil-zone derived gaseous CO2; and (3) calcite precipitation (drip degassing of

CO2). There exist other sources of CO2 in other cave environments (geothermal input, respiration of organics in the cave, respiration of organics in the aquifer) but there is no evidence of these sources in Hollow Ridge Cave. Two CO2 sinks exist: (1) export to the outside atmosphere; and

(2) calcite/limestone dissolution. Degradation of organics inside the cave is considered negligible in Hollow Ridge Cave because no observed evidence exists (only crushed limestone and clay on the floor) of this process. Equation 6 accounts for the three sources and two sinks. Exchange with the outside atmosphere (import and export) is accounted for by ventilation, while ΔCO2 accounts for soil derived gaseous CO2, drip degassed CO2, and consumption of CO2 by calcite dissolution. -2 -1 σet ΔCO2 rates are highest (approximately 72 mmol m day ) July through September when outside temperatures are warm and ventilation is low. This rate slows during autumn to a winter minimum (cold, lower production in the soil zone, and litter decay) of 12 mmol m-2 day-1

(Figure 3.7). Diurnal variability of ΔCO2 rises in a sawtooth pattern in the morning and falls 1-2 -2 -1 hours after sunset (Figure 3.7). Hourly ΔCO2 ranges from -1.2 to 30 mmol m hr in the summer.

Because ΔCO2 is a net flux term (from the cave to the epikarst), negative values indicate greater consumption than transport of CO2 from the epikarst, and suggest calcite dissolution occurs on cave surfaces (Figure 3.7). Diurnal variability in ΔCO2 during the winter diminishes, having an amplitude of 0.5 mmol m-2 day-1.

τnce ΔCO2 is estimated, re-arrangement of Equation 3.6 allows estimation of the net mass of CO2 outgassed from the cave to the atmosphere over time when the chamber volume

(VChamber) is applied:

 (C C )   dC  CO2 cave CO2 atmos  AChamber  CO2  V      V (3.7)   Chamber  CO2   Chamber   v  VChamber   dt 

The net mass of CO2 outgassed from the cave is controlled by ventilation and ΔCO2. In general, as both ventilation and ΔCO2 increase, CO2 outgassing increases (Figure 3.7). Multiple linear regression analyses of ventilation and ΔCO2 on CO2 outgassing reveal ΔCO2 has a strong linear 2 relationship (R =0.961) with CO2 outgassing, whereas ventilation has a less significant linear 2 relationship with CO2 outgassing (R =0.62).

Average net CO2 outgassing from Hollow Ridge Cave during the vegetation growing season (summer period – June to August) was 5 mol hr-1 (120 mol day-1). Net outgassing slowed during autumn, averaging 1.5 mol hr-1 (36 mol day-1) to winter minima of 0.5 mol hr-1 (12 mol -1 day ). The net CO2 outgassed from the system can be used to estimate the seasonality and amplitude of total calcite precipitation and dissolution rates in Hollow Ridge Cave.

3.7. Conclusions 3.7.1. Seasonal variation of ventilation. Three major ventilation regimes are identified at Hollow Ridge Cave. In summer, lower air density in the outside atmosphere relative to cave air density creates stable air stratification between the cave and outside atmosphere, inhibiting 222 ventilation, allowing cave air to stagnate and Rn and CO2 to build up. During the late summer and early autumn, a combination of winds across the entrances and variable density differences result in a strong diurnal variation in ventilation rates. Ventilation occurs at night while stagnation occurs during the day, resulting in high diurnal concentration variations in 222Rn and

CO2. This suggests a strong diurnal cycle in drip water CO2 degassing rates, with enhanced CO2 degassing at night while cave air CO2 concentrations are low, leading to greater calcite precipitation rates. Warmer air masses inside the cave during winter tend to rise, pulling in denser (colder) outside air resulting in continuous ventilation and persistent low concentrations 222 222 of Rn and CO2. Spectral analyses of Rn, CO2, air density differences between the atmosphere and cave, and wind speeds suggest winds are responsible for variations in air chemistry in the summer and density differences are responsible for variations in the winter.

3.7.2. Seasonality of CO2 Outgassing. Modeling of ventilation and net CO2 flux from the epikarst allow estimation of net CO2 outgassing to the atmosphere. The rate of CO2 outgassing significantly depends on both the ventilation rate and CO2 flux from the epikarst.

However, CO2 flux from the epikarst has a more significant effect on net CO2 outgassing

(Section 3.5.2). τur modeled ΔCO2 indicate increased CO2 flux from the epikarst to the cave during the summer and autumn periods than during the winter period (Figure 3.7). As the pCO2 difference between cave air and drip waters increases (soil pCO2 is assumed to be much higher during the summer than the winter) the degassing rate increases. Increased drip degassing leads to faster saturation with respect to calcite. When drip waters reach calcite saturation, subsequent degassing results in one mole CaCO3 precipitated for every mole of CO2 degassed. Also, our modeling of CO2 outgassing suggests more CO2 is exported from the cave in the summer and autumn. This should result in greater calcite precipitation, although calcite precipitation was not directly measured. Thus, a basic understanding of CO2 outgassing seasonality is imperative to correctly interpret paleoclimate proxy records from stalagmites.

3.7.3. Implications for speleothem paleoclimate investigations. Seasonality in CO2 outgassing rates must be known or inferred when using speleothems as paleoclimate indicators because it offers insight to calcite precipitation rates and timing of deposition. With simple, 222 continuous measurements of Rn and CO2 in a cave system, ventilation and net CO2 flux from the epikarst can be estimated, allowing net CO2 outgassing rates to be modeled. Speleothem stable isotope records are typically interpreted as paleo-rainfall indicators (Cruz et al., 2005a; Cruz et al., 2005b; Baldini et al., 2006b; Cobb et al., 2007). Our research suggests rainfall amount has a lesser effect on calcite precipitation than net CO2 flux to the cave, consistent with previous studies of calcite precipitation (Banner et al., 2007). Thicker layers of speleothem calcite have typically been interpreted as periods of increased rainfall (Fairchild et al., 2006), however layer thickness may respond to seasonal effects due to ventilation, CO2 flux, and net

CO2 outgassing - these processes cannot be disregarded. This study details the importance of understanding individual cave systems and their unique ventilation and chemical mechanics to enable better interpretation of speleothem paleoclimate records. Some assumptions of the seasonality of calcite precipitation may not be appropriate at all cave sites, and we suggest calcite precipitation rates are not primarily influenced by rainfall amount but rather CO2 flux and ventilation rates (net CO2 outgassing), 222 previously in part suggested by Banner et al (2007). Further investigation of CO2 and Rn sources will constrain transport and production rates inside the cave. In our model we assumed cave air was homogeneous throughout the system. Development of multiple-box models similar to Perrier et al. (2005) will better describe the movement of cave air through different sections of the cave. Investigation of the fraction of cave air CO2 derived from drip degassing will help constrain calcite precipitation rates. We believe drip water derived CO2 will contain a seasonal rainfall signal, because increased drip rates should increase the CO2 flux from the epikarst to the cave, although we did not differentiate between drip water degassed CO2 and CO2 directly transported through fissures from the soil zone. These investigations will further constrain CO2 222 fluxes and Rn emission and assure more accurate modeling of CO2 exchange with the outside atmosphere and resulting calcite precipitation/dissolution rates.

3.8. Acknowledgements This research was supported by the Florida State University EPPES Foundation (PNF) and teaching and research assistantships through Florida State University (AJK). We thank the Southeastern Cave Conservancy, Inc (SCCi) for supporting research at the Hollow Ridge Cave preserve. We especially thank Allen Mosler of the SCCi, and Craig Gaffka, Darrel Tremaine, and Brian Kilgore of FSU for field support and assistance, and sampling collection. We also thank to Dr. Jeff Chanton and Claire Langford for analyzing CO2 samples. We thank Nicole Tibbetts, Sammbuddha Misra, Dr. Tom Scott, Dr. Bill Burnett, Dr. Rick Peterson, Darrel Tremaine, and three anonymous reviewers for editorial comments.

Table 3.1μ Average and Annual “Seasonal” Values for Time-Series Measurements. The maxima and minima of measured parameters (relevant to ventilation and CO2 exchange) over the entire 15-month study period and average values for each “season”, as determined by cave air chemistry and ventilation characteristics (Figure 3.4). “Summer” occurs May 7 to July 11, “Autumn” occurs July 11 to τctober 1, and “winter” occurs October 1 to May 7. Analytical precision for each measurement is included.

Location/ Average Maximum Minimum Summer Autumn Winter Analytical Sensor 2008 (Date) (Date) Average Average Average Precision MET Temp 18.24 37.72 -8.11 24.9 24.9 13.0 ± 0.3°C (°C) (8 Jun 08) (5 Feb 09) BP 1018 1035 993 1017 1016 1019 ± 0.6 mbar (mbar) (16 Jan 09) (30 Nov 08) WS 0.26 2.54 0 0.2 0.2 0.3 ± 0.5 (m s-1) (8 Mar 08) m s-1 Cave 1 Ballroom Temp 18.77 17.16 17.9 ± 0.3°C (°C) (1 Nov 07) (5 Jan 08) CO2 2489 340 508 ± 4% (ppmv) (1 Nov 07) (20 Jan 08) 222Rn 441.9 8.2 48 ± 2% (dpm L-1) (1 Nov 07) (14 Feb 08) Cave 1 ENT Temp 23.91 13.47 21.6 22.3 16.9 ± 0.3°C (°C) (7 Sep 08) (6 Feb 09) CO2 2325 258 684 698 355 ± 4% (ppmv) (8/22/08) (4 Feb 09) 222Rn 534 0.5 102 65 31.4 ± 2% (dpm L-1) (22 Jun 08) (14 Nov 08) Airflow 881 0 1.2 20.4 53.6 1 cm s-1 (cm s-1) (20 Jul 08) (at throat)

Ventilation 44.6 0 4.0 4.3 2.5 Rate (hr-1) (14 Nov 08)

Cave 2 Signature Room

Temp 19.60 21.65 18.02 19.4 20.9 19.2 ± 0.3°C (°C) (25 Sep 08) (7 Feb 09)

CO2 899 4220 351 1828 901 694 ± 4% (ppmv) (2 Jul 08) (15 Jan 08)

222Rn 284 1413.2 11.8 826 119 158 ± 2% (dpm L-1) (24 Jun 08) (14 Aug 08)

Ventilation 0.334 3.04 0 0.05 0.59 0.34 Rate (hr-1) (10 Jan 09)

Table 3.2: Radon-222 Emission Rates in Hollow Ridge Cave. Radon-222 emission rates (Φ222) were estimated by two methods. A and B were estimated from the timed increase in 222Rn in a chamber sealed over a wall. C and D were estimated by the greatest hourly increase measured in 222Rn concentration at Cave Station 2 during two flooding events when normal ventilation paths were cut off

A B C D Emission 800 dpm m-2 3,700 dpm 4,444 dpm 20,000 dpm -1 -2 -1 -2 -1 -2 -1 Rate (Φ222) hr m hr m hr m hr

mass mass 2 Rn and CO Rn and 222 sources and sinks, and and sources 2 Rn and CO and Rn 222 balance equations associated with caves and cave cave and associated caves ventilation. with equations balance Dynamics. of Karst Atmosphere Representation 3.1: SimplifiedFigure Visual reactions, chemical lithologic showing the cave zones, A conceptual

Figure 3.2: Location of Hollow Ridge Cave. Hollow Ridge Cave is located in the city of Marianna, Jackson County, FL (3046‟58.17”σ, 8512‟13.15”W, 30 m asl). Hollow Ridge Cave is the 9th longest dry (above water) cave in Florida (Florea, 2008).

page. Full on next Hollow Ridge Cave. 3.3: Map of caption Figure

Figure 3.3: Map of Hollow Ridge Cave. A Schematic plan view of Hollow Ridge Cave with locations of sampling stations inside and above the cave (see legend). Black lines are surveyed passage walls. Dashed lines are unsurveyed passage. Entrances A, B, and C are along a bluff at the edge of the floodplain of the Chipola River. Entrance D is located on the ridge. Stations are: 1) Cave Station 1 (T, RH, BP, 222 13 222 13 Rn, CO2) and CO2- C. 2) Cave Station 2 (T, Rn, CO2) and CO2- C. 3) Drip water 13 13 collection, drip rates, calcite growth plates, and CO2- C. 4) CO2- C. 5) Sump water 13 collection and CO2- C. 6) Meteorology Station (T, RH, BP, Wind Speed and Direction, Solar Intensity). 7) Air Flow Sensor. Cave Station 1* was operational October 31, 2007 to February 16, 2008. Cave Station 1 was operational from June 18, 2008 onwards.

Fifteen month meteorological and cave air time-series air and cave Hollow Ridge from front monthCave. 2008) A cold 20-21, meteorological Tropical Fifteen (January and 8). Two flooding events 5.3 (Figure in Section as mechanics used of ventilation examples were 2008) 23-25, (August Storm Faye rose River over inundating Chipola the 5 m water instrumental when the depth during nearby period Hollow Ridge Cave, occurred Room. the Smith Jones and Room, Fissure, and the except Chamber, Signature Entrance the the passages flooding all Figure 3.4: Meteorological and Air Chemistry Time Series Inside and Cave. Ridge and of Hollow Outside Inside Chemistry Time Series and Air 3.4: Meteorological Figure

Figure 3.5: Keeling plot of Hollow Ridge Cave and Obir Cave Air. 13 δ CO2 vs 1/[CO2] from grab samples in Hollow Ridge Cave (this study) and Obir Cave (Austria-red dashed line, Spotl et al. (2005)) representing Rayleigh distillation (mixing line) between two CO2 end-member sources. The slope of the linear best fit (black dashed line) represents the mixing relationship between the two end-member CO2 concentrations while the 13 intercept is the  C value of soil gas CO2 above each cave. The end-member sources are 13 13 atmospheric CO2 (-7 to -10 ‰  C under a forest canopy) and soil gas CO2 (-22 to -24 ‰  C in forest litter dominated soils). Data for Obir Cave are picked off Figure 4 in Spotl et al., (2005).

. Full caption on next page. page. next . Full on caption 2 Rn and CO and Rn 222 Figure 3.6: Weather Ventilation Events and Ventilation 3.6: Weather Events Figure

222 Figure 3.6: Weather Ventilation Events and Rn and CO2. Events in two seasons (TS Faye - autumn, Cold Front - winter) reveal different ventilation and air chemistry characteristics. A: Wind speed and direction from the Marianna Municipal Airport (6 km N of Hollow Ridge Cave). B: Barometric Pressure (mbar) at Hollow Ridge Cave. C: Air Density Difference between 222 outside atmosphere and cave (atmosphere minus cave). D: Cave air Rn slopes (dC222/dt) reveal intervals of increasing and decreasing radon. E: Radon-222 concentrations at Cave Stations 1 and 2. F: CO2 concentrations at Cave Stations 1 and 2. G: Ventilation rates at Cave Stations 1 and 2 222 determined from the Rn model at each station. H: Modeled net CO2 transport from the epikarst (ΔCO2: production minus consumption) in Hollow Ridge Cave. I: Modeled CO2 outgassing from Hollow Ridge Cave Cave. Tick marks on bottom calendar scale are located at midnight (00:00) and midnight (24:00) of the date. Grey boxes represent the timing of the two events as they passed Hollow Ridge Cave.

Vertical dashedVertical lines

outgassing suggests the net outgassing suggests the net 2 from the epikarst is an order of is an order epikarst the from 2 from Hollow Ridge Cave, the import Cave, Ridge of Hollow from 2 to the atmosphere. to the 2

(Section 5.2). Even though ventilation rates on average though on average Even 5.2). rates ventilation (Section 2 outgassing during the winter. Negative outgassing winter. outgassing during the Negative 2 Outgassing June 2008 to March 2009. 2008 to March June Outgassing 2 from the epikarst is greatest during the summer and autumn seasons. autumn during the summer Although both ventilation is epikarst and the greatest from Import, and CO Import, Rn at Cave Station 1 is fastest during the summer and autumn and at Cave Station 2 is and Cave autumn fastest at and summer during the 1 is fastest Station Cave Rn at 2 2 222 from the epikarst are significant factors in the outgassing are significant CO of epikarst the from 2 consumption in Hollow Ridge Cave. Even so, the 24-hour so, the of Even CO in Hollow moving Cave. Ridge average consumption 2 from the epikarst has a more significant role in CO significant has of the outgassing a more epikarst the from Hollow of CO is a source Ridgetherefore Cave and outgassing flux is positive 2 2 CO Ventilation rates modeled from modeled from rates Ventilation the import of CO and CO than winter the autumn, slower not significantly during CO and importthe summer of are we the lowest observed amount of CO reason and is the magnitude less net CO signifies during autumn. The import of CO import of The during autumn. Figure 3.7: Ventilation Rates, CO Rates, 3.7: Ventilation Figure in 4. discussed Figure ventilation 4.1 and same Section “periods” the indicate

CHAPTER 4

IN SITU CAVE MONITORING AT HOLLOW RIDGE CAVE

4.1 Previous Studies The use of speleothems as paleoclimatic archives has led to significant progress in constraining the timing of major climatic shifts previously found in ice and sediment core records (Wang et al., 2001; Fairchild et al., 2006; Wang et al., 2008). Even so, interpretations of most ancient speleothem records are not globally, or even regionally, comparable over similar time periods because of internal cave system dynamics (Dorale et al., ; Fairchild et al., 2006; Lachniet, 2009). In fact, ancient speleothems collected from different sections in the same cave system have revealed variable paleoclimate records (Baker et al., 2007). The transfer of climate signals through the epikarst and cave environment to speleothems is dependent upon flow rates, drip rates, soil composition, and the chemical composition of the cave air among a multitude of other factors. Under the assumption that transfer functions have remained relatively unchanged over time, investigation of these functions in modern cave environments is essential for the complete understanding of speleothem formation mechanisms under varying cave climate regimes, which can be ultimately related to local and global climates. A paucity of research on the effect of cave air dynamics on the transfer of climate signals to speleothems highlights that relatively little is known about these processes. The unique architecture found in each cave system results in various cave systems having unique internal meteorology although caves can be classified by general passage characteristics, such as ascending/descending shafts fissures (canyons), and tubes (Palmer, 2007). The meteorological dynamics in each of these passage types have been previously studied, but the effect on cave air and water chemistry has been largely neglected with respect to the attention speleothem paleoclimate archives have received (Moore and Sullivan, 1981; Palmer, 2007). Linking modern calcite deposition to local temperature, rainfall, vegetation, and drip water hydrochemical and isotopic cycles (proxy calibration) can help to better interpret speleothem geochemical records. Because variations in speleothem geochemistry are acquired through variations in temperature, rainfall amount, rainfall source, drip residence time, and changes in vegetation atop the epikarst, site-specific cave air and speleothem studies can help constrain interpretations of local

56 speleothem geochemical records (McDermott, 2004; Treble et al., 2005a; Fairchild et al., 2006). Here we discuss previous research on cave ventilation and cave air and drip water geochemical cycling and investigate some of the links to surface climate conditions.

4.1.1 Ventilation. The movement of air into, out of, and throughout cave systems plays a significant role in modifying cave air chemistry and the chemistry of drip and sump waters (Spotl et al., 2005; Palmer, 2007). Caves typically have “dynamic” passages (significant air movement) and “static” passages (passages with little air flow – stagnant) (Pflitsch and Piasecki, 2003; Palmer, 2007). The movement of cave air is primarily caused by the differences in density between cave and atmosphere air masses due to differences in temperature, relative humidity, and barometric pressure. However, exterior winds across the entrance(s) can create a “venturi” effect, resulting in air movement inside the system. Entrainment of air by flowing water (cave streams, waterfalls) can also create significant air currents in certain passages. Detection of these air currents can be accomplished using a variety of instruments and methods: 2D and 3D sonic anemometers that detect physical eddy currents (Pflitsch and Piasecki, 2003), high sensitivity thermistors to detect slight variations in the temperatures of different air masses (Wilson et al.,

2008), monitoring of the cave air CO2 concentrations (Baldini et al., 2008), and most importantly, 222Rn measurements (Wilkening and Watkins, 1976; Fernandez et al., 1986; Perrier et al., 2005; Richon et al., 2005; Fernandez-Cortes et al., 2006; Lario et al., 2006). The long term monitoring of 222Rn concentrations to detect air movement throughout cave systems can offer insight to the dynamics of ventilation between the cave and outside atmosphere (Wilkening and Watkins, 1976; Przylibski, 1999). Radon-222 constantly emits from limestone surfaces in caves (limestone contains an average 1.3-2.5 ppm 238U), and, therefore, 222Rn is found in all limestone caves at concentrations higher than the outside atmosphere

(Fernandez et al., 1986; Hakl et al., 1997). Radon-222 has a well-established half-life (t1/2 = 3.82 days), is chemically inert, and can be used as a physical tracer for the movement of air masses in caves (Weast, 1981). Air mass movement in caves include physical exchange with the outside atmosphere (ventilation). Wilkening and Watkins (1976) developed the first 222Rn mass balance equations to estimate ventilation rates within cave chambers by long term monitoring of 222Rn. However, the majority of cave ventilation and air exchange modeling with 222Rn time-series have

57 been used to estimate radiation dosage levels received by miners, cave tour guides, and tourists (Wilkening and Watkins, 1976; Fernandez et al., 1986; Perrier et al., 2005; Richon et al., 2005). Monitoring of cave ventilation is essential to determine diurnal and seasonal cycles in cave air CO2 concentrations, which, in turn, affect the rate and timing of dissolved CO2 degassing from drip waters. Increased ventilation rates (faster movement of air masses) will 222 bring greater amounts of low CO2 and low Rn atmospheric air into the cave. This lowering of the cave air pCO2 (as mixing occurs) will, therefore, result in faster degassing of dissolved CO2 from drip waters, increasing the calcite saturation index (SICaCO3) until secondary calcite 222 precipitation occurs. By monitoring ventilation via continuous Rn and CO2 measurements, quantitative estimates of air mass movement and CO2 outgassing (loss from the cave) can be made.

4.1.2: Cave air and drip water geochemical cycles. The investigation of cave air and drip water geochemical cycles is essential to properly interpret speleothem geochemical records. As previously stated, cave architecture affects the ventilation (and therefore air chemistry) in different sections of caves (Pflitsch and Piasecki, 2003; Palmer, 2007). In the same sense, the architecture of the epikarst (soil depth, limestone porosity and permeability, overburden depth, and fractures) affects the geochemistry (isotopic and trace element composition) of drip waters (Fairchild et al., 2006). Site-specific, long-term investigations of drip water chemistry and the local weather can help decipher the relationships between climate and speleothem geochemistry because knowledge of drip water isotopic and trace element cycles can be used to determine how climate signals are recorded in speleothems (Cruz et al., 2005b; Spotl et al., 2005; Fairchild et al., 2006; Cobb et al., 2007; Cruz et al., 2007; Mattey et al., 2008). Because speleothem 18O cycles are generally interpreted as direct climate proxies (rainfall amount or source), it is essential to conduct time-series investigations of drip water isotopic signals to determine if drip waters become well-mixed or retain a seasonal 18O signal in the epikarst (Fairchild et al., 2006; Mattey et al., 2008). Two main factors determine whether drip waters will carry a seasonal cycle. First, the pool size, input (precipitation) rate, and overburden architecture (permeability and fractures) will determine the residence time in the epikarst, and second, the source determines the isotopic composition of precipitation. Drip waters with long residence times will contain an averaged isotopic signal reflecting that of average local

58 precipitation, while drip waters with short residence times will contain isotopic signals that follow precipitation events. Drip waters with short epikarst residence times are more likely to carry seasonal cycles in 18O. Long term investigation of drip water isotopic composition will reveal seasonality, if any, in drip water isotope composition. Previous investigations of drip water 18O have focused on relating the 18O of precipitation to drip water (Cruz et al., 2005b; Cobb et al., 2007; Onac et al., 2008). Drip waters reflect the 18O of precipitation, having little to no influence by soil processes and dissolution of limestone as it percolates through the epikarst (Hendy, 1971; Lachniet, 2009). Drip water time- series from cave systems in Brazil and Borneo display seasonal 18O cycles that reflect the 18O of local precipitation (Cruz et al., 2005b; Cobb et al., 2007). These drip water 18O time-series display ~2‰ seasonal ranges, reflecting different seasonal sources of precipitation (Cruz et al., 2005a; Cruz et al., 2005b; Cobb et al., 2007). However, not all cave systems display seasonal 18O cycles in drip waters. Drip water from cave systems in Florida and Austria display homogeneous 18O compositions that are independent of rainfall amount and drip discharge (Spotl et al., 2005; Onac et al., 2008). Drip waters at the Florida Caverns State Park (a few kilometers from Hollow Ridge Cave) are ultimately sourced from the Gulf of Mexico and display a 18τ variation of less than 0.5 ‰ throughout the year, while precipitation (excluding tropical storms) displays 18τ variations on the order of 3 ‰ (Onac et al., 2008). Drip waters at this site reflect the average isotopic composition of precipitation, suggesting near complete homogenization in the epikarst and long residence times. Because knowledge of site-specific precipitation and drip water isotope cycles will enhance interpretation of speleothem 18O records, it is imperative to investigate these site-specific parameters. Additionally, the trace element composition of drip waters can support the conclusions derived from 18O and 13C drip water time-series (Fairchild et al., 2006). The trace elements in drip waters are derived from the soils and limestone above the cave system. The main ion source in drip waters is the limestone (calcite and/or dolomite) bedrock in which the caves are formed although the presence of salts and clays in the soil zone also influence the trace element composition of infiltration waters (Spotl et al., 2005; Fairchild et al., 2006). Complications arise when generalizing conclusions drawn from trace element profiles of drip waters because of the complexity of karst hydrology and the heterogeneity of soil zones and epikarst above different

59 caves. However, a common parameter measured in drip waters is the calcite saturation index

(SICaCO3). Knowledge of temporal variation in the SICaCO3 offers insight to possible seasonal variations in calcite deposition rates (Spotl et al., 2005). Other uses of drip water trace elements include investigating infiltration water flow-through time (residence times in the soil zone and epikarst) by Mg/Ca and Sr/Ca elemental ratios, the uranium isotope composition, and Si concentration of drip waters (Fairchild et al., 2000; Frumkin and Stein, 2004; Hu et al., 2005; Fairchild et al., 2006). The investigation of cave air and drip water geochemical cycles has proven to be a useful tool for enhancing interpretations developed from speleothem paleoclimate records (Spotl et al., 2005; Baldini et al., 2006a; Baldini et al., 2008). Without long-term (multi-year), site-specific investigations of cave air and drip water geochemical cycles, only general conclusions can be 13 drawn from speleothem paleo-records. Incorporating cave air pCO2 and  C and drip water trace element and isotope investigations will allow complete, site-specific conclusions to be drawn from speleothem geochemical records. The lack of in situ studies of drip and cave air geochemistry (in comparison to speleothem studies) demands incorporation of such studies into future investigations of speleothem paleoclimate records for proper interpretation.

4.2. Cave Monitoring Methods 4.2.1. Site description. Hollow Ridge Cave is located near the city of Marianna, FL, in Jackson County (30 46‟ 58.17” σ, 85 12‟ 13.15” W, 30 m a.s.l.), 105 km west of Tallahassee and Florida State University (Figure 4.1). The cave is owned and managed by the Southeastern Cave Conservancy, Inc (SCCi), who also monitor access to the site via a research agreement (Appendix A.1). The Chipola River flows approximately 600 m west of Hollow Ridge Cave, and the Chipola floodplain is bordered to the east and west by limestone bluffs, rising 20 meters above the floodplain (Figure 4.2). The three lower entrances (A, B, C) lie within the floodplain, allowing periodic inundation of the lower levels of the cave (Figure 4.3). The Florida Caverns State Park (2 km to the northwest), Brooks Quarry Cave (6 km to the west-northwest), and the Marianna Municipal Airport (5 km north-northeast) are in close proximity to the cave preserve (Figure 4.4). Hollow Ridge Cave has 1036 m of mapped passage developed in the flat-lying Bumpnose and Marianna limestone formations (Oligocene- Figure 4.5) with 9 m total vertical relief (Puri, 1957; Puri and Vernon, 1964; Boyer, 1975). The cave is overlain by a thin soil

60 veneer (average < 0.5 m thick) composed of Plio-Pleistecene sands and clays with numerous outcrops (Maddox, 1993) and currently hosts an upland mixed pine and oak forest (White, 2006). Hollow Ridge Cave has four known entrances, located in the southwest section of the cave, converging in the main entrance chamber (Figure 4.3). The majority of passages are low (<1 m) and wide (> 3 m), typical of North Florida caves that intersect the water table. However, there are three breakdown (collapse) chambers of significant volume, created by the weakening and subsequent collapse of the cave ceiling (the Entrance Chamber. the Smith and Jones Room, and the Signature Room). There is also a vertical fissure that follows an east-west transect. Vertical relief exceeds 8 m in these breakdown rooms and fissure passage. The Smith and Jones Room, Signature Room, and Fissure extend upwards into the Marianna Formation. All other lower passages are formed in the Bumpnose formation. Passage orientation is primarily in the 150-330° and 100-280° directions (Figure 4.6). Upon entering the Entrance Chamber, multiple passages lead to the other entrances (A, B, and C) and a highly decorated (many speleothems) section aptly named “Fantasy Land”. The main passage connects to a low passage that leads to the Ballroom, a low and wide chamber with a mud floor up to 1.25 m thick. This section of the cave is typically wet, contains numerous active speleothems and is the intersection of the „Throat‟ with the entrances to other sections of the cave. A second low crawl leads to the Smith and Jones Room in the southeast section of the cave. This is the largest breakdown room and contains active speleothems and a permanent sump that springs when aquifer levels are high. The fissure passage leads from the Smith and Jones room to the Signature Room (Cave Station 2) via a winding, sloping fissure with a parallel upper passage (in the Marianna Formation) formed by a false floor of a clastic, sandy deposit containing quartzite and chert (Boyer, 1975). The fissure passage and the Signature Room are formed in the upper Marianna Formation while lower passages are in the Bumpnose Formation. The Signature room contains speleothems (stalactites) that appear active only during rain events and are most likely fracture fed. The northeast section of the cave, “the sewers”, is a series of interconnected low (<1 m) crawls where speleothems are scarce.

4.2.2. Cave monitoring equipment. In situ air chemistry measurements were initiated in May 2007. Grab samples were collected and analyzed to determine the necessary instrumental parameters for future deployment during three sampling transects. Sampling evolved into

61 continuous high resolution monitoring with the deployment of three micro-meteorology stations 222 throughout and above the system in October 2007. Collection of cave air CO2, Rn, and drip and sump water samples occurred semi-continuously from May 2007 to April 2009, while three micro-meteorology stations were deployed continuously from October 2007 to May 2009. An intensive study designed to capture and characterize the spatio-temporal 222Rn concentration gradient was conducted in November 2008. All in situ cave monitoring techniques were developed for this study. Figure 4.7 gives dates of sample collections, grab sampling transects, periods of station and instrument deployment, and “on-line/ off-line” status May 2007 through March 2009. Wiring, power, and plumbing diagrams for the Meteorology (MET) Station (A.2), Cave Station 1 (A.3 and A.4), and Cave Station 2 (A.5 and A.6) are located in the appendices. One meteorology station (MET) was installed above the cave on September 15, 2007, and two micrometeorology stations were installed inside the cave on October 31, 2007 (Figure 4.3). These three stations are described in Table 4.1. The MET station measures and records continuous wind velocities, temperature (T °C), relative humidity (RH), barometric pressure (BP), solar radiation intensity, and precipitation. A Campbell Scientific CR1000 datalogger , powered by a 12 volt 25 amp-hour, gel-cel, sealed lead-acid (SLA) battery, controls instrumentation, records and stores average measurements over 15-minute intervals. The CR1000 datalogger provides power and commands to each sensor using a CRBasic program (Appendix A.7). The Marianna Municipal Airport, 5 km NNE of Hollow Ridge Cave, maintains a weather station, allowing continuous comparison of surface meteorology. Cave Station 1 was originally located approximately 100 m from the main entrance in the area of the cave known as “The Ballroom”. This site was chosen because it is the junction point (Throat) of the four entrances to the main cave, and air exchange with the outside atmosphere must pass through this section. Cave Station 1 monitored T, RH, BP, airflow, drip rates, 222Rn activities, and CO2 concentrations. A Campbell Scientific CR1000 datalogger records the 30- 222 minute averages of these data (T, RH, BP, CO2, airflow), while the RAD7 records hourly Rn activities using a custom protocol (Table 4.2). A flooding event in February 2008 inundated the cave with Chipola River water, completely submerging all lower passages. Cave Station 1 was submerged for approximately 7 days before water levels receded enough to remove the station. Instrumentation was inspected and returned for repair or replacement to Campbell Scientific Co. and Durridge Co. in March 2008. Cave Station 1 was redeployed (renamed Cave Station 1*) in

June 2008 in the Entrance Chamber to prevent damage to instrumentation by future inundation events. The CR1000 datalogger is powered by a 12V 9 Ah SLA battery, the LiCor Li820 and pump are powered by two 12 V 100 Ah SLA batteries in series, and the RAD7 portable 222Rn unit is powered by a 12V 33 Ah SLA battery. The CR1000 datalogger program is in Appendix A.8. Cave Station 2 is located approximately 175 m from the main entrance at the end of the Signature Room (Figure 4.3). The Signature Room location has semi-stagnant (static) characteristics and measurements recorded in this location. Cave Station 2 records the 30 minute 222 average of T and CO2 concentrations and hourly averages of the cave air Rn activities. A

Campbell Scientific CR1000 datalogger records these data (T and CO2) while the RAD7 records 222Rn measurements (Table 4.1 and Table 4.2). The power system at Cave Station 2 is the exact same as the power system at Cave Station 1. The CR1000 datalogger program for Cave Station 2 is in Appendix A.9. Bi-weekly trips to the cave were required to download data, exchange and replace batteries, and replace used desiccant. These trips also provided an opportunity to monitor the cave conditions first-hand, collect drip water samples, collect cave air grab samples, and monitor equipment status to make necessary adjustments and repairs.

4.2.3 Grab sampling– cave air 13C, 222Rn transects, and drip water isotopes. Periodic grab sampling transects were conducted (Figure 4.7) to collect 222Rn concentrations, cave air from five locations (Figure 4.3, locations 1, 2, 4, 6, and 7), drip water (Figure 4.3, location 4) and sump water (Figure 4.3, location 7) samples for isotopic and geochemical analyses. Grab samples of cave air were obtained by flushing a 60 ml syringe and injecting it into evacuated 30 ml glass vials sealed with a butyl rubber septum. Vials were then stored in a dark drawer in the lab until analysis. These samples were analyzed for CO2 concentrations via LiCor 13 Li820 CO2 gas analyzers and for inorganic  C of CO2 via direct injection to a Finnegan MAT Delta S Mass Spectrometer and HP 5890 Series II Gas Chromatograph. This method and instrument have a long term reproducibility of ± 0.05 ‰ as calculated by repeat measurements of 13 an internal CO2 standard. All  C samples are reported against VPDB. Samples were analyzed by Claire Langford in Dr. Jeff Chanton‟s stable isotope geochemistry group.

Cave air 222Rn transects were conducted on May 9, August 8, and October 12 of 2007 to determine 222Rn concentration gradients. Radon-222 was determined by a Durridge RAD7 Portable Radon Detector that was hand-carried throughout the cave. The RAD7 recorded the 222Rn concentration every five minutes during each transect, possible by programming the RAD7 to continuously pump air through the chamber while in „SσIFF‟ mode. Drip water and sump water samples were collected periodically starting October 2007 (See Figures 4.3 and 4.7). Drip water samples were collected for stable isotope analyses by overfilling 5 ml glass serum vials held approximately two inches below an active stalactite, capping with a butyl rubber stopper, and then crimping with an aluminum seal in the cave. Overfilling prevented creation of an air headspace in the vial, which prevents equilibration between water and air during storage. Drip water samples for major and trace elemental analyses were collected by overfilling an eight ml, acid-cleaned, HDPE sample bottles held approximately two inches below an active stalactite and capping in the cave. Sump water samples for stable isotope analyses were collected by completely submerging a five ml glass serum vials and capping with a butyl rubber stopper and crimping with an aluminum seal. Sump water samples for major and trace elemental analyses were collected by completely submerging an eight ml, acid-cleaned, HDPE sample bottles and capping. A 0.5 ml aliquot of each drip and sump water sample was analyzed for water isotope (18O and D) composition using the on-line, continuous- flow system (Finnegan GasBench II) coupled to a Finnegan DELTAplus XP in the geochemistry laboratory at the National High Magnetic Field Laboratory (NHMFL) following the method of Spotl et al. (2005). Calibration of the mass spectrometer is accomplished using in-house (YW- ST-2, SLC-tap, MAG-DI, MAG-QD) and national (VSMτW) standards. The 1 analytical uncertainties for 18O and D are better than 0.05 and 0.75 ‰, respectively.

4.2.4 Intensive. A 30-hour intensive study of cave air 222Rn concentrations was conducted over November 11 and 12, 2008 to investigate air movement patterns throughout the system. In addition to the two RAD7 portable 222Rn detectors at Cave Stations 1 and 2, five other RAD7s were placed in the system, and one RAD7 above the cave next to the MET Station (see Figures 4.3 and 4.28). During this intensive study, RAD7s were placed at the MET Station (above the cave), Cave Station 1 (25 m from Entrance D, Figure 4.3), the “τld Sparkley” speleothem formation (60 m from Entrance D- location 3), the Ballroom (80 m from Entrance D-

64 location 4), the Tube (100 m from Entrance D- location 5), the Sump (110 m from Entrance D- location 7), the Sewers (150 m from Entrance D- location 6), and Cave Station 2 (175 m from Entrance D- location 2). Appendix A.18 contains a map of RAD7 locations. Appendix A.19 contains the headers and first few lines of data from each RAD7 and calculations (calculated 222Rn concentration, changes in 222Rn, and turnover rates) involved in analyses. The six additional units measured and recorded the cave air 222Rn concentration every fifteen minutes. Each RAD7 unit was set to Central Standard Time (CST) and clocks synchronized on-site. Drierite gas drying units, filled with anhydrous calcium sulfate and cobalt chloride (indicator) were attached in-line to each RAD7 to ensure relative humidity inside each RAD7 remained below 10%. RAD7 settings are summarized in Table 4.2.

4.2.5 222Rn emission rate estimation. To accurately determine ventilation rates in 222 222 Hollow Ridge Cave, the Rn emission rate (Φ222Rn) is required to solve the cave air Rn mass balance equation (see section 4.3.3). Radon-222 emission rates were estimated using three different methods: 1) two wall flux chamber measurements, 2) two flooding events, and 3) 222Rn ingrowth from a machined limestone block. Results are listed in Table 4.3. Wall flux chamber measurements were modified after the closed 222Rn accumulation chamber method of Ferry et al. (2001). Inlet and outlet ports were installed on two metal buckets of known volume (bucket volume = 3536.43 cm3) and area (open area against limestone = 221.77 cm2) to attach a portable RAD7 222Rn detector to continuously measure 222Rn concentrations over time. One bucket was placed in the Signature Room next to Cave Station 2 and the other was placed in the Tube (Figure 4.3). Both buckets were sealed with plumber‟s clay against the limestone floor to minimize air leakage. A RAD7 was attached in-line to each bucket to measure the increase in 222 Rn concentration over a period of 4 to 6 hours. The emission rate (Φ222Rn) is calculated by Equation 4.1:

Vcyl dC222Rn 222Rn   (4.1) Scyl dt

3 Where Vcyl is the volume of the cylinder (3536.43 cm ), Scyl is the surface area of the 2 222 limestone bedrock covered by the bucket (221.77 cm ), and dC222Rn is the change in Rn concentration measured over time dt. The wall flux chamber method results in 222Rn emission

65 rates of approximately 800 dpm m-2 hr-1 in the Tube and approximately 3700 dpm m-2 hr-1 in the Signature Room (Table 4.4). The second method for estimating the 222Rn emission rate was to measure the short-term rate of 222Rn increase in the Signature Room during two flooding events when high Chipola River levels (greater than approximately 17 feet gage height) closed normal ventilation pathways. The effective “sealing” of the Signature Room prohibits loss of 222Rn by ventilation and the rapid rise in cave air 222Rn concentrations is a function of emission from the limestone surfaces. Decay is assumed to be negligible because the decay over a period of one hour results in the decay of less than 1% of the total 222Rn atoms. The RAD7 portable 222Rn detector located at Cave Station 2 recorded the 222Rn concentrations throughout both flooding events and the greatest rates of increase (dC222Rn/dt) are used in Equation 4.1 with a surveyed 9:1 cave surface area to cave volume scale length (Scave/Vcave) to convert an area flux to a volumetric flux. This method results in maximum 222Rn emission rates of approximately 4,500 dpm m-2 hr-1 in February 2008 and 20,000 dpm m-2 hr-1 in December 2008. However, it must be noted that these two measurements may be time-lagged because the RAD7 was in “σormal” Mode (as it was during the entire study) and measured „old‟ and „new‟ 222Rn. Calculation of these emission rates was re-done using the maximum rates of increase (dC222Rn/dt) from data in “Sniff” Mode, which resulted in emission rates approximately 10% higher (6,666 dpm m-2 hr-1 for Flood #1 and 22,222 dpm m-2 hr-1 for Flood #2). The third method for estimating the emanation fraction of the total 222Rn emission rate involved machining limestone blocks from both the Marianna and Bumpnose Formations and sealing them in individual glass Erlenmeyer flasks, modified after the method of Corbett et al. (1998). Blocks were cut to approximately 13x16x33 mm (surface areas were 23.12 cm2 for the Bumpnose cube and 25.57 cm2 for the Marianna cube) to maximize sample size in the 100 mL flasks. Blocks were sanded smooth with 100 grit sandpaper and dried at 80 C in an oven to evaporate pore waters. They were then sealed in the flasks and flushed with He gas to provide a zero background 222Rn concentration. After flushing, sample tubes were crimped and were placed on a shelf for approximately three weeks to allow in-growth of 222Rn to secular equilibrium before plugging into the radon extraction line of Dr. Burnett‟s radio-isotope group at FSU‟s Department of Oceanography. Total activities were 0.39 dpm for the Bumpnose cube and 0.56 dpm for the Marianna cube. The total Inventory is calculated by dividing the total activity

66 by the surface area, which resulted in Inventories of 168.8 dpm m-2 for the Bumpnose and 219 dpm m-2 for the Marianna. Because the total activity was measured at secular equilibrium we can use the inventory (I) and decay constant of 222Rn to find the total flux (emanation rate) from the limestone surfaces of samples using Equation 4.2.

F  I  222 (4.2) This resulted in rates of 1.656 dpm m-2 hr-1 for the Marianna Formation and 1.275 dpm m-2 hr-1 for the Bumpnose Formation. However, these rates are much lower than those calculate by the wall flux chambers and flood events, and may be the true “emanation” rates for the Marianna and Bumpnose Formations in completely dry conditions, which are assumed to never be present in Hollow Ridge Cave. Also, a leak in either the collection flasks or the radon extraction line would result in loss of 222Rn leading to lower total activities. A summary of results and methods is included in Table 4.3. The BET surface area of theses two limestone blocks (including accessible pore spaces) were measured via gas sorption. Analyses were carried out with a Beckman Coulter SA 3100 Surface Area and Pore Size Analyzer with Dr. Lynn Dudley of Florida State Universities Department of Geological Sciences. Measurement of the adsorption and desorption of nitrogen

(N2) gas as a monolayer film onto the surfaces of the limestone blocks yields very accurate specific surface areas. BET analyses indicate the Marianna Formation has a larger specific surface area (2.988 m2 g-1) and more pore space than the Bumpnose Formation (2.196 m2 g-1). This indicates the Marianna Formation is more porous than the Bumpnose Formation, and should have a higher transmissivity and flow-through for percolation water and gases.

4.3. Cave Monitoring Results and Discussion Long term continuous monitoring of cave meteorology, aerochemistry, and grab sampling of cave air have allowed us to investigate cave ventilation via 222Rn, patterns of 18 13 rainfall, drip, and sump water  O, diurnal and seasonal patterns of cave air CO2 and  C of

CO2, and the exchange of CO2 between the epikarst, cave, and outside atmosphere. The results of each experiment are discussed in this section, along with the implications of our experimental results. The combination of grab sampling transects and continuous long-term monitoring of cave meteorology and air chemistry has produced a thorough study of cave air conditions.

4.3.1 Grab sampling transects radon-222 and CO2. Grab sampling transects through 222 Hollow Ridge Cave were initiated to obtain an understanding of the Rn and CO2 13 concentrations and gradients and the  C of CO2, and also to obtain initial information to better select instrumentation for future continuous in situ monitoring of cave meteorology and air chemistry. Grab sampling transects were continued after installation of continuous micro- 13 meteorology stations inside the cave to obtain cave air samples for CO2 and  C analysis. Drip water and sump water samples for 18O analyses were also obtained at regular two-week 222 intervals. The dates of Rn and CO2 transects, drip water, and sump water sample collection are displayed in Figure 4.7. A RAD7 Portable 222Rn detector was carried through Hollow Ridge Cave in early May 2007 to obtain 222Rn concentrations throughout the main passages of the cave. Radon-222 outside the cave was found to be zero (within error) at the start of the transect, and a zero value is used for base atmospheric values of 222Rn. This initial transect had a near linear increase in 222Rn concentrations with increasing distance from the entrance, similar to readings in north Florida and southern Georgia caves (Maddox, 1993). The first transect has a 222Rn increase of 0.76 dpm L-1 m-1 from the entrance to the back of the cave (Figure 4.8). A second transect conducted in August 2007 also found an increase in 222Rn from the entrance. However, this gradient had a concave up shape, indicating movement of outside air into the cave (Figure 4.9, second transect). A third transect conducted in October 2007 (Figure 4.8) has a linear increase similar to the first transect in May 2007, although with a shallower slope (0.23 dpm L-1 m-1). This increase from the entrance is primarily due to ventilation with the outside atmosphere, and is further discussed in Sections 4.3.3 and Chapter 3. In addition to 222Rn transects, air samples were also collected at five locations (Figure 4.3) 13 from May 2007 to May 2009 (Figure 4.7) to analyze cave air CO2 concentrations and  C of 13 CO2. Three primary conclusions are drawn from these CO2 transects: (1) the  C of cave air

CO2 has a strong positive linear relationship with inverse CO2 concentrations (Figure 4.10); (2)

CO2 generally increases with distance away from the entrance (Figure 4.11); and (3) cave air 13 CO2 concentrations are generally higher and  C lighter in the summer and fall seasons than the 13 winter and spring (Figure 4.12). A linear relationship between  C-1/[CO2] in Hollow Ridge

Cave (Figure 4.10) indicate cave air CO2 has two sources, soil gas and outside atmosphere, and that cave air CO2 should fall on the mixing line between these two endmembers (Keeling, 1958;

Bowling et al., 2008). The linear best fit of these data indicate that the soil-gas endmember has a 13  CO2 value of -22.1‰, potentially a factor of the overlying upland mixed pine and oak forest (White, 2006).

A two endmember mixing model can be generated to explain cave air CO2 composition, and by varying the soil (isotopically light) endmember, we can account for seasonal variability in 13 cave air CO2 concentrations and  CO2 values. The outside free atmosphere (isotopically heavy) 13 endmember has a  CO2 value of -6.8 ‰ and was measured to be 450 ppmv under the forest canopy. The soil gas endmember compositions were generated using the three best-fit lines to cave air CO2 samples, and are (1) -21.5 ‰ and 2,000 ppmv, (2) -20.5 ‰ and 7,000 ppmv, and (3) -21.5 ‰ and 10,000 ppmv. These compositions should represent soil gas in the winter (1), spring (2), and summer (3). Figure 4.13 illustrates the three theoretical mixing lines and the relation to cave air samples. Cave air CO2 is a mixture of outside atmosphere and soil gas CO2, and in the two endmember system ranges from 100% outside atmosphere CO2 to 100% soil gas

CO2. The composition of cave air CO2 can be expressed as the sum of the fractions of soil gas and outside atmosphere CO2:

 13C  CO  f  13C  CO  f  13C CO (4.3) 2 caveair soil gas 2  soil gas outsideatmos2  outsideatmos and

fsoil gas  foutsideatmos 1 (4.4)

Equations 4.3 and 4.4 are used to develop the three mixing lines present in Figure 4.13. The range of soil gas endmembers accounts for all but one cave air sample, however, only two soil gas CO2 measurements were analyzed and had CO2 compositions of 3800 ppmv and -20.5 ‰ 13 13  CO2 and 2400 ppmv and -1λ.1 ‰  CO2. The contribution from outside atmosphere CO2 to cave air CO2 is depicted along each mixing line as a percentage (Figure 4.13). Note that even a small contribution from soil gas (< 10% soil gas) will drastically alter the isotopic signature of cave air without a large change in CO2 concentration. These mixing lines provide a clear view to the extent of ventilation with the outside atmosphere. This sampling and analytical method

69 allows us to determine the atmospheric influence in different sections of Hollow Ridge Cave, independent of ventilation modeled via 222Rn, creating an easy and simple way to determine the extent of atmospheric influence throughout the entire system via the two endmember mixing model.

4.3.2 Rainfall, drip, and sump water isotope composition. The collection and analysis of rainfall, drip, and sump water samples over the course of this study allows conclusions to be made on how the isotopic composition of rainfall is transferred to drip waters in Hollow Ridge Cave, and ultimately, the north Florida aquifer system. By investigating the D and 18O of local rainfall, we can determine if precipitation falls on the meteoric water line (MWL). Understanding how the isotopic composition of this local rainfall is transferred to drip water should allow theoretical calculation of the isotopic composition of deposited calcite, and lead to a more complete understanding of cave processes. The collection and analysis of the isotopic composition of local rainfall, drip water, and sump water in Tallahassee and Hollow Ridge Cave allow us to characterize how the isotopic composition of water is transferred from rainfall to drip water and from drip water to speleothems.

4.3.2.1 Rainfall. Continuous collection and isotopic analysis of local Tallahassee rainfall from May 2006 to September 2008 by Dr. Yang Wang of Florida State University‟s Department of Geological Sciences has allowed us to compare local rainfall to drip and sump waters collected at Hollow Ridge Cave, 105 km west of Tallahassee. The isotopic compositions (18O and D) of rainfall, drip, and sump waters from October 2007 to February 2009 are illustrated in Figure 4.14. The 18O of local rainfall generally falls between -2.5 and -5.5 ‰, and is primarily sourced from the Gulf of Mexico, which has an isotopic composition of approximately 1‰ (Richey et al., 2007). Rainfall in north Florida falls very close to the global meteoric water line (GMWL) (Figure 4.15). There is no evident seasonal distinction in the isotopic composition of local rainfall in Tallahassee, however, this record only covers twelve months during our study period.

4.3.2.2 Drip Water. Cave drip waters in Hollow Ridge Cave are ultimately sourced from local rainfall. The collection and isotopic analysis of these drip waters from October 2007 to

February 2009 indicates that any seasonal isotopic signal in local rainfall is filtered out by mixing in the epikarst. Drip waters collected in the Ballroom vary between -3.8 and -4.0 ‰ 18O over the study period, and have no variation coinciding with local rainfall amounts or 18O (Figure 4.14). Drip water D is centered around -1λ ‰, ranging from -24 to -17 ‰ (Figure 4.15). Weak variation reflects attenuation of the local rainfall through homogenization in the epikarst. All cave drip samples are clustered on the GMWL around -3.λ ‰ 18O and -1λ ‰ D, which is close to the published value of the mean annual isotopic composition of rainfall (-3.13 ‰ 18O) in north Florida (GNIP and Precipitation, 2009). Cave drip water from the Florida Caverns State Park (2 km northwest) also have little variability (>0.4 ‰ 18O) in their isotopic compositions, ranging from -3.6 ‰ to -4.0 ‰ 18O, with a weighted average value of -3.8 ‰ (Onac et al., 2008). Rainfall 18O at Florida Caverns State Park ranged from -1.2 ‰ to -4.86 ‰ during their study period (February 2006 to February 2007), indicating that drip water is homogenized in the epikarst above Florida Caverns State Park (Onac et al., 2008). These two cave sites indicate that even with intense local rainfall events (Tropical Storm Faye, August 2008 – 40+ cm), drip waters retain long residence times (> 14 days), assuring homogenization in the epikarst. A significant correlation exists between drip water 18O and drip rate (R2 = 0.53, n = 14, Figure 4.16), but no significant correlation exists between rainfall 18O and amount of rainfall in Tallahassee (Figure 4.17). A significant correlation between drip 18O and drip rate was previously observed in Borneo, indicating drip waters have a coherent response to intraseasonal and interannual precipitation variability in amount and isotopic composition (Cobb et al., 2007). Although a significant correlation between drip 18O and drip rate is observed in Hollow Ridge Cave, the same argument cannot be mad because the variability in drip 18O is not large enough to make a direct connection between drip waters and seasonal precipitation.

4.3.2.3 Sump Water. Sump waters from Hollow Ridge Cave are representative of the local groundwater. The sump reaches a depth of approximately 9 meters and the presence of blind albino crayfish (Procambarus palidus) indicates direct connection to the aquifer rather than the Chipola River. The North Floridan Aquifer is sourced from the rainfall in the region of north Florida and southern Georgia, so that the isotopic composition of the aquifer should represent a longer mean annual rainfall composition than drip waters and rainfall (Miller, 1997). Sump water

18O displays little variation over the study period, ranging between -4.0 and -4.2‰ (VSMOW) (Figure 4.14). Sump water 18O is consistently 0.1 to 0.2‰ lighter than drip water 18O suggesting drip water is representative of rainfall over the preceding week to month as it filters through the epikarst above the cave, while sump water (local aquifer) likely represents rainfall over a much longer period (years to decades). Assuming speleothem calcite precipitates under isotopic equilibrium from drip water, 18 18 speleothem  Ocalcite is determined by drip water  O and the temperature dependent fractionation during crystallization (Hendy, 1971; Gascoyne, 1992). The fractionation constant between calcite and water (αcalcite-water) can be calculated using a mean cave temperature of 20° C (293.15 K) in Equation 4.5 (Hendy, 1971; Friedman and O'Neill, 1977; White, 2004):

.2 78 106 1000lncalcitewater   .2 89 (4.5) T 2

Equation 4.4 yields a fractionation constant (αcalcite-water) of 1.029658 in Hollow Ridge Cave. 18 Using the calculated fractionation constant (αcalcite-water = 1.029658) and the measured  Odw 18 (-3.9‰ VSMOW) we predict speleothem calcite isotopic composition ( Ocalcite) to be 25.64‰ (VSMOW) using Equation 4.6 (White, 2004):

1  103 18O   calcite calcitewater 3 18 (4.6) 1  10  Owater

Converting calculated calcite 18O from the VSMOW to the VPDB scale (Equation 4.7) (Sharp, 2006), we predict current speleothem calcite deposited will have an oxygen isotopic composition of -5.06 ‰ (VPDB).

18 18  OVPDB  .0 97006* OVSMOW  29.94 (4.7)

The modern drip water 18O, cave temperature, and fractionation constant give insight to what conditions may have been present in the past that would affect the isotopic composition of speleothem calcite. Using a 1400-year multi-proxy sea surface temperature (SST) and seawater

18O record from a northern Gulf of Mexico sediment core, we can estimate conditions in north Florida over that period (Richey et al., 2007). SST from 1400 annum (a) to the present varied between 22.5 and 26.5° C, and air temperature variations over land may have experienced greater variation. Seawater 18τ varied between 0.4 and 1.6 ‰ (VSMτW), with temperature increases correlating with lighter seawater18O. This record indicates that over the past millennium, temperatures were slightly cooler in north Florida and seawater 18O was heavier by an average of approximately 0.5 ‰, with the exception of an excursion at 500 a (Figure 4.18)(Richey et al., 2007). If drip water 18O was approximately 0.5 ‰ heavier than modern drip water, and temperatures were cooler by one to two degrees C, we estimate speleothem calcite 18O precipitated over the past 1000 years should range between -4.5 and -5.5 ‰ VPDB. We can estimate speleothem 18O over a much larger range of climate conditions by extending the range of cave temperatures (temperature of deposition) and the 18O of drip waters. Please refer to Table 4.5 for the range of fractionation constants and Figure 4.19 for the estimated speleothem calcite 18O for a range of temperatures and drip water 18O at Hollow Ridge Cave. Temporal collection and analysis of the 18O of drip water is essential to understanding variations in speleothem 18O. If there is a strong seasonality present in drip water 18O, due to either seasonal variation in rainfall amount, or variable moisture source, it will influence the 18O of seasonally deposited calcite, resulting in distinct patterns in speleothem 18O. However, if drip water 18O has no distinct seasonal variation, possibly due to long residence times in the epikarst or little variation in rainfall 18O, there will be little variation in the 18O of precipitated calcite. At Hollow Ridge Cave there was little drip water 18O variation observed (> 0.2 ‰) over a period of 18 months. Furthermore, temperature variations inside the cave over this period are less than 3°C. As a result, there are no observed seasonal variations in either cave temperatures or drip water 18O that should affect the 18O of deposited calcite, leading to the conclusion that variations in speleothem 18O records are due to either drastically changing moisture sources or long-term temperature variations, or a combination of both processes. Figure 4.19 indicates that variations in modern speleothem calcite at Hollow Ridge Cave are primarily due to temperature variations, because the effect observed temperature variations have on 18O fractionation during calcite precipitation are greater than the observed drip 18O variations (shaded area). The fractionation constants have a slope very near 1 (α ≈ 1), and a change in source 18O will result

73 in a similar change in speleothem 18O ( 1‰ source 18O:  1‰ speleothem 18O ratio). A shift of 5°C will bring a similar change as a 1‰ shift in source water (5°C: 1‰ speleothem 18O). Observed variations in drip water 18O should account for 18O variations in speleothem calcite less than 0.3‰, however, observed temperature variations could account for variations as high as 1‰ 18O in speleothem calcite, depending on the location in the cave. Collection of a speleothem spanning the Holocene and comparison to an independent climate record from Florida (ie, pollen record or sediment core) will verify whether speleothem 18O variations are drip water 18O or temperature driven.

4.3.2.4 Drip Rates. Drip rates were measured in the Ballroom from June 2008 to March 2009. Hourly drip readings were stored on a Driptych Company „Stalagmate‟ Drip logger. The drip water from the target stalactite is inferred to be fed by seepage flow, because it is one of the few continuously dripping stalactites in the cave, even during dry periods (Figure 4.20). In the summer, convective rainfall is approximately balanced by evapotranspiration because no apparent change in drip rate is observed after these rain episodes. A positive water excess should result in an increase in drip rates. However, the only significant increases are observed after periods of very heavy rainfall (> 100 mm over two to three days). Drip rates exhibit a range of approximately 30 drips per hour at the minimum to over 1300 drips per hour at the maximum (Figure 4.20). There is an apparent threshold at 1300 drips per hour, suggesting a point at which the epikarst reaches complete saturation and the maximum hydraulic head is attained above the Ballroom. Any additional infiltration above the threshold likely flows horizontally down the hydraulic gradient around the cave instead of directly vertical through it. This threshold was reached after Tropical Storm Faye and an extended stationary cold front in December 2008 (Figure 4.20). The period from late June to late August 2008 indicates drip rates decrease exponentially when recharge is minimal. An initial rate of 1000 drips per hour th th (Ao) on June 18 decays to a minimum rate of 30 drips per hour (A) by August 6 , a period of 49 days. Assuming first-order loss (Equation 4.8):

dript A  oeA (4.8)

We calculate a loss rate (drip) of 0.07156 drips per day under normal conditions. This loss rate yields a half life of 10 days and a mean life of 14 days in the epikarst, indicating water spends just over two weeks in the epikarst as it seeps to the drip site in the Ballroom. Previous studies have found drip rates experience exponential decay, indicating this phenomenon is not unique to Hollow Ridge Cave (Genty and Deflandre, 1998). This conclusion is enhanced by an observed two week response to heavy rainfall events, seen in Figure 4.21. However, in the winter period where evapotranspiration is reduced, drip rates experience a slower loss, and an exponential loss model does not fit the observed trend from early October 2008 onward. In addition, over the period modeled (6/18/2008 to 8/6/2008) about 25 cm of rain fell. While 80% of this was likely evapotranspired, there is sufficient uncertainty in the “closed water balance” assumption in Equation 4.9 to suggest the true epikarst water residence time ranges between a week to a month. Another interesting observation is the moderately significant indirect correlation between drip rates and atmospheric barometric pressures (Figure 4.22). Over the entire drip rate measurement period (June 18 2008 to February 7 2009) there exists little correlation (R2=0.05) between drip rates and barometric pressure, although over short periods (a few days to a week) there exists a significant indirect linear correlation (R2=0.82) between the two. Barometric pressure has a low amplitude semi-diurnal cycle, typically varying less than 4 mbar per day. As the barometric pressure drops, drip rates rise. As the barometric pressure rises, drip rates drop. Similar findings from the same Belgium cave mentioned above show a strong correlation over short (24-hour or less) periods (Genty and Deflandre, 1998). This semi-diurnal variation in drip rate is on average 10% of the total drip rate. This strong negative correlation with barometric pressure is likely influenced by the semi-diurnal atmospheric (barotropic) tides. Initially, this semi-diurnal cycle in drip rate was inferred to be a product of evapotranspiration in the summer, however, this cycle continued into the winter. No other measured variable displays semi-diurnal characteristics. Therefore, we propose that barotropic semi-diurnal (“Earth” or “atmospheric”) tides influence drip rates by influencing the pore-fluid pressure and two-phase (gas and water) flow through the epikarst (Genty and Deflandre, 1998). Barotropic tides are global-scale period oscillations of the atmosphere developed by solar heating, and follow the solar cycle instead of the lunar cycle. In essence, lower barometric pressure results in a lower air component in the karst micro-fissures (higher water component), producing a higher pore fluid pressure and faster drip rate. Conversely, higher barometric pressures result in a higher air component in the karst

75 micro-fissures (lower water component), producing lower pore fluid pressures and slower drip rates (Genty and Deflandre, 1998). In summary, barotropic tides influence the pore fluid pressure, and have a strong correlation to drip rates.

4.3.3 Time series data. This section will discuss how outside meteorology affects cave meteorology, cave aerochemistry, and drip rate cycles. Continuous monitoring of cave and local atmospheric meteorology and aerochemistry from October 2007 to March 2009 indicate Hollow Ridge Cave has both seasonal and diurnal cycles in meteorology and air chemistry. Cave meteorology and aerochemistry are directly influenced by outside meteorology (Baldini et al., 2006a; Fernandez-Cortes et al., 2006; Asrat et al., 2008; Baldini et al., 2008; Hu et al., 2008a). Temperature, pressure, and wind driven ventilation influence cave aerochemistry (Chapter 2). 222 Typically, winter cold fronts flush the entire cave system and lower cave air Rn and CO2 222 concentrations by dilution with outside atmosphere (low in Rn and CO2). Warm outside 222 atmosphere summer conditions result in weak ventilation allowing Rn and CO2 concentrations to increase. Strong diurnal variability in ventilation in the fall (strong night time, weak daytime ventilation) result in high amplitude diurnal cycles of 222Rn (10 to 600 dpm L-1 diurnally) and

CO2 (360 to 2500 ppmv diurnally) concentrations, similar to conditions found an English cave system (Baldini et al., 2008). Temperatures at Hollow Ridge Cave reflect the mean annual temperature in Marianna and display a dampened seasonality compared to the outside temperatures (Figure 4.23), similar to findings in other cave systems (Palmer, 2007). Maximum and minimum temperatures extremes at Cave Station 2 occur approximately two months after the outside extremes, reflecting a delayed and damped transfer of heat through the thin epikarst (Moore and Sullivan, 1981). Temperatures observed at Cave Station 1* (Entrance Chamber), however, more closely follow the trend of outside temperatures, and reach extremes less than a month after outside temperatures. A full description of the outside atmosphere and cave meteorology and air chemistry is detailed in Figure 4.23 and Table 4.6. Winds above the cave (at the MET Station) normally have a diurnal pattern. It is calm at night, then wind speeds pick up during the morning, reach a peak in the afternoon, and fall during evening (Figure 4.24). Winds typically follow the ridge orientation (30° N). We invoke wind (venturi effect) and density (gravitational effect)

76 driven ventilation to be the primary driving forces behind air exchange observed at Hollow Ridge Cave. Air density differences between the cave and outside atmosphere are primarily driven by temperature variations and are calculated using the barometric pressure (P), universal gas constant (Rd), and virtual temperature (Tv) (Equation 4.9) (Brice and Hall, 2008). The virtual temperature is calculated using the air temperature (t), dew point (Td), and barometric pressure (P) (Equation 4.10) (Brice and Hall, 2008).

P air (4.9) Rd  Tv

5.7 Td .6 1110 2377. Td T (t  273.15  .0(1() 379 )) (4.10) v P

The air density difference is calculated by subtracting the cave air density from the outside free atmosphere density (MET- Cave Station 1*). When the outside free atmosphere is denser than the cave, there is a positive density difference. When the cave air is denser than the outside free 222 atmosphere, the density difference is negative. We observe that variations in Rn and CO2 concentrations at Cave Station 1* coincide with both wind shifts and a reverse in the air density difference (shifting from positive to negative and vice-versa). When cave air is denser than 222 outside atmosphere air (negative air density difference) ventilation slows, and Rn and CO2 build up. This process is discussed in section 4.3.5. 222 Cave air Rn and CO2 typically display similar diurnal and seasonal patterns although 222 Rn is a monitor of physical processes (emission, decay, ventilation) and CO2 a monitor of physical and chemical processes (soil production, drip degassing, calcite precipitation/dissolution, ventilation). At Cave Station 1*, concentrations of both gases are -1 222 generally low during the winter, around 400 ppmv CO2 and 30 dpm L Rn. These average winter conditions are interrupted by storm fronts (with low barometric pressures) that decrease 222 -1 ventilation and allow CO2 and Rn to build up to 800 ppmv and 400 dpm L . In the summer, a pattern of diurnal ventilation causes CO2 to fluctuate between 360 and 2500 ppmv daily, and 222Rn between 10 and 600 dpm L-1 daily. Ventilation slows during the day as the outside 222 atmosphere warms and becomes less dense than cave air, allowing Rn and CO2 to rise. At

77 night, as the outside atmosphere cools and becomes denser than cave air, ventilation increases 222 and lowers cave air Rn and CO2 concentrations as atmospheric air flushes into the cave. This pattern continues through the fall at Cave Station 1*, and then in early to mid October diurnal 222 ventilation diminishes and Rn and CO2 concentrations fall back to winter averages. 222 At Cave Station 2, CO2 and Rn concentrations display a stronger seasonal pattern. Winter concentrations are slightly higher than at Cave Station 1*, averaging around 450 ppmv and 100 dpm L-1 because of the lower average ventilation rate (Table 4.6). Furthermore, the 222 effect winter warm fronts have on CO2 and Rn concentrations are amplified at Cave Station 2. 222 These periodic fronts decrease ventilation and cause CO2 to rise as high as 1000 ppmv and Rn over 600 dpm L-1. As outside temperatures rise in the early summer (early May), ventilation 222 decreases drastically at Cave Station 2 (cave air denser than atmosphere) and CO2 and Rn concentrations increase at a rate of approximately 120 ppmv day-1 and 40 dpm L-1 day-1 until reaching maximums of around 4200 ppmv and 1400 dpm L-1 by early June. Although in early

July cave air is still denser than outside atmosphere air, we observe a drastic decrease in CO2 and 222Rn concentrations. At this time Cave Station 2 displays diurnal variability similar to that observed at Cave Station 1* during the summer. One explanation for this phenomenon is linked to the decrease in drip rate observed in the Ballroom. Evapotranspiration increases as the summer progresses, and the epikarst becomes less saturated with water. Drying out of the epikarst would allow micro-fissures present in the limestone to channel outside atmosphere air 222 through the epikarst into the cave, significantly lowering CO2 and Rn concentrations. However, “sniff” tests conducted with a portable RAD7 above the cave to find 222Rn leaking from fissures yielded no information, probably because of dilution with the atmosphere. Furthermore, in the winter season we observe the Southern Shield fern (Thelypteris kunthii) in multiple slight depressions above the cave, a fern species that requires warm air to survive in the winter months. This supports the idea of multiple micro-fissures through which outside atmosphere air exits and enters the cave apart from the entrances. Similar seasonal trends in cave meteorology and aerochemistry have been observed in caves in Japan and Poland (Tanahara et al., 1997; Przylibski, 1999; Pflitsch and Piasecki, 2003), 222 however, the addition of drip water studies and the combination of CO2 and Rn monitoring gives insight to both the physical and chemical processes inside the cave. For physical air exchange, we have invoked both wind driven and gravitational driven ventilation, and these are

78 both discussed further in section 4.3.5. Further discussion of the mechanisms behind ventilation is also found in Chapter 3, section 3.5. Ventilation, however, is not always the driving force 222 behind variations in CO2 and Rn. Under normal conditions ventilation determines CO2 and 222Rn concentrations, but under flood conditions ventilation is restricted because the Throat section of the cave is completely submerged, preventing air exchange in all sections past the Throat. 222 When air exchange to the back of the cave (Signature Room) is restricted, CO2 and Rn concentrations dramatically increase because of continuing emission (Φ222Rn), transport from the epikarst (ΔCO2), and zero loss via air exchange. Increased precipitation during these flood events results in the epikarst becoming saturated, while increased percolation water flow-through 222 transports higher than normal CO2 and Rn into the cave. Before flooding event #1, CO2 and 222Rn increase because of greater transport from the epikarst (Figure 4.25). However, during the flooding event, CO2 decreases. This is because most of the soil gas CO2 in the epikarst would have been flushed into the cave during the heavy rainfall and possible calcite dissolution would consume CO2 in the Signature Room. Also, low soil CO2 concentrations are expected because of the winter season. The fastest rate of 222Rn increase gives insight to 222Rn emission rates during flooding -1 -1 -2 events. An observed increase of 40 dpm L hr results in a calculated Φ222Rn of 4,444 dpm m -1 hr , similar to that observed in the Wall Flux Chamber Φ222Rn experiment (Table 4.3). The shape of the ingrowth curve suggests 222Rn is approaching secular equilibrium. A secular equilibrium concentration of approximately 5,200 dpm L-1 is estimated using Equation 4.11, assuming 222 constant emission rate (Φ222Rn) and decay of Rn in the cave.

 A  (222t)  chamber  A222Rn  A0 222Rn  e  222Rn t    (4.11)  Vchamber  Where step-wise iteration in one-hour increments (t=1 hr for each iteration) of the cave air 222Rn activity combines the decay and emission during that time increment. Achamber/Vchamber is the scale length to convert an area flux (the 222Rn emission rate) to a volumetric flux, and a 9/1 m-1 scale length is used for the Signature Room. For these calculations, the volumetric flux is converted from dpm m-3 hr-1 to dpm L-1 hr-1 using the 1000 L to m3 conversion. When time (t) is much greater than the half-life of 222Rn (>25 days in a closed system), secular equilibrium is reached as

79 the ingrowth of 222Rn from 226Ra decay is balanced by the decay of 222Rn. A secular equilibrium value of 5200 dpm L-1 is estimated using an emission rate of 4,444 dpm m-2 hr-1. The observed 222Rn peak (~2,100 dpm L-1) falls far short of the predicted secular equilibrium because the system was closed (sealed) for only two days. A second flooding event occurred in December 2008, when the Chipola River again inundated the lower passages of Hollow Ridge Cave (Figure 4.26). An initial increase in CO2 and 222Rn was again observed during the heavy rainfall period preceding flooding of the cave. However, the increase in 222Rn before the second flood was much greater than that preceding the first flood. Two possible explanations are (1) higher 222Rn storage in the overlying epikarst (unlikely), and (2) exchange with air having high 222Rn concentrations from the back of the cave 222 (likely). In contrast to the first flood event, the higher CO2 and Rn concentrations prior to flooding are lowered to normal winter concentrations by ventilation. Again, when the entrances are sealed with water, cave air 222Rn increases dramatically (180 dpm L-1 hr-1 maximum) until ventilation pathways open when flood levels drop. The maximum rate of 222Rn increase results in an emission rate of approximately 20,000 dpm m-2 hr-1, five times higher than observed in the previous flood event. These two flooding events offer insights to conditions in Hollow Ridge Cave prior to opening of the entrances, and indicate what the air chemistry may be in underground cavities having no air exchange. They also offer a new in situ method for determining the 222Rn emission rate. However, these field results are only applicable during flood conditions, as other 222Rn emission experiments yielded different results. Also, it must be noted that these calculated emission rates during flood events are likely time-lagged (as previously stated in section 4.2.5) because while the RAD7s are in “normal” mode, changes in 222Rn are time-lagged because both 214Po and 218Po are counted (more time required for counting). Re-calculation of these emission rates using the data collected while in „sniff‟ mode (less precision, but faster response) results in these emission rates increasing by approximately 10% to 6,666 dpm m-2 hr-1 during Flood #1 and 22,222 dpm m-2 hr-1 during Flood #2.

4.3.5 Intensive. An intensive study conducted November 11-12, 2008 included five additional portable RAD7 222Rn monitors in Hollow Ridge Cave and one above the cave, allowing us to monitor ventilation in various sections of the cave (Figure 4.27). The observation of cave air 222Rn gradients indicate mixing must have a role in 222Rn variability and movement

(Figure 4.28). Radon-222 has a molecular diffusion coefficient (D) in air of 10.4 ±5.8 x10-6 m2/s (Chauhan et al., 2008) and according to Equation 4.12, the average length (L) a 222Rn molecule will travel by molecular diffusion alone is calculated by:

L  D /  (4.12) which results in a molecular diffusion path length of 2.22 m (Hirst and Harrison, 1939; Chauhan et al., 2008). In the absence of mass flow (advection), this indicates molecular diffusion alone is too small to account for rapid variations in 222Rn concentrations. Also, for 222Rn to travel the distance L (X2-X1) between two stations by diffusion alone, the required diffusion coefficient (D) 222 can be calculated using Rn concentrations (N1 and N2) at these two stations by Equation 4.13:

2  X 2  X1   D   (4.13) lnN1 / N2 

The calculated diffusion coefficient must be greater than 5.6*10-4 m2/s for 222Rn to travel from one station to another before decay, which is two orders of magnitude larger than all published values for 222Rn in air. We can therefore assume that variations in 222R concentrations over short periods of time (hours to days) are primarily due to horizontal advection and mixing. The RAD7s placed in Hollow Ridge Cave during this intensive recorded similar 222Rn patterns. Increasing 222Rn concentrations are observed farther from the entrances. All RAD7s, except at Cave Station 2, display a synchronous rise in 222Rn concentrations starting around 9 am CST, November 11 (Figure 4.28). Peak 222Rn concentrations at locations 3 (Old Sparkley), 4 (Ballroom), 5 (Tube), 6 (Sewers), and 7 (Sump) occur around 6 pm CST, November 11, while at locations 1 (Cave Station 1) and 2 (Cave Station 2) 222Rn peaks occur around 7 pm CST (Cave Station 1) and 9 pm CST. The observed lag at Cave Station 2 may be caused by the isolated nature of this chamber. However, we observe a double peak in 222Rn concentrations at Cave

Station 1. We also observe that CO2 concentrations at Cave Stations 1 and 2 have similar patterns observed in 222Rn, indicating that advection and mixing are the primary forces driving variations in cave air chemistry (Figure 4.28).

The increase in 222Rn concentrations inside the cave occurs when ventilation slows or ceases when the air density difference approaches zero from the positive side as the outside atmosphere warms and becomes less dense than cave air (Figure 4.28). Additionally we observe that air flow speeds at Entrance A (Location 9) measured via a 2-dimensional sonic anemometer slow during the daytime (Figure 4.28). The direct observation of air flow slowing down at the entrances (air exchange) while the air density difference switches from positive to negative supports the idea that air exchange during November 2008 was primarily driven by gravitational overturn. Also, we observe that the air flow direction at Entrance A is into the cave while air density differences are positive, indicating exchange with the outside atmosphere. When air density differences become negative, the air flow weakens and changes directions, so that air is flowing out of the cave at Entrance A. The observation that cave air 222Rn concentrations increase when the air density difference becomes negative (cave denser than outside atmosphere) indicate gravitational overturn has an important role in determining air exchange. We observe air exchange at all seven stations (calculated via Equation 4.11) in the cave significantly weakens during this period of negative air density difference (Figure 4.29). The largest variation in air exchange is observed closer to the entrances, where air exchange at Cave Station 1, Old Sparkley, and in the Ballroom decrease by approximately 82%. Variations in air exchange at Cave Station 2 and the Sewers are also still significant, decreasing by approximately 70% during this period. When periods of positive air density differences occur, we observe little variation in 222Rn concentrations at all stations. This indicates that loss of 222Rn via air exchange is approximately balanced by constant emission from limestone walls and drip waters. However, once air exchange weakens, 222Rn and

CO2 increase. The observation of the dynamics of air exchange at seven locations in Hollow Ridge 222 Cave provides insight to the factors driving variations in cave air Rn and CO2. We observed that variations in 222Rn occur almost simultaneously throughout the cave, except in isolated chambers and near the entrances, suggesting air exchange in the entire cave system reacts as a whole to variations in air density differences, as opposed to different sections of the system reacting sequentially. We also observed that air exchange weakens when cave air is denser than the outside atmosphere air, and air movement at Entrance A drastically weakens when this occurs. Air exchange near the entrances is faster than that observed towards the back of the cave.

This intensive study has provided the opportunity to observe the spatial and temporal variations in air exchange throughout Hollow Ridge Cave and to resolve the effect air density differences has on ventilation.

4.4 Cave Monitoring Conclusions This research project at Hollow Ridge Cave is likely one of the most comprehensive cave monitoring studies to date. We monitored above and below ground meteorology, cave 222 aerochemistry, ventilation via Rn, CO2 exchange, drip and aquifer water isotopes, and cave air

CO2 composition. Previous cave monitoring research has primarily focused on ventilation via 222Rn (Wilkening and Watkins, 1976; Dueñas et al., 1999; Przylibski, 1999; Pflitsch and

Piasecki, 2003; Perrier et al., 2005; Richon et al., 2005), cave air CO2 variations (Ek and Gewelt, 1985; Spotl et al., 2005; Baldini et al., 2006a; Baldini et al., 2008), or drip water geochemistry (Cruz et al., 2005b; Spotl et al., 2005; Baldini et al., 2006b; Cobb et al., 2007; Mattey et al., 2008; Onac et al., 2008), but none have combined all three fields to properly investigate the effects cave meteorology have on speleothem deposition. The primary objective of this study was to establish methods to investigate all cave parameters and determine the effects each has on speleothem deposition and geochemical records. Conclusions derived from continuous monitoring of the outside atmosphere, cave meteorology, and air chemistry suggests multiple complex physical and chemical processes that influence speleothem geochemistry. First of all, grab sampling transects reveal that 222Rn concentrations increase with distance away from the entrance, indicating suppressed ventilation away from the entrances (Maddox, 1993). Also, isotopic analysis of cave air CO2 indicates this system has two end-member sources of CO2: the outside atmosphere and soil gas. Cave air CO2 2 -1 13 has a significant (R = 0.81) log-linear relationship when [CO2] is graphed vs the  C of CO2, previously noted in atmosphere, forest, and alpine snowpack systems (Keeling, 1958; Bazzaz and Williams, 1991; Bowling et al., 2008). This relationship can be applied to cave air samples to determine the degree of atmospheric influence in the cave (Spotl et al., 2005). Secondly, drip water isotopic and drip rate analyses reveal little to no seasonal cycles in the isotopic composition of drip waters (a constant -3.λ ‰ 18O), indicating complete homogenization in the epikarst. This inference is enhanced by an estimated two week residence time in the epikarst, calculated via a logarithmic decay in drip rate. The observed semi-diurnal cycle in drip rates is a

83 function of varying pore fluid pressures influenced by atmospheric tides (Genty and Deflandre, 1998). Thirdly, observed variations in cave meteorology (temperature, relative humidity, air flow) indicate ventilation occurs via the „venturi‟ effect (winds across the entrances) and gravitational displacement of lighter air masses by denser air masses. Temperature, CO2, and 222Rn variations are dampened at Cave Station 2 relative to Cave Station 1*, also indicating ventilation decreases with increasing distance away from the entrance. Air exchange rates are determined by continuous monitoring of 222Rn at both stations inside the cave (Figure 4.30). Determination of physical mixing indicates rapid ventilation occurs in the late summer and fall, although diurnal variations in ventilation rates are present at both stations during this time periodμ rapid ventilation is followed by a „slack‟ period where ventilation stagnates. Continuous slower ventilation in the winter tends to keep cave air 222Rn at a minimum. Lastly, and most 222 importantly, ventilation rates via Rn are used to determine net CO2 outgassing from the cave

(Chapter 3). Net outgassing of CO2 can greatly influence the rate and timing of speleothem deposition, and must be considered in establishing the seasonality of calcite deposition in individual cave systems. The comprehensive in situ cave monitoring project at Hollow Ridge Cave is by no means complete, and further more in-depth investigations of each investigation will enhance interpretations developed from this research. In addition to continued collection and analysis of drip water isotopic cycles, drip water geochemical analyses will allow calculation of the calcite saturation index (SIcalcite), which may help constrain seasonality in calcite deposition (Spotl et al.,

2005). Refinement of cave air CO2 sampling techniques would allow increased sample collection without influence by expired breath, although our current analyses indicate no contamination from expired breath. A more accurate survey of the system would help constrain the surface area of the cave, volume of chambers, and the surface area to volume scale length used to determine ventilation rates. A pulse-chase experiment introducing SF6 or a similar tracer gas may allow more accurate determination of the total volume of the cave, or if used in individual chambers, 222 the chambers themselves, which would help constrain Rn emission, ventilation, and CO2 outgassing rates. Also, introduction of more cave stations over a greater period would allow development of a multiple-box model to be used in ventilation modeling, and would result in refinement of estimated air exchange rates (Perrier et al., 2005). However, the architecture of Hollow Ridge Cave poses a significant barrier to developing a multiple box model, and may be

84 beyond the scope of all but the most intense research. Finally, the long-term deployment of glass and quartz plates under active drips will allow collection of modern calcite deposition and will help determine seasonality in speleothem growth. Glass plates were deployed in the October 2008, however, multiple flooding events and the slow rate of calcite deposition resulted in little calcite deposited, which prohibited any conclusions to be inferred. This research at Hollow Ridge Cave was not all-inclusive, but included more parameters and was carried out to a greater overall extent than many other cave studies.

Table 4.1: Cave Monitoring Equipment. Locations, parameters, instrumentation, and the range and precision for instruments deployed at the MET Station, Cave Station 1, and Cave Station 2. Ranges and precisions are reported from instrument manuals.

Location Parameter Instrument Range Precision -40-60° C ± 0.5° C MET Temperature Vaisala HMP45C 0-40° C ± 0.3° C Relative 0-90% ± 2% Vaisala HMP45C Humidity 90-100% ± 3% Barometric CS100 Setra 278 800-1100 mbar ± 0.6 mbar Pressure Wind Speed RM Young Wind Sentry 0-50 m s-1 ± 0.5 m s-1 0-360° Wind Direction RM Young Wind Sentry ± 5° horizontal Precipitation Texas Electronics TE525 0.01 mm Apogee SP-110 Solar Radiation 0-1750 W m-2 ± 5% Pyranometer -40-60° C ± 0.5° C Cave 1 Temperature Vaisala HMP45C 0-40° C ± 0.3° C Relative 0-90% ± 2% Vaisala HMP45C Humidity 90-100% ± 3% Barometric CS100 Setra 278 800-1100 mbar ± 0.6 mbar Pressure WindSonic 2D Sonic Airflow Speed 0-60 m s-1 0.01 m s-1 Anemometer Airflow WindSonic 2D Sonic 0-360° ± 3° Direction Anemometer Temperature Campbell Scientific T107 -35-50° C ± 0.01° C 222Rn Activity Durridge RAD7 0-22,000 dpm L-1 ± 2% CO LiCor-820 CO Gas 2 2 0-20,000 ppmv ± 4% Concentration Analyzer Cave 2 Temperature Campbell Scientific T107 -35-50° C ± 0.01° C 222Rn Activity Durridge RAD7 0-22,000 dpm L-1 ± 2% CO LiCor-820 CO Gas 2 2 0-20,000 ppmv ± 4% Concentration Analyzer Driptych Stalagmate Drip Ballroom Drip Rate 0-5 drips s-1 Counter

Table 4.2: RAD7 Portable 222Rn Detector Settings Table of the settings used to program each RAD7 that was used in each 222Rn monitoring technique, including grab sampling treks, the intensive, and the long-term cave monitoring at Cave Stations 1 and 2.

Grab Sampling Intensive Long Term Cave Set-up Command Treks Nov 11-12, 2008 Monitoring

Protocol Sniff User User Cycle 00:05 00:15 1:00 Recycle 00 00 00 Mode Sniff Auto Auto Thoron Off Off Off Pump Auto Auto Auto Tone Off Off Off Format Off Off Off Units pCi/L pCi/L pCi/L Savuser NA NA NA Clock CST CST CST

Table 4.3: Radon-222 Emission Rates in Hollow Ridge Cave. Radon-222 emission rates (Φ222) were estimated by three methods. A and B were estimated from the timed increase in 222Rn in a chamber sealed over a wall. C and D were estimated by the fastest hourly increase measured in 222Rn concentration at Cave Station 2 during two flooding events when normal ventilation paths were cut off. The chamber volume (Vchamber), surface area (Achamber), and measured instantaneous rate of increase (dC222/dt) are used to convert the 222 concentration increase to an emission rate (Φ222). E was estimated by measuring the Rn ingrowth to secular equilibrium from machined Marianna and Bumpnose limestone cuboids.

A B C D E Emission 800 dpm m-2 3,700 dpm 4,444 dpm 20,000 dpm 1.275 dpm m-2 hr-1 -1 -2 -1 -2 -1 -2 -1 Rate (Φ222) hr m hr m hr m hr (Bumpnose) 1.656 dpm m-2 hr-1 (Marianna)

Method Wall Flux Wall Flux Rise during Rise during Machined LS Chamber #1 Chamber #2 Flood event Flood event Cube (Ferry et al., (Ferry et al., #1 (Feb #2 (Dec (Corbett et al., 2001) 2001) 2008) 2008) 1998)

Table 4.4: Radon-222 Emission Rates from Wall Flux Chambers. ) ) -1 hr

-2

800 800 3,700 3,700 = dpm m dpm = Emission Rate Rate Emission 222 (Φ ) ) 2

221.67 221.67 221.67 Limestone Limestone Area (cm Area ) ) 3

3,536.43 3,536.43 3,536.43 Chamber Chamber Volume (cm Volume

2 2 1 -Growth -Growth In Period (hrs) (hrs) Period

) ) -1

222Rn 222Rn 10.499 10.499 22.926 dC

(dpm L (dpm

Rn between the start and end (1-2 and end hrs) to the start is used Rn between 222 ) ) -1

64.547 64.547 67.241 69.292 70.602 68.825 71.237 74.920 75.047 39.085 46.285 49.150 55.028 58.294 62.011 Rn (dpm L (dpm Rn 222 3-pt Moving Average Average Moving 3-pt ) ) -1

64.679 64.679 61.275 67.688 72.761 67.428 71.618 67.428 74.666 82.666 67.809 29.281 42.288 45.686 50.882 50.882 63.320 60.681 62.032 Rn (dpm L Rn (dpm 222 Date Date Tube Tube (2/7/09) (2/7/09) (1/24/09) (1/24/09) Signature Room Room Signature 2/7/2009 12:48:00 12:48:00 2/7/2009 13:03:00 2/7/2009 13:18:00 2/7/2009 13:33:00 2/7/2009 13:48:00 2/7/2009 14:03:00 2/7/2009 14:18:00 2/7/2009 14:33:00 2/7/2009 1/24/2009 12:45:00 12:45:00 1/24/2009 13:00:00 1/24/2009 13:15:00 1/24/2009 13:30:00 1/24/2009 13:45:00 1/24/2009 14:00:00 1/24/2009 14:15:00 1/24/2009 14:31:00 1/24/2009 14:46:00 1/24/2009 15:01:00 1/24/2009

Table 4.4: Radon-222 4.4: Radon-222 Emission FluxTable Chambers. Wall from Rates al. in the Signature modified afteret Ferry Room chamber and the experiments, flux conducted (2001) wall were Two by sealing in-line A with metal 4.3) B (Method in Table and the cave buckets withTube clay. against walls RAD7s the and in concentrationsaveraged, change were Radon-222 calculated 4.1. using emission equation rates. Emission are Rates determine

18 Table 4.5: Range of calcite-water and equilibrium  Ocalcite with temperature variations. The calculated range of calcite-water for a temperature range of 10 to 25° C, and the associated 18 variations in  Ocalcite of deposited speleothems for drip water of constant isotopic composition. 18 Fractionation constants are calculated using Equation 4.4,  Ocalcite (VSMOW) is calculated 18 using Equation 4.5, and the conversion from VSMOW to VPDB for  Ocalcite is calculated using Equation 4.6.

18 18 18 Temp C  Odrip water Temp K Fractionation  Ocalcite  Ocalcite (‰ VSMOW) Constant (αcw) (‰ VSMOW) (‰ VPDB)

10 -3.9 283.15 1.03204 28.015 -2.764 15 -3.9 288.15 1.03082 26.799 -3.943 20 -3.9 293.15 1.02966 25.644 -5.064 25 -3.9 298.15 1.02856 24.548 -6.126

Table 4.6: Summary of Time Series Data at Hollow Ridge Cave. The maximum, minimum, and seasonal averages for each measured meteorological and aerochemical parameter at each station. Blank spaces are where no data were collected.

Maximum Minimum Fall 07 Winter 08 Spring 08 Summer 08 Fall 08 Winter 09 (Date) (Date) Average Average Average Average Average Average ND JFM AMJ JAS OND J MET Temperature 37.72 -8.11 12.58 11.71 22.3 25.02 13.91 9.3 (T °C) (8 Jun 08) (5 Feb 09) RH 100 13.2 84 75.2 75.3 82.8 82 75.5 (%) (10 Feb 08) BP 1035 993 1020 1019 1017 1016 1019 1018 (mbar) (16 Jan 09) (30 Nov 08) Wind Speed 2.54 0 0.2 0.36 0.28 0.18 0.22 0.31 (m s-1) (8 Mar 08) Solar Rad 861 0 183 250 (W m-2) Cave 1 – Ballroom Temp 18.77 17.16 18.21 17.53 (T °C) (1 Nov 07) (5 Jan 08) RH 100 96.6 97.5 98.6 (%) (18 Dec 08) BP 1046 1009 1024 1026 (mbar) (3 Jan 08) (13 Feb 08) CO2 2489 340 558 441 (ppmv) (1 Nov 07) (20 Jan 08) 222Rn 441.9 8.2 46.3 50 (dpm L-1) (1 Nov 07) (14 Feb 08) Airflow Speed 15 0 1.6 1.4 (cm s-1) (1/31/08) Ventilation 3.9 hr-1 0 hr-1 1.35 hr-1 1.48 hr-1 -1 Rate (222 ) (14 Feb 08) (hr-1) Drip Rate 1307 33 490 779 1232 (drips hr-1) (9 Jan 09) (9 Aug 08) Cave 1- ENT Temp 23.91 13.47 22.32 17.61 15.31 (T °C) (7 Sep 08) (6 Feb 09) RH 100 88.5 98.6 99.6 99.9 (%) (30 Dec 08) BP 1043 1003 1020 1026 1027 (mbar) (16 Jan 09) (30 Nov 08) CO2 2325 258 700 368 321 (ppmv) (8/22/08) (4 Feb 09) 222Rn 534 0.5 69.6 31.9 29.9 (dpm L-1) (22 Jun 08) (14 Nov 08) Airflow 881 0 18 44.5 72.3 (cm s-1) (20 Jul 08) (Throat) (ENT A) (ENT A) Ventilation 44.64 0 1.92 4.3 2.6 2.3 -1 Rate (222 ) (14 Nov 08) (hr-1) Cave 2 Temp 21.65 18.02 20.0 18.49 18.94 20.77 20.0 18.44 (T °C) (25 Sep 08) (7 Feb 09) CO2 4220 351 853 736 1143 1106 611 442 (ppmv) (2 Jul 08) (15 Jan 08) 222Rn 1413.2 11.8 126 161.2 611.7 197.8 150.7 96.9 (dpm L-1) (24 Jun 08) (14 Aug 08) Ventilation 2.64 0 0.3 0.3 0.1 0.5 0.4 0.45 -1 Rate (222 ) (14 Aug 08) (hr-1)

Figure 4.1: Location of Hollow Ridge Cave. Hollow Ridge Cave is located in the city of Marianna, Jackson County, FL (3046‟58.17”σ, 8512‟13.15”W, 30 m a.s.l.). Hollow Ridge Cave is the 9th longest dry (above water) cave in Florida at 1030 m of surveyed passage (Florea, 2008). Marianna is located ~105 km west of Tallahassee, the state capital, and Florida State University. Mean annual temperature is ~20° C. Average annual precipitation is 1500 mm. The Florida Caverns State Park is located 2 km N of Hollow Ridge Cave and contains 2 of the 5 longest dry caves in the state. The Chipola River flows through the heart of Marianna. Hollow Ridge Cave is located approximately 600 m from the river in a bluff at the edge of the eastern floodplain. Typical community ecosystem types in the area are upland hardwood, mixed, and pine forests and floodplain forests and swamps (predominantly C3 ecosystems). The ecosystem above Hollow Ridge Cave is an upland mixed forest.

Figure 4.2: LIDAR Survey of Hollow Ridge Cave Vicinity. LIDAR (Light-Detection-And- Ranging) aerial image of the city of Marianna and vicinity, Jackson County, Florida conducted for the Northwest Florida Water Management District (NWFWMD, 2007). LIDAR surveying uses a fast-pulse-narrow-short wavelength laser beam to attain high spatial resolution topography and bathymetry of physical features. The SCCi-owned Hollow Ridge Cave Cave Preserve is highlighted by the black arrow and label. Figure from Leigh Brooks. Elevation scale on lower left of figure.

Full page. on follwing caption Cave. Ridge of Hollow 4.3: Map Figure

Figure 4.3: Map of Hollow Ridge Cave. Schematic plan view of Hollow Ridge Cave with locations of sampling stations inside and above the cave (see legend). The cave has a total surveyed passage length of 1030 m. Black lines are surveyed passage walls. Dashed lines are unsurveyed passage (approximate). Entrances are lettered A-D. Entrances A, B, and C are along a bluff at the edge of the floodplain of the Chipola River. Entrance D is located on the ridge. The brown shaded area depicts a silt organic mud sediment floor. The rest of the cave has a stone/dirt floor, except for a sump in the SE corner (shaded blue). Vertical relief inside the cave is approximately 9 meters. Base cave level is approximately 1 meter above the edge of the floodplain, except for the shaded grey chambers at Entrance D (also Cave Station 1), the Signature Room (also Cave Station 2), the Smith and Jones Room, and the Fissure Passage which have vertical relief of 6-8 m. 222 13 Stations are: 1) Red Triangle - Cave Station 1 (T, RH, BP, Rn, CO2) and CO2- C. 2) Blue 222 13 222 Triangle - Cave Station 2 (T, Rn, CO2) and CO2- C. 3) Yellow Circle – 30-hour Rn sample site. 4) Blue Circle - 30-hour 222Rn sample site, drip water collection, drip rates, calcite 13 222 growth plates, and CO2- C. 5) Green Circle - 30-hour Rn sample site. 6) Red Circle - 30- 222 13 222 hour Rn sample site and CO2- C. 7) Black Circle - 30-hour Rn sample site, Sump 13 (Aquifer) water collection, and CO2- C. 8) Yellow Star - Meteorology Station (T, RH, BP, Wind Speed and Direction, Solar Intensity). 9) Black Diamond - Air Flow Sensor. Cave Station 1 was redeployed to current location (red triangle) in June 2008 after a major flooding event in February 2008 destroyed equipment at original location (Blue circle).

Ocala Ocala Platform Chattahoochee Chattahoochee Anticline

ft An aerial view of Marianna, FL, located in the northwest panhandle region. Marianna Marianna FL, located panhandle region. view northwest (whitein the Marianna, An aerial of

square) is 105 km west of Tallahassee, the state capital (white star). Vadose caves are typically are Chattahoochee in the found Vadose ofis 105 star). the state km west caves (white capital Tallahassee, square) Chipola Brooks Quarry River, StatePlatform (Yellow and The and Cave Park, Caverns Ocala Florida Oval) Oval). Anticline (Blue © Google is up. Map from proximity North in close all diamond). (white to Hollow Ridgeare Cave FL. of Marianna, 4.4: Map Figure

Figure 4.5: Generalized Upper Stratigraphy of the Marianna Area. Stratigraphic sequence of the upper ~30 m of Brooks Quarry cave and Hollow Ridge Cave. Cavity development is primarily in the Bumpnose and Marianna Limestone Formations, shown as a black void. Modified after Scott (1991).

Figure 4.6: Rose Diagram of Hollow Ridge Cave Passages. Compass Rose diagram displaying 360° orientations of passage trends in Hollow Ridge Cave. Cumulative passage lengths are shown in 15 degree intervals (0-15°, 15-30°, etc). For example, cumulative passage length is 250 m in the 147.5-327.5° orientation. The majority of passage development is in the 147.5-327.5° and 97.5-277.5° orientations, likely reflecting fracture development and average long term water table flow direction.

Figure 4.7: Sampling and instrumentation time-line for Hollow Ridge Research. Full on following caption Hollow Ridge Research. for 4.7: Sampling time-line Figure and instrumentation page.

Figure 4.7: Instrumentation and Sample Collection Time-line at Hollow Ridge Cave. Time-lines display intervals of instrument deployment and location, cave air, drip, and sump water grab sampling, and events (floods, storms, etc) from May 1, 2007 to May 1, 2009. Refer to Figure 3.3 for a map of Hollow Ridge Cave showing sample and station locations inside and outside of the cave.  MET Station - Installed October 31, 2007. o Temperature (red) o Relative Humidity (light blue) - Sensor originally positioned at Cave Station 2. Moved to MET November 9, 2007. o Barometric Pressure (grey) o Wind Speed and Direction (black) o Precipitation (dark blue) o Solar Radiation (orange) - Installed November 25, 2008.  Cave Station 1 - Installed Oct 31 2007. Originally positioned in Ballroom, relocated (June 08) to Entrance Chamber after Flood # 1 (February 2008). Station was out of cave April 1 to June 18, 2008. o Temperature (red) o Relative Humidity (light blue) - Sensor first positioned at Cave Station 2, relocated November 9, 2007. o Barometric Pressure (grey) o Airflow Velocity (black) in three locations (listed above interval at location) o CO2 Concentration (burnt orange) o 222Rn Concentration (green) - Missing data due to power failures  Cave Station 2 - Installed October 31 2007. Missing data (February 2008) due to power failure. o Temperature (red) o Relative Humidity (light blue) - Sensor moved to MET November 9, 2007 o CO2 Concentration (burnt orange) - Missing data due to power failures and removal from cave for calibration (June 2008) o 222Rn Concentration (green).  Grab Samples o Cave Air (red circles) o Drip Water (blue diamonds) o Sump Water (black diamonds)  Ballroom Drip Rates (blue line) - Installed June 2008  Glass Slides for Calcite Farming (golden line) - Placed November 2008  Events (short blue lines) - Start Date o Flood # 1 - February 20, 2008 o TS Faye - August 23, 2008 o Intensive 222Rn Study - November 11-12, 2008 o Flood # 2 – December 13, 2008

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Figure 4.8: Two Transects of 222Rn vs Distance at Hollow Ridge Cave. The first (May 9, 2007- solid triangles) and third (October 12, 2007- open circles) cave transects have similar linear characteristics with high R2 values. The first transect was conducted towards the end of the spring season when ventilation towards the back of the cave slows, allowing 222Rn to build up. The third transect was conducted during the fall after the first cold fronts, flushing 222Rn out of the cave during fast ventilation periods. Ventilation is discussed further in sections 3.3.5 and 4.5

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Figure 4.9: Three Transects of 222Rn vs Distance at Hollow Ridge Cave. The second 222Rn transect was conducted during a warm period when ventilation weakens and 222Rn rises. Weak ventilation towards the back of the cave allows 222Rn to reach very high levels in sections of the Sewers. Transect 2, unlike the first and third transect, has an exponential curve (concave up), indicating that there is steady ventilation near the entrances that drastically weakens towards the back. The slopes of the 222Rn increase in Transects 1 and 3 show similar trends in 222Rn from the entrance to 80 m (increase of approximately 1.25 dpm/l/m), but past 80 m 222Rn increases at a rate of approximately 30 dpm/l/m.

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Figure 4.10: Keeling plot of Hollow Ridge Cave and Obir Cave Air. 13 δ CO2 vs 1/[CO2] from grab sampling transects in Hollow Ridge Cave (this study) and Obir Cave (Austria-red dashed line, Spotl et al. (2005)) representing Rayleigh distillation (mixing line) between two CO2 end-member sources. The slope of the linear best fit (black dashed line) represents the mixing relationship between the two end-member CO2 concentrations while the 13 intercept is the  C value of soil gas CO2 above each cave. Notice the linear best fit line intersects the current outside free atmosphere point (390 ppmv and -7.25‰ 13C) even though this point is not included with the cave air samples. The end-member sources are atmospheric 13 13 CO2 (-7 to -10‰  C under a forest canopy) and soil gas CO2 (-22 to -24‰  C in forest litter dominated soils). Data for Obir Cave are picked off Figure 4 in Spotl et al., (2005).

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13 Figure 4.11: Cave Air [CO2] and  CO2 with distance from Entrance D. 13 222 Cave air [CO2] and  CO2 display a similar relationship to that found in the Rn transects, typically having a steady increase in concentration from the entrance to the back of the cave. Cave air samples are collected at the entrance and at five locations inside the cave. As cave air 13 [CO2] increases, the  CO2 becomes lighter, indicating a greater fraction of soil-derived light CO2 in the cave air.

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13 Figure 4.12: Cave Air [CO2] and  CO2 over the study period. 13 Cave air typically has higher [CO2] and lighter  CO2 during the summer seasons, and lower 13 [CO2] and heavier  CO2 over during the winter season. Two factors affect the [CO2] and 13  CO2 inside the cave: ventilation and CO2 import to the cave. Weaker ventilation and greater CO2 import from the soil horizon in summer result in higher CO2 concentrations and lighter 13  CO2 values. Enhanced ventilation and weaker CO2 import from the soil horizon in the winter 13 lead to lower CO2 concentrations and heavier  CO2 values because atmospheric CO2 has a larger contribution than soil CO2.

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Figure 4.13: Atmospheric Contribution to Cave Air CO2. 13 Crossplot of the  CO2 vs the CO2 concentration of cave air at Hollow Ridge Cave. Black diamonds are measured cave air samples, and open diamonds are measured atmosphere and soil 13 gas CO2. The red, green, and blue lines are soil gas mixtures having theoretical  CO2 and CO2 concentrations, illustrating the application of a two endmember CO2 (outside atmosphere are soil gas CO2) mixing system. Open crosses represent the theoretical soil gas endmember value for each mixing line. Each dash on the mixing lines represents a 10% change in the contribution of atmospheric CO2 to that mixing line.

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Figure 4.14: Rainfall, Drip, and Sump Water Isotopes vs Time. The monthly average 18O and D of rainfall collected in Tallahassee (orange, grey) displays no apparent seasonal pattern, and is smoothed as it mixes and travels through the epikarst. Drip water (blue, green) and sump water (pink) 18O have small ranges (< 0.3‰) and represent meteoric water as it mixes in the overlying epikarst. The residence time of water in the shallow epikarst above Hollow Ridge Cave must be long enough to result in complete homogenization, resulting in little variation of the 18O and D signals over time. Heavy rainfall events from periodic tropical storms (TS Faye) have lighter 18O and D signals, however, even these events are homogenized in the epikarst. Tallahassee rainfall data were collected and analyzed by Dr. Yang Wang of Florida State University (Wang, 2009).

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Figure 4.15: Drip, Sump, and Rainfall Samples Plotted on the GMWL. The global meteoric water line (blue dashed), Tallahassee MWL (green dashed), and drip and sump waters collected at Hollow Ridge Cave. Drip and sump water samples fall on the Tallahassee MWL and are centered at -3.λ‰ 18O and -1λ‰ D. The variation in D is larger than expected for the range in 18O, however, the range in D is within acceptable instrumental and analytical error limits. Drip waters collected in the Signature Room (black) fall directly on the Tallahassee MWL. These drip waters are present only during rain events, and therefore indicate a fracture and direct pathway from the soil to the cave for rainfall to quickly pass through. All other drip waters are collected from a continuously dripping stalactite, which is likely fed by porous flow.

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Figure 4.16: Drip Rate vs Drip 18O. Drip water 18O composition vs the drip rate at the date of collection. The timespan covered is from June 2008 to January 2009. A weak positive correlation is seen in the linear best fit, likely because high drip rates follow intense rainfall events (storms) that have a lighter 18O composition because of the amount effect.

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Figure 4.17: Rainfall Amount vs 18O and D. Comparison of the rainfall amount to the isotopic composition of rainfall in Tallahassee, FL, suggests there is no correlation between the two. Tallahassee rainfall samples were collected and analyzed by Dr. Yang Wang (Wang, 2009).

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18 Figure 4.18: Mg/Ca ratios, Sea Surface Temperature, and  Oseawater from a northern Gulf of Mexico Sediment Core. 18 A) Mg/Ca ratios and sea surface temperature (SST) and B)  Oseawater from G. Ruber in a northern Gulf of Mexico sediment core (Richey et al., 2007). Discussion of temperature and 18 ฀ Oseawater (ultimate source water for drip water in Hollow Ridge Cave) variations are in Section 4.3.2.

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18 Figure 4.19: Theoretical  Ocalcite Precipitated from Drip water in Hollow Ridge Cave. 18 Lines are theoretical speleothem  Ocalcite precipitated from drip waters as a function of 18 temperature and drip water ( Odw). Lines are generated using equations 4.4, 4.5, and 4.6 for the range of temperatures and fractionation constants. The grey shaded area represents the observed 18 18 range in temperatures and drip water  Odw at Hollow Ridge Cave. A shift of 1‰  Odw will 18 result in an approximate 1‰ shift in speleothem  Ocalcite, while a change of approximately 5° C 18 will result in a 1‰ shift in speleothem  Ocalcite. This range represents the extremes Hollow Ridge Cave may have encountered the past 100 ka.

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Figure 4.20: Cumulative Rainfall and Drip Rates in the Ballroom. Cumulative rainfall (mm total- left axis) and drip rates (drips per hour- right axis) are shown from October 1, 2007 to March 1, 2009. The drip logger was first deployed June 18, 2008. During the winter months, strong rainfall events can flood the Chipola River, inundating the lower passages of Hollow Ridge Cave where the drip logger is located (Flooding Events 1 and 2). However, strong evapotranspiration in the summer decreases the likelihood of the Chipola River flooding. It also reduces the total amount of meteoric water available to percolate through the epikarst to the cave, resulting in lower drip rates in the summer, even when daily rainfall is high. During Flooding Event #2 the drip logger floated off its stand and did not collect data for over two weeks, being submerged. „ET‟ = Evapotranspiration.

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Tropical Drip Delay Storm Faye

Figure 4.21: Daily Rainfall and Drip Rates in the Ballroom. Drip rate (blue, left axis) and total daily rainfall (green, right axis) from June 15, 2008 to November 15, 2008. There is an observed two week delay in drip rate response to heavy rainfall events at this stalactite. A drip water mean life of 14 days in the epikarst was calculated applying a first-order loss equation to drip waters from June 18 to August 6, 2008 (see text). Figure 4.25 is an expanded version of Figure 4.24.

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Figure 4.22: Barometric Pressure and Drip Rates in the Ballroom. Barometric pressure (black, left axis) and drip rates (blue, right axis) from November 11, 2008 to November 18, 2008. Thin black vertical lines are positioned at midnight CST of each day, and vertical red lines are positioned at noon CST of each day. There is a negative correlation between barometric pressure and drip rate, due to the effect barometric pressure has on the pore fluid pressure in the limestone overlying the cave. When barometric pressure increases, there is a higher proportion of air in pore fluids, decreasing the pore water height and thus pressure, reducing the drip rate. As barometric pressure drops, the proportion of air in pore fluids decreases and fluid pressure increases, resulting in a greater pore water height and faster drip rate. The semi-diurnal variation in barometric pressure is due to the semi-diurnal oscillation of atmospheric (so-called “earth”) tides. The semi-diurnal variation in drip rates is approximately 10% of the total drip rate. This is observed throughout the study period.

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Full on caption

Figure 4.23: Meteorological and Aerochemical Time Series Inside and Time Cave. Ridge and of Hollow and Aerochemical Outside Inside Series 4.23: Meteorological Figure following page. following page.

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Figure 4.23: Meteorological and Aerochemical Time Series Inside and Outside of Hollow Ridge Cave. Fifteen month meteorological and cave air time-series from Hollow Ridge Cave. A) Total Daily Precipitation. B) 24-hour Average Atmospheric Barometric Pressure- MET Station. C) Raw (grey) and 24-hour Average (black) Air Density Difference Between Atmosphere and Cave (MET– Cave). D) Raw (light blue) and 24-hour Average (dark blue) Atmosphere and Cave (red and black) Temperatures. E) Raw (grey-Cave Station 2, orange- Cave Station 1) and 24-hour Average (black- Cave Station 2, red- Cave Station 1) Cave Air 222Rn activities. F) Raw (grey- Cave Station 2, orange- Cave Station 1) and 24-hour Average (black- Cave Station 2, red- Cave Station 1) Cave Air CO2 concentrations. A cold front (January 20-21, 2008) and Tropical Storm Faye (August 23-25, 2008) are used as examples of ventilation mechanics in Section 4.5 (Figure 4.6). Two flooding events occurred during the instrumental period when the nearby Chipola River rose over 5 m water depth inundating Hollow Ridge Cave, flooding all passages except the Entrance Chamber, the Signature Room, the Fissure, and the Smith and Jones Room. The calculation of outside free atmosphere and cave air density is discussed in section 3.3.3 and is calculated using equations 3.5 and 3.6.

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Figure 4.24: Meteorological and Aerochemical Time Series Inside and Outside of Hollow Ridge Cave Over One Week in October 2008. Seven Day meteorological and cave air time-series from Hollow Ridge Cave. A) Total hourly Precipitation. B) Atmospheric Barometric Pressure- MET Station. C) Air Density Difference Between Atmosphere and Cave (MET– Cave). D) Atmosphere (Blue), Cave Station 1 (Red), and Cave Station 2 (black) Temperatures. E) Wind Direction above cave (MET Station). F) Wind Speeds near the cave entrances (MET Station). G) Radon-222 concentrations at Cave Stations 1 (Red) and 2 (Black). H) Drip Rate below a Ballroom Stalactite. I) CO2 concentrations at Cave Stations 1 (Red) and 2 (Black). The calculation of outside free atmosphere and cave air density is discussed in section 4.3.3 and is calculated using equations 4.7 and 4.8.

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222 Figure 4.25: Cave Station 2 CO2 and Rn during Flood #1, February 2008. 222 The CO2 and Rn concentrations at Cave Station 2 increased before and during the flooding of 222 the Chipola River, indicating increased transport of CO2 and Rn to the cave during heavy rainfall before the closure of entrances. The drastic increase of 222Rn is due to elimination of ventilation to outside air. However, the decrease in CO2 indicates no transport from the epikarst (flushed into the cave before the flood) and a possible loss of CO2 by calcite dissolution while 222 the Signature Room was sealed. When ventilation pathways re-opened, CO2 and Rn fall back to normal winter levels. Date ticks are positioned at midnight CST of each day.

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222 Figure 4.26: Cave Station 2 CO2 and Rn during Flood #2, December 2008. 222 The CO2 and Rn concentrations at Cave Station 2 again increased before and during the flooding of the Chipola River. The increase during the heavy rainfall period before flooding 222 represents increased transport of CO2 and Rn to the cave. The CO2 increase is higher than that observed during Flood #1 because this period is in the early winter and degradation of organic 222 matter in the soil horizon should still produce CO2. The maximum Rn concentration reached is similar to that during Flood #1. Again, when ventilation pathways open as flood waters recede, 222 CO2 and Rn concentrations decrease drastically. Date ticks are positioned at midnight CST of each day.

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Rn Intensive Map. Map. Rn Intensive 222 The intensive study conducted on November 11-12, 2008 included 5 additional RAD7s placed in the cave, and one outside by in the one and the study conducted intensive cave, 11-12, on November placed RAD7s The 5 additional 2008 included positioned at A. 2D sonic of each RAD7. displays The Entrance was This map anemometer the locations 3-8). MET Station (numbers Figure 4.27: Hollow Ridge Cave Cave 4.27: HollowFigure Ridge

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Figure 4.28: Air Density Difference, Airflow Direction and Speed, and 222Rn During Intensive. The air density difference between the MET Station and Cave Station 1 (plot A), airflow 222 direction (red = in, blue = out) and speed (plot B), and Rn and CO2 concentrations during the intensive study November 11-12, 2008 suggest ventilation is density driven. Locations involved in the study are shown map in Appendix A.18.

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Figure 4.29: Air Turnover Rates in Hollow Ridge Cave During Intensive. The turnover rates calculated from the 222Rn mass balance at each station during the intensive study November 11-12, 2008 indicate air exchange is generally weaker farther from the entrances. Turnover at Cave Station 1 does not fit the general pattern of greater air exchange closer to the entrances. We believe that because of the location of Cave Station 1 (junction of all entrances, ~5 m off the floor), complex stratified air currents often draining the interior are responsible for the nature of ventilation at this location. For each station, we used an emission rate of 3700 dpm L-1 and an area to volume scale length of 9:1 m-1.

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Figure 4.30: Ventilation Rates at Cave Stations 1 and 2 over the Study Period. Ventilation Rates at both Cave Stations are higher in the summer months than in the winter or spring, except for strong ventilation events during winter cold fronts.

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CHAPTER 5

SPELEOTHEM RESEARCH

5.1 Introduction Speleothems, particularly stalagmites and flowstones, can contain high resolution (sub- annual) paleoclimate records that may extend over thousands or even hundreds of thousands of years. Three calcite stalagmites were collected from a cave in Marianna, FL. These stalagmites were analyzed for stable isotopes (δ18τ and δ13C), trace elements, radiocarbon ages, U-series ages, mineralogy, calcite color spectrum, and relative internal density by CAT-scans (computed tomography). Analytical techniques for stable isotope (Lachniet, 2009), trace element (Treble et al., 2003), U-series dating (Hu et al., 2008b), and computed tomography (Mickler et al., 2004) sampling are well established, and these techniques were applied to three stalagmites collected in northern Florida.

5.2 Previous Research Speleothems are a major source of global paleoclimate records spanning the past 400 ka, and rival sediment and ice cores in their interpretation with absolute dating techniques and global distribution (Fairchild et al., 2000; Fairchild et al., 2006). Paleoprecipitation records developed 18 13 from δ Ocalcite and variations in vegetation cover developed from δ Ccalcite are common records produced from speleothems (Denniston et al., 1999; Genty et al., 2003; Cruz et al., 2005a; Dykoski et al., 2005). Speleothem records from southern China (Dongge, Hulu, Sanbao and Heshang caves) reveal variable Asian Monsoon strength over the past ~160 ka (Wang et al., 2001; Kelly et al., 2006). The Asian Monsoon has a strong summer monsoon component out of the southwest (SW) Pacific and summer monsoon intensity is described as a function of summer insolation (Dykoski et al., 2005; Wang et al., 2005). High resolution oxygen isotope analyses from these four caves are interpreted as the strength of the summer monsoon (precipitation amount) and thus the intensity of northern hemisphere summer insolation. The Florida panhandle region has a slight seasonality of precipitation and speleothem oxygen isotope variations may be due to annual

125 temperature variations, tropical storm intensity/frequency or changes in the extent of the Southwest Monsoon (Markham, 1970; Poore et al., 2007). 13 The isotopic composition of soil CO2 is a factor in the δ C of speleothem calcite, with variations in soil CO2 typically due to changing C3 and C4 vegetation types (McDermott, 2004;

Fairchild et al., 2006). If one assumes equilibrium CO2 degassing (minimal kinetic fractionation of isotopes) then variations in the δ13C record of speleothems are due to changing C3/C4 vegetation ratios, and can be used as a paleotemperature/precipitation record (Dorale et al., 1998). Speleothem δ13C records associated with C3 dominated vegetation typically have compositions of -14 to -6 ‰, and variations in the δ13C record of sample BC1 range from -9 to -4 ‰, suggesting slight variations in the C3/C4 vegetation ratio or in soil water residence time (McDermott, 2004; Froelich et al., 2007). Interpretations of speleothem isotope records include variations in paleoprecipitation, paleotemperature, seasonality of precipitation, vegetation and soil changes, atmospheric circulation re-organization, and residence time of water in the epikarst zone (Fairchild et al., 2006). The worldwide availability of speleothem records makes them potentially more useful than ice and sediment cores, and as new methods to absolutely relate climate to isotope and trace element records their usefulness will increase exponentially.

5.3 Methods In December 2006 three speleothems were collected from the Brooks Quarry Cave (30° 48‟ 21.λ” σ, 85° 15‟ 36.7” W), located in the Marianna Lime Company Quarry, Marianna, FL with permission from the owner (Figure 5.2). Collection sites in the cave for each sample are shown in Figure 5.2. The three stalagmite samples are: BC1, 65 cm length; BC2, 7.5 cm; and BC3, 11 cm. Sample BC1 has been mapped, radiocarbon dated, U-series dated, analyzed for carbonate stable isotopes (δ18O and δ13C), trace elements, mineralogy, and internally imaged using Computed Tomography. BC2 has been mapped, analyzed for isotopes, trace elements, radiocarbon dated, and layer counted. BC3 has been mapped, analyzed for isotopes, and radiocarbon dated. Sampling was conducted at three resolutions: macro-sampling involved the collection of speleothems and sectioning them into reference and working halves; micro- sampling involved the drilling of powders for stable isotope and dating analyses; analytical

126 sampling involved the analysis of speleothem samples and powders for stable isotopes, trace element, mineralogy, and internal density via computed tomography.

5.3.1: Macro-sampling. Speleothems were cut longitudinally into two sections along the growth axis using water-lubricated rock saws at the Florida State University Geology department and the Florida Geological Survey core repository. The reference halves were polished to λ.5 m with 8 inch Beuhler Carbimet polishing disks and set in plaster. Working halves were polished and set in plaster in preparation to micro-drill powders for stable isotope analyses, radiocarbon dating, and U-series dating. For laser ablation (LA-ICP-MS) trace element analyses, small speleothem sections were cut into one inch square tablets and polished to 0.3 m with a polishing wheel and alumina slurries following standard lab polishing techniques.

5.3.2: Micro-sampling. A Sherline 5400A Digital Readout (DRO) microdrill with a 500 m carbide drill bit was used to drill powders for isotope analyses, radiocarbon dating, and U- series dating down the growth axis. For each sample, approximately 200 g of calcite was collected in 500 m intervals for isotope analyses. Five samples from BC1 (0, 14, 34, 54, and 61 cm from the tip) were drilled for radiocarbon and U/Th analyses. Two samples each were drilled from BC2 (0.7 and 6.8 cm) and BC3 (0.4 and 8.2 cm) for radiocarbon analyses. Sample powders for radiocarbon analyses were sent to the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) in Woods Hole, MA for 14C and 13C. Radiocarbon ages were determined via inorganic carbon 14C dating by hydrolysis and accelerator mass spectrometry (AMS) techniques (NOSAMS, 2009). Sample powders for U/Th dating were sent to Dr. Christina Gallup at the University of Minnesota-Duluth, Department of Geology. U-series ages were determined via MC-ICP-MS by Dr. Gallup following the method of Hu et al. (Hu et al., 2008b).

5.3.3: Analytical techniques. Speleothem samples were analyzed for stable isotope composition, trace element composition, color scans, mineralogy, and internal density structure via X-ray computed tomography. Calcite powders (200 g/sample) are analyzed for δ18O and δ13C via standard techniques on a Thermo Finnegan Delta-plus XP mass spectrometer in conjunction with a Gas Bench II Auto-carbonate Device (Fairchild et al., 2006). Eight standards

127 are included in each run; four at the beginning, two after 44 samples, and two at the end of the run. The carbonate standards used were NBS-19, MERK, ROY-CC, and MB-CC. NBS-19 is a national standard developed by the United States Geological Survey (USGS). The MERK, ROY- CC, and MB-CC standards were FSU Geochemistry in-house standards. Calibration curves were created using the linear best fit through the measured standards and then were applied to all powder samples measured each run (Figure 5.4). Color is a highly diagnostic property of marine sediments (Rothwell, 2006), and has been shown to indicate sediment composition and can also give information on the oxidation state of iron (Giosan et al., 2002a; Giosan et al., 2002b). In speleothems, however, color has a complex origin that can be attributed to metallic ion content (White, 1981), the oxidation state of metal cations, speleothem crystalline structure (Beck, 1978), and staining by organic pigments (White, 1984). Photo-mapping of BC1 was accomplished with the GEOTEK core scanner at the University of Florida Geology Department. High resolution Red/Green/Blue (RGB) color scans were combined with high-resolution color photographs to map “sparves”. The GEτTEK was equipped with a macro-lens at an aperture of 5.6 and has a resolution of 20 m. The GEτTEK MSCL Image Tools 2.4.1 software environment was used to create the RGB scans used in photo- mapping. The mineralogy of sample BC1 was analyzed via standard X-ray diffraction (XRD) powder techniques at the Center for Materials Research and Technology (MARTEK) in the Geophysical Fluid Dynamics Institute at FSU (Azaroff et al., 1974). Sample BC1 is a low-Mg calcite. High-resolution X-ray Computed Tomography (HRXCT) is an established technique to image density variations in bones that has been applied recently to determine interior growth structures of speleothems (Mickler et al., 2004). Samples BC1, BC2, and BC3 were imaged at the Radiology Imaging Unit of Capital Regional Medical Center with Drs. Don McCardle and Angel Lluveras using a GE Lightspeed VCT. Speleothems were imaged at a max power of 140 KeV and currents of 525.0 mA for BC1 and 625.0 mA for BC2 and BC3, with slice thicknesses of 0.6 mm. Files were processed using the eFilm Lite v 2.1.0 medical software environment. Trace element composition of samples BC1 and BC2 were determined using a New Wave UP-213 nm Nd:YAG laser ablation system coupled to a Finnegan MAT Element I Inductively-Coupled Plasma Mass Spectrometer (LA-ICP-MS). Methods were developed to

128 measure the elements 25Mg, 29Si, 43Ca, 55Mn, 57Fe, 85Rb, 88Sr, 138Ba, 140Ce, 232Th, and 238U. Gas blanks are estimated by flushing the sample chamber with ultra-high purity He and measured without firing the laser. Tracks are analyzed along ablation lines with the following parameters: 10 m/sec step rate, 10 Hz pulse rate, beam width of 80 m, and laser energy level of 65%. All analyses are blank subtracted and normalized to 43Ca (Treble et al., 2003). Elemental concentrations are estimated by sample-standard bracketing with an average of five samples between standard measurements. Trace element concentrations are estimated from the response of a Si-glass standard NIST SRM-612 using the preferred concentrations of (Pearce et al., 1997). NIST SRM-612 is a sufficient standard for calcite laser ablation, as differences between doped synthetic carbonates and NIST SRM-612 are less than 10% (within instrument error) across the REE series (Tanaka et al., 2007). Macro and micro-sampling techniques used in this study are common practices in speleothem studies (Fairchild et al., 2006; Lachniet, 2009). Analytical methods are modified after techniques developed for δ18τ and δ13C isotope analyses, trace element analyses, and CT scanning in samples BC1, BC2, and BC3 (Treble et al., 2003; Mickler et al., 2004; Fairchild et al., 2006).

5.4 Results and Discussion 5.4.1 BC1. Sample BC1 was collected in the northeast section of Brooks Quarry Cave (Figure 5.3). The sample was broken at the base previous to collection (not actively growing). U- series dating indicates speleothem BC1 grew approximately between 65-70 ka, and may include D-O event 19 (68 ka) (Dansgaard et al., 1993). U-series and radiocarbon dates from all three speleothem samples are in Appendix B.1. BC1 is a low-Mg calcite, analyzed by XRD and trace element analyses. Figure 5.5 illustrates a true color photograph, U-series ages, color scans, and the isotopic composition of the upper 25 cm. All radiocarbon dates are older than 46 kyr BP, indicating the sample is radiocarbon dead and older than 46 ka. Visual linear best fit lines on the U-series ages suggest an estimated continuous growth rate between 0.122 and 0.244 mm/yr (Figure 5.6). The upper 25 cm of BC1 was analyzed for δ18τ and δ13C, which have no correlation to each other, suggesting calcite growth was in isotopic equilibrium with drip waters and cave air (Hendy, 1971). Complete analyses of speleothem δ18τ and δ13C to the base of BC1 should reveal if this specimen recorded abrupt climate events as witnessed in speleothem δ13C

129 records from French speleothems (Dansgaard et al., 1993; Genty et al., 2003). Initial analyses suggest that a +3‰ δ13C excursion at 7 cm may coincide with the leading or lagging edge of DO Event 19 in the GRIP ice core record (Johnsen et al., 2001). Excursions in the δ13C record of a speleothem from Villars Cave (southwest France) have been suggested to coincide with the timing of DO events in GRIP and GISP 2 ice core δ18O records and are interpreted as variations in soil-CO2 production due to temperature variations (Genty et al., 2003). While uncorrelated, both δ18τ and δ13C values follow a trend to heavier values with increasing distance from the base. The δ18O record has an average value of -3.2‰, with a 1 variance of ± 0.5‰, with a shift of mean values at 11 cm from the tip from -3.5‰ (11-25 cm) to -2.8‰ (0-11 cm from tip). This may indicate a minor shift in average precipitation amounts, temperature, or precipitation source. The δ13C record has an average value of -6.6‰, with a 1 variance of 0.8‰. Multiple short-term excursions to heavier δ13C values are imprinted over the long-term trend to heavier δ13C values. In other speleothems, similar δ13C excursions have been interpreted as vegetation regime changes, from primarily forest at lighter values to primarily savannah at heavier values (Dorale et al., 1998). However, recent investigations on cave meteorology suggest variations in speleothem 13C are influenced by cave air ventilation rates, water residence time in the epikarst, and drip water CO2 content (Baker et al., 1997; Spotl et al., 2005; Banner et al., 2007; Baldini et al., 2008; Kowalczk and Froelich, 2009). The tip (upper 1.7 cm) of BC1 was analyzed via LA-ICP-MS for a suite of trace elements (Figure 5.8). Individual layers are resolvable in trace element ratios, grouped into “classic” and “crustal” components representing trace elements that are dependent on epikarst water residence time and precipitation (Ba, Sr, Mg = classic elements) and soil/redox chemistry (Mn, Fe, Si, Ce, Th, U = crustal elements) (Treble et al., 2003; Fairchild et al., 2006). Water residence time in the epikarst influences the dissolution of trace elements. Long residence times increase the amount of trace elements dissolved. Where dolomite comprises parts of the epikarst, increased water residence times allow greater dissolution of dolomite (which is more insoluble than limestone) and will increase the Mg/Ca ratios of percolation waters (Fairchild et al., 2006; Palmer, 2007). The ratios of Sr/Ca and Ba/Ca co-vary over the upper 1.7 cm of BC1, and should reflect variations in soil water residence time with higher Sr/Ca and Ba/Ca ratios reflecting longer residence times in the epikarst (Verheyden et al., 2000). Higher excursions in the ratio of Mg/Ca 18 are consistent with enriched δ Ocalcite, and both records may indicate increased precipitation

130 rates during these periods of greater Mg/Ca ratios (Fairchild et al., 2006). The crustal group is defined as the trace elements typically dependant upon soil redox chemistry (Froelich et al., 2007). Mn, Fe, Si, Ce, Th and U all co-vary over the measured interval, with higher [X]/Ca ratios possibly indicating increased soil redox potential. Further analysis of trace elements will strengthen interpretations developed from carbon and oxygen isotopes and allow a more complete view of climate variations over the life of the speleothem. Isotope (Appendix B.2), trace element (Appendix B.3), and color scan data (Appendix B.4) for sample BC1 are located in the appendices. High-resolution X-ray Computed Tomography (HRXCT) imaging is a non-destructive technique that can be applied to speleothems before destructive sampling to determine the interior growth structure and suitability for paleoclimate reconstructions (Mickler et al., 2004). However, sample BC1 was sectioned in half along the growth axis before it could be CT imaged. Even so, HRXCT imaging of BC1 reveals a complex internal density structure, with the upper 35 cm of the sample comprised of dense calcite while the lower 30 cm of the sample is comprised of highly porous calcite (Figure 5.9). A video composite of HRXCT images (> 300 images) starting at the base of BC1 show internal density variations along the growth axis, and is available in digital format.

5.4.2: BC2. Sample BC2 was collected at Entrance 1 of Brooks Quarry Cave (Figure 5.3). The sample was broken prior to collection, likely from mining operations. Radiocarbon dating suggests that BC2 is younger than 10 ka, and may span much of the Holocene (Figure 5.10). The stable isotope record of BC2 (δ18τ and δ13C) suggests little variation in hydrological processes above the cave (rainfall source, amount, and residence time) and substantial variations in either cave air ventilation and/or drip water CO2 degassing or the vegetation regime over the life of the sample(Figure 5.10). The δ18O composition varies between -2.5 and -4 ‰ (VPDB) for most of the record, with a few excursions to -5 ‰ (VPDB). This steady speleothem δ18O record 18 indicates little change in the hydrologic cycle, and variations in  Ocalcite are likely from slight variations in the amount of rainfall over the region. However, large variations in speleothem δ13C compositions typically represent either variations in the ratio of C3 to C4 vegetation above the cave or variations in ventilation and drip water CO2 processes (Baker et al., 1997; Spotl et al., 2005; Fairchild et al., 2006; Banner et al., 2007; Baldini et al., 2008; Kowalczk and Froelich,

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2009). Short, large variations in speleothem 13C (> 4‰) are likely a factor of cave ventilation and drip water CO2 processes (Banner et al., 2007; Baldini et al., 2008; Kowalczk and Froelich,

2009). Increased ventilation lowers CO2 concentrations and increases drip water CO2 degassing 13 rates. Increased CO2 degassing enriches the  C of dissolved CO2, which leads to an enrichment in speleothem 13C (Spotl et al., 2005). It has been suggested that variations in the C3/C4 ratio of local vegetation are likely responsible for long term shifts in speleothem 13C as opposed to short, large variations in speleothem 13C because there is little evidence for major shifts in the vegetation regime in north Florida over the past 10,000 years (Watts, 1969; Watts and Stuiver, 1980; Watts et al., 1992; Watts and Hansen, 1994). Analyses of the “classic” (Mg, Sr, Ba) and “crustal” (Si, Mn, Rb, Ce, Th, U) trace elements indicates that variations in the classic trace elements (Mg, Sr, Ba) are likely due to hydrologic effects (residence time) while variations in the crustal trace elements are likely due to soil water residence time and dissolution of clay particles in infiltration water (Baldini et al., 2002; Fairchild et al., 2006). The timing of the peaks and valleys in Mg, Sr, and Ba concentrations co-vary over the upper 1.1 cm interval of BC2, although the amplitudes of variation are not similar. The observed trend in Sr concentrations co-varies with the 1.5‰ variation in δ18O, likely indicating a shift from drier climate to slightly wetter climate. Sr/Ca ratios are dependent upon water residence time in the epikarst. Longer residence times occur during drier climates and increase Sr/Ca ratios (Baldini et al., 2002). During drier periods, the δ18O of rainfall should be heavier because heavy rain precipitates first, and less rainfall should result in rainfall having a heavier δ18O composition. When rainfall increases, the amount effect results in precipitation having a lighter isotopic composition, and increased precipitation amounts increase infiltration rates through the epikarst. When residence times in the epikarst are shorter (higher rainfall) Sr/Ca ratios decrease because less limestone bedrock is dissolved by infiltration waters. The concentrations of the “crustal” trace elements increase in layers that are visually dark in color, indicating that incorporation of these trace elements stains the calcite. Crustal trace element concentrations increase by over an order of magnitude above base levels at approximately 0.5, 1.5, and 3.5 mm from the tip. These excursions line up with dark bands in a true color scan of the sample (Figure 5.11). Hu et al (2005) suggest that adsorbed Si may represent paleorainfall amounts. However, this is unlikely in sample BC2 because there is no

132 correlation between Si concentrations and the δ18O composition. A more probable explanation for the variations in the “crustal” trace elements can be attributed to aerosol deposition on speleothems. If a constant rate of aerosol deposition is assumed in the cave, variations in the “crustal” trace elements derived from aerosols should be attributed to calcite deposition rates. On the tip of actively depositing stalagmites, adsorption or incorporation of aerosols should occur at a near constant rate. However, when calcite deposition slows or stops, aerosol deposition continues, resulting in higher concentrations of these trace elements during periods of slow calcite deposition (Figure 5.11). In seasonally depositing stalagmites, there should accompany a spike in these “crustal” trace element concentrations with each growth band or pair of growth bands. Analyses of these trace element patterns can then be used to count “annual” banding under the assumption that annual calcite deposition patterns will create these observed spikes in trace element concentrations. Isotope (Appendix B.5), trace element (Appendix B.6), and color scan data (Appendix B.7) for sample BC2 are located in the appendices.

5.4.3: BC3. Sample BC3 was collected near the convergence of Entrances 1, 2, and 3 in Brooks Quarry Cave (Figure 5.3). Radiocarbon ages indicate this sample deposited within the past 30 ka (Figure 5.12). The radiocarbon date from the top of the speleothem (12800 yrs BP) suggests the upper region of the sample is likely younger than 10 ka. Nevertheless, the tip may be as young as late Holocene because the sample was wet (actively growing) at the time of collection. It is likely that sample BC3 underwent a period of very slow or no growth. Variations in calcite coloring coincide with shifts in the 18O and 13C records at 2.3 and 6 cm from the tip. Sectioning of the sample prevented isotopic and photographic analyses of a 0.5 cm section in the middle. Observations of two inferred growth hiatus occur at 2.3 cm and 6 cm from the tip, suggesting at least two periods of slow to no growth where calcite dissolution occurs. HRXCT scans of the upper section of BC3 reveal a low density calcite band 2.3 cm from the tip, exactly where a +1‰ ฀18O excursion and -3‰ 13C shift occurs (Figure 5.13). A larger shift in both the 18O (= -1‰) and 13C (= -5‰) records occur in the missing section at 6 cm. A similar shift in 13C is also observed at 6 cm from the tip, and may possibly represent changes in vegetation above the cave during the last glacial max. However, without additional radiocarbon and U-series dating it remains unknown whether a depositional hiatus exists or a short, major vegetation regime shift occurred. Another possible explanation for the observed variations in

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13C is variations in cave ventilation and drip water CO2 processes, which both affect the transfer of the carbon isotopic signal from the epikarst to the speleothem. CT scans of the upper section of BC3 indicate the middle section of the sample (from 2.3 to 6 cm from the tip) consists of a lower density calcite than the upper section (0 to 2.3 cm from the tip), although this cannot be quantified with available data and may be an artefact of CT imaging (Figure 5.13). Isotope (Appendix B.8) and color scan data (Appendix B.9) for sample BC3 are located in the appendices.

5.5 Summary Isotopic, trace element, HRXCT, color scan, and age analyses of three speleothems from Brooks Cave in northwest Florida offer insight to past climate conditions. Sample BC1 spans a period from approximately 65 ka to 69 ka, while samples BC2 and BC3 are much younger and may span the last glacial max up to the present. While BC1 was absolute dated via U-series techniques, BC2 and BC3 were dated using radiocarbon techniques, which are inherently inaccurate in carbonate speleothems because a major source of carbon (limestone bedrock) is radiocarbon dead. Accurate U-series dating of these two samples may allow direct comparison to climate records developed from pollen and lake sediment cores (Watts et al., 1992; Watts and Hansen, 1994) and speleothems (Beynen et al., 2007) in Florida. Accurate radiocarbon dating of speleothems is complicated because the amount of dissolved limestone (radiocarbon dead) in drip waters varies with water residence time in the epikarst. Radiocarbon from the soil zone is diluted by the addition of limestone carbon, and potentially ranges from zero to 95% or more limestone-derived carbon (Palmer, 2007). However, radiocarbon dating of speleothems is an inexpensive and fast method to obtain maximum sample ages. Radiocarbon dates can be tuned to U-series dates from the same speleothem to determine an offset, which can then be applied to other radiocarbon dates to increase chronological resolution (Webster et al., 2007). This method can be useful for large speleothems requiring many dates to obtain accurate chronology. 18 The  Ocalcite values of the three samples are very similar, varying between approximately -2 to -4‰ VPDB. This suggests that northwest Florida has likely experienced little variation in the isotopic composition of precipitation over the past 70 ka, and long term 18 variations are likely to follow the  Oseawater of the Gulf of Mexico. It has been suggested that the southeastern US should have experienced increased monsoonal activity and precipitation

134 from 9 to 3 ka, however evidence from sediment cores and our speleothem samples suggests this may not be the case (Kutzbach, 1987; Watts et al., 1992). Although the 18O composition from samples BC1, BC2, and BC3 suggest little variation in the isotopic composition of rainfall in northwest Florida, long term variations in temperature and rainfall amount likely are responsible for changing vegetation assemblages. The 13C composition of our speleothem samples covers a range of over 10‰ (BC3 has the largest individual range), suggesting major shifts in the vegetation type (likely responsible for long term 13C variations) or major shifts in cave 13 ventilation and drip water CO2 processes (likely responsible for short term  C variations) (Watts, 1969; Watts, 1980; Watts and Stuiver, 1980; Watts et al., 1992; Spotl et al., 2005; Banner et al., 2007; Baldini et al., 2008; Kowalczk and Froelich, 2009). Although samples BC2 and BC3 are not absolutely dated via U-series techniques, isotopic and trace element analyses suggest that detailed climate records can be derived from speleothems in northwest Florida. Absolute dating of these samples or other speleothems from northwest Florida will aid in paleoclimate investigations of Holocene climate in the southeast US. Comparison of these records to other speleothem records from Florida (Beynen et al., 2007) and Alabama (Lambert and Aharon, 2007) and pollen records from Florida (Watts, 1975; Watts and Stuiver, 1980; Grimm et al., 1993; Watts and Hansen, 1994; Grimm et al., 2006) should constrain the timing and magnitude of climatic shifts affecting the southeast US.

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Ocala Ocala Platform Chattahoochee Chattahoochee Anticline

ft An aerial view of Marianna, FL, located in the northwest panhandle region. Marianna Marianna FL, located panhandle region. view northwest (whitein the Marianna, An aerial of

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Figure 5.2: Map of Brooks Quarry Cave. Brooks Plan 5.2: Map of Brooks view caveFigure three speleothem Quarry for Quarry of recovered were where samples is shown in red. group by collected One of South studies. Karst Florida from speleothem the University Map paleoclimatic 2008). Roberts (Roberts, Sean

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Figure 5.3 Typical Calibration Curves for Stable Isotope Analyses. Analyses of 13C and 18O on the Thermo Finnegan Delta-plus XP mass spectrometer require calibration of measured standards to known isotopic values to determine sample isotopic values vs PDB. The δ 13C and δ 18O calibration curves are different for each run, but typically have R2 values of 0.9997 to 1.0.

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Figure 5.4. Uranium-series dates, true color photograph, red color spectrum, and isotopes from BC1. Color scans of sample BC1 indicate that the lower section of the stalagmite (the bright white section starting approximately 35 cm from the tip) has greater color reflectance than the upper 35 cm of the sample. The darker color of the upper 35 cm is likely due to incorporation of organics (humics and fulvics) and trace elements into the calcite lattice, while the lower section is likely devoid of organics and trace elements. There is no visual correlation between the isotopic composition and color of the speleothem. Layer counting found approximately 3540 ± 424 laminae with an average thickness of 180 ± 21m.

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Figure 5.5: Age-Distance Scale of BC1. U-Series ages of BC1 plotted against distance from growth tip. Age Error bars are shown in red. Ages are in chronological order within error. The top point is ignored in the slow growth scenario because of the large error associated with high detrital 232Th present at the tip of the speleothem. Laminae counting resulted in an average of 3540 individual layers in speleothem BC1. If individual lamina are assumed to represent annual growth, layer counting is in good agreement with U-series ages and suggests the speleothem covers time-span of 3540 years. The average growth rate determined by layer counting of 0.180 mm yr-1 which is also in good agreement with the average growth rate from U-series ages of 0.16 mm yr-1.

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Ca normalized cps with cps normalized Ca 43 m). Calibrations (horizontal bars (horizontal Calibrations m). at  -20,000 -20,000 (0 Ca count ratios from NIST SRM-612, NIST from is a calcium-enriched ratios which count Ca 43 X/ mn O and the crustal elements (Si, Mn, Fe, Ce, Th, U) to the color scan. The x-axis color is to the (Si, Ce, Th, U) Mn, Fe, elements the crustal O and 18 the bottom of each graph) were estimated from the graph) from estimated were the bottom of each Figure 5.6: Trace of of Color (~125 ScanElement, BC1Speleothemcm trace Records Isotope, and 5.6: 1.7 Figure years) Trace upper BC1. The between Ba/Sr between strong Ce/Th and visual correlation records and correlation and isotope strong statistical show element Mg and y-axis and the element, for ranges tipeach down from concentration is distance standard. glass silicate

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A region approximately 18 cm from the tip is also a white, porous calcite. The sample was broken at 49 broken and tip 18 at the is during collection, The from approximately sample was cm a cm calcite. also region white, porous 49 at HRXCT technique. starting with the A video not HRXCT images imaged composite section was of horizontal the lower ending tip tip the the and is available digitally. from at cm Figure 5.7: Photograph and CT scan of BC1. CT scan 5.7: and Photograph Figure shift color that the sample BC1 (top) reveals color an of (bottom) and photograph true HRXCT image of a Comparison 34 the tip, at the the from is from highlycm contains tip shift speleothem Below 34 cm observed also a density. in calcite higher density. while bright density.are density, lower areasthe CT are areas In dark a lower average image has and porous

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Figure 5.8: Radiocarbon dates, true color scan, red color spectrum, and isotopes from BC2. 13 There exists a visual correlation between the  Ccalcite and color of the sample, where depleted 13  Ccalcite values coincide with greater red color reflectance. Lighter, more translucent sections (between 0.8-1.5 cm, 3-4 cm, and 5.7 to 6.7 cm) tend to have heavier 13C compositions, while darker, more opaque sections have lighter 13C compositions. 480 ± 18 individual laminae were counted by layer counting three times for speleothem BC2.

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le . We observed that variations in the “crustal” derived derived that variations. We in the “crustal” observed Sr concentrations, due to the fact the Sr/Ca ratios are fact to the are due Sr/Ca the ratios Sr concentrations, 88 O composition and O composition 18  thought to b controlled by hydrological processes processes al., 2003) by hydrological thoughtet to b controlled (Treble that t hese indicating visible all photograph, „sparves‟, coincide with major elements in the color elements trace trace “crustal” Figure 5.9: Isotope, Trace Element concentrations, and Color Photograph Records of the upper of the 1.1 of BC2. concentrations,cm Records Color Element Photograph and 5.9: Isotope, Trace Figure whi ty elementsfor, the trace of the analyzed portion isotope and are pically contains upper speleothems “classic” The figure There trace in elements. c” the trace of elements measured to the “crustal” portion addition figure are the “classi the lower the between slightexists visual a correlation speleothem color effect large in 1981; White, determining a 1984). (White, have likely

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Figure 5.10: Radiocarbon dates, true color scan, red color spectrum, and isotopes from BC3. The middle section of BC3 was removed during cutting and sectioning, and was not analyzed for isotopes or color scans. A large shift occurs in both isotopic records at approximately 6 cm from the tip, and a large shift in 13C also occurs at approximately 2 cm from the tip. These are discussed in the text in Chapter 5.4.3. Multiple layer counts resulted in an average of 380 ± 12 individual laminae counted for speleothem BC2.

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Figure 5.11: CT scan (left) and true color scan (right) of BC3. Comparison of an HRXCT image (left) and true color scan (right) of the upper section of sample BC3 shows the sample is mostly dense, non-porous calcite. However, a clear band (“sparve”) approximately 2 cm from the tip consists of less dense calcite. In the true color scan, this layer is optically clear. The lower section (see Figure 5.12) of BC3 was not imaged using HRXCT techniques.

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CHAPTER 6

SUMMARY OF THESIS

The ongoing, continuous, in situ cave monitoring project at Hollow Ridge Cave has provided new insight to the dynamics of cave ventilation and cave air chemistry and their relations to local above-ground meteorology. This study has been the first of its kind to thoroughly investigate local above-ground meteorology, cave ventilation, cave air chemsistry, cave meteorology, and cave hydrochemistry at the same sight. Previous cave monitoring projects have been thorough, but not all-inclusive (Spotl et al., 2005; Banner et al., 2007; Asrat et al., 2008). This study of an active dripstone cave is unique in that we overcome many of the problems that in the past have plagued in situ cave monitoring research, namely in regularity of site visits and sampling interval. Continuation of the Hollow Ridge Cave project will only improve conclusions derived from the 15 month time-series collected as part of this research. In review, grab sampling transects suggest cave air CO2 is a result of two end-member mixing between soil gas CO2 and outside atmospheric CO2. Minor contributions of soil gas CO2 to cave air have a large effect on the isotopic composition of cave air CO2. These grab sampling transects also show cave air 222Rn concentrations typically follow a near-linear rise with increasing distance from the entrances. Near continuous collection of cave air chemistry and meteorology time-series reveal a 222 strong seasonal pattern in concentrations of cave air Rn and CO2. High concentrations are observed in the summer (warm, high soil productivity, decreased ventilation) while low cave air concentrations are observed in the winter (cold, low soil productivity, increased ventilation). 222 Modeling of ventilation rates via Rn mass balances allows modeling of CO2 outgassing rates.

CO2 outgassing rates from the cave to the outside atmosphere can have a significant impact on speleothem deposition because the removal of CO2 from cave air significantly affects the rate of drip water CO2 degassing (Banner et al., 2007; Baldini et al., 2008). During periods of increased

CO2 outgassing, we infer increased calcite deposition by increased degassing of CO2 from drip waters (Kowalczk and Froelich, 2009). Deployment of slides in the cave over active stalagmites to “farm calcite” should have provided a direct measurement of calcite deposition rates, but multiple flood events and slow calcite precipitation rates prevented analysis of these plates as

147 part of this project. Continuation of this project should incorporate the collection of actively growing calcite for comparison to ventilation and CO2 outgassing rates in order to establish a direct link (Banner et al., 2007). However, calcite deposition rates are likely too slow for direct comparison to the hourly modeled ventilation and CO2 outgassing rates, and would have to be compared to averaged seasonal or annual rates. Comparison of continuous drip rates and bi-weekly collection of drip water isotopes (18O and D) suggests insignificant correlation between the two, whereas previous drip water studies found that isotopically lighter drip waters typically occur during periods of increased drip rates, primarily influenced by the “amount affect” (Cobb et al., 2007). Observation of semi- diurnal variations in drip rates are suggested to be driven by the affect atmospheric tides have on pore water fluid pressures, and were previously observed in a cave in Belgium (Genty and Deflandre, 1998). Unfortunately this is the only other published observation of this phenomenon and it cannot be stated whether this is a common signal. An alternative suggestion for this phenomenon is that the reservoir in the porous limestone bedrock has a long time scale compared to a day, so the pore pressure is the averaged over a long time (days to weeks). When atmospheric pressure is high (high tide), the pressure gradient between the atmosphere and the limestone temporarily increases, increasing the drip rate. Even so, the lack of direct measurements of pore fluid pressure prevents direct correlation between the two. The semi- diurnal variation in drip rate is unrelated to transpiration processes, as the variation in drip rate was a consistent 10% throughout the study period. This study emphasizes the well known fact that transfer functions developed are unique to each cave system, and that proxies established at a site cannot be uncritically applied to other systems (Spotl et al., 2005). However, we do present a novel cave monitoring method to investigate the effects of cave meteorology and air chemistry on geochemical proxies. Collection and analysis of three speleothems from Brooks Quarry Cave, FL indicate there is likely a high fidelity and high resolution paleoclimate record from northwest Florida that can be created from these three samples. U-series dating on sample BC1 indicates it was deposited around D-O event 19, about 65-68 ka (Dansgaard et al., 1993). Radiocarbon ages of samples BC2 and BC3 indicate these two samples may provide a climate record spanning 30 ka to the present, although uncertainties inherent in radiocarbon dating of speleothems prevent direct comparisons to existing climate records until they are absolutely dated via U-series.

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The development of new methods and techniques for this in situ cave monitoring project provides other projects new ways to monitor cave aerochemistry and cave meteorology. In order to create site-specific proxies that can be applied to speleothem paleoclimate records, in situ cave monitoring programs like the one presented here should be created for more accurate interpretations of these records. In northwest Florida, a robust speleothem paleoclimate record should offer insight on the variability of the southeast monsoon and precipitation records. Because of this project, Hollow Ridge Cave is an obvious location to collect speleothems to develop a paleoclimate record.

149

APPENDIX A

HOLLOW RIDGE CAVE RESEARCH FILES

A.1: SCCi Research Agreement. The obligations of both FSU and the SCCi are outlined in this research agreement considering the work at Hollow Ridge Cave.

150

151

152

153

154

155

156

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A.2: MET Station CR1000 Datalogger Program. This program was created using Campbell Scientific‟s software Short Cut, v2.5 and is written in the CRBasic computing language.

'CR1000- MET Station 'Created by Short Cut (2.5) 'Edited 11/25/08 to include Apogee SP-110 Pyranometer

'Declare Variables and Units Public Batt_Volt Public BP_mbar Public Rain_mm Public WS_ms Public WindDir Public AirTC Public RH Public SlrW Public SlrMJ

Units Batt_Volt=Volts Units BP_mbar=mbar Units Rain_mm=mm Units WS_ms=meters/second Units WindDir=Degrees Units AirTC=Deg C Units RH=% Units SlrW=W/m² Units SlrMJ=MJ/m²

'Define Data Tables DataTable(METdata,True,-1) DataInterval(0,15,min,10) Average(1,Batt_Volt,FP2,False) Average(1,BP_mbar,FP2,False) Totalize(1,Rain_mm,FP2,False) WindVector (1,WS_ms,WindDir,FP2,False,0,0,0) FieldNames("WS_ms_S_WVT,WindDir_D1_WVT,WindDir_SD1_WVT") Sample(1,WindDir,FP2) Average(1,AirTC,FP2,False) Sample(1,RH,FP2) Average(1,SlrW,FP2,False) Totalize(1,SlrMJ,IEEE4,False) EndTable

DataTable(Table2,True,-1)

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DataInterval(0,1440,Min,10) Minimum(1,Batt_Volt,FP2,False,False) EndTable

'Main Program BeginProg Scan(15,min,1,0) 'Default Datalogger Battery Voltage measurement Batt_Volt: Battery(Batt_Volt) 'CS100 Barometric Pressure Sensor measurement BP_mbar: PortSet(1,1) VoltSE(BP_mbar,1,mV2500,1,1,0,_60Hz,0.2,600.0) BP_mbar=BP_mbar*1.0 'TE525/TE525WS Rain Gauge measurement Rain_mm: PulseCount(Rain_mm,1,1,2,0,0.254,0) '03001 Wind Speed & Direction Sensor measurements WS_ms and WindDir: PulseCount(WS_ms,1,2,1,1,0.75,0.2) If WS_ms<0.21 Then WS_ms=0 BrHalf(WindDir,1,mV2500,2,1,1,2500,True,0,_60Hz,355,0) If WindDir>=360 Then WindDir=0 'HMP45C (6-wire) Temperature & Relative Humidity Sensor measurements AirTC and RH: PortSet(9,1) Delay(0,150,mSec) VoltSE(AirTC,1,mV2500,3,0,0,_60Hz,0.1,-40.0) VoltSE(RH,1,mV2500,4,0,0,_60Hz,0.1,0) PortSet(9,0) If RH>100 And RH<108 Then RH=100 'CS300 Pyranometer measurements SlrMJ and SlrW: VoltSE(SlrW,1,mV250,5,1,0,_60Hz,1,0) If SlrW<0 Then SlrW=0 SlrMJ=SlrW*0.000075 SlrW=SlrW*5.0

'Call Data Tables and Store Data CallTable(METdata) CallTable(Table2) NextScan EndProg

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A.3: Cave Station 1 CR1000 Datalogger Program. This program was created using Campbell Scientific‟s software CRBasic Editor, and is written in the CRBasic programming language. It includes notes on the evolution of the program to its final stage.

'Program for Hollow Ridge Cave internal instrumentation 'includes: CS100 barometer, WindSonic1 anemometer, HMP45C T/RH, TE525 rain gauge, LiCor 820 CO2 monitor, and A6REL relay driver 'Measure sensors every 30 minutes, taking average values over the 30 minutes 'Have the A6REL power the Li820 starting at 18-30 and 48-59 minutes into the hour

'CR1000 'Created by Short Cut (2.5), Andrew Kowalczk(FSU), and Bart Nef (CSI) '10/8/07

'MODIFIED 6/12/08 FOR STATION TETSTING! 'ADDITION OF MEASURING CELLTEMP ON LICORS 'MEAZSURING 2 LICORS AT SAME TIMES 'CHANGING CO2 FROM SAMPLE TO AVERAGE 'LEAVE THE LICOR ON, TURN PUMP ON AND OFF 'MEASURE EVERY 15 MINUTES

'MODIFIED 061708 FOR DEPLOYMENT 'ONLY 1 LICOR PRESENT! 'changed to measuring 30 minutes again!

'MODIFIED 030909 'ADDED ANOTHER TEMP SENSOR - T107

'CS100 Wiring 'Red: 12V 'Green: C3 'Blue: SE1 (Blue 1) 'Yellow: Any Ground Symbol 'Black: Any G 'Clear: Any G

'HMP45C Wiring 'Red: SW-12 'Yellow: SE2 (Blue 2) 'Blue: SE3 (Blue 3) 'White: Any Ground Symbol 'Black: Any G 'Clear: Any G

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'Gill WindSonic 'Red: SW-12 'Green: C1 'White: C2 'Black: Any G 'Clear: Any G

'TE525MM Tipping Rain Gage 'Black: P1 'White: Any G 'Clear: Any G

'LiCor #1 'LiCor- CO2 Sensor (DAC1) 'Voltage High: SE5 (Blue 5) 'Voltage Low: SE6 (Blue 6) 'Voltage Ground: Any Ground Symbol

'LiCor #1 'LiCor- CellTemp (DAC2) 'Voltage High: SE7 (Blue 7) 'Voltage Low: SE8 (Blue 8)

'A6REL12 (CONTROLLER) 'A6REL12 Control: C4

'T107 'Black: EX1 'Red: SE9 (Blue 9) 'Clear: Ground 'Purple: Ground

'Declare Variables and Units Public Batt_Volt Public BP_mbar Public Rain_mm Public AirTC Public RH Public CO2 Public CellTemp Public wind_direction Public wind_speed Public diag Public wind_speed_run_mean Public T107_C

161

Units Batt_Volt=Volts Units BP_mbar=mbar Units Rain_mm=mm Units AirTC=Deg C Units RH=% Units CO2=mV Units CellTemp=mV Units wind_direction = degrees Units wind_speed = m/s Units diag = unitless Units wind_speed_run_mean = m/s Units T107_C=Deg C

Dim in_bytes_str As String * 18 Dim in_bytes_sub_str(4) As String * 6 Dim nmbr_bytes_rtrnd Dim disable_flag As Boolean Dim one Units one = samples

'Variables and constant value to bring in datalogger time and control one relay on a A6REL-12. Public SensorPwr As Boolean 'Use this variable to control the switching on the A6REL- 12. Const On = True Const Off = False

Public rTime(9) 'declare as public and dimension rTime to 9 Alias rTime(1) = Year 'assign the alias Year to rTime(1) Alias rTime(2) = Month 'assign the alias Month to rTime(2) Alias rTime(3) = DOM 'assign the alias Day to rTime(3) Alias rTime(4) = Hour 'assign the alias Hour to rTime(4) Alias rTime(5) = Minute 'assign the alias Minute to rTime(5) Alias rTime(6) = Second 'assign the alias Second to rTime(6) Alias rTime(7) = uSecond 'assign the alias uSecond to rTime(7) Alias rTime(8) = WeekDay 'assign the alias WeekDay to rTime(8) Alias rTime(9) = Day_of_Year 'assign the alias Day_of_Year to rTime(9)

162

Totalize (1,one,IEEE4,disable_flag) FieldNames ("n_TOT") Totalize (1,one,IEEE4,diag<>1) FieldNames ("diag_1_TOT") Totalize (1,one,IEEE4,diag<>2) FieldNames ("diag_2_TOT") Totalize (1,one,IEEE4,diag<>4) FieldNames ("diag_4_TOT") Totalize (1,one,IEEE4,diag<>8) FieldNames ("diag_8_TOT") Totalize (1,one,IEEE4,diag<>9) FieldNames ("diag_9_TOT") Totalize (1,one,IEEE4,diag<>10) FieldNames ("diag_10_TOT") Totalize (1,one,IEEE4,diag<>NaN) FieldNames ("no_data_TOT") Sample(1,Batt_Volt,FP2) Average(1,BP_mbar,FP2,False) Totalize(1,Rain_mm,FP2,False) Average(1,AirTC,FP2,False) Average (1,RH,FP2,False) Sample (1,CO2,FP2) Average (1,CellTemp,FP2,False) Average(1,T107_C,FP2,False) EndTable

'Main Program BeginProg one = 1 SerialOpen (Com1,38400,3,0,145) 'SerialOpen buffer size is number of bytes * five.

Scan(1,Min,1,0) 'Default Datalogger Battery Voltage measurement Batt_Volt: Battery(Batt_Volt) RealTime (rTime())

'Set A6REL-12 via time. Only make comparison against time of sensor is already off. If SensorPwr = Off Then If Minute >= 18 AND Minute <= 30 Then SensorPwr = On 'Set A6REL-12 via time. If Minute = 48 AND Minute <= 59 Then SensorPwr = On EndIf

'CS100 Barometric Pressure Sensor measurement BP_mbar:

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'CS100 Connected to C3. Power the sensor on, wait 2 seconds, take a measurement, 'power the sensor back off. PortSet(3,1) Delay(0,2,Sec) VoltSe(BP_mbar,1,mV2500,1,1,0,_60Hz,0.2,605.480) BP_mbar=BP_mbar*1.0 PortSet(3,0)

'TE525MM Rain Gauge measurement Rain_mm: PulseCount(Rain_mm,1,1,2,0,0.1,0)

'Generic Differential Voltage measurements LiCor #1-CO2: VoltDiff(CO2,1,mV5000,3,True,0,_60Hz,1.0,0.0) 'Generic Differential Voltage measurements LiCor #1-CellTemp: VoltDiff(CellTemp,1,mV5000,4,True,0,_60Hz,1.0,0.0)

'HMP45C (6-wire) Temperature & Relative Humidity Sensor measurements AirTC and RH: PortSet(9,1) 'Turns on HMP45C AND Gill WindSonic! Delay(0,150,mSec) VoltSe(AirTC,1,mV2500,2,0,0,_60Hz,0.1,-40.0) VoltSe(RH,1,mV2500,3,0,0,_60Hz,0.1,0) If RH>100 AND RH<108 Then RH=100

'107 Temperature Probe measurement T107_C: Therm107(T107_C,1,9,1,0,_60Hz,1.0,0.0)

'Get data from WindSonic. Delay (0,6,Sec) SerialInRecord (Com1,in_bytes_str,&h02,0,&h03,nmbr_bytes_rtrnd,01) SplitStr (in_bytes_sub_str(1),in_bytes_str,",",4,6) 'Parse out the data using the commas as a delimiter. wind_direction = in_bytes_sub_str(1) wind_speed = in_bytes_sub_str(2) diag = in_bytes_sub_str(4) disable_flag = (wind_direction=NaN) OR (diag<>0) PortSet (9 ,0) 'Turns off HMP45C & Gill Windsonic!

' 'Allow data into the running mean only if there are not diagnostic flags set. ' 'A 20 sample running mean on 2 Hz data is a 10 second running mean. ' If ( diag=0 ) Then ( AvgRun (wind_speed_run_mean,1,wind_speed,20) )

'Call Data Tables and Store Data CallTable(data1)

164

If data1.output(1,1) Then SensorPwr = Off

'Allows manual control of the A6REL-12 If SensorPwr = On Then PortSet (4 ,1 ) 'Turn channel 1 on the A6REL-12 ON. Else PortSet (4 ,0) 'Turn channel 1 on the A6REL-12 OFF. EndIf

NextScan EndProg

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A.4: Cave Station 2 CR1000 Datalogger Program. This program was created using Campbell Scientific‟s software CRBasic Editor, and is written in the CRBasic programming language. It includes notes on the evolution of the program to its final stage.

'Site 2

'Program for Hollow Ridge Cave internal instrumentation 'includes: HMP45C T/RH, TE525 (6" opening) rain gauge, LiCor 820 CO2 monitor 'Measures T, RH, Rn, [CO2] 'Measure sensors every 30 minutes, taking average values over the 30 minutes 'does not use A6REL12, but just a regular relay switch 'Licor runs continuously 'Pump runs continuously (10/28/07)

'CR1000 'Created by Short Cut (2.5), Andrew Kowalczk(FSU), and Bart Nef (CSI) '10/16/07 'modified 11/2/07 to switch HMP45C to MET station and T107 temp sensor to cave station2

'Declare Variables and Units Public Batt_Volt Public BP_mbar Public Rain_mm Public T107_C Public CO2 Public wind_direction Public wind_speed Public diag Public wind_speed_run_mean

Units Batt_Volt=Volts Units BP_mbar=mbar Units Rain_mm=mm Units T107_C=Deg C Units CO2=mV Units wind_direction = degrees Units wind_speed = m/s Units diag = unitless Units wind_speed_run_mean = m/s

Dim in_bytes_str As String * 18 Dim in_bytes_sub_str(4) As String * 6 Dim nmbr_bytes_rtrnd

166

Dim disable_flag As Boolean Dim one Units one = samples

'Define Data Tables DataTable(data1,True,-1) DataInterval(0,30,Min,10) WindVector (1,wind_speed,wind_direction,IEEE4,disable_flag,0,0,0) FieldNames ("mean_wind_speed,mean_wind_direction,std_wind_dir,Batt_Volt,WS_ms_cup,WindDir_cup,R ain_mm") Average (1,wind_speed_run_mean,IEEE4,FALSE) Totalize (1,one,IEEE4,disable_flag) FieldNames ("n_TOT") Totalize (1,one,IEEE4,diag<>1) FieldNames ("diag_1_TOT") Totalize (1,one,IEEE4,diag<>2) FieldNames ("diag_2_TOT") Totalize (1,one,IEEE4,diag<>4) FieldNames ("diag_4_TOT") Totalize (1,one,IEEE4,diag<>8) FieldNames ("diag_8_TOT") Totalize (1,one,IEEE4,diag<>9) FieldNames ("diag_9_TOT") Totalize (1,one,IEEE4,diag<>10) FieldNames ("diag_10_TOT") Totalize (1,one,IEEE4,diag<>NaN) FieldNames ("no_data_TOT") Sample(1,Batt_Volt,FP2)

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Average(1,BP_mbar,FP2,False) Totalize(1,Rain_mm,FP2,False) Average(1,T107_C,FP2,False) Sample (1,CO2,FP2) EndTable

'Main Program BeginProg one = 1 SerialOpen (Com1,38400,3,0,145) 'SerialOpen buffer size is number of bytes * five.

Scan(1,Min,1,0) 'Default Datalogger Battery Voltage measurement Batt_Volt: Battery(Batt_Volt) RealTime (rTime())

'Set A6REL-12 via time. Only make comparison against time of sensor is already off. If SensorPwr = Off Then If Minute >= 24 AND Minute <= 30 Then SensorPwr = On 'Set A6REL-12 via time. If Minute >= 53 AND Minute <= 59 Then SensorPwr = On EndIf

'CS100 Barometric Pressure Sensor measurement BP_mbar: 'CS100 Connected to C3. Power the sensor on, wait 2 seconds, take a measurement, 'power the sensor back off. PortSet(3,1) Delay(0,2,Sec) VoltSe(BP_mbar,1,mV2500,1,1,0,_60Hz,0.2,605.480) BP_mbar=BP_mbar*1.0 PortSet(3,0)

'TE525 (regular 6" opening) Rain Gauge measurement Rain_mm: PulseCount(Rain_mm,1,1,2,0,0.254,0)

'Generic Differential Voltage measurements CO2: VoltDiff(CO2,1,mV5000,3,True,0,_60Hz,1.0,0.0)

PortSet(9,1) 'Turns on T107 AND Gill WindSonic! Delay(0,150,mSec) '107 Temperature Probe measurement T107_C: Therm107(T107_C,1,3,1,0,_60Hz,1.0,0.0)

'Get data from WindSonic.

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Delay (0,6,Sec) SerialInRecord (Com1,in_bytes_str,&h02,0,&h03,nmbr_bytes_rtrnd,01) SplitStr (in_bytes_sub_str(1),in_bytes_str,",",4,6) 'Parse out the data using the commas as a delimiter. wind_direction = in_bytes_sub_str(1) wind_speed = in_bytes_sub_str(2) diag = in_bytes_sub_str(4) disable_flag = (wind_direction=NaN) OR (diag<>0) PortSet (9 ,0) 'Turns off HMP45C & Gill Windsonic!

'Call Data Tables and Store Data CallTable(data1) If data1.output(1,1) Then SensorPwr = Off

'Allows manual control of the A6REL-12 If SensorPwr = On Then PortSet (4 ,1 ) 'Turn channel 1 on the A6REL-12 ON. Else PortSet (4 ,0) 'Turn channel 1 on the A6REL-12 OFF. EndIf

NextScan EndProg

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Figure A.1: Wiring and Plumbing Diagram for MET Station. The CR1000 Datalogger is powered by a 12V/25 Ah SLA battery, and in turns supplies power to all attached sensors. Each sensor communicates with the datalogger via the signal cable, and the inputs are labeled on the diagram. The exhaust tube for the barometer is the brown line. All power cables are colored red (positive) and black (negative/ground).

170

Figure A.2: Wiring Diagram for Cave Station 1. The CR1000 Datalogger is powered by a 12V/25 Ah SLA battery, and in turns supplies power to all attached sensors. The RAD7 has a separate battery supply. Each sensor communicates with the datalogger via the signal cable, and the inputs are labeled on the diagram by the datalogger. All power cables are colored red (positive) and black (negative/ground).

171

Figure A.3: Plumbing Diagram for Cave Station 1. The Li820, RAD7 and barometer require plumbing to correctly route air for sampling. The exhaust tube for the barometer is the brown line and requires no air movement. The Li820 requires a pump to flush air into the sample chamber. Cave air is brought in through a pump to the inlet side of the Li820, travels through the sample chamber, and then directly to the cave by the outlet port. The air is not required to be dry because the Li820 sample chamber is at 50 C. However, for the RAD7 sample air must be dry. A “drystik” is used to extend the life of the drierite pellets. Air flows into the inlet port of the drystik, through the central nafion tube, and to the drierite tubes. The dry sample air travels from the drierite tubes to the inlet on the RAD7, where it goes to the sample chamber. From the sample chamber, air flows through the outlet to the exhaust side of the drystik, through the outer tube, and then out the exhaust port of the drystik. The outflowing dry air from the RAD7 pulls moisture from the incoming sample air in the drystik through the nafion membrane.

172

Figure A.4: Wiring Diagram for Cave Station 2. The CR1000 Datalogger is powered by a 12V/25 Ah SLA battery, and in turns supplies power to all attached sensors. The RAD7 has a separate battery supply. Each sensor communicates with the datalogger via the signal cable, and the inputs are labeled on the diagram by the datalogger. All power cables are colored red (positive) and black (negative/ground).

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Figure A.5: Plumbing Diagram for Cave Station 2. The Li820, RAD7 and barometer require plumbing to correctly route air for sampling. The exhaust tube for the barometer is the brown line and requires no air movement. The Li820 requires a pump to flush air into the sample chamber. Cave air is brought in through a pump to the inlet side of the Li820, travels through the sample chamber, and then directly to the cave by the outlet port. The air is not required to be dry because the Li820 sample chamber is at 50 C. However, for the RAD7 sample air must be dry. A “drystik” is used to extend the life of the drierite pellets. Air flows into the inlet port of the drystik, through the central nafion tube, and to the drierite tubes. The dry sample air travels from the drierite tubes to the inlet on the RAD7, where it goes to the sample chamber. From the sample chamber, air flows through the outlet to the exhaust side of the drystik, through the outer tube, and then out the exhaust port of the drystik. The outflowing dry air from the RAD7 pulls moisture from the incoming sample air in the drystik through the nafion membrane.

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Figure A.6: Picture of MET Station at Hollow Ridge Cave. The above ground meteorology station at Hollow Ridge was installed in September 2007

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Figure A.7: Picture of Cave Station 1. Cave Station 1* was deployed in June 2008. Original deployment was in October 2007 in the Ballroom section of the cave. A flooding event resulted in Cave Station 1 being off-line from February 2008 to June 2008.

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Figure A.8: Picture of Cave Station 2. Cave Station 2 was deployed in October 2007 in the Signature Room. Craig Gaffka pictured.

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Table A.1: Hollow Ridge Cave Time Series Data and Headers. Presented here is a representative „snapshot‟ of the continuous time-series data from the study at Hollow Ridge Cave as a guide to the full digital dataset. This snapshot is from November 26, 2008, between 8:30 am and 10:00 am, although the data exist in digital format for the entire study period. Included in the headers for each column are the station location, label, description of measurement or units, how it was obtained, calculations involved, and other comments, in that order. The data in this spreadsheet are time-marked by the synchronized dataloggers at all stations. The next sixteen pages of this table are the headers, description, and the snapshot of the data from 8:30 am to 10:00 am, November 26, 2008.

MET MET Precipitation Precipitation mm total per day day per total mm

sum of previous 24 hours hours 24 of sum previous

0 0 0 0 0 MET MET none

Precipitation Precipitation

mm per 30 minutes minutes 30 mm per

Texas Instruments TR525 TR525 Instruments Texas

none 1021 1022 1022 1022 mbar mbar

MET Station Station MET

CS100 Setra 278 278 Setra CS100 Barometric Pressure Pressure Barometric

Datalogger Datalogger All Stations Stations All TIMESTAMP TIMESTAMP Timestamp from all all from Timestamp 11/26/2008 8:30:00 8:30:00 11/26/2008 8:52:00 11/26/2008 8:55:00 11/26/2008 9:00:00 11/26/2008 9:00:00 11/26/2008 9:10:05 11/26/2008 9:30:00 11/26/2008 9:52:00 11/26/2008 9:55:00 11/26/2008 11/26/2008 10:00:00 10:00:00 11/26/2008 dataloggers set to CST. to set CST. dataloggers

Label Label Station Station

Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units

Calculations involved involved Calculations

178

Table A.1 Continued

0.11 0.11 3.89 7.90 8.63 MET MET none celcius celcius Temperature Temperature Vaisala HMP45C HMP45C Vaisala

0 0 0 0 265 MET MET none degrees (from) (from) degrees Average Wind Direction Direction Wind Average RM Young Wind Sentry 3001 3001 Sentry Wind RM Young

m/s m/s 0.00 0.00 0.00 0.00 0.26 MET MET none Average Wind Speed Speed Wind Average RM Young Wind Sentry 3001 3001 Sentry Wind RM Young

0 0 0 0 0 MET MET mm total total mm Cumulative Total Precipitation Precipitation Total Cumulative sum of all previous measurements measurements previous of sum all

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

179

Table A.1 Continued

MET MET mbar mbar 6.159002 6.159002 8.068702 calculated calculated 10.645570 10.645570 11.189186 Saturated vapor pressure pressure vapor Saturated es = 6.11*10^(7.5T/(237.7+T)) 6.11*10^(7.5T/(237.7+T)) es =

MET MET none MJ/m2 MJ/m2 0.001148177 0.001148177 0.003948572 0.006928164 0.007193395 Total Solar Flux Flux Solar Total Apogee SP-110 Pyranometer Pyranometer SP-110 Apogee

MET MET none 76.55 76.55 263.2 461.9 479.6 W/m2 W/m2 Solar Flux Density Density Flux Solar Apogee SP-110 Pyranometer Pyranometer SP-110 Apogee

% % 93.2 93.2 78.6 66.1 MET MET none 100.0 100.0 Vaisala HMP45C HMP45C Vaisala Relative Humidity Humidity Relative

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

180

Table A.1 Continued ta))) ta)))

MET MET kelvin kelvin calculated calculated 273.266248 273.266248 277.047726 281.054719 281.787726 Virtual Temp Temp Virtual Tv = Tv((T+273.15)/(1-0.379*((6.11*10^(7.5*Td)/(237.7+Td))/Ps =

MET MET celcius celcius 0.110000 0.110000 2.892836 4.404354 2.654388 calculated calculated Dewpoint Temp Temp Dewpoint Td = (237.7log((es*RH)/611))/(7.5-log((es*RH)/611)) Td = (237.7log((es*RH)/611))/(7.5-log((es*RH)/611))

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

181

Table A.1 Continued

299 298 298 297 none CAVE 1 CAVE 1 degrees (from) (from) degrees Airflow Direction Airflow Direction WindSonic 2D Sonic Anemometer Anemometer Sonic 2D WindSonic

98 91 107 105 cm/s cm/s CAVE 1 CAVE 1 calculated calculated Airflow Speed Speed Airflow Airflow Speed(m/s) *100 *100 Speed(m/s) Airflow

m/s m/s 1.07 1.07 1.05 0.98 0.91 none CAVE 1 CAVE 1 Airflow Speed Speed Airflow WindSonic 2D Sonic Anemometer Anemometer Sonic 2D WindSonic

MET MET Kg/m3 Kg/m3 calculated calculated Air Density Air Density Rd= 287.05 287.05 Rd= 1.28506065 1.28506065 1.26673956 1.301568617 1.301568617 1.263444422 ρair = P/(Rd*Tv) = ρair

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

182

Table A.1 Continued

mbar mbar CAVE 1 CAVE 1 calculated calculated 17.67617677 17.67617677 17.68749072 17.69881102 17.73281005 Saturated vapor pressure pressure vapor Saturated es = 6.11*10^(7.5T/(237.7+T)) 6.11*10^(7.5T/(237.7+T)) es =

820 2 2

336 338 338 328 CO none ppmv ppmv CAVE 1 CAVE 1 LiCor-

% % 99.4 99.4 99.5 99.5 99.6 none CAVE 1 CAVE 1 Vaisala HMP45C HMP45C Vaisala Relative Humidity Humidity Relative

none 15.58 15.58 15.59 15.60 15.63 celcius celcius CAVE 1 CAVE 1 Temperature Temperature Vaisala HMP45C HMP45C Vaisala

none 1029 1030 1030 1030 mbar mbar CAVE 1 CAVE 1 rometric Pressure Pressure rometric CS100 Setra 278 278 Setra CS100 Ba

ons

Datalogger Datalogger All Stati All TIMESTAMP TIMESTAMP Timestamp from all all from Timestamp 11/26/2008 8:30:00 8:30:00 11/26/2008 8:52:00 11/26/2008 8:55:00 11/26/2008 9:00:00 11/26/2008 9:00:00 11/26/2008 9:10:05 11/26/2008 9:30:00 11/26/2008 9:52:00 11/26/2008 9:55:00 11/26/2008 11/26/2008 10:00:00 10:00:00 11/26/2008 dataloggers set to CST. to set CST. dataloggers

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

183

Table A.1 Continued ta)))

kelvin kelvin CAVE 1 CAVE 1 calculated calculated Virtual Temp Temp Virtual 290.6106592 290.6106592 290.6220007 290.6332783 290.6690247 Tv = Tv((T+273.15)/(1-0.379*((6.11*10^(7.5*Td)/(237.7+Td))/Ps =

celcius celcius CAVE 1 CAVE 1 calculated calculated 15.48598615 15.48598615 15.51168343 15.52167725 15.56735452 Dewpoint Temp Temp Dewpoint Td = (237.7log((es*RH)/611))/(7.5-log((es*RH)/611)) Td = (237.7log((es*RH)/611))/(7.5-log((es*RH)/611))

Label Label Station Station involved involved Calculations Calculations Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units

184

Table A.1 Continued

1)  t  

฀ -980.6 -980.6 2528.8 2528.8 Cave 1 Cave calculated calculated (dpm/m3)/  222Rn(n)-222Rn(n- Change in 222Rn (dc/dt) (dc/dt) in 222Rn Change

222

8102.5 8102.5 Cave 1 Cave dpm/m3 dpm/m3 10631.3 calculated calculated Radon- 222Rn(dpm/l)*1000 222Rn(dpm/l)*1000

1.4 1.4 1.6 none dpm/L dpm/L Cave 1 Cave Durridge Co RAD7 RAD7 Co Durridge Radon 2-sigma error error 2-sigma Radon

222

8.1 8.1 10.6 10.6 none dpm/L dpm/L Cave 1 Cave Radon- Durridge Co RAD7 RAD7 Co Durridge

Kg/m3 Kg/m3 CAVE 1 CAVE 1 calculated calculated Air Density Air Density Rd= 287.05 287.05 Rd= 1.233477281 1.233477281 1.234627812 1.234579904 1.234428076 ρair = P/(Rd*Tv) = ρair

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

185

Table A.1 Continued

none 19.53 19.53 19.54 19.53 19.53 celcius celcius CAVE 2 CAVE 2 Temperature Temperature Vaisala HMP45C and CS T107 T107 CS and HMP45C Vaisala ) ) 

222

 hrs 1/ Cave 1 Cave 0.25114 0.25114 0.30511 calculated calculated Air Turnover Time ( Time Air Turnover

222) 

1/hrs 1/hrs Cave 1 Cave 3.98192 3.98192 3.27755 calculated calculated -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) Air Turnover Rate ( Rate Air Turnover [(Φ222Rn*A/V) [(Φ222Rn*A/V)

8592.7 8592.7 9366.9 Cave 1 Cave dpm/m3 dpm/m3 calculated calculated Average 222Rn (Cavg) (Cavg) 222Rn Average [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2

Label Label Station Station involved involved Calculations Calculations Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units

186

Table A.1 Continued

1)  t  

฀ 5165.2 5165.2 Cave 2 Cave -1844.4 -1844.4 calculated calculated (dpm/m3)/  222Rn(n)-222Rn(n- Change in 222Rn (dc/dt) (dc/dt) in 222Rn Change

222

Cave 2 Cave dpm/m3 dpm/m3 58089.9 56245.5 calculated calculated Radon- 222Rn(dpm/l)*1000 222Rn(dpm/l)*1000

3.4 3.4 3.3 none dpm/L dpm/L Cave 2 Cave Durridge Co RAD7 RAD7 Co Durridge Radon 2-sigma error error 2-sigma Radon

222

58.1 58.1 56.2 none dpm/L dpm/L Cave 2 Cave Radon- Durridge Co RAD7 RAD7 Co Durridge

820

442 442 442 442 CO2 CO2 none ppmv ppmv CAVE 2 CAVE 2 LiCor-

% % none CAVE 2 CAVE 2 Vaisala HMP45C HMP45C Vaisala Relative Humidity Humidity Relative

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

187

Table A.1 Continued ) ) 

222

 hrs 1/ Cave 2 Cave 1.646902 1.646902 2.124515 calculated calculated Air Turnover Time ( Time Air Turnover

222) 

1/hrs 1/hrs Cave 2 Cave 0.607201 0.607201 0.470696 calculated calculated -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) Air Turnover Rate ( Rate Air Turnover [(Φ222Rn*A/V) [(Φ222Rn*A/V)

Cave 2 Cave dpm/m3 dpm/m3 57167.7 58828.0 calculated calculated Average 222Rn (Cavg) (Cavg) 222Rn Average [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

188

Table A.1 Continued

820

none ppmv ppmv 336.8 336.8 LiCor- CO2 Exchange Exchange CO2 Cave Station 1 CO2 Concentration Concentration 1 CO2 Station Cave  air-CS1 

kg/m3 kg/m3 calculated calculated 0.068091336 0.068091336 0.050432838 0.032159656 0.029016346 air-MET - air-MET  Air Density Difference Difference Air Density MET(air density) - Cave Station 1(air density) density) 1(air Station Cave - density) MET(air

463 none Drip Rate Rate Drip Ballroom Ballroom Total Drips per Hour Hour per Total Drips Driptych Stalagmate Drip Counter Counter Drip Stalagmate Driptych

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

189

Table A.1 Continued m ppm to to m ppm

mg/m3 mg/m3 827.64 CO2 Exchange Exchange CO2 CO2 concentration in mg/m3 in concentration CO2 ie: 893.16+684 = 1577.16 mg/m3 mg/m3 = 1577.16 ie: 893.16+684 add column AX + 380 ppmv converted to mg/m3 (684 mg/m3) (684 mg/m3 to converted ppmv 380 + AX column add subtracted low atm, add real atm (380 ppm), converted fro converted ppm), (380 atm real add atm, low subtracted

mg/m3 mg/m3 143.64 calculated calculated CO2 Exchange Exchange CO2 also known as (Ccave-Catm) (Ccave-Catm) as known also use ppmv-257.2 ppmv, then convert to mg/m3 mg/m3 to convert then ppmv, use ppmv-257.2 [CO2(ppmv)-257.2(baseline from LiCor)]*(44.01/24.45) LiCor)]*(44.01/24.45) from [CO2(ppmv)-257.2(baseline Net CO2 Export (CO2 content above atmospheric values) atmospheric above content (CO2 Export CO2 Net

CST. CST. 10:00:00 10:00:00 Datalogger Datalogger 11/26/2008 11/26/2008 All Stations Stations All TIMESTAMP TIMESTAMP dataloggers set to set dataloggers Timestamp from all all from Timestamp 11/26/2008 8:30:00 8:30:00 11/26/2008 8:52:00 11/26/2008 8:55:00 11/26/2008 9:00:00 11/26/2008 9:00:00 11/26/2008 9:10:05 11/26/2008 9:30:00 11/26/2008 9:52:00 11/26/2008 9:55:00 11/26/2008

Label Label Station Station involved involved Calculations Calculations Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units

190

Table A.1 Continued

mg/m3 hr hr mg/m3 calculated calculated 571.9623869 571.9623869 CO2 Exchange Exchange CO2 ie: column AW*AZ AW*AZ column ie: NET CO2 exchange exchange NET CO2 Net CO2 Export *Air Turnover Rate Rate Turnover *Air Export CO2 Net

222) 

1/hrs 1/hrs calculated calculated 3.98191581 3.98191581 -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg) CO2 Exchange Exchange CO2 Air Turnover Rate ( Rate Air Turnover [(Φ222Rn*A/V) [(Φ222Rn*A/V) 

1)  t (mg/m3)

฀  7.56 7.56 calculated calculated CO2 Exchange Exchange CO2 (CO2)/ CO2(n)-CO2(n-  Change in CO2 (dc/dt) (dc/dt) in CO2 Change

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

191

Table A.1 Continued

mol/hr mol/hr calculated calculated 1.949428721 1.949428721 CO2 Exchange Exchange CO2 Export CO2 Net Net CO2 Export[mmol/hr] /1000 /1000 Export[mmol/hr] CO2 Net (also net CaCO3 ppt/diss in mol/hr) mol/hr) in ppt/diss CaCO3 net (also

mmol/hr mmol/hr calculated calculated 1949.428721 1949.428721 CO2 Exchange Exchange CO2 Export CO2 Net Net CO2 Export[mg/hr] /44.01 /44.01 Export[mg/hr] CO2 Net (also net CaCO3 ppt/diss in mmol/hr) mmol/hr) in ppt/diss CaCO3 net (also

mg/hr mg/hr calculated calculated BA*150 m3 m3 BA*150 85794.35803 85794.35803 CO2 Exchange Exchange CO2 Export CO2 Net chamber vol = 150 m3 150 vol = chamber Net CO2 Exchange *Chamber Volume Volume *Chamber Exchange CO2 Net

ons

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

192

Table A.1 Continued

calculated calculated mmol/m2 hr hr mmol/m2 1.463107846 1.463107846 CO2 Transport Transport CO2 CO2 Transport[mg/m2 hr]/44.01 hr]/44.01 Transport[mg/m2 CO2 CO2 Transport/Emanation Rate from the Cave Surfaces Surfaces Cave the from Rate Transport/Emanation CO2  )+dc/dt)*(V/A) 

or mg/m2 hr mg/m2 calculated calculated 64.39137632 64.39137632 CO2 Transport Transport CO2 (((AW)*AZ)+AY)*(1/9) (((AW)*AZ)+AY)*(1/9) (((AX-684mg/m3)*AZ)+AY)*(1/9) (((AX-684mg/m3)*AZ)+AY)*(1/9) co2=(((Ccave-Catm)*  CO2 Transport/Emanation Rate from the Cave Surfaces Surfaces Cave the from Rate Transport/Emanation CO2

Label Label Station Station Obtained How? How? Obtained Other Comments Comments Other Description/Units Description/Units Calculations involved involved Calculations

193

Table A.2: Hollow Ridge CO2 Transect Data. 13 Grab samples of cave air were collected and analyzed for CO2 concentration and  C content. Methods are described in Chapter 4.2.3.

Distance 13 Trek Date Location from CO2 concentration 1/CO2  C value Entrance D (ppmv) (‰ VPDB) 5/9/2007 Entrance Chamber 25 m 556 0.001798238 -13.17 Gonzo 80 m 594 0.001682935 -14.75 Sump 110 m 699 0.001431025 -15.41 Sewers 150 m 827 0.001209629 -15.55 Signature Room 175 m 752 0.001330318 -15.98 8/8/2007 Entrance Chamber 25 m 734 0.001361841 -14.9 Gonzo 80 m 4805 0.000208117 -19.955 Sump 110 m 1281 0.00078064 -21.125 Sewers 150 m 13638 7.33245E-05 -21.465 Signature Room 175 m 899 0.001112842 -16.88 10/12/2007 Entrance Chamber 25 m 770 0.001298701 -15.79 Gonzo 80 m 601 0.001663894 -13.89 Sump 110 m 897 0.001114827 -17.59 Sewers 150 m 985 0.001015228 -18.83 Signature Room 175 m 1780 0.000561798 -20.08 7/2/2008 Entrance Chamber 25 m 867 0.001153243 -15.767 Gonzo 80 m 2524 0.000396275 -19.001 Sump 110 m 2691 0.000371568 -19.262 Sewers 150 m 4042 0.000247427 -20.066 Signature Room 175 m 3921 0.00025507 -19.784 7/16/2008 Entrance Chamber 25 m 1852 0.000539909 -18.926 Gonzo 80 m 4212 0.000237423 -20.285 Sump 110 m 3287 0.00030421 -20.024 Sewers 150 m 7651 0.000130704 -21.103 Signature Room 175 m 1899 0.000526621 -19.638 10/15/2008 Entrance Chamber 25 m 787 0.00126989 -16.087 Gonzo 80 m 1320 0.000757818 -19.129 Sump 110 m 1695 0.000589876 -20.395 Sewers 150 m 5230 0.000191223 -21.664 Signature Room 175 m 1120 0.00089266 -18.383 10/29/2008 Entrance Chamber 25 m 512 0.001951303 -11.875 Gonzo 80 m 469 0.00213005 -10.008 Sump 110 m 531 0.001883536 -12.51 Sewers 150 m 863 0.001158414 -16.616 Signature Room 175 m 562 0.00177948 -14.235 10/15/2008 Entrance Chamber 25 m 941 0.001062699 -14.9 (re-run) Gonzo 80 m 1490 0.000671141 -17.7 Sump 110 m 1829 0.000546747 -19.15 Sewers 150 m 5284 0.000189251 -20.9 Signature Room 175 m 1281 0.00078064 -16.9 10/29/2008 Entrance Chamber 25 m 696 0.001436782 -11.6 (re-run) Gonzo 80 m 778 0.001285347 -8.5

194

Table A.2 Continued

 Distance  13 Trek Date Location from CO2 concentration 1/CO2  C value Entrance D (ppmv) (‰ VPDB) 10/29/2008 Sump 110 m 683 0.001464129 -11.3 Sewers 150 m 1009 0.00099108 -15.1 Signature Room 175 m 723 0.001383126 -13.6 11/25/2008 Entrance Chamber 25 m 586 0.001706485 -10.41 Gonzo 80 m 679 0.001472754 -11.789 Sump 110 m 719 0.001390821 -12.173 Sewers 150 m 749 0.001335113 -13.358 Signature Room 175 m 1062 0.00094162 -16.105 12/16/2008 Entrance Chamber 25 m 873 0.001145475 -15 1/10/2009 Entrance Chamber 25 m 677 0.001477105 -11.763 Gonzo 80 m 760 0.001315789 -12.946 Sump 110 m 633 0.001579779 -12.265 Sewers 150 m 737 0.001356852 -12.813 Signature Room 175 m 1018 0.000982318 -15.663 1/24/2009 Entrance Chamber 25 m 704 0.001420455 -10.829 Gonzo 80 m 867 0.001153403 -14.838 Sump 110 m 712 0.001404494 -10.15 Sewers 150 m 1455 0.000687285 -15.843 Signature Room 175 m 782 0.001278772 -13.596 3/7/2009 Soil Gas Outside 2427 0.000412031 -19.1 Entrance D, breathing out Outside 837 0.001194743 -12.23 4/11/2009 Forest Canopy Outside 457 0.002188184 -6.807 Soil Gas Outside 3811 0.000262398 -20.504

195

Table A.3: Hollow Ridge Cave 222Rn Transect Data. Three transects were completed in Hollow Ridge Cave by hand-carrying a RAD7 to measure cave air 222Rn concentrations in various sections of the cave. Each transect is color-coded. Please see Chapter 4.2.3 and 4.3.1 for methods and analyses of these transects.

Transect #1 5/9/2007 Transect #2 8/8/2007 Transect #3 10/12/2007

Distance from 222Rn Distance from 222Rn Distance from 222Rn Entrance D (m) (dpm/l) Entrance D (m) (dpm/l) Entrance D (m) (dpm/l)

0 1.0647 1.00E-05 1.2308 0 1.2066 0 0 1.00E-05 6.096 1.2066 0 0 1.00E-05 12.192 6.0332 0 0 1.00E-05 3.6923 18.288 2.4133 0 0 15.24 24.384 3.6199 7.62 1.0704 45.72 8.6154 30.48 2.4133 15.24 1.0704 76.2 8.6154 45.72 9.6531 15.24 19.268 106.68 19.692 60.96 8.4465 32.004 24.62 103.63 24.615 73.152 10.86 42.672 35.325 91.44 33.231 85.344 15.686 51.816 28.902 76.2 47.023 99.06 21.719 57.912 25.691 91.44 57.846 106.68 28.959 60.96 31.942 99.06 96.522 100.58 32.579 64.008 38.536 114.3 675.53 91.44 34.992 83.82 47.1 121.92 1186.1 73.152 26.546 99.06 50.311 129.54 1358.4 121.92 33.786 115.82 54.593 121.92 1119.2 152.4 32.579 121.92 74.26 124.97 608.44 137.16 26.546 128.02 94.709 99.06 180.41 152.4 37.406 121.92 106.55 76.2 59.723 167.64 31.373 115.82 100.09 91.44 32.579 121.92 92.556 60.96 26.546 124.97 101.17 128.02 104.39 115.82 116.23 106.68 134.18 109.73 119.46 115.82 72.79 121.92 89.327 129.54 83.946 137.16 96.861

196

Table A.4: Hollow Ridge Cave Drip and Sump Water Isotopes. The 18O and D data for drip waters from the Entrance Chamber, Signature Room, Ballroom, and Sump Waters.

Hollow Hollow Ballroom Ballroom Signature Signature Ridge Ridge Location Drip Drip Room Drip Room Drip Sump Sump Entrance Entrance Isotope 18O D 18O D 18O D 18O D Sample Date

10/12/2007 -4.12 -18.60 1/19/2008 -3.48 -14.30 4/30/2008 -3.75 -17.42 5/20/2008 -3.94 -17.28 5/20/2008 -3.96 -17.44 6/7/2008 -3.91 -17.92 6/7/2008 -3.90 -17.99 6/18/2008 -3.90 -16.61 6/18/2008 -3.90 -19.11 7/2/2008 -3.92 -16.53 -4.04 -17.39 7/2/2008 -3.93 -16.11 7/16/2008 -3.93 -16.26 -4.06 -21.18 7/29/2008 -3.97 -17.84 -3.91 -20.55 8/13/2008 -3.08 -11.89 -4.09 -18.08 8/15/2008 -3.33 -13.10 8/22/2008 -4.05 -19.75 8/27/2008 -4.02 -20.21 -4.11 -18.96 9/10/2008 -3.90 -19.48 -4.00 -22.99 9/25/2008 -3.90 -19.73 -4.10 -22.02 10/10/2008 -3.90 -19.04 -4.10 -23.32 10/10/2008 -3.90 -19.40 10/28/2008 -4.00 -17.89 -4.10 -22.96 11/12/2008 -3.90 -18.67 -4.10 -23.46 11/25/2008 -4.00 -19.37 -4.10 -21.66 12/10/2008 -4.00 -21.64 -4.10 -23.15 12/16/2008 -4.30 -22.61 12/16/2008 -4.10 -21.71 12/16/2008 -4.00 -20.77 1/10/2009 -3.90 -18.23 -4.10 -19.81 1/10/2009 -3.90 -20.90 1/23/2009 -3.90 -18.02 -4.00 -19.79

197

Table A.5: Hollow Ridge Cave 222Rn Intensive Data. Presented here is a representative „snapshot‟ of the continuous time-series data from the intensive study conducted November 10-12, 2008 as a guide to the full digital dataset. The first twenty-five data points of the intensive are listed from each station, although the data exist in digital format for the entire study period. Included in the headers for each column are the station location, label, description of measurement or units, how it was obtained, calculations involved, and other comments, in that order. The data in this spreadsheet are time-marked by the synchronized dataloggers at all stations. The intensive study included 5 additional RAD7s placed in the cave, and one outside by the MET Station. There are 8 stations total: Cave Station 1, MET Station, Old Sparkley, Gonzo/Ballroom, Sewers, Sump, Tube, and Cave Station 2. Locations are shown in Figure 4.27. The next 9 pages of this table are the headers, description, and the snapshot of the intensive data from November 10-12, 2008.

None None dpm/l dpm/l RAD7 RAD7 2.5734 2.5734 4.3826 7.2184 6.1872 6.9606 5.4138 6.7028 Old Sparkley Old Sparkley Old Sparkley 222Rn 222Rn Old Sparkley

dpm/l dpm/l 2.214196 2.214196 2.214522 2.276022 2.460562 2.091482 2.645102 MET Station Station MET MET 5-pt box bin bin box 5-pt MET 5-pt moving average average moving 5-pt

None None dpm/l dpm/l RAD7 RAD7 2.4606 2.4606 2.4606 3.6908 1.5379 2.7681 3.3833 0.92108 0.92108 0.92271 MET 222Rn 222Rn MET MET Station Station MET

None None dpm/l dpm/l RAD7 RAD7 37.637 37.637 22.418 13.785 10.993 CS1 222Rn 222Rn CS1 Cave Station 1 1 Station Cave

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

DATE/TIME DATE/TIME 11/10/2008 18:45:00 18:45:00 11/10/2008 19:00:00 11/10/2008 19:15:00 11/10/2008 19:30:00 11/10/2008 19:45:00 11/10/2008 20:00:00 11/10/2008 20:15:00 11/10/2008 20:30:00 11/10/2008 20:45:00 11/10/2008 21:00:00 11/10/2008 21:15:00 11/10/2008 21:30:00 11/10/2008 21:45:00 11/10/2008 22:00:00 11/10/2008 Time of sample (CST) (CST) sample Time of

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

198

Table A.5 continued

dpm/m3 dpm/m3 5748.48 6264.54 6367.66 6290.32 Old Sparkley Old Sparkley [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2 OS 222Rn Average (Cavg) (Cavg) Average OS 222Rn

-257.8 -257.8 568.08 568.08 464.04 103.12 Old Sparkley Old Sparkley D(dpm/m3)/Dt D(dpm/m3)/Dt OS D 222Rn (dc/dt) (dc/dt) OS 222Rn D 222Rn(n)-222Rn(n-

dpm/m3 dpm/m3 5464.44 6032.52 6496.56 6238.76 6341.88 Old Sparkley Old Sparkley 1000*(dpm/l) OS 5-pt box bin dpm/m3 dpm/m3 bin box OS 5-pt

dpm/l dpm/l 5.46444 5.46444 6.03252 6.49656 6.23876 6.34188 Old Sparkley Old Sparkley OS 5-pt box bin bin box OS 5-pt 5-pt moving average average moving 5-pt

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

199

Table A.5 continued

dpm/m3 dpm/m3 8444.82 8730.76 7665.98 7949.86 8162.82 8375.76 8733.84 8875.82 1000*(dpm/l) 1000*(dpm/l) Gonzo/Ballroom Gonzo/Ballroom Gonzo 5-pt box bin dpm/m3 dpm/m3 bin box 5-pt Gonzo

dpm/l dpm/l 8.44482 8.44482 8.73076 7.66598 7.94986 8.16282 8.37576 8.73384 8.87582 Gonzo/Ballroom Gonzo/Ballroom Gonzo 5-pt box bin bin box 5-pt Gonzo 5-pt moving average average moving 5-pt

None None dpm/l dpm/l RAD7 RAD7 5.6684 5.6684 12.422 9.2276 6.3883 8.5178 7.0981 7.0981 10.647 7.4531 9.5825 Gonzo 222Rn 222Rn Gonzo Gonzo/Ballroom Gonzo/Ballroom -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg)

1/hour 1/hour Old Sparkley Old Sparkley 5.695903026 5.695903026 5.243449636 5.271926403 5.279344883 222Rn*t*Cavg) -(- OS 222Rn Turnover Rate Rate Turnover OS 222Rn [(Φ222Rn*A/V)

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

200

Table A.5 continued

None None dpm/l dpm/l 42.94 42.94 RAD7 RAD7 17.763 17.763 38.298 41.006 41.006 38.366 35.653 39.141 31.778 36.041 36.816 39.528 31.715 34.717 Sewers Sewers Sewers 222Rn 222Rn Sewers -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg)

1/hour 1/hour 3.846192201 3.846192201 4.193550049 4.230432301 4.108846757 4.003087201 3.852584347 3.767779858 222Rn*t*Cavg) Gonzo/Ballroom Gonzo/Ballroom -(- Gonzo 222Rn Turnover Rate Rate Turnover 222Rn Gonzo [(Φ222Rn*A/V)

8554.8 8554.8 dpm/m3 dpm/m3 8587.79 8198.37 7807.92 8056.34 8269.29 8804.83 Gonzo/Ballroom Gonzo/Ballroom [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2 Gonzo 222Rn Average (Cavg) (Cavg) Average 222Rn Gonzo

285.94 285.94 283.88 212.96 212.94 358.08 141.98 -1064.78 -1064.78 D(dpm/m3)/Dt D(dpm/m3)/Dt Gonzo/Ballroom Gonzo/Ballroom 222Rn(n)-222Rn(n- Gonzo D 222Rn (dc/dt) (dc/dt) 222Rn D Gonzo

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station involved involved Description Description Calculations Calculations Obtained How? How? Obtained

201

Table A.5 continued

35562 Sewers Sewers dpm/m3 dpm/m3 38262.9 39594.5 38950.1 38111.6 36692.3 36040.8 36273.3 35918.2 35469.5 35213.3 [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2 Sewers 222Rn Average (Cavg) (Cavg) Average 222Rn Sewers

993 310 775 - - 168.6 168.6 587.8 -402.8 -402.8 -294.6 4120.6 4120.6 Sewers Sewers -1457.4 -1457.4 -1845.6 -1485.2 D(dpm/m3)/Dt D(dpm/m3)/Dt 222Rn(n)-222Rn(n- Sewers D 222Rn (dc/dt) (dc/dt) 222Rn D Sewers

35066 Sewers Sewers dpm/m3 dpm/m3 36202.6 40323.2 38865.8 39034.4 37188.8 36195.8 35885.8 36660.8 35175.6 35763.4 35360.6 1000*(dpm/l) 1000*(dpm/l) Sewers 5-pt box bin dpm/m3 dpm/m3 bin box 5-pt Sewers

dpm/l dpm/l 35.066 35.066 Sewers Sewers 36.2026 36.2026 40.3232 38.8658 39.0344 37.1888 36.1958 35.8858 36.6608 35.1756 35.7634 35.3606 Sewers 5-pt box bin bin box 5-pt Sewers 5-pt moving average average moving 5-pt

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

202

Table A.5 continued

Sump Sump 17054 17127 dpm/m3 dpm/m3 15601.8 15255.4 16204.2 15743.2 16279.6 16225.2 15795.4 1000*(dpm/l) 1000*(dpm/l) Sump 5-pt box bin dpm/m3 dpm/m3 bin box Sump 5-pt

dpm/l dpm/l Sump Sump 17.054 17.054 17.127 15.6018 15.6018 15.2554 16.2042 15.7432 16.2796 16.2252 15.7954 Sump 5-pt box bin bin box Sump 5-pt 5-pt moving average average moving 5-pt

None None dpm/l dpm/l Sump Sump RAD7 RAD7 13.192 13.192 20.594 20.005 15.592 15.887 13.557 12.968 18.273 20.336 13.582 16.239 Sump 222Rn Sump 222Rn -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg)

1/hour 1/hour Sewers Sewers 0.89855504 0.89855504 0.764492939 0.764492939 0.879724043 0.852501423 0.924065925 0.936500259 0.934444216 0.970346103 0.924152789 0.949609476 0.955921573 222Rn*t*Cavg) -(- Sewers 222Rn Turnover Rate Rate Turnover 222Rn Sewers [(Φ222Rn*A/V)

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

203

Table A.5 continued

Tube Tube None None dpm/l dpm/l 25.45 25.45 16.64 RAD7 RAD7 7.3282 7.3282 22.473 16.611 18.565 20.066 18.108 22.513 20.066 Tube 222Rn 222Rn Tube -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg)

Sump Sump 1/hour 1/hour 1.946069515 1.946069515 2.129997355 2.182671147 2.058572221 2.115426626 2.048157035 2.054165356 2.108646276 222Rn*t*Cavg) -(- Sump 222Rn Turnover Rate Rate Turnover Sump 222Rn [(Φ222Rn*A/V)

Sump Sump dpm/m3 dpm/m3 17090.5 16364.4 15428.6 15729.8 15973.7 16011.4 16252.4 16010.3 [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2 Sump 222Rn Average (Cavg) (Cavg) Average Sump 222Rn

73 461 - -54.4 -54.4 948.8 948.8 536.4 Sump Sump -346.4 -346.4 -429.8 -1525.2 -1525.2 D(dpm/m3)/Dt D(dpm/m3)/Dt 222Rn(n)-222Rn(n- Sump D 222Rn (dc/dt) (dc/dt) 222Rn Sump D

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

204

Table A.5 continued

Tube Tube 20898 dpm/m3 dpm/m3 19168.6 19518.1 20552.1 20310.7 19380.8 18086.62 18086.62 [222Rn(n)+222Rn(n-1)]/2 [222Rn(n)+222Rn(n-1)]/2 Tube 222Rn Average (Cavg) (Cavg) Average 222Rn Tube

8 8 691 1377 Tube Tube -685.2 -685.2 -489.4 -1370.4 -1370.4 2155.96 2155.96 D(dpm/m3)/Dt D(dpm/m3)/Dt 222Rn(n)-222Rn(n- Tube D 222Rn (dc/dt) (dc/dt) 222Rn D Tube

Tube Tube 20066 dpm/m3 dpm/m3 19164.6 19172.6 19863.6 21240.6 20555.4 18695.6 17008.64 17008.64 1000*(dpm/l) 1000*(dpm/l) Tube 5-pt box bin dpm/m3 dpm/m3 bin box 5-pt Tube

Tube Tube dpm/l dpm/l 20.066 20.066 19.1646 19.1646 19.1726 19.8636 21.2406 20.5554 18.6956 17.00864 17.00864 Tube 5-pt box bin bin box 5-pt Tube 5-pt moving average average moving 5-pt

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

205

Table A.5 continued

None None dpm/l dpm/l RAD7 RAD7 111.01 111.01 113.48 115.18 116.97 CS2 222Rn 222Rn CS2 Cave Station 2 2 Station Cave -(dc/dt)]/(Cavg) -(dc/dt)]/(Cavg)

Tube Tube 1/hour 1/hour 1.723828096 1.723828096 1.738688723 1.672595653 1.555161928 1.628131746 1.665515577 1.790794483 222Rn*t*Cavg) -(- Tube 222Rn Turnover Rate Rate Turnover 222Rn Tube [(Φ222Rn*A/V)

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Record # Record

Label Station Station Description Description Obtained How? How? Obtained Calculations involved involved Calculations

206

Table A.6μ Recalculation of Φ222Rn during Flood Events.

Rn Rn t1)

- Po 222 35.55 35.55 56.34 56.95 19.09 45.36 (t2  106.27 106.27 186.42 198.81 214

-1 230.60 230.60 266.15 322.48 379.43 398.52 443.89 130.60 236.86 423.29 622.09 dpm dpm L Sniff Mode Mode Sniff

t1) Rn

- 222 (t2 25.54 42.99 57.77 27.72 41.90 71.42 71.42 

138.29 138.29 180.39

-1 Po decay). We re-calculated the re-calculated the We Po decay). 214 Mode Mode 218.12 218.12 243.66 286.65 344.43 372.14 414.05 116.67 188.08 326.37 506.76 Normal Normal dpm dpm L

Counts Counts 2310.28 2310.28 2491.45 2832.87 3487.94 3888.31 4321.04 1159.82 1594.33 2638.19 4464.09 Channel C C Channel

Po decay) and and C ( Po decay) 218

se “normal” mode measures mode “normal” the longerse isotope lived Counts Counts 2412.63 2412.63 2784.56 3373.98 3969.83 4169.59 4644.20 1366.37 2478.19 4428.65 6508.71 Channel A A Channel

55.7 55.7 55.7 55.7 55.7 55.7 55.7 55.7 55.7 55.7 55.7 (min) (min) Rn concentrations are easily measured. The easily The measured. efficiency of the are in RAD7 Rn concentrations Live Time Live Time 222

Rn emission (Section 4.2.5). 4.2.5). Rn emission (Section during Flood Events. during Flood 222

Rn Rn

ch measures Channels measures A ( ch 222Rn 222

4874 5428 6366 7649 8273 9233 2648 4229 7308 11359 Counts Counts Total Total state detector is greater than is greater mode because approximatelystate it counts twice while in “sniff” detector Rn during these two events using the data from “sniff” mode. While in “normal” mode, the using mode, the in “normal” from two events mode. While “sniff” the data these Rn during 222

Date Flood Event #1 #1 Event Flood 2/25/2008 0:22:00 0:22:00 2/25/2008 2/24/2008 19:22:00 19:22:00 2/24/2008 20:22:00 2/24/2008 21:22:00 2/24/2008 22:22:00 2/24/2008 23:22:00 2/24/2008 2:16:00 12/13/2008 3:16:00 12/13/2008 4:16:00 12/13/2008 5:16:00 12/13/2008 Flood Event #2 Event Flood emission rate of of emission rate Φ of Recalculation A.6μ Table Radon-222 2008, the portable RAD7 2008 December inand February detector events two flooding the During mode, whi set in “normal” was solid- of the efficiency although is a time-delay many decays, becau as there of hour. in “sniff” mode, only Channel life an While A is half nearly has C),an which effective (Channel infast large and variations measured, the RAD7 mode is 0.417. manualmode is 0.863, for see complete a in “sniff” Please „normal‟ operator and more in the those used modes. The previous “sniff” are bold numbers in “normal” and difference of the description re-calculation and of calculation

207

APPENDIX B

SPELEOTHEM DATA FILES AND HEADERS

Table B.1: Speleothems BC1, BC2, and BC3 U-series and Radiocarbon Dates. Presented here are U-series and Radiocarbon dates from all three speleothem samples collected from Brooks Cave. U-series ages were analyzed by Dr. Christina Gallup of the University of Minnesota-Duluth, Department of Geology via MC-ICP-MS techniques. Radiocarbon ages were analyzed at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) via hydrolysis and accelerator mass spectrometry (AMS) techniques. For BC1 all radiocarbon ages are radiocarbon dead. For BC2 and BC3 the radiocarbon ages undoubtedly contain a detrital radiocarbon component.

Distance U-series Age U-series Radiocarbon Radiocarbon from tip (cm) (yrs BP) error (yrs) Age (yrs BP) error (yrs) BC1 0 69014 2316 46300 780 14 66391 1780 48800 770 34 67569 753 45100 500 54 69419 624 46200 610 61 69143 459 45600 570

BC2

0.7 2320 35 6.8 9350 50

BC3 0.4 12800 60 8.2 29600 170

208

Table B.2: Speleothem BC1 Stable Isotope Data. Presented here are the 18O and 13C values from sample BC1. The sample distance from the tip is centered (midpoint) on the drill hole. The drill bit diameter is 0.5 mm (0.05 cm). For example, the sample at a distance of 0.025 cm covers 0 to 0.05 cm. Blanks are missing data. Samples were analyzed via standard techniques on a Thermo Finnegan Delta-plus XP mass spectrometer in conjunction with a Gas Bench II Auto-carbonate device.

Distance Distance from calibrated calibrated from calibrated calibrated Tip (cm) 13C 18O Tip (cm) d13C d18O 0.025 -5.59 -3.97 1.975 -5.96 -2.13 0.075 -6.85 -2.27 2.025 -6.02 -2.11 0.125 -6.94 -2.82 2.075 -5.98 -2.29 0.175 -7.02 -2.59 2.125 -5.44 -2.44 0.225 -6.71 -2.80 2.175 -5.45 -2.62 0.275 -6.59 -2.96 2.225 -5.40 -2.73 0.325 -6.63 -2.90 2.275 -5.34 -2.79 0.375 -5.87 -2.83 2.325 -5.67 -2.64 0.425 -5.73 -2.80 2.375 -5.77 -2.89 0.475 -6.15 -2.98 2.425 -5.39 -3.03 0.525 -6.55 -3.32 2.475 -5.33 -2.96 0.575 -6.54 -3.16 2.525 -5.04 -2.89 0.625 -6.65 -3.06 2.575 -5.37 -2.65 0.675 -6.36 -2.85 2.625 -5.60 -2.85 0.725 -6.12 -2.64 2.675 -5.42 -2.72 0.775 -5.82 -2.19 2.725 -5.52 -2.67 0.825 -6.00 -2.17 2.775 -5.76 -2.97 0.875 -6.46 -2.21 2.825 -5.46 -3.05 0.925 -6.61 -2.58 2.875 -5.14 -2.94 0.975 -6.48 -2.16 2.925 -5.26 -3.00 1.025 -6.37 -2.37 2.975 -5.33 -3.18 1.075 -6.22 -2.60 3.025 -5.49 -3.24 1.125 -5.76 -2.22 3.075 -5.60 -3.05 1.175 -5.58 -2.08 3.125 -5.59 -3.15 1.225 -6.12 -2.60 3.175 -5.59 -2.77 1.275 -5.73 -2.92 3.225 -5.41 -2.50 1.325 -5.79 -3.02 3.275 -5.66 -2.71 1.375 -5.86 -3.01 3.325 -5.76 -2.75 1.425 -5.61 -3.22 3.375 -5.86 -2.87 1.475 -5.56 -3.09 3.425 -5.88 -2.75 1.525 -5.56 -3.08 3.475 -5.74 -3.02 1.575 -6.07 -3.31 3.525 -5.64 -2.68 1.625 -6.21 -3.06 3.575 -5.74 -2.39 1.675 -6.18 -3.11 3.625 -5.81 -2.53 1.725 -6.05 -3.25 3.675 -5.87 -2.85 1.775 -6.30 -2.78 3.725 -6.12 -3.04 1.825 -5.95 -2.47 3.775 -6.18 -3.03 1.875 -5.55 -2.23 3.825 -6.43 -2.67 1.925 -5.85 -2.14

209

Table B.2 Continued Distance from calibrated calibrated

Distance Tip (cm) d13C d18O from calibrated calibrated 6.275 -6.84 -2.59 Tip (cm) d13C d18O 6.325 -6.70 -2.53 3.875 -6.25 -2.83 6.375 -6.30 -2.34 3.925 -6.17 -2.59 6.425 -6.33 -2.62 3.975 -6.23 -2.56 6.475 -6.08 -2.32 4.025 -5.96 -2.47 6.525 -5.92 -2.80 4.075 -6.05 -2.49 6.575 -5.90 -2.87 4.125 -6.20 -2.41 6.625 -5.28 -2.70 4.175 -6.39 -2.43 6.675 -5.23 -2.75 4.225 -6.24 -2.47 6.725 -5.06 -2.57 4.275 -6.30 -2.45 6.775 -5.14 -2.92 4.325 -6.18 -2.45 6.825 -4.94 -3.06 4.375 -6.37 -2.59 6.875 -4.81 -2.98 4.425 -6.44 -2.44 6.925 -4.64 -2.51 4.475 -6.38 -2.59 6.975 -4.65 -2.44 4.525 -6.51 -2.82 7.025 -4.96 -2.65 4.575 -6.08 -2.35 7.075 -5.07 -2.93 4.625 -6.19 -2.53 7.125 -4.99 -2.85 4.675 -6.36 -2.69 7.175 -5.30 -2.71 4.725 -6.74 -3.12 7.225 -5.05 -2.83 4.775 -6.55 -3.33 7.275 -4.58 -2.57 4.825 -6.29 -2.79 7.325 -5.16 -2.62 4.875 -6.68 -3.02 7.375 -5.19 -2.76 4.925 -6.92 -3.07 7.425 -5.28 -2.82 4.975 -6.82 -2.83 7.475 -4.66 -2.71 5.025 -6.73 -2.77 7.525 -5.31 -3.34 5.075 -6.74 -3.05 7.575 -5.61 -3.29 5.125 -6.56 -2.76 7.625 -5.35 -3.17 5.175 -6.66 -2.69 7.675 -5.49 -3.50 5.225 -6.62 -2.81 7.725 -5.57 -2.99 5.275 -6.62 -2.81 7.775 -5.48 -2.92 5.325 -6.54 -3.35 7.825 -5.58 -3.20 5.375 -6.32 -2.92 7.875 5.425 -6.55 -3.02 7.925 5.475 -6.75 -3.12 7.975 -5.58 -3.55 5.525 -6.60 -3.26 8.025 5.575 -6.66 -3.14 8.075 5.625 -6.84 -3.18 8.125 -6.09 -3.53 5.675 -6.72 -3.90 8.175 -6.39 -3.61 5.725 -6.80 -2.88 8.225 -6.44 -2.95 5.775 -6.91 -2.44 8.275 -6.53 -3.19 5.825 -6.92 -2.49 8.325 -6.49 -2.92 5.875 -7.13 -2.63 8.375 5.925 -7.11 -2.69 8.425 -6.40 -3.00 5.975 -7.16 -2.42 8.475 -6.37 -2.76 6.025 -7.24 -2.50 8.525 -6.47 -3.09 6.075 -7.15 -2.58 8.575 -6.63 -2.52 6.125 -7.32 -2.57

210

Table B.2 Continued Distance from calibrated calibrated

Distance Tip (cm) d13C d18O from calibrated calibrated 10.975 -7.16 -2.87 Tip (cm) d13C d18O 11.025 -7.09 -3.54 8.625 11.075 -7.13 -3.32 8.675 -6.24 -2.85 11.125 -7.13 -3.42 8.725 -6.23 -2.74 11.175 -7.19 -3.33 8.775 -6.18 -2.69 11.225 -7.19 -3.30 8.825 -6.53 -3.04 11.275 -7.00 -3.39 8.875 -6.62 -2.98 11.325 -6.93 -3.65 8.925 -6.91 -2.70 11.375 -6.77 -3.54 8.975 -6.90 -2.67 11.425 -6.95 -3.58 9.025 -7.14 -2.48 11.475 -6.85 -3.48 9.075 -7.33 -3.04 11.525 -6.85 -3.59 9.125 -7.27 -2.75 11.575 -6.94 -3.76 9.175 -7.31 -3.15 11.625 -6.71 -4.04 9.225 -7.52 -3.66 11.675 -6.45 -3.83 9.275 -7.71 -2.77 11.725 -6.76 -4.05 9.325 -7.70 -3.35 11.775 -6.69 -4.34 9.375 -7.57 -3.18 11.825 -6.83 -4.31 9.425 -7.80 -3.18 11.875 -6.54 -3.97 9.475 -7.84 -3.57 11.925 -6.64 -3.64 9.525 -7.54 -3.11 11.975 -6.41 -3.86 9.575 -7.62 -2.95 12.025 -6.06 -3.49 9.625 -7.64 -3.27 12.075 -6.09 -3.41 9.675 -7.58 -2.99 12.125 -6.26 -3.75 9.725 -7.12 -3.00 12.175 -6.26 -3.73 9.775 -7.40 -3.29 12.225 -5.87 -3.44 9.825 -7.08 -2.97 12.275 -5.99 -3.74 9.875 -6.70 -2.96 12.325 -6.52 -3.70 9.925 -6.17 -3.24 12.375 -5.79 -3.40 9.975 -6.13 -2.74 12.425 -5.78 -3.27 10.025 -5.59 -2.77 12.475 -6.15 -3.48 10.075 -5.63 -2.77 12.525 -5.92 -3.39 10.125 -5.52 -3.27 12.575 -5.32 -3.15 10.175 -5.76 -3.33 12.625 -5.63 -3.26 10.225 -5.68 -3.63 12.675 -5.81 -3.85 10.275 -5.62 -3.51 12.725 -5.73 -3.54 10.325 -5.70 -3.62 12.775 -5.64 -3.02 10.375 -5.56 -3.28 12.825 -5.89 -3.16 10.425 -5.80 -3.11 12.875 -5.89 -3.54 10.475 -5.31 -3.22 12.925 -5.93 -3.28 10.525 -5.87 -3.25 12.975 -5.76 -3.53 10.575 -5.91 -3.43 13.025 -5.96 -3.66 10.625 -5.98 -2.55 13.075 -5.98 -3.49 10.675 -6.08 -2.82 13.125 -5.85 -3.39 10.725 -6.53 -2.74 13.175 -6.06 -3.38 10.775 -6.90 -2.81 13.225 -6.45 -3.86 10.825 -6.92 -2.90 13.275 -6.39 -3.78

10.875 -6.85 -3.04

211

Table B.2 Continued Distance from calibrated calibrated

Distance Tip (cm) d13C d18O from calibrated calibrated 15.725 -6.98 -4.55 Tip (cm) d13C d18O 15.775 -6.96 -3.36 13.375 -6.66 -4.14 15.825 -6.92 -3.53 13.425 -6.27 -3.66 15.875 -6.94 -4.01 13.475 -6.16 -3.70 15.925 -7.02 -3.90 13.525 -6.23 -3.94 15.975 -6.85 -4.04 13.575 -6.08 -3.81 16.025 -6.90 -3.77 13.625 -5.96 -3.60 16.075 -6.88 -3.72 13.675 -5.95 -3.83 16.125 -6.97 -3.15 13.725 -6.02 -3.83 16.175 -6.85 -2.97 13.775 -5.94 -3.48 16.225 -6.63 -3.34 13.825 -6.02 -3.60 16.275 -6.76 -3.72 13.875 -6.16 -3.50 16.325 -6.74 -5.09 13.925 -6.08 -3.41 16.375 -6.78 -3.87 13.975 -6.02 -3.63 16.425 -7.08 -3.72 14.025 -6.29 -3.65 16.475 -6.98 -3.63 14.075 -6.25 -3.44 16.525 -6.87 -3.54 14.125 -6.28 -3.65 16.575 -7.06 -3.94 14.175 -6.33 -3.51 16.625 -6.90 -3.24 14.225 -6.34 -3.68 16.675 -7.21 -3.65 14.275 -6.28 -3.51 16.725 -7.05 -4.52 14.325 -6.21 -3.57 16.775 -7.03 -4.05 14.375 -6.06 -3.53 16.825 -6.92 -4.87 14.425 -5.90 -2.87 16.875 -6.65 -3.64 14.475 -6.06 -2.72 16.925 -6.68 -3.76 14.525 -6.33 -3.00 16.975 -6.44 -3.12 14.575 -6.20 -2.85 17.025 -5.97 -2.87 14.625 -6.24 -3.01 17.075 -6.43 -2.99 14.675 -5.97 -3.20 17.125 -6.69 -3.18 14.725 -6.05 -3.12 17.175 -6.59 -3.41 14.775 -6.30 -3.53 17.225 -6.57 -4.84 14.825 -6.22 -3.42 17.275 -6.19 -3.30 14.875 -6.48 -3.43 17.325 -6.28 -3.89 14.925 -6.75 -3.55 17.375 -6.80 -4.20 14.975 -7.00 -3.61 17.425 -6.99 -4.06 15.025 -6.90 -3.59 17.475 -7.07 -3.74 15.075 -6.78 -3.54 17.525 -6.70 -3.63 15.125 -6.79 -3.88 17.575 -6.40 -3.57 15.175 -6.84 -3.37 17.625 -6.40 -3.98 15.225 -6.97 -3.34 17.675 -6.23 -3.66 15.275 -6.95 -3.35 17.725 -6.03 -3.47 15.325 -7.03 -3.38 17.775 -6.45 -3.82 15.375 -7.36 -4.46 17.825 -6.50 -3.18 15.425 -7.30 -3.74 17.875 -6.49 -3.03 15.475 -7.08 -3.65 17.925 -6.40 -3.13 15.525 -6.86 -3.48 17.975 -6.57 -3.42 15.575 -6.90 -3.72 18.025 -6.70 -3.55 15.625 -6.96 -3.68

212

Table B.2 Continued Distance from calibrated calibrated

Distance Tip (cm) d13C d18O from calibrated calibrated 20.475 -5.28 -2.71 Tip (cm) d13C d18O 20.525 -5.72 -2.47 18.125 -6.97 -3.79 20.575 -6.52 -3.17 18.175 -6.98 -3.75 20.625 -6.91 -2.87 18.225 -7.14 -3.85 20.675 -7.43 -3.19 18.275 -7.02 -3.69 20.725 -7.40 -2.98 18.325 -6.48 -3.32 20.775 -7.31 -3.26 18.375 -6.27 -3.33 20.825 -7.16 -3.37 18.425 -5.98 -3.41 20.875 -7.24 -3.03 18.475 -6.20 -3.51 20.925 -7.53 -3.33 18.525 -5.97 -3.33 20.975 -7.56 -3.60 18.575 -5.82 -3.00 21.025 -7.41 -3.67 18.625 -5.98 -3.13 21.075 -7.76 -3.30 18.675 -5.85 -3.20 21.125 -7.84 -3.44 18.725 -5.67 -3.64 21.175 -7.43 -3.41 18.775 -5.86 -3.70 21.225 -7.40 -3.40 18.825 -6.53 -3.58 21.275 -7.53 -3.62 18.875 -6.64 -3.22 21.325 -7.41 -3.36 18.925 -6.64 -3.08 21.375 -8.08 -3.29 18.975 -6.26 -2.99 21.425 -8.25 -3.12 19.025 -6.49 -3.23 21.475 -7.96 -3.40 19.075 -6.83 -3.15 21.525 -7.43 -3.20 19.125 -6.66 -2.98 21.575 -7.52 -3.47 19.175 -6.49 -3.27 21.625 -7.61 -3.23 19.225 -6.49 -3.47 21.675 -7.58 -3.12 19.275 -6.72 -3.28 21.725 -7.86 -3.43 19.325 -6.97 -3.41 21.775 -7.72 -3.64 19.375 -7.10 -3.40 21.825 -8.06 -3.53 19.425 -6.91 -3.49 21.875 -8.23 -3.33 19.475 -6.66 -3.08 21.925 -8.17 -2.95 19.525 -6.88 -3.14 21.975 -8.09 -4.53 19.575 -7.16 -3.31 22.025 -8.29 -3.58 19.625 -7.17 -3.31 22.075 -8.25 -3.08 19.675 -7.34 -3.32 22.125 -7.77 -4.01 19.725 -7.34 -3.33 22.175 19.775 -7.40 -3.70 22.225 -8.41 -3.57 19.825 -7.05 -3.03 22.275 -8.42 -3.23 19.875 -6.95 -3.08 22.325 -8.56 -3.35 19.925 -6.98 -3.07 22.375 -8.39 -3.70 19.975 -6.97 -3.22 22.425 -8.31 -3.78 20.025 -7.01 -3.32 22.475 -8.24 -3.51 20.075 -7.52 -3.69 22.525 -8.23 -3.66 20.125 -7.44 -3.65 22.575 -8.21 -3.17 20.175 -7.16 -3.21 22.625 -8.20 -3.19 20.225 -7.31 -3.43 22.675 -8.37 -2.98 20.275 -7.23 -3.17 22.725 -8.43 -3.86 20.325 -7.26 -4.06 22.775 -8.22 -3.20 20.375 -7.60 -3.85

213

Table B.2 Continued Distance from calibrated calibrated Distance from calibrated calibrated Tip (cm) d13C d18O Tip (cm) d13C d18O 24.375 -6.47 -2.79 22.875 -7.76 -3.16 24.425 -6.48 -2.55 22.925 -7.89 -3.25 24.475 -7.36 -3.38 22.975 -7.62 -4.30 24.525 -7.23 -3.19 23.025 -7.58 -3.49 24.575 -7.50 -3.23 23.075 24.625 -7.64 -3.30 23.125 24.675 -7.81 -3.97 23.175 24.725 -7.87 -4.06 23.225 24.775 -7.95 -3.46 23.275 -6.93 -4.30 24.825 -7.96 -3.38 23.325 -7.48 -3.03 24.875 -8.08 -3.61 23.375 -7.65 -3.16 24.925 -8.08 -3.48 23.425 -7.57 -2.98 24.975 -7.81 -3.97 23.475 -7.91 -3.29 23.525 -8.04 -3.48 23.575 -7.85 -2.99

23.625 -8.01 -4.08

23.675 -7.98 -3.44 23.725 -7.70 -3.20 23.775 -8.00 -2.91 23.825 -7.98 -2.88 23.875 -7.96 -3.27 23.925 -7.94 -2.90 23.975 -8.08 -3.13 24.025 -7.81 -3.35 24.075 -7.66 -2.98 24.125 -7.86 -3.39 24.175 -7.82 -3.48 24.225 -7.62 -3.25 24.275 -7.60 -3.37

214

Table B.3: Speleothem BC1 Trace Element Data. Presented here are a representative „snapshot‟ of trace element ratios for sample BC1 as a guide to the full digital dataset, although the entire dataset exists in digital form. All ratios are presented as count ratios of that isotope to calcium-43 as nnX/43Ca (cps/cps). Trace elements were analyzed via LA-ICP-MS techniques, presented in Chapter 5.3. Calibrations are discussed in Figure 5.6.

Ca 43 U/ 238 0.000707 0.000707 0.000767 0.000554 0.000705 0.000826 0.000667 0.000673 0.001035 0.001227 0.000737 0.000656 0.000544 0.000625

Ca 43 / Th 0.000022 0.000022 0.000055 0.000035 0.000043 0.000047 0.000047 0.000056 0.000033 0.000053 0.000022 0.000025 0.000010 0.000027 232

Ca 43 / Ce 0.000151 0.000151 0.000185 0.000178 0.000154 0.000313 0.000339 0.000209 0.000331 0.000368 0.000431 0.000160 0.000086 0.000115 140

Ca 43 / Ba 0.050380 0.050380 0.059123 0.046575 0.044259 0.070242 0.042022 0.048310 0.054768 0.081309 0.036546 0.044589 0.033742 0.036602 138

Ca 43 / Mo 0.000005 0.000005 0.000011 0.000004 0.000013 0.000005 0.000002 0.000002 0.000013 0.000060 0.000000 0.000002 0.000003 95 -0.000001 -0.000001

Ca 43 / Sr 88 0.061740 0.061740 0.072392 0.073032 0.060443 0.096341 0.075345 0.066986 0.072733 0.126768 0.053449 0.071141 0.047058 0.056267

Ca 43 / Rb 0.001773 0.001773 0.000204 0.000263 0.000454 0.000295 0.000203 0.000240 0.000215 0.000365 0.001063 0.000178 0.000146 0.000153 85

Ca 43 / Fe 0.001411 0.001411 0.002684 0.001105 0.001139 0.001982 0.001393 0.001309 0.001693 0.008917 0.001109 0.001085 0.001138 0.000978 57

Ca 43 / Mn 0.000902 0.000902 0.001063 0.001392 0.000728 0.001290 0.000898 0.001456 0.001231 0.001307 0.000771 0.000460 0.000461 0.000501 55

Ca 43 / Ca 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 1.000000 43

Ca 43 / Si 29 0.005979 0.005979 0.017307 0.008304 0.007901 0.018050 0.008730 0.008533 0.008983 0.013405 0.006481 0.006726 0.006569 0.007028

Ca 43 / Mg 0.043488 0.043488 0.061141 0.055027 0.046356 0.066294 0.044763 0.050131 0.048537 0.086465 0.040974 0.043302 0.041758 0.045069 25

m) 0 0 9 18 27 36 45 54 63 72 81 90 99 108 tip ( Distance from from Distance

215

Table B.4: Speleothem BC1 Color Spectrum Data and Headers. Presented here is representative „snaptshot‟ of the Geotek RBG color scan for sample BC1 as a guide to the full digital dataset, although the entire dataset exists in digital form. Color data were collected every 20 microns (0.002 cm) using the Geotek MSCL analysis software Image Tools 2.4.1. These data are presented in Chapter 5.3 and 5.4. These data represent color intensities relative to the RGB standard for the core logger.

Distance from tip (cm) Red Green Blue 0 90 67 57 0.002 90 68 61 0.004 96 71 64 0.006 100 74 67 0.008 104 77 68 0.01 108 79 70 0.012 112 82 72 0.014 113 84 73 0.016 117 90 73 0.018 119 91 72 0.02 121 92 74 0.022 123 93 73 0.024 123 96 73 0.026 122 95 73 0.028 120 93 75 0.03 123 96 76 0.032 121 97 76 0.034 122 96 78 0.036 122 100 77 0.038 123 98 80 0.04 123 98 79 0.042 123 98 79 0.044 124 101 78 0.046 124 103 78 0.048 123 103 76 0.05 123 99 76 0.052 123 98 74 0.054 123 99 74 0.056 120 97 73

216

Table B.5: Speleothem BC2 Stable Isotope Data. Presented here are the 18O and 13C values from sample BC2. The sample distance from the tip is centered (midpoint) on the drill hole. The diameter of the drill bit is 0.5 mm (0.05 cm). For example, the sample at a distance of 0.085 cm covers 0.06 to 0.11 cm. Blanks are missing data. Samples were analyzed via standard techniques on a Thermo Finnegan Delta- plus XP mass spectrometer in conjunction with a Gas Bench II Auto-carbonate device.

Distance  Distance   from Tip 13C 18O from Tip 13C 18O (cm) VPDB VPDB (cm) VPDB VPDB 0.085 -9.13 -3.87

0.135 -9.12 -3.94   0.185 1.885 -6.00 -3.43 0.235 -6.41 -3.62 1.935 -5.93 -3.00 0.285 -6.31 -3.82 1.985 -5.39 -3.16 0.335 -5.98 -3.45 2.035 -6.03 -3.20 0.385 -5.97 -3.28 2.085 -6.59 -3.44 0.435 -5.85 -3.31 2.135 -6.61 -3.29 0.485 -5.85 -3.17 2.185 -6.41 -3.25 0.535 -5.00 -3.25 2.235 -6.56 -3.22 0.585 -5.54 -3.20 2.285 -7.20 -4.76 0.635 -5.07 -2.96 2.335 -6.93 -3.54 0.685 -5.16 -3.23 2.385 -6.77 -3.47 0.735 -5.25 -3.50 2.435 -6.83 -3.25 0.785 -4.41 -3.11 2.485 -7.47 -3.46 0.835 -4.14 -3.04 2.535 -7.54 -3.44 0.885 -3.77 -3.30 2.585 -7.69 -3.83 0.935 -3.71 -2.91 2.635 -7.42 -3.88 0.885 -3.83 -2.87 2.685 -6.87 -3.37 0.985 -4.24 -2.84 2.735 -6.91 -3.14 1.035 -3.93 -2.82 2.785 -6.55 -3.52 1.085 -3.84 -2.65 2.835 -6.49 -3.33 1.135 -4.21 -3.19 2.885 -5.95 -3.43 1.185 -4.15 -3.20 2.935 -6.13 -3.36 1.235 -4.27 -2.98 2.985 -6.26 -3.31 1.285 -4.39 -3.08 3.035 1.335 -4.57 -3.09 3.085 -5.85 -3.19 1.385 -5.15 -3.05 3.135 -6.35 -3.70 1.435 -5.69 -3.10 3.185 -6.31 -3.49 1.485 -5.59 -3.06 3.235 -6.01 -3.44 1.535 -5.55 -3.05 3.285 -5.74 -3.48 1.585 -5.40 -3.04 3.335 -5.77 -3.99 1.635 -5.44 -3.26 3.385 -6.03 -4.64 1.685 -6.00 -2.85 3.435 -6.05 -4.78 1.735 -5.88 -3.10 3.485 -6.08 -3.17 1.785 -6.25 -3.35 3.535 -5.75 -3.57 1.835 -6.08 -3.23 3.585 -6.21 -3.40 3.635 -5.77 -3.54     3.685 -6.10 -3.31    

217

Table B.5 Continued   Distance    from Tip 13C 18O Distance   (cm) VPDB VPDB from Tip 13C 18O (cm) VPDB VPDB 5.985 -4.19 -3.63 3.735 -6.16 -4.29 6.035 -4.73 -3.06 3.785 -6.62 -3.68 6.085 -5.67 -3.20 3.835 -6.31 -3.50 6.135 -5.19 -3.10 3.885 -6.21 -3.62 6.185 -4.75 -3.01 3.935 -6.36 -4.36 6.235 -4.42 -3.00 3.985 -5.96 -3.57 6.285 -4.52 -3.00 4.035 -6.18 -3.58 6.335 -5.21 -2.93 4.085 -6.22 -3.57 6.385 -6.36 -3.17 4.135 -6.28 -4.38 6.435 -5.93 -2.89 4.185 -7.09 -3.33 6.485 -5.62 -3.06 4.235 -7.01 -3.24 6.535 -5.64 -3.20 4.285 -7.54 -3.16 6.585 -5.45 -2.89 4.335 -7.54 -3.12 6.635 -5.66 -3.25 4.385 -7.85 -5.99 6.685 -6.66 -2.94 4.435 -7.94 -3.70 6.735 -6.56 -2.83 4.485 -8.27 -5.25 6.785 -7.09 -2.74 4.535 -7.73 -3.95 6.835 -7.31 -2.30 4.585 -8.07 -3.46 6.885 -7.64 -2.80 4.635 -7.69 -3.87 6.935 -7.60 -2.62 4.685 -7.80 -3.75 6.985 -7.96 -2.84 4.735 -8.20 -3.69 7.035 -8.03 -2.73 4.785 -7.74 -3.60 7.085 -8.05 -2.57 4.835 -7.99 -5.77 7.135 -8.02 -2.58 4.885 -7.56 -3.48 7.185 -8.40 -3.10 4.935 -7.97 -3.48 7.235 -8.47 -3.06 4.985 -8.92 -3.53 7.285 -9.26 -3.22 5.035 -8.53 -3.80 7.335 -9.35 -3.09 5.085 -7.91 -4.00 7.385 -9.03 -3.01 5.135 -8.19 -3.57 5.185 -7.97 -3.30   5.235 -7.76 -3.47   5.285 -7.69 -3.43 5.335 -7.27 -3.32 5.385 -7.08 -3.76 5.435 -7.31 -3.09 5.485 -7.90 -3.94 5.535 -7.61 -3.18 5.585 -7.50 -4.07 5.635 -7.83 -3.40 5.685 -6.38 -3.37 5.735 -4.44 -3.29 5.785 -5.22 -3.46 5.835 -4.50 -3.87 5.885 -4.35 -3.33 5.935 -4.32 -3.43

218

Table B.6: Speleothem BC2 Trace Element Data. Presented here is a representative „snapshot‟ of trace element concentrations for sample BC2 as a guide to the full digital dataset, although the entire dataset exists in digital form. All elements are in elemental concentrations of ppm. Trace elements were analyzed via LA-ICP-MS techniques, presented in Chapter 5.3. Elemental concentrations are estimated by assuming the calcium concentration in calcite is 40.2659 wt %, and then referencing to the NIST SRM-612 standard.

U 0.2629 0.33546 0.23049 0.23428 0.234871 0.269443 0.250195 0.303806 0.219024 0.275461 0.235647 0.289471 0.318234

Th 0.15379 0.19913 0.16703 0.100169 0.157578 0.171602 0.143647 0.208831 0.145342 0.146168 0.150735 0.124199 0.145495

Ce 2.0445 1.13965 1.42737 1.86554 1.66324 2.66968 2.12117 2.41041 1.35433 1.56481 1.79987 1.19239 1.52762

Ba 7.9069 6.3483 7.38934 8.00063 5.32441 5.65813 5.37029 6.75227 5.76059 5.47328 8.62331 4.91725 5.52669

Sr 18.7322 17.7001 18.5107 16.4035 17.7798 16.3342 15.8546 15.7498 14.8836 15.2565 14.8157 14.4606 14.4552

Rb 0.79254 0.695374 0.575695 0.864212 0.709982 0.727379 0.637776 1.204067 0.644616 0.676603 0.706919 1.149738 0.859225

Fe -183.454 -222.682 -216.289 -199.191 -229.072 -186.771 -206.426 -216.481 -232.764 -280.286 -230.891 -237.828 -214.604

Mn 8.79679 8.89716 12.5139 14.2688 14.6358 16.3112 18.9329 15.7698 14.3853 15.7197 19.9058 13.2144 17.9002

Ca 402659 402659 402659 402659 402659 402659 402659 402659 402659 402659 402659 402659 402659

Si 1146.6 1266.02 1237.29 1234.37 1085.22 1198.48 1203.24 1503.36 1037.11 1135.69 1178.91 1565.57 1362.97

Mg 696 569.4 632.7 675.2 659.3 677.4 555.3 708.7 630.2 681.8 597.3 540.7 712.9

m m 0 0 10 20 30 40 50 60 70 80 90 100 110 120 from tipfrom Distance

219

Table B.7: Speleothem BC2 Color Spectrum Headers. Presented here is representative „snaptshot‟ of the Geotek RBG color scan for sample BC2 as a guide to the full digital dataset, although the entire dataset exists in digital form. Color data were collected every 20 microns (0.002 cm) using the Geotek MSCL analysis software Image Tools 2.4.1. These data are presented in Chapter 5.3 and 5.4. These data represent color intensities relative to the RGB standard for the core logger.

Distance from tip (cm) Red Blue Green 0 177 149 107 0.005 176 147 106 0.01 176 144 104 0.015 173 144 98 0.02 178 148 100 0.025 183 154 102 0.03 188 162 106 0.035 195 166 113 0.04 195 168 116 0.045 191 166 119 0.05 185 158 115 0.055 179 151 112 0.06 174 147 105 0.065 170 141 103 0.07 164 134 102 0.075 154 126 96 0.08 146 120 91 0.085 144 117 90 0.09 144 118 88 0.095 150 123 89 0.1 156 130 93 0.105 157 131 96 0.11 155 129 97 0.115 153 126 94 0.12 148 122 93 0.125 144 118 90 0.13 140 112 86 0.135 140 113 84

220

Table B.8: Speleothem BC3 Stable Isotope Data. Presented here are the 18O and 13C values from sample BC3. The sample distance from the tip is centered (midpoint) on the drill hole. The diameter of the drill bit is 0.5 mm (0.05 cm). For example, the sample at a Distance of 0.025 cm covers 0 to 0.05 cm. Blanks are missing data. Samples were analyzed via standard techniques on a Thermo Finnegan Delta-plus XP mass spectrometer in conjunction with a Gas Bench II Auto-carbonate device.

Distance 13 18 Distance   from  C  O 13 18 Tip (cm) VPDB VPDB from  C  O Tip (cm) VPDB VPDB 0.025 -10.01 -3.05 2.225 -8.11 -2.01 0.075 -9.63 -3.53 2.275 -7.30 -2.24 0.125 -8.95 -2.72 2.325 -7.61 -2.24 0.225 -9.31 -2.65 2.375 -7.94 -2.34 0.275 -9.85 -2.81 2.425 -7.90 -2.53 0.325 -10.40 -2.88 2.475 -7.68 -2.26 0.375 -10.62 -3.06 2.525 -7.85 -2.33 0.425 -10.28 -2.86 2.575 -8.02 -2.49 0.475 -9.43 -2.46 2.625 -7.75 -2.53 0.525 -9.46 -2.48 2.675 -7.88 -2.41 0.575 -9.68 -2.58 2.725 -7.79 -2.51 0.625 -10.15 -2.67 2.775 -8.01 -2.49 0.675 -9.31 -2.82 2.825 -8.49 -2.50 0.725 -9.24 -2.67 2.875 -8.34 -2.37 0.775 -10.62 -2.47 2.925 -7.90 -2.35 0.825 -10.13 -2.46 2.975 -7.41 -2.24 0.875 -10.44 -2.54 3.025 -7.31 -2.08 0.925 -10.80 -2.40 3.075 -7.20 -2.25 0.975 -10.56 -2.40 3.125 -7.47 -2.42 1.025 -10.08 -2.48 3.175 -7.78 -2.35 1.125 -10.67 -2.29 3.225 -8.03 -2.64 1.275 -10.22 -2.29 3.275 -7.97 -2.30 1.325 -10.15 -2.21 3.325 -8.13 -3.00 1.375 -11.17 -2.69 3.375 -7.68 -2.30 1.425 -11.02 -2.59 3.425 -7.95 -2.47 1.525 -10.73 -2.28 3.475 -7.94 -2.43 1.575 -10.49 -2.12 3.525 -8.10 -3.67 1.625 -10.83 -2.54 3.575 -8.24 -2.56 1.725 -10.54 -2.64 3.625 -8.07 -2.76 1.875 -10.12 -2.49 3.675 -7.98 -3.50 1.925 -9.71 -2.59 3.725 -7.64 -2.26 1.975 -9.33 -2.81 3.775 -7.84 -3.09 2.025 -10.17 -2.28 3.825 -7.94 -2.62 2.075 -10.02 -1.73 3.875 -7.66 -4.56 2.125 -10.26 -1.73 3.925 -7.81 -2.29 2.175 -8.95 -1.69 3.975 -7.89 -2.41

221

Table B.8 Continued Distance from 13C 18O  Tip (cm) VPDB VPDB Distance   from 13C 18O 7.05 -3.82 -2.11 Tip (cm) VPDB VPDB 7.1 -2.61 -2.05 4.025 -8.29 -2.55 7.15 -2.18 -1.93 4.075 -8.26 -2.61 7.2 -2.69 -1.82 4.125 -8.27 -2.53 7.25 -3.10 -1.87 4.175 -8.28 -4.54 7.3 -3.39 -2.06 4.225 -7.91 -2.45 7.35 -3.47 -2.39 4.275 -8.34 -2.91 7.4 -1.99 -2.05 4.325 -8.47 -2.42 7.45 -2.92 -2.41 4.375 -8.70 -3.10 7.5 -2.71 -1.93 4.425 -8.60 -2.84 7.55 -2.29 -1.90 4.475 -8.22 -2.52 7.6 -2.73 -2.12 4.525 -8.23 -2.47 7.65 -2.87 -1.97 4.575 -8.15 -2.85 7.7 -3.58 -2.06 4.625 -8.26 -2.66 7.75 -3.91 -1.81 4.675 -8.34 -2.61 7.8 -4.77 -2.07 4.725 -8.70 -3.95 7.85 -4.67 -1.87 4.775 -8.40 -4.21 7.9 -3.41 -1.83 4.825 -8.49 -2.69 7.95 -3.09 -1.84 4.875 -8.43 -2.54 8 -2.73 -1.77 4.925 -8.36 -2.45 8.05 -2.14 -1.92 4.975 -8.88 -2.64 8.1 -2.39 -1.89 5.025 -8.74 -2.39 8.15 -2.64 -1.87 5.075 -8.58 -2.40 8.2 -2.63 -1.90 5.125 -8.70 -2.55 8.25 -2.36 -1.75 5.175 -8.91 -2.49 8.3 -1.89 -2.00 5.225 -8.75 -2.30 8.35 -1.62 -1.02 5.275 -8.67 -2.34 8.4 -0.85 -2.12 5.325 -8.89 -2.55 8.45 -0.80 -1.98 5.375 -8.93 -2.47 8.5 -0.99 -2.05 5.425 -8.97 -2.68 8.55 -0.93 -2.15 5.475 -8.62 -2.58 8.6 -1.22 -2.15 5.525 -8.59 -2.65 8.65 -1.38 -2.20 5.575 -8.84 -2.77 8.7 -1.64 -2.31 5.625 -8.78 -2.44 8.75 -1.62 -2.16 6.4 -4.38 -2.00 8.8 -1.64 -2.18 6.45 -3.64 -1.79 8.85 -1.86 -2.17 6.5 -3.52 -1.67 8.9 -2.13 -2.19 6.55 -3.58 -1.74 8.95 -2.10 -2.00 6.6 -3.69 -1.51 9 -2.66 -2.04 6.65 -3.82 -1.58 9.05 -2.75 -2.25 6.7 -4.06 -1.80 9.1 -3.30 -2.24 6.75 -4.55 -2.33 9.15 -3.56 -2.11 6.8 -4.26 -2.04 9.2 -3.44 -2.09 6.85 -4.12 -1.99 9.25 -3.18 -2.01 6.9 -3.45 -1.97 9.3 -2.93 -1.90 6.95 -3.47 -2.06 9.35 -2.85 -1.92 7 -3.96 -2.14 9.4 -5.54 -2.00

222

Table B.9: Speleothem BC3 Color Spectrum Headers. Presented here is representative „snaptshot‟ of the Geotek RBG color scan for sample BC3 as a guide to the full digital dataset, although the entire dataset exists in digital form. Color data were collected every 20 microns (0.002 cm) using the Geotek MSCL analysis software Image Tools 2.4.1. These data are presented in Chapter 5.3 and 5.4. These data represent color intensities relative to the RGB standard for the core logger.

Distance from tip (cm) Red Green Blue 0 92 92 78 0.002 86 88 79 0.004 90 92 82 0.006 85 89 85 0.008 87 91 86 0.01 84 85 78 0.012 88 90 82 0.014 100 94 75 0.016 97 92 73 0.018 115 103 74 0.02 130 117 88 0.022 136 124 85 0.024 136 124 85 0.026 138 125 85 0.028 148 135 95 0.03 151 137 95 0.032 154 140 98 0.034 164 149 106 0.036 167 152 109 0.038 168 153 110 0.04 162 147 103 0.042 154 140 98 0.044 158 144 101 0.046 168 156 113 0.048 174 162 120 0.05 177 166 124 0.052 184 172 131 0.054 185 176 144 0.056 183 174 142 0.058 182 172 141 0.06 192 183 152 0.062 202 192 162 0.064 201 192 162

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BIOGRAPHICAL SKETCH

Andrew Jason Kowalczk was born in the middle of a dark, cold, and stormy night in Anchorage, Alaska on October 3rd, 1983 to John and Roseann Kowalczk. Both of his brothers were born in similar fashion, and the love for the outdoors instilled by his parents has stayed with him throughout his life. Andrew grew up skiing, hunting, fishing, playing soccer and football, and spending much of his time outdoors. Influenced greatly by his middle and high school teachers, Andrew gained his love for the physical sciences during field trips throughout Alaska. The interest in physical sciences turned towards the ocean when Andrew first learned how to scuba dive in the 8th grade. After high school, he decided to attend Texas A&M University in Galveston and pursue a career in Marine Sciences. Andrew began his research career studying the effects albedo has on a toxic algae bloom in central Texas. During his tenure as a Sea Aggie, Andrew also learned the art of surfing and renewed his passion for diving, adventuring into science and technical diving. In spite of these new found hobbies, Andrew was still able to graduate Magna Cum Laude in May 2006 with a Bachelors of Science in Marine Science. Interested in continuing his education, Andrew jumped at the chance to attend Florida State University to study caves, and to be able to combine science and a new-found passion for exploration. Andrew received funding as a both a research assistant and teaching assistant. His involvement in local soccer clubs and cave diving networks offered stress release and temporary respite from the rigors of graduate school. In 2008 Andrew became one of the youngest cave divers to receive the Abe Davis Safe Cave Diving Award from the National Speleological Society Cave Diving Section. His continued dedication to the study, conservation, and exploration of caves keeps Andrew an active member of both the National Speleological Society and Southeastern Cave Conservancy to this day.

Education Background

B.S. Marine Science, 2006; Texas A&M University at Galveston Minor in Chemistry; GPA: 3.857, Magna Cum Laude

M.S. Chemical Oceanography, 2009 (Defended 10/12/2009, Graduated December 2009); Florida State University Dept. of Oceanography; GPA: 3.97

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Research Interests

Speleology, geological oceanography, chemical oceanography, paleoclimate, environmental chemistry. My primary interests lie in the formation and modification of caves and speleothems, cave meteorology and air chemistry, and paleoclimate records from speleothems. My secondary interests lie in sediment dynamics and geomorphology in all aquatic and marine environments

Research Experience

8/2006- 10/2009 High Resolution Microclimate study of Hollow Ridge Cave: Relationships Between Cave Meteorology, Air Chemistry, and Hydrology and the Impact on Speleothem Deposition.. Master‟s Thesis, Florida State University Dept. of Oceanography and National High Magnetic Field Laboratory, under Dr. Philip N Froelich

8/2005-6/2006 Effect of albedo and solar radiation on the toxic golden algae bloom in Lake Whitney, TX, under Dr. Ayal Anis at the Texas Institute of Oceanography

6/2005-8/2005 Application of digital x-radiograph imaging for the determination of bulk density in York River, VA sediments, under Dr. Carl Friedrichs at the Virginia Institute of Marine Science Summer Research Experience for Undergrads Program.

9/2004-5/2005 Studies of albedo in Galveston Bay, TX, under Dr. Ayal Anis at the Texas Institute of Oceanography.

Publications, Presentations, and Posters

Kowalczk, AJ, Froelich, PN. 2009. Cave air ventilation and CO2 outgassing by Radon-222 modeling: How fast do caves breathe? Earth and Planetary Science Letters. In Prep.

Kowalczk, AJ, Froelich, PN, Gaffka, C, Tremaine, D. 2008. High Resolution Time Series Cave Ventilation Processes and the Effects on Cave Air Chemistry and Drip Waters: Speleoclimatology and Proxy Calibration. EOS Trans. AGU, 89(53), Fall Meet. Suppl., Abstract PP51C-1521. Poster and Abstract

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Kowalczk, AJ, Froelich, PN, Gaffka, CJ, Tremaine, D. 2008. High Resolution Time Series Cave Ventilation Processes and the Effects on Cave Air Chemistry and Drip Waters – Speleoclimatology and Proxy Calibration. 3rd Annual Department of Oceanography Student Symposium, November 13th, 2008. Poster.

Kowalczk, AJ, Gaffka, CJ, Froelich, PN. 2008. Continuous Monitoring of the Micrometeorolgy of a Natural Cave System: Hollow Ridge Speleoclimatology. Presentation, National Speleological Society 2008 Convention, August 11th, 2008. Oral Presentation.

Kowalczk, AJ, Gaffka, CJ, Froelich, PN. 2008. Continuously Monitoring the Micrometeorolgy of a Natural Cave System: Hollow Ridge Speleoclimatology. EOS Trans. AGU 89 (23), Jt. Assem. Suppl., Abstract # PP21A-07. Oral Presentation and Abstract.

Kowalczk, AJ, Froelich, PN, Mosler, A. 2007. Speleoclimatology of a Wild Florida Cave: the Present is Key to the Past. EOS Trans. AGU 88(52), Fall Meet. Suppl., Abstract PP43A-0999. Poster and Abstract.

Froelich, PN, Kowalczk, AJ, McCardle, D, Tibbetts, N. 2007. Speleothem Paleoclimate Records from the Floridian Panhandle. EOS Trans. AGU, 88(52), Fall Meet. Suppl., Abstract PP43A- 0998. Poster and Abstract.

Kowalczk, AJ, Froelich, PN. 2007. Speleoclimatology of a Wild Florida Cave. 2nd Annual Department of Oceanography Student Symposium, November 16th, 2007. Oral Presentation.

Kowalczk, AJ. 2007. Caving into the Past! NHMFL Girls in Science Summer Program, Guest Lecture. July 24th, 2007. Oral Presentation.

Kowalczk, A. 2006 Application of digital x-radiograph imaging for the determination of bulk density, EOS Trans. AGU 87(36), Ocean Sci. Meet. Suppl., Abstract OS26B-03, Invited. Poster and Abstract.

Kowalczk, A. 2006. Albedo and Solar Radiation Measurements in Lake Whitney, TX, and relation to the toxic golden algae bloom. 2nd annual TAMUG Student Research Symposium, April 16th, 2006. Galveston, TX. Poster.

Kowalczk, A., Anis, A. 2005. Sea Surface Albedo Measurements in Galveston Bay. TAMUS Pathways Symposium, Nov 4-5, 2005, Texas A&M University-Kingsville. Poster.

Kowalczk, A. 2005. Application of digital x-radiograph imaging for the determination of bulk density. Research Experience for Undergrads (REU) Symposium, August 2nd, 2005. The Virginia Institute of Marine Science, Gloucester Point, VA. Oral presentation.

Kowalczk, A. 2005. Sea Surface Albedo Measurements in Galveston Bay. 1st annual TAMUG Student Research Symposium, April 19th, 2005. Galveston, TX. Poster

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Other Skills

 Technical Cave Diver, Normoxic Trimix Diver, Advanced Nitrox, Decompression, and American Academy of Underwater Scientists (AAUS) scuba diver certifications  International Association for Nitrox and Technical Divers (IANTD) Gas Blender for Technical Scuba Diving  Professional Cylinder Inspectors/ Professional Scuba Inspectors (PCI/PSI) Visual Tank Inspector # 21540  Proficient in the Campbell Scientific, Inc. CRBasic Programming Language  Proficient in Spreadsheet and Data Analysis Programs (Microsoft Excel, MATLAB, and Kaleidagraph)  Proficient in Horizontal and Vertical Caving Techniques  Surveying Experience in both dry and aquatic cave systems, and beach profiling and survey  Small boat and sailboat operation and handling experience

Professional Memberships

American Geophysical Union 2005-Present American Society of Limnology and Oceanography 2005-2007 Geological Society of America 2007-2009 National Speleological Society (NSS # 57507) 2006-Present Southeastern Cave Conservancy, Inc 2008-Present

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