Phosphorus Flux from the Sediments in the Kissimmee Chain of Lakes

PHOSPHORUS FLUX FROM THE SEDIMENTS IN THE KISSIMMEE CHAIN OF LAKES

CHAKESHA S. MARTIN

A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2004

Chakesha S. Martin

This thesis is dedicated to my parents and brothers. I thank them all for their continued patience, love, and support.

ACKNOWLEDGMENTS

I would like to especially thank my committee chair, Dr. John R. White, for giving me the opportunity to study under him and learn so much from his wisdom and guidance.

AN additional thanks go to my committee members, Dr. Jana Newman and Dr. K.R.

Reddy, for their support and encouragement.

I appreciate Matt Fisher’s expertise in the field and for creating the maps used for this project. I am grateful for Dr. Marco Belmont’s help in the field, as well as Paul

Washington. Special thanks go to Ms. Yu Wang for her guidance in the laboratory. I would also like to especially thank Alicia Callery for her invaluable assistance with experiments. This project would not have been possible without funding from the South

Florida Water Management District.

I really appreciate all the encouragement I have received from my fellow graduate students, professors and friends. Special thanks go to my family for being so instrumental in shaping the person I am today. Above all, I would like to thank God, who without, none of this would have been achievable.

TABLE OF CONTENTS

page

ACKNOWLEDGMENTS ...... iv

LIST OF TABLES...... vii

LIST OF FIGURES ...... xii

ABSTRACT...... xv

CHAPTER

1 INTRODUCTION ...... 1

Study Rationale...... 6 Objectives ...... 8 Site Description ...... 8

2 SEDIMENT CHARACTERIZATION...... 13

Introduction...... 13 Hypothesis ...... 16 Objective...... 16 Field Methods ...... 16 Laboratory Techniques ...... 21 Physical and Chemical ...... 21 Inorganic P Fractionation ...... 23 Data Analysis...... 25 Results...... 26 Physical and Chemical ...... 26 Metals ...... 27 Inorganic P Fractionation ...... 28 Discussion...... 33 Physical and Chemical ...... 33 Metals ...... 39 Inorganic P Fractionation ...... 45 Conclusion ...... 49

3 PHOSPHORUS FLUX OF SEDIMENTS UNDER DIFFERENT SIMULATED LOADING CONDITIONS...... 51

Introduction...... 51 Hypothesis ...... 54 Objectives...... 54 Site Selection...... 54 Materials and Methods ...... 60 Data Analysis...... 61 Results...... 61 Discussion...... 83 Overall Conclusion ...... 94

APPENDIX

A PHOSPHORUS FRACTIONATION DATA...... 98

B METALS DATA...... 101

C NUTRIENTS ...... 103

D AEROBIC WATER COLUMN SRP DATA...... 106

E PRELIMINARY SURVEY...... 116

F SEDIMENT TYPE AND COORDINATES ...... 126

LIST OF REFERENCES...... 129

BIOGRAPHICAL SKETCH ...... 135

LIST OF TABLES

Table page

2-1 Average Bulk Density (BD), Loss on Ignition (LOI), Total C, Total N, and Total P for Lakes Tohopekaliga, Cypress, Hatchineha, Kissimmee, and Istokpoga. n=10 per lake...... 27

2-2 HCl extractable Ca and Mg concentrations and oxalae extractable Fe and Al concentrations for Lakes Tohopekaliga, Istokpoga, Cypress, Kissimmee, and Hatchineha. Values are reported as mean and standard deviation (n=10) per lake.28

2-3 Mean and standard deviations for P forms: KCl- Pi, NaOH Pi, HCl-Pi, TPi, NaOH Pi, residue P, total Po and total P (n=10) for each lake in mg kg-1 for all P forms...... 32

2-4 Mean and standard deviations for P forms for sand sediments: bulk density (BD), mass loss on ignition (LOI), total carbon (TC), total nitrogen (TN), total phosphorus (TP) per lake in mg kg-1 for all P forms...... 34

2-5 Mean and standard deviations for P forms for mud sediments: bulk density (BD), mass loss on ignition (LOI), total carbon (TC), total nitrogen (TN), total phosphorus (TP) per lake in mg kg-1 for all P forms...... 35

2-6 Pearson correlations for selected metals and total P ...... 40

2-7 Mean and standard deviations for P forms for sand sediments: HCl-Ca and Mg and Oxalate Fe and Al mg kg-1 for all lakes...... 41

2-8 Mean and standard deviations for P forms for mud sediments: HCl-Ca and Mg and Oxalate Fe and Al mg kg-1 for all lakes...... 41

2-9 Mean and standard deviations for P forms for sand sediments: KCl- Pi, NaOH Pi, HCl-Pi, TPi, NaOH Pi, residue P, total Po and total P per lake in mg kg-1 for all P forms...... 47

2-10 Mean and standard deviations for P forms for mud sediments: KCl- Pi, NaOH Pi, HCl-Pi, TPi, NaOH Pi, residue P, total Po and total P ...... 47

3-1. X and Y coordinates of each station. All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 59

vii

3-2. Percent change in Water Column SRP (mg L-1) under no P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6 for all lakes except Cypress in which n=4...... 63

3-3 Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at no P additions at 2, 7, and 25 days. n=6 for all lakes except Cypress (n=4)...... 63

3-4 Sediment characteristics of all stations for each lake for bulk density, mass loss on ignition (LOI), and total C, N, and P (mg kg-1). N=10...... 64

3-5 Sediment characteristics of all stations for each lake for oxalate-Fe and Al and HCl-Ca and Mg. n=10...... 65

3-6 Correlation between sediment properties with the Pearson correlation on top and the P-value on the bottom in parentheses. All correlations are significant to P<0.05. n=10 ...... 67

3-7 Correlation between P flux and EPCw with sediment properties with the Pearson correlation on top and the P-value on the bottom in parentheses. All correlations are significant to P<0.05. n=10 ...... 68

3-8 Percent change in SRP mg L-1 at 15 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6 for all lakes except Cypress in which n=5...... 70

3-9 Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 15 ug L-1 P additions at 2, 7, and 25 days. n=6 for all lakes except Lake Cypress n=5 ...... 72

3-10 Percent change in SRP mg L-1 at 30 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicate a decrease in SRP concentration while a positive (+) percent change indicate an increase in SRP concentrations. n=6 ...... 74

3-11 Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 30 ug L-1 P additions at 2, 7, and 25 days...... 76

3-12 Percent change in SRP mg L-1 at 60 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6...... 78

3-13 Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 60 ug L-1 P additions at 2, 7, and 25 days..80

viii

3-14 Percent change in SRP mg L-1 at 120 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6...... 82

3-15 Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 120 ug L-1 P additions at 2, 7, and 25 days...... 83

3-16 Ranges of sediment-water SRP fluxes (mg m-2 d-1)...... 86

3-17 Correlation between Porewater Equilbrators (Peepers) and P flux rate with the Pearson correlation on top and the P-value on the bottom in parentheses. All correlations are significant to P<0.05. n=10 ...... 87

3-18 Equilibrium Water Column Phosphorus Concentrations (EPCw) values determined at two stations in each lake. Water column concentrations below these concentrations indicate conditions favorable for release of P n=3...... 88

A-1 Characterization of inorganic P forms (mg kg-1) in Tohopekaliga, Cypress, and Hatchineha raw data for sand sediments...... 98

A-2 Characterization of inorganic P (mg kg-1) forms in Kissimmee and Istokpoga raw data for sand sediments...... 99

A-3 Characterization of inorganic P (mg kg-1) forms in Tohopekaliga, Cypress and Hatchineha raw data for mud sediments...... 99

A-4 Characterization of inorganic P (mg kg-1) forms in Kissimmee and Istokpoga raw data for mud sediments...... 100

B-1 Characterization of metals (mg kg-1) for Tohopekaliga, Cypress, Hatchineha raw data for sand sediments...... 101

B-2 Characterization of metals (mg kg-1) for Kissimmee and Istokpoga raw data for sand sediments...... 101

B-3 Characterization of metals (mg kg-1) for Tohopekaliga, Cypress, Hatchineha raw data for mud sediments...... 102

B-4 Characterization of metals (mg kg-1) for Kissimmee and Istokpoga raw data for mud sediments...... 102

C-1 Characterization of nutrients (mg kg-1) in Tohopekaliga, Cypress, and Hatchineha raw data for sand sediments...... 103

C-2 Characterization of nutrients (mg kg-1) in Kissimmee and Istokpoga raw data for sand sediments...... 104

C-3 Characterization of nutrients (mg kg-1) in Tohopekaliga, Cypress and Hatchineha raw data for mud sediments...... 104

C-4 Characterization of nutrients (mg kg-1) in Kissimmee and Istokpoga raw data for mud sediments...... 105

D-1 Water Column SRP for Lake Tohopekaliga under aerobic conditions for 25 days for station T10 (Coordinate x (461809 meters), y (3116800 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 106

D-2 Water Column SRP for Lake Tohopekaliga under aerobic conditions for 25 days for station T2. (Coordinate x (460252 meters), y (3125825 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 107

D-3 Water Column SRP for Cypress Lake under aerobic conditions for 25 days for station C16. Coordinate x (469875 meters), y (3106370 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 108

D-4 Water Column SRP for Cypress Lake under aerobic conditions for 25 days for station C15. Coordinate x (468261 meters), y (3105828 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 109

D-5 Water Column SRP for Lake Hatchineha under aerobic conditions for 25 days for station H107. Coordinate x (461341 meters), y (3098421 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 110

D-6 Water Column SRP for Lake Hatchineha under aerobic conditions for 25 days for station H103. Coordinate x (458082 meters), y (3100650 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 111

D-7 Water Column SRP for Lake Kissimmee under aerobic conditions for 25 days for station K1004. Coordinate x (472394 meters), y (3084179 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 112

D-8 Water Column SRP for Lake Kissimmee under aerobic conditions for 25 days for station K1012. Coordinate x (473188 meters), y (3088426 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 113

D-9 Water Column SRP for Lake Istokpoga under aerobic conditions for 25 days for station I10007. Coordinate x (472779 meters), y (3026915 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 114

D-10 Water Column SRP for Lake Istokpoga under aerobic conditions for 25 days for station I10004. Coordinate x (469916 meters), y (3030750 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17...... 115

E-1 Coordinates (x and y), water depth, sediment depth and thickness for Cypress Lake. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17...... 121

E-2 Coordinates (x and y), water depth, sediment depth and thickness for Lake Hatchineha. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17...... 122

E-3 Coordinates (x and y), water depth, sediment depth and thickness for Lake Istopokga. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17...... 123

E-4 Coordinates (x and y), water depth, sediment depth and thickness for Lake Kissimmee. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17...... 124

E-5 Coordinates (x and y), water depth, sediment depth and thickness for Lake Tohopekaliga. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17...... 125

F-1 Coordinates (x and y) and sediment type for stations chosen to sample for Lake Tohopekaliga and Cypress Lake. n=10. All coordinates are Universal Transverse Mercator, North American Datum 1983, units meters, UTM zone 17...... 126

F-2 Coordinates (x and y) and sediment type for stations chosen to sample for Lake Hatchineha and Kissimmee Lake. n=10. All coordinates are Universal Transverse Mercator, North American Datum 1983, units meters, UTM zone 17...... 127

F-3 Coordinates (x and y) and sediment type for stations chosen to sample for Lake Istokpoga Lake. n=10. All coordinates are Universal Transverse Mercator, North American Datum 1983, units meters, UTM zone ...... 128

LIST OF FIGURES

Figure page

1-1 Location of Lake Istokpoga and Upper Chain of Lakes in relation to Lake Okeechobee...... 7

1-2 The percent of landuse by county area for Osceola and Highlands for which the lakes are located. The total acres for Osceola and Highlands are 620,016 and 487,207, respectively...... 9

1-3 Historical TP levels (mg L-1) for Kissimmee upper chain of lakes (personal communication with SFWMD)...... 12

2-1 Sampling stations for Lake Tohopekaliga...... 17

2-2 Sampling stations for Cypress Lake...... 18

2-3 Sampling stations for Lake Hatchineha...... 19

2-4 Sampling stations for Lake Kissimmee...... 20

2-5 Sampling stations for Lake Istokpoga...... 21

2-6 Inorganic P fractionation scheme after Reddy et al. 1998...... 25

2-7 Amount of metals, HCl-Mg, HCl-Ca, Oxalate-Fe, and Oxalate Al, in mg kg-1 for all lakes...... 29

2-8 Distribution of P forms in Lakes Tohopekaliga and Hatchineha...... 31

2-9 Distribution of P forms in Lakes Cypress and Kissimmee...... 32

2-10 Regression between concentrations of total C (g kg-1) to loss on ignition (%). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 35

2-11 Regression between concentrations of total N (g kg-1) to loss on ignition (%). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 36

xii

2-12 Regression between concentrations of total P (g kg-1) to loss on ignition (%). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 37

2-13 Regression between concentrations of total P (mg kg-1)and with total C (g kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 38

2-14 Regression between concentrations of total P (mg kg-1) and with total N (g kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 39

2-15 Regression between concentrations of oxalate-Al (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 42

2-16 Regression between concentrations of oxalate-Fe (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 43

2-17 Regression between concentrations of HCl-Ca (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 44

2-18 Regression between concentrations of HCl-Mg (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph...... 45

2-19 The mean percent of mean TP (mg kg-1) of each P fractions (KCl-Pi, NaOH-Pi, HCl-Pi, NaOH-Po, and Residue P) for both mud and sand sediments for all the lakes...... 48

3-1 Location of sampling stations for Lake Tohopekaliga...... 55

3-2 Location of sampling station for Cypress Lake...... 56

3-3 Location of sampling stations for Lake Hatchineha...... 57

3-4 Location of sampling stations for Lake Kissimmee...... 58

3-5 Location of sampling stations for Lake Istokpoga...... 59

3-6 Phosphorus retention by sediments from station T2 of Lake Tohopekaliga at 60 ug L-1 P additions...... 77

3-7 Phosphorus retention by sediments from station I10007 of Lake Istokpoga at 120 ug L-1 P additions...... 81

xiii

3-8 Water Column SRP (mg L-1) versus spike concentration ug L-1 for each lake at day 2, 7, and 25...... 84

3-9 Release/retention of P related to water column concentration for Lake Tohopekaliga-stations-T10 (top) and T2 (bottom)...... 89

3-10 Release/retention of P related to water column concentration for Lake Cypress- station C16 (top) and C15 (bottom)...... 90

3-11 Release/retention of P related to water column concentration for Lake Hatchineha-station H107 (top) and H103 (bottom)...... 91

3-12 Release/retention of P related to water column concentration for Lake Kissimmee-stations K1004 (top) and K1012 (bottom)...... 92

3-13 Release/retention of P related to water column concentration for Lake Istokpoga- station 10007 (top) and 10004 (bottom)...... 93

E-1 Sediment thickness map for Cypress Lake...... 116

E-2 Sediment thickness map for Lake Hatchineha...... 117

E-3 Sediment thickness map for Lake Istokpoga...... 118

E-4 Sediment thickness map for Lake Kissimmee...... 119

E-5 Sediment thickness map for Lake Tohopekaliga...... 120

xiv

Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science

PHOSPHORUS FLUX FROM THE SEDIMENTS IN THE KISSIMMEE CHAIN OF LAKES

Chakesha S. Martin

May 2004

Chair: John R. White Major Department: Soil and Water Science

Phosphorus (P) coming from wastewater treatment plants and runoff from urban

and agricultural areas have impacted water quality in many Florida lakes over the last few

decades. The continual input of P into lakes can lead to poor water quality, which can

result in massive fish kills and harm to humans and animals through drinking water.

Bottom sediments also control the trophic status of a lake, even after the external load has been reduced. The P flux study examined the response of lake sediments to changes in water column SRP concentrations in 5 contributory lakes of Lake Okeechobee in Florida.

The objectives of this study were to characterize the pools of inorganic and organic

P, determine the SRP flux rates using intact sediment cores, and determine the equilibrium water column P concentration (EPCw) of the sediment.

Sediments were collected from 10 stations per lakes for the P characterization

study. Sediment samples were collected from the top 10 cm and analyzed for moisture

content, bulk density, mass loss on ignition (LOI), HCl extractable Ca and Mg, oxalate Fe

and Al, inorganic and organic P fractions, as well as total C, N, P.

Intact cores were taken from two stations per lake and 15 cores per station (total of

150 cores) to determine the SRP flux rate for a range of mud and sand sediments and to

-1 calculate the EPCw. Five water column concentrations (0, 15. 30, 60, 120 ug L ) were added once and evaluated in triplicate for the SRP flux rate measurements and incubated in the dark under aerobic conditions for 25 days.

The sediment P characterization revealed that the mud sediments contained greater amounts of organic matter, total C, N, and P, as well as Ca, Mg, Fe, and Al. Total P concentrations ranged from 38 to 1812 mg kg-1 for the sediments. There was a strong positive correlation found between TP and organic matter (R2=0.94), suggesting that P is

a consistent portion in the organic fraction. Most of the inorganic P was associated with

the Fe/Al portion. The total organic P fraction was the greatest overall pool, suggesting

that the TP coming into the lakes may be associated with organic matter.

The aerobic SRP flux rates suggest that P release was highest at ambient water

column SRP (6 ± 4 ug L-1) and decreased with an increase in P loading. However, an

increase in P loading also maintained high water column SRP concentrations. Flux rates

results indicate that sediments in 4 of the 5 lakes are releasing P to the water column at

ambient water column SRP concentrations and retaining P at higher concentrations. The

EPCw showed that 2 of the 5 lakes have a low potential for release of SRP from the

sediments as the water column SRP concentrations decrease over time. Results from this

study will assist water managers in determining the internal load of P during efforts to

reduce P export to downstream Lake Okeechobee.

xvi CHAPTER 1 INTRODUCTION

For years there have been concerns about the impact of excess nutrients

(phosphorus (P), nitrogen (N) and carbon (C)) entering lakes from wastewater treatment

plants and runoff from urban and agricultural areas on deteriorations to surface water

quality (Carpenter et al. 1998, Sharpley et al. 1999). Phosphorus, N, and C are all macronutrients essential for growth of organisms but P is often considered one of the most limiting nutrients in freshwater systems (i.e., lakes, and rivers) throughout the world. Phosphorus is documented as a major source influencing phytoplankton mass in freshwater and is generally derived from controllable point sources (Marsden 1989).

However, for N and C there are difficulties in controlling the exchange of N and C between the atmosphere and the water and the fixation of atmospheric N by some blue- green algae (Sharpley et al. 1999). Alternatively, as salinity increases, as in estuarine systems, N is sometimes considered the limiting nutrient controlling aquatic productivity

(Sharpley et al. 1999).

In Florida, there is a particular concern in water quality because of surface water

eutrophication from excess P coming from external sources (i.e., wastewater treatment

plants, agriculture, and urban sources). Eutrophication can be described as an increase in

the fertility status of natural waters that cause accelerated growth of algae as well as aquatic weeds (Pierzynski et al. 2000). The growth of undesirable algae and weeds that

later die off and decompose cause oxygen depletion that can result in massive fish kills

and harm to humans and animals through drinking water (Backer 2002, Carpenter et al.

1 2

1998). A few examples of degrading water systems due to continual external inputs of P

are Loosdrecht lakes (Netherlands); Skaha Lake (British Columbia), Lake Okeechobee,

Florida (USA); and the Everglades (USA) (Keizer and Sinke 1992, Nordin 1983, Reddy

et al 1995, White and Reddy 1999).

Phosphorus Forms

Phosphorus enters the surface water of lakes in both organic and inorganic forms

and can be in either soluble or insoluble forms. Phosphorus can be classified into four

forms: i). soluble reactive P (SRP); ii) dissolved organic P; iii) particulate inorganic P;

and particulate organic P (Reddy et al. 1999). Soluble reactive P is the form most available for plants and microbes. The other three forms must be transformed into the bioavailable form through decomposition processes regulated by enzymatic hydrolysis.

Phosphorus Cycling

3- Inorganic P enters primarily in the form of orthophosphate (PO4 ) and can enter the

water column of a lake by four pathways: i) settling of insoluble (particulate) inorganic and organic P, ii) uptake of soluble reactive P (SRP) by primary producers (algae) and its

subsequent settling, iii) sorption of soluble inorganic or organic P onto particles that settle

onto the sediments, and iv) sorption of soluble inorganic and organic P directly onto

sediment particles (Reddy et al. 1999). Sediments act as a net sink of P; however, when

porewater P concentrations exceed the overlying water column concentration, SRP can be

released from the sediment to the water (Moore et al. 1991).

The exchange of P between the sediment and water column may depend on

processes such as i) diffusion and advection (wind/wave action, flow, and bioturbation),

ii) processes within the water column (biotic uptake and release, mineralization, and

sorption by particulate matter), iii) diagenetic processes (mineralization, sorption,

precipitation, and dissolution) in bottom sediments, iv) redox conditions (oxygen

content), v). organic matter content, vi) pH, vii) temperature, and viii) the presence of

metals bound to P (Bostrom and Pettersson 1982, Holdren and Armstrong 1980, Moore et

al. 1991, Wetzel 2001). Inorganic P is most associated with crystalline or amorphous

compounds such as iron (Fe), aluminum (Al), calcium (Ca) and magnesium (Mg).

Organic P is mostly associated with undecomposed residues, microbes, and organic

matter (Sharpley et al. 1999).

Phosphorus Retention Mechanisms

Understanding the forms and properties of P in lake sediments are important to

identify factors that control P release from the sediment to the overlying water column.

Inorganic P is usually found as i) labile or loosely sorbed P, ii) Al and Fe bound P; and

iii) Ca and Mg bound P (Reddy et al. 1995). The most available form of P is labile P or

exchangeable P, which is essential for plant growth. The slowly available form of P is

associated with Fe/Al, Ca/Mg, and labile organic compounds. The very slowly available

P is associated with discrete mineral forms of Fe, Al, and Ca, and highly decomposed

organic matter.

Metals (Fe, Al, Ca, and Mg) play a important role in inorganic P retention. The

ability of P to be retained by Fe/Al and Ca/Mg compounds depend on pH and/ or redox

conditions of the sediments (Patrick and Khalid 1974). Phosphorus is retained by Fe/Al

compounds under acidic conditions and is more stable under low pH conditions. The

reduction of insoluble ferric iron (Fe3+) to a more soluble ferrous iron (Fe2+) compound can lead to P released from the sediments (Patrick and Khalid 1974). When there is a

dominance of Ca/Mg P in the sediments, P is more stable under high pH or alkaline

conditions (Patrick and Khalid 1974). Organic acids from settling or deposited

decomposing organic matter can lower pH short term and lead to dissolution of Ca bound

P (Marsden 1989).

Phosphorus External Load Reduction

Over the years, improvements in water quality have focused on external

phosphorus load reductions. The response of a lake after external load reductions

depends on the recycling of phosphorus from the sediment to water column (Marsden

1989). Some studies have shown that reducing the external P loading can significantly

improve water quality in lakes (Smith and Shapiro 1981). However, other studies have

shown that a reduction in external P load does not always result in a decrease in TP in the

water column of a lake due to high internal sediment P load (Marsden 1989, Nordin

1983, Welch and Cooke 1995). The idea of internal loading is based on the recycling of

nutrients from bottom sediment in lakes to the overlying water column (Carpenter 1983).

After load reductions, the internal load of sediments will determine the trophic status of a lake and the amount of lag time for recovery (Petterson 1998).

Many studies have investigated the diffusive release of phosphorus from the sediments measured from intact sediment cores in the laboratory (Fisher and Reddy 2001,

Petterson and Bostrom 1985). Phosphorus release rates are stimulated by low redox potential (Istvanovics 1988, Marsden 1989, Mortimer 1941) and high temperature

(Holdren and Armstrong 1980, Kamp-Nielsen 1974). In shallow lakes, sediments resuspension can be important for internal loading (Reddy et al 1996, Welch and Cooke

1995). The mobilization of this internal P load in the sediment is determined by the

5 forms of P in the sediment (Keizer and Sinke 1992). Sediments characterized with a dominance of iron (Fe) associated P can release P under low redox, as well as high pH conditions (Petterson and Bostrom 1985). In other instances, sediments characterized by a dominance of calcium (Ca) may release P under low pH conditions (Marsden 1989).

In eutrophic lakes, macrophyte species with high annual biomass turnover can be a potential internal source of nutrients to the overlying water column (Carpenter 1983). In oligotrophic lakes biomass turnover and the biomass of macrophytes are not as large and there may not be a great release of P to the water column from the senescenes of macrophytes. Macrophytes release phosphorus as well as other nutrients from living shoots, but most of the phosphorus released occurs after the shoot dies and decays

(Carpenter 1983). The decay of macrophytes at the sediment surface lowers the oxygen concentration and redox potential which can cause a flux of P from the sediment to water column of a lake (Carpenter 1983). One management suggestion to reduce the flux of P is to spray with herbicides; however, this may not be an effective control method

(Carpenter 1983). Harvesting macrophytes may be a more effective in removing nutrients and reducing internal nutrient loads because it removes the nutrients from the system.

The equilibrium phosphorus concentration (EPC) can be used to determine the extent to which the internal load will be released during restoration of a lake after external load reductions. The EPC is defined as the P in solution that is in equilibrium with the P in the solid phase or the point where P is neither being retained nor released from the sediment to the water column (Olila and Reddy 1993). At water column SRP

concentration above the EPC, P is retained by the sediments, and at concentrations below,

the sediments serve as P source.

Study Rationale

Lake Okeechobee, a large (1800 km2), shallow (mean depth ~2.7 m) eutrophic lake, located in south Florida, has been impacted by nutrient loads from point and nonpoint sources of pollution for over 30 years (Havens 1997; Havens and Walker 2002; Reddy et al. 1995). Lake Okeechobee serves as a primary source of water for surrounding cities, recharge water for the South Florida aquifer, source of irrigation water for agriculture, source of habitat for wildlife, and as a source of recreational and commercial fishing

(Havens and James 1997). Since the early 1970’s to present, the total phosphorus concentrations in Lake Okeechobee have more than doubled from around 50 ug L-1 to

100 ug L-1 (Havens 1997). Lake Okeechobee, located in south Florida is a large (1800 km2), shallow (mean depth ~2.7 m) eutrophic lake

Recognizing the need for restoration of water quality in Lake Okeechobee, Florida, the Florida Legislature in 1987 adopted the Surface Water Improvement and

Management (SWIM) Act (sections 373.451 to 373.4595 FL statues) that states that the

South Florida Water Management District (SFWMD) must create and implement a

program to protect the quality of water in Lake Okeechobee (Havens and James 1997).

The SWIM Act also mandated a P loading target for Lake Okeechobee.

In 1998, the Florida Department of Environmental Protection (FDEP) submitted

Lake Okeechobee on a list of impaired waters to the United States Environmental

Protection Agency (USEPA) (Havens and Walker 2002). In 2000 FDEP began the

process of developing a TMDL for Lake Okeechobee. The TMDL goal to Lake

Okeechobee is established at 198 metric tons of TP and the in-lake P concentration is 40

ug L-1 within the pelagic region.

Phosphorus load to Lake Okeechobee from water discharging from the Kissimmee upper chain of lakes have increased in phosphorus over the last five years from 23-91

metric tons (personal communication with SFWMD). Thus, quantifying P load from

these major contributory lakes (Tohopekaliga, Cypress, Hatchineha, Kissimmee, and

Istokpoga) is vital for Lake Okeechobee’s restoration (Figure 1-1). This study fulfills

parts of the requirements of the Lake Okeechobee Protection Act (Chapter 373.4595),

which required an assessment of P sources from the Kissimmee upper chain of lakes and their contribution to the quality of water in Lake Okeechobee (Walker and Haven 2002).

Figure 1-1. Location of Lake Istokpoga and Upper Chain of Lakes in relation to Lake Okeechobee.

In considering factors affecting water quality in the upper chain of lakes and P

export to downstream Lake Okeechobee, several questions arose, including: i) What are

the physical and chemical characteristics of surface sediments, with particular emphasis on the forms of P and compounds that can affect P sorption or release? ii) What is the current contribution of phosphorus (internal loading) from the sediments to the water column of these lakes? iii) What are the Equilibrium Phosphorus Concentrations of the sediments in these lakes? These questions focus on whether P is being stored in organic or inorganic forms, the relative availability of P forms, and the extent to which the internal load will be released as external P loads decline and the water column P concentrations are reduced.

Objectives

The objectives of this study were to i) characterize and quantify the forms of inorganic P and organic P in the sediment, ii) determine the P flux rate from the sediment to the water column and iii) determine the equilibrium P concentration of the

sediment.

Site Description

Lakes Tohopekaliga (98.4 km2) Cypress (22 km2), Hatchineha (71.6 km2),

Kissimmee (179 km2) and Istokpoga (112 km2) are shallow, eutrophic lakes located in the

Upper Kissimmee River Basin (Walker and Havens et al. 2002; Williams 2001). The

mean depths are 2.6, 1.9, 2.1, 3.4, and 2.7 m respectively for Lakes Tohopekaliga,

Cypress, Hatchineha, Kissimmee, and Istokpoga (Havens et al. 2000, Walker and Havens

2002). The surface water pH ranges from 6-8, and secci depth ranges from 0.6-1.2 m for

all lakes (Havens et al. 2000, Walker and Haven 2002). The entire Kissimmee River

Basin (KRB) comprises 3,013 square miles; however, the upper basin covers 1600 square miles (USACE 1996)

Lake Tohopekaliga is at the headwaters of the KRB, proximal to Walt Disney

World, and about 25 km south of the city of Orlando and Kissimmee (James et al. 1992).

These hydrological connected lakes in Central Florida flow throughout the counties of

Osceola and Highlands in a heavily populated and intensively developed part of the watershed (Figure 1-2). The lakes are located in an area that is the hub of the cattle industry in central Florida, St. Cloud, and Haines City (USACE 1996). Citrus farming, tourism and sod farming, as well as the cattle industry are economic bases for the surrounding communities. Citrus industry dominates north of Lake Cypress and sod farming is prevalent within the Kissimmee Upper Basin.

300000

250000

200000 Osceola 150000 Highlands Acres 100000

50000

s r st ulture Urban Wate c Fore Barren gri Wetlands A Rangeland Landuse

Figure 1-2. The percent of landuse by county area for Osceola and Highlands for which the lakes are located. The total acres for Osceola and Highlands are 620,016 and 487,207, respectively.

The lakes are used for recreation, irrigation and flood control. There are less urban and residential development located around Lakes Kissimmee, Cypress, and Hatchineha in comparison to Lake Tohopekaliga (Havens et al. 2000, USACE 1996). Each of the

10 five lakes receives flow contributions from other water systems within the KRB: Lake

Tohopekaliga (Shingles Creek and East Lake Tohopekaliga), Lake Cypress (Canoe Creek and Dead River), Lake Hatchineha (Reedy and Catfish Creek), Lake Kissimmee (Lake

Tiger), and Lake Istokpoga (Josephine Creek and Arbuckle Creek) (Walker and Haven

2002, Williams 2001).

Under natural conditions, prior to significant alterations to the watershed, the lake stages fluctuated seasonally from about 0.6-3.1 m (2-10 ft) and stored water in the wet summer season overflowing into the marshes connected to each lake (USACE 1996).

There were no hydrologic connections between the lakes during the dry season.

Currently, lake levels are regulated and maintained by the South Florida Water

Management District (SFWMD) through a series of water control structures and canals.

Some nuisance or problem vegetation is hydrilla (Hydrilla verticillate), water hyacinth (Pistia stratiotes), water lettuce (Eichhornia crassipes) and the American lotus

(Nelumbo luteal). The dominant vegetation in the littoral zone of the lakes includes vegetations such as willow (Salix spp), buttonbush (Cephalanthus occidentalis), topedo grass (Panicum repens), maidencane (Panicum hemitomon), sawgrass (Claidium jamaicense), cattail (Typha spp.), and pickerel weed (Pontederia cordata), (USACE

1996). The lakes are surrounded by pine flatwoods, dry and wet praires and cypress domes.

The water quality in the lakes have been affected by Waste Water Treatment

Effluent (WWT) coming from four waste treatment plants via canals and streams into

Lake Tohopekaliga, since the late 1950’s (Williams 2001). The water discharged from

Lake Tohopekaliga has contributed to the degradation of water quality in the downstream

lakes. The lakes have not only been affected by nutrients coming from wastewater

treatment plants, but also pollution coming from agricultural and urban sources. Since

the lake 1960’s, a few lake drawdowns, muck removal projects, and control of invasive

plants by use of herbicide applications have been utilized as a way to restore water

quality and habitat for endangered species within the Kissimmee upper chain of lakes

(USACE 1996, Williams 2001). In the mid 1980’s the nutrients levels coming from

wastewater treatment plants to Lake Tohopekaliga were diverted.

In general, TP levels in the water column of the Kissimmee upper chain of lakes

have declined over time; since 1980’s (Figure 1-3). In reviewing past water quality data

collected by the South Florida Water Management District, since the 1980’s ( no water

quality data available prior to 1980), the average TP concentrations were greater than 100

ug L-1 in Cypress, Tohopekaliga, and Hatchineha; however, the concentrations were much lower in Kissimmee and Istokpoga at less than 50 ug L-1. In the 1990’s, the water

column TP concentrations decreased to less than about 65 ug L-1 in Tohopekaliga,

Cypress, and Hatchineha, but concentrations nearly double to over 100 ug L-1 for Lake

Kissimmee. The water column TP concentration for Istokpoga remained the same as in

the 1980’s. Currently, the water column TP concentrations have remained relatively the

same for most all lakes since the 1990’s, except concentrations have nearly doubled in

Istokpoga to 60 ug L-1 and concentrations have declined in Kissimmee from over 100 ug

L-1 to 60 ug L-1. However, it should be noted that although water column TP concentrations have declined, in general, the concentrations in the lakes are well above the in-lake P concentration goal of 40 ug L-1 in the pelagic region of Lake Okeechobee.

200 180 )

-1 160 Cypress 140 Hatchineha 120 Tohopekaliga Kissimmee 100 Istokpoga 80 60 40 Water Column TP (ug L 20 0 80-89 90-99 00-03 Years

Figure 1-3. Historical TP levels (mg L-1) for Kissimmee upper chain of lakes (personal communication with SFWMD).

In efforts to restore water quality in the Kissimmee upper chain of lakes and reduce

P effort to downstream Lake Okeechobee there have been efforts made to control water

quality deteriorations coming from nonpoint and point sources of pollution by

implementing Best Management Practices (BMP’s). Some management practices to

reduce the external load of P entering a lake include retention or infiltration areas, wet

detention ponds, constructed wetlands, sand filters, and bio-retention areas. The main

BMP’s are usually efficient fertilizers applications (directed in some part to educating

citizens), effective stormwater systems, and control of erosion and sediment.

CHAPTER 2 SEDIMENT CHARACTERIZATION

Introduction

Over the years there have been concerns about the impact of excess P leaving

urban and agricultural areas on water quality in many Florida lakes (i.e., Lake Apopka

and Lake Okeechobee). Although, P is a limiting nutrient essential for plant growth, too

much P can lead to eutrophic conditions, resulting in harm to the quality of water within

an aquatic system including declines in fish populations, changes in vegetation, and limitations to recreation (Carpenter et al. 1998). Chemical, physical, and microbial processes control the exchange of P between the sediment and water column. Thus, for restoration to occur in a lake, it is important to understand the forms and properties of P in lake sediments to identify the factors that control P release from the sediment to the overlying water column.

Phosphorus in soils and sediments exists in both organic and inorganic forms.

External inputs of P from such entities as urban and agricultural sources and wastewater treatment plants can be in soluble or insoluble particulate forms. P can be classified into four forms: i) soluble reactive P (SRP) or dissolved inorganic P; ii) dissolved organic P;

(iii) particulate inorganic P; and (iv) particulate organic P (Reddy et al. 1999). Soluble reactive P is the form most available for plants and microbes. The other three forms must be transformed into the bioavailable form through decomposition processes regulated by enzymatic hydrolysis.

13 14

Inorganic P primarily enters into lakes in the form of orthophosphate and can be

transported to the sediments first by uptake by phytoplankton (biological) and through

subsequent settling of particulate inorganic and organic P (Faulkner and Richardson,

1989, Syers et al. 1973). The forms of inorganic P which exist in sediments include the

3- 2- - ions PO4 , HPO4 and H2PO4 with the dominant form dependent on pH. Sediment in

2- - lake systems in Florida typically range from 6-8, with the HPO4 and H2PO4 forms most

dominant. Inorganic phosphorus is usually found as (i) labile or loosely absorbed P; ii)

Al and Fe bound P; and (iii) Ca and Mg bound P (Reddy et al. 1995). The most available

form of P is the labile P or exchangeable P. The slowly available P is associated with

Fe/Al, Ca/Mg and labile organic compounds. The very slowly available P is associated with discrete mineral forms of Fe, Al, and Ca. and highly decomposed organic matter.

Factors that regulate inorganic P retention are pH, redox (Eh), organic matter content, calcium carbonate content, temperature, and amounts of Fe, Al, Ca and Mg

compounds. The ability of P to be retained by Fe/Al and Ca/Mg depends on the pH

and/or redox conditions of the sediments (Patrick and Khalid 1974). Phosphorus is retained by Fe/Al compounds under acidic conditions and is more stable under low pH conditions. The reduction of insoluble ferric iron (Fe3+) to a more soluble ferrous iron

(Fe2+) compound can lead to P released from the sediment (Patrick and Khalid 1974).

When there is a dominance of Ca/Mg P in the sediments, P is more stable under high pH or alkaline conditions (Patrick and Khalid 1974). Organic acids from settling or deposited decomposing organic matter can lower the pH short term and lead to dissolution of Ca bound P (Marsden 1989).

Organic P is contained in undecomposed residues, microbes and organic matter

(Sharpley 1999). The most common form of organic P is inositol phosphates, which are

found as hexaphosphates (Ivanoff et al. 1998). Inositols are high molecular weight phosphates (up to 60% of total Po) that are the most stable or resistant to degradability;

thus microbes do not readily have access to inositols (Anderson 1976, Ivanoff et al.

1998). Other forms of organic P compounds are phospholipids, nucleic acids, glucose-1-

phosphate, glycerophosphate, and phosphoproteins, which make up only 2% of total organic P (Ivanoff et al. 1998). Phospholipids are commonly found in plant material and

animal waste, or found through the process of microbial synthesis (Ivanoff et al. 1998).

Since much of organic P is contained in sediment particles and organisms, it is not readily

available to microbes and plants. Therefore, organic P must be transformed into the

bioavailable form of phosphorus (Wetzel 1999).

Chemical fractionation schemes have been used to distinguish and quantify the

various forms of P in sediments (Graetz and Nair 1999). There are several methods that

have been developed to quantify the various forms of P; but, there is not a widely

accepted method to measure organic P content (Change and Jackson 1957, Hieltjes and

Lijklema 1980, Ruttenberg 1992). Organic P can be measured indirectly through

inorganic P fractionation schemes.

There have been criticisms of the sequential fractionation schemes. It is

important to keep in mind that various chemical reagents only extract a pool of P related

to a given chemical group. Therefore, it is critical that adequate tests of sequential

extraction methods be calibrated (Ruttenberg 1992). Phosphorus extraction methods are

often considered operationally defined and therefore subject to broad interpretations

(Graetz and Nair 1999). It can be difficult to compare data between researchers who use vastly different P fractionation methods thus complicating data interpretation obtained among literary sources (Graetz and Nair 1999). Nevertheless, sequential fractionation schemes do provide a method of determining various pools of P in lake sediments.

Hypothesis

Recently accreted mud sediments will contain significantly higher P than the natural sand sediment bottom.

Objective

The objective of this study was to characterize and quantify the forms of P in the sediments.

Field Methods

We performed a preliminary sediment survey of the lakes (August/2002) that provided information for selection of each sampling station. A jet probe rod was used to determine where soft sediments were located and how thick (Appendix E). During the initial survey, coordinates, water depth, sediment depth, and thickness were recorded

(Appendix E). In addition, sediment type was recorded in which there were clean sand to organic muds for all lakes. After reviewing the preliminary sediment survey observations and measurements, 10 stations per lake were chosen to be sampled and were representative of the major sediment types in each lake (Figure 2-1 to Figure 2-5).

Using GPS equipment, each station was located within +/- 5 m of the true coordinates and sediment type was recorded (Appendix F). Dissolved oxygen and temperature measurements were taken at three depths: 30cm below the water surface, mid-depth, and 30 cm from the bottom using a YSI hand-held DO meter. In general, the dissolved oxygen levels were greater than 5 (mg L-1) in the top 30 cm and decrease with

an increase in depth. The temperature measure was relatively the same at all depth a mean of 29.9 ± 1.21 for all lakes.

Sediment samples (0-10cm) were collected from each site for analysis of various forms of P and a number of physical and chemical properties. Samples were extruded in the field using plexiglas tubes and immediately sectioned immediately into 10 cm intervals. Immediately following sectioning, the sediment samples were transferred to air tight pre-weighted glass jars, purged with nitrogen gas to maintain anaerobic conditions, and placed on ice. Samples were stored at 4°C upon return to the laboratory until analysis.

Y# 1

# 2 Y

3 Y# 4 #Y

N 5 #Y

9 10 #Y #Y 7 Y# 6 #Y

8 #Y

02468Kilometers

L. Tohopekaliga

Figure 2-1. Sampling stations for Lake Tohopekaliga

N 13 Y#

14 #Y 12 #Y 16 #Y 15 #Y 17 11 #Y #Y

18 20 #Y #Y 19 #Y

01234Kilometers

Cypress Lake

Figure 2-2. Sampling stations for Cypress Lake.

101 #Y

102 Y#

103 #Y 109 106 Y# #Y

105 #Y 110 107 #Y #Y 104 108 #Y #Y

01234Kilometers

L. Hatchineha

Figure 2-3. Sampling stations for Lake Hatchineha.

1010 Y# N 1011 1009 Y# Y#

1012 Y# Y# 1006 1005 Y# 1003 1004 Y# Y#

1002 Y#

1001 01234Kilometers Y#

L. Kissimmee

Figure 2-4. Sampling stations for Lake Kissimmee

10001 N #Y 10002 #Y

10003 10004 #Y Y# 10005 Y#

10006 #Y

10007 #Y

10008 #Y 10010 #Y

10009 0 1 2 3 4 Kilometers #Y

L. Istokpoga

Figure 2-5. Sampling stations for Lake Istokpoga.

Laboratory Techniques

Physical and Chemical

All sediment sub-samples were measured for a number of physical and chemical properties: water content, bulk density, mass loss on ignition (LOI), and total C, N, and

P. Percent moisture was determined after drying a known amount of moist sediment at

70°C to a constant dry weight. Total C and N were determined on dried, ground sub-

samples and analyzed on the Carlo-Erba NA-1500 C-N-S Analyzer (Haak-Buchler

Instruments, Saddlebrook, NJ) (White and Reddy 2000).

For the measurement of sediment total P, 0.5 g dried ground sub-samples were weighed and placed in a muffle furnace initially at 250°C and increased to 550°C for 4

hours. The remaining ash was treated with 20 mL of 6 M HCl and placed on a hot plate

at approximately 120°C (Anderson 1976). The samples were cooled and filtered through

Whatman #41 filter paper. The total P concentrations were determined using an

automated ascorbic acid colorimetric technique (Method 365.4, USEPA, 1993). The

organic matter content was determined by LOI.

Oven dried sub-samples were weighed out to approximately 0.5 g for analyses of

total inorganic P using 25 mL of a 1 M HCl extraction on oven dried sediment (Reddy et

al. 1998). The samples were shaken on a mechanical shaker for 3 hours and the

supernatant was filtered with 0.45 um filter paper. Total inorganic P concentrations were

analyzed using an automated ascorbic acid colorimetric method (Method 365.4, USEPA,

1993). The same 1 M HCl extraction was analyzed for metals, which were Ca and Mg

(Reddy et al. 1998). Sub-samples of approximately 0.25 g of dry ground sediment were

weighed and treated with 20 mL of oxalate reagent. Samples were shaken in the dark for

about 4 hours, centrifuged for 10 minutes, and filter through with 0.45 um filter paper.

The oxalate extraction was used to determine the Fe and Al bound P, which is the reactive fraction of amorphous Fe-Al oxides. Metal analyses were determined by inductively coupled argon plasma spectrometry (model Spectro Ciros CCD, manufactured by Spectro AI, Inc, Fitch burg, MA). Analyses were determined using a

modified version of EPA Method 200.7 (EPA 1983). Total organic P was calculated as

the difference between total P and total inorganic P.

Inorganic P Fractionation

The fractions of inorganic P were determined based on a scheme by Change and

Jacksons 1957 in which acid and alkaline reagents were used to extract various pools of P

in the soil. In this study, a modified version of Change and Jacksons’ scheme by Reddy

et al. 1998 was used to determine the various inorganic P fractions (Figure 2-6). It is

important to keep in mind that various chemical reagents only extract a pool of P related

to a given chemical group. The chemicals used in this study were 1.0 M potassium

chloride (KCL), 0.1 M sodium hydroxide (NaOH), and 0.5 M, 6.0 M hydrochloric acid

(HCL) in which, (i) bioavailable or loosely adsorbed Pi; ii) Pi associated with Fe and Al; and iii) Pi associated with Ca and Mg were extracted, respectively. The remaining

sediment P was considered to be the residual, recalcitrant organic P.

For the KCl-Pi extraction, samples were weighed out to a 0.5 g dry weight

equivalent and placed in centrifugation tubes in an oxygen-free gloved box to maintain

anaerobic conditions. Dissolved oxygen readings were less than 0.10 mg L-1. Samples

were placed in centrifuge tubes with caps outfitted with rubber septa. Using a syringe needle, 25 mL of 1 M KCl were added. The samples were placed on a mechanical shaker

for 2 hours, followed by centrifugation at 6000 (reps per minute) rpm for 10 minutes.

The supernantant of the solutions were filtered through with 0.45 um Whatman filter

paper under anaerobic conditions. Extracts were analyzed for soluble reactive

phosphorus (SRP), using a Shimadzu UV-160 visible spectrophotometer (Method 365.1,

USEPA 1993).

The residual sediment sample was treated with 25 mL of 0.1 M NaOH. Sediment

suspensions were agitated on a mechanical shaker, followed by centrifugation for 10

minutes. The supernatant solution were filtered through with 0.45 um filter paper. For

analysis of SRP (NaOH-Pi), concentrated sulfuric acid (H2SO4) was added to each

solution. This portion is represented as the Fe-Al bound P. The solutions were also

analyzed for total phosphorus (NaOH-TP) by digestion with 11 N sulfuric acid (H2SO4) and potassium persulfate (K2S2O8) at 380°C. Extraction with 0.1 M NaOH also removed

the P associated with humic and fulvic acids. The difference between NaOH-TP and

NaOH-Pi is alkali extractable organic P ( NaOH-Po) associated with both fulvic and

humic acids.

The residual soils from the NaOH extraction were treated with 25 mL of 0.5 M

HCl. Sediment solutions were shaken continuously for 24 hrs, followed by centrifugation

for 10 minutes. The supernatants were filtered through 0.45um filters. Filtered solutions

were analyzed for HCL-Ca-Mg bound P fraction.

The residue from the 0.5 M HCL extraction was combusted at 550°C for 4 hours.

Samples were filtered with Whatman #41 filter paper and the ash was dissolved in 6 M

HCl. All supernatants, except the KCl extractions, were analyzed by using the automated

ascorbic acid colorimetric method (EPA 365.1, 1993).

Soil Wet samples weighed out to a 0.5 g dry weight equivalent 1 M KCl [2 hrs] Readily available Pi [SRP]

Residue

0.1 M NaOH [17 hrs] [TP[TP] - [SRP] NaOH-Po

Fe-Al bound Pi [SRP] Residue (acidified)

0.5 M HCl [24 hrs] Ca-Mg bound Pi [SRP]

Ashed @ 550°C Residue Residual P o [TP] 6 M HCl digestion

Figure 2-6. Inorganic P fractionation scheme after Reddy et al. 1998.

Data Analysis

A variance check was conducted to test for normality. The data was not normal, so we transformed the data using two transformations (log and square root). However, the transformations were found not to be normal. A Wilcoxon/Kruskal-Wallis test was performed to compare the medians instead of the means using JMP Statistics, Version 4

(SAS Institute). Microsoft excel (Microsoft 2000) was used to performed any regression analyses and correlations.

Results

Physical and Chemical

Several physical and chemical sediment properties were measured for each

sample station including bulk density and organic matter. Bulk density ranged from

0.06-1.18 g cm-3, for all the lakes, with sediment texture varying from organic mud to sand. Lake Tohopekaliga had the highest average bulk density (0.83 ± 0.31g cm-3) and

Lake Kissimmee had the lowest (0.42 ± 0.47 g cm-3) of all the lakes (Table 2-1). The

loss on ignition (LOI), which estimates organic matter content, ranged from 0-55%. The

higher percent values represent the greatest content of organic matter in the sediment.

Lake Kissimmee had the highest average LOI value (26.3 ± 25.1%) and Lake

Tohopekaliga had the lowest (3.2 ± 3.6%). There were no significant differences found

between the lakes for bulk density and LOI due to high standard deviations, an artifact of

the different sediment types.

Total analyses of macroelements were conducted for the sediments of each lake

(Table 2-1). Total carbon values for the sediments ranged from 4-293 g kg-1 for all lakes, with an overall mean of 70.6 ± 85.9g kg-1. The mean total C values were higher in Lake

Kissimmee (124 ± 121 g kg-1) and lowest in Lake Tohopekaliga (16.3 ± 18.8 g kg-1).

Total nitrogen values ranged from 0.32-26.5 g kg-1 with an overall mean of 6.4 ± 7.98 g

kg-1. The highest value of total N was in Lake Kissimmee (11.7 ± 11.3 g kg-1) and the

lowest was Lake Tohopekaliga (1.37 ± 1.38 g kg-1).

The total P values ranged from 38.1-1811 mg kg-1 with an overall mean of 468 ±

557 mg kg-1. The highest total P levels were found in Lake Kissimmee (703 ± 685 mg

kg-1) and lowest levels were found in Lake Tohopekaliga (138 ± 127 mg kg-1). There

were no significant differences found between the lakes for total C, N, and P due to high standard deviations, an artifact of the different sediment types.

Table 2-1. Average Bulk Density (BD), Loss on Ignition (LOI), Total C, Total N, and Total P for Lakes Tohopekaliga, Cypress, Hatchineha, Kissimmee, and Istokpoga. n=10 per lake.

Lake BD LOI Total C Total N Total P g cm-3 % g kg-1 g kg-1 mg kg-1 Tohopekaliga 0.83 ± 0.31 3.2 ± 3.6 16.3 ± 18.8 1.37 ± 1.38 138 ± 127 Cypress 0.47 ± 0.43 17.8 ± 17.8 79.8 ± 85.5 7.36 ± 7.87 642 ± 700 Hatchineha 0.51 ± 0.47 17.8 ± 18.6 51.8 ± 83.7 7.8 ± 8.1 581 ± 594 Kissimmee 0.42 ± 0.47 26.3 ± 25.1 124 ± 121 11.7 ± 11.3 703 ± 685 Istokpoga 0.63 ± 0.44 10.7 ± 12.6 51.8 ± 61.9 3.88 ± 4.63 276 ± 297

Metals

Sediments were analyzed for select metals using a 1 M HCl extraction to

determine Calcium (Ca) and Magnesium (Mg) and an oxalate extraction was used to

determine the iron (Fe) and aluminum (Al) concentrations (amorphous & poorly-

crystalline). The range of Ca values was from 11585-12367 mg kg-1 with an overall mean of 3290 ± 3601 mg kg-1 (Table 2-2). Lake Hatchineha had the higher average Ca

value (5090 ± 5123 mg kg-1) while Lake Tohopekaliga had the lowest (912 ± 918 mg kg-

1). There was no significant difference in Ca among the lakes, due to the high standard

deviation, an artifact of different sediment types.

The mean value of Mg was 549 ± 731 and ranged from 0-2756 mg kg-1. Lake

Hatchineha had the higher amount (936 ± 1077 mg kg-1) and Lake Tohopekaliga was

found to have the least amount of Mg (102 ± 79 mg kg-1). There was no significant

difference in Mg between the lakes. The mean Fe amount was 6409 ± 8082 mg kg-1 ranging from 383-26473 mg kg-1. Lake Kissimmee had the highest mean value of Fe

(11736 ± 11003 mg kg-1) and Lake Tohopekaliga had the lowest (1515 ± 1333 mg kg-1).

The Fe concentration in Lake Tohopekaliga was significantly lower than in Lake

Kissimmee (P < .05). Aluminum ranged from 517-36135 mg kg-1 with a mean value of

8180 ± 10541 mg kg-1. Lake Hatchineha had the highest amount of Al (12733 ± 14068)

-1 -1 mg kg ) and Lake Tohopekaliga had the lowest (2578 ± 3166 mg kg ). There was no

significant difference found for Al between the lakes. Overall, Al was higher in all lakes

(8180 ± 10541 mg kg-1) while Mg had the lowest concentration (549 ± 731 mg kg-1)

(Figure 2-7).

Table 2-2. HCl extractable Ca and Mg concentrations and oxalae extractable Fe and Al concentrations for Lakes Tohopekaliga, Istokpoga, Cypress, Kissimmee, and Hatchineha. Values are reported as mean and standard deviation (n=10) per lake.

Lake Ca Mg Fe Al mg kg-1 mg kg-1 mg kg-1 mg kg-1 Tohopekaliga 912 ± 918 102 ± 79 1515 ± 1333 2578 ± 3166 Cypress 3515 ± 3283 676 ± 779 8423 ± 9174 11943 ± 13224 Hatchineha 5090 ± 5123 936 ± 1077 7458 ± 7803 12733 ± 14068 Kissimmee 4159 ± 3970 639 ± 645 11736 ± 11003 10194 ± 10204 Istokpoga 2775 ± 2432 390 ± 502 2913 ± 3208 3457 ± 3895

Inorganic P Fractionation

Inorganic P extracted with 1 M KCl is identified as the labile Pi portion that is most

bioavailable and readily released to the overlying water column of a lake (Reddy et al.

1998). The proportions of the P fractions were relatively similar across all five lakes

(Figure 2-8 and Figure 2-9). The KCl-Pi represented <1% of total P in all 5 lakes. The

NaOH-Pi fraction, considered to represent Fe and Al bound P, ranged from 21 to 37% of

total P with a mean of 29%. The greatest concentration of Fe and Al bound P was found

in Lake Cypress (221 ± 250 mg kg-1) while the lowest concentration was found in Lake

Tohopekaliga (39.6 ± 43.3 mg kg-1) (Table 2-3).

16000

Tohopekaliga Cypress 12000 Hatchinea Kissimmee Istokpoga -1 8000 mg kg

4000

0 HCl-Mg HCl-Ca Oxa-Fe Oxa-Al

Figure 2-7. Amount of metals, HCl-Mg, HCl-Ca, Oxalate-Fe, and Oxalate Al, in mg kg-1 for all lakes.

The HCl-Pi fraction which represents the Ca and Mg bound P ranged from 4 to 8% of total P with a mean of 5%. Calcium and Mg bound P were found to be the highest in

Lake Hatchineha (39.5 ± 37.1 mg kg-1) and the lowest in Lake Tohopekaliga (11.6 ± 11.7

mg kg-1). Total inorganic phosphorus (TPi) was calculated by summing the KCl, NaOH,

and HCl extract values, and represented between 26-39% of total P. Lake Cypress was

found to have the highest amount of total inorganic P (246 ± 265 mg kg-1) while Lake

Tohopekaliga had the least amount (52.3 ± 54.9).

Some organic P fractions such as NaOH Po, which is associated with humic and

fulvic acids were identified. The distribution of NaOH Po ranged from 17 to 34% of total

P with a mean of 26%. Lake Kissimmee had the highest amount (214 ± 238 mg kg-1) of humic and fulvic acids while Lake Tohopekaliga had the least amount (40.9 ± 46.8 mg kg-1). The residual organic P, which is considered the most recalcitrant fraction ranged,

from 28-43% of total P with a mean of 40% with Lake Kissimmee having the higher

amount (291 ± 296 mg kg-1) while Lake Tohopekaliga had the least of amount (51.0 ±

59.9 mg kg-1) of residual organic P. Total organic P, calculated by summing NaOH-Po

and residual organic P, represented between 59-74% of total P. The highest amount of

total organic P was found in Lake Kissimmee (506 ± 508 mg kg-1) and the least amount

was found in Lake Tohopekaliga (91.9 ± 106 mg kg-1). The percent of total organic P

was much higher than total inorganic P at 65 and 35%, respectively.

Sediment total P values for the lakes were 144, 274, 511, 660, and 680 mg kg-1 for lakes Tohopekaliga, Istokpoga, Hatchineha, Cypress, and Kissimmee, respectively.

There was no significant difference found between each lake for each P forms determined, which may be due to the high standard deviations, an artifact of different sediment types.

Lake Tohopekaliga

0.76%

27% 36% KCl-Pi NaOH-Pi HCl-Pi NaOH-Po 8% Residue-P

28% TP=144 mg kg-1

Lake Cypress

0.18%

37% KCl-Pi 42% NaOH-Pi HCl-Pi NaOH-Po Residue-P

4% 17% TP=600 mg kg-1

Lake Hatchineha

0.23%

29% KCl-Pi 38% NaOH-Pi HCl-Pi NaOH-Po 8% Residue-P

25% TP=510 mg kg-1

Figure 2-8. Distribution of P forms in Lakes Tohopekaliga and Hatchineha.

Lake Kissimmee

0.16% 21%

KCl-Pi 43% NaOH-Pi 4% HCl-Pi NaOH-Po Residue-P

-1 TP=680 mg kg 32%

Lake Istokpoga

0.58%

28% 32% KCl-Pi NaOH-Pi HCl-Pi NaOH-Po Residue-P 6%

33% TP=274 mg kg-1

Figure 2-9. Distribution of P forms in Lakes Cypress and Kissimmee.

Table 2-3. Mean and standard deviations for P forms: KCl- Pi, NaOH Pi, HCl-Pi, TPi, NaOH Pi, residue P, total Po and total P (n=10) for each lake in mg kg-1 for all P forms.

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga P forms

KCl-Pi 1.1 ± 0.8 1.1 ± 0.4 1.2 ± 0.7 1.1 ± 0.6 1.6 ± 1.0 NaOH-Pi 39.6 ± 43.3 221 ± 250 150 ± 162 145 ± 174 87.2 ± 93.4 HCl-Pi 11.6 ± 11.7 23.9 ± 22.1 39.5 ± 37.1 27.7 ± 48.3 17.6 ± 17.1

TPi 52.3 ± 54.9 246 ± 265 191 ± 190 173 ± 174 106 ± 110

NaOH-Po 40.9 ± 46.8 103 ± 97.4 125 ±127 214 ± 238 92.0 ± 114 Residue P 51.0 ± 59.9 251 ± 272 193 ± 225 291 ± 296 75.8 ± 84.1 Total Po 91.9 ± 106 354 ± 366 319 ± 322 506 ± 508 167 ± 196 Total P 144 ± 160 600 ± 629 510 ± 510 680 ± 660 274 ± 298

Discussion

Physical and Chemical

The lakes characterized as mud had less than 62 um of clay and silt in the

sediments of the lakes and all other lakes were defined as sand (>63 um) (Oui and

McComb 2000). The lakes, such as Cypress, Kissimmee, and Hatchineha, with a high mean total P contained primarily mud sediments with low bulk density and high

concentrations of total C, N and organic matter. Lake sediments with low total P, high

bulk density, and low total C, N and organic matter, such as Istokpoga and Tohopekaliga

were dominantly sand sediments. These results are comparable to the mud and sand

sediments of Lake Okeechobee, Florida (McArthur 1991, Olila and Reddy 1993).

Typically, nutrient content tends to increase with an increase in organic matter (Farnham

and Finney 1965).

The sample data was divided into sand and mud sediment type to compare the

distribution of bulk density, LOI, and total P, N, and C between the two major types.

There were 26 sand stations and 24 mud stations for all lakes combined (Table 2-4 and

Table 2-5). When looking at the individual stations and their respective sediment type,

the muds had bulk densities ranging from 0.04 to 0.50 g cm-3 while the sands had bulk

densities ranging from 0.56 to 1.18 g cm-3. The muds had higher organic matter content

and nutrients compared the sands.

There were no differences found between the sand stations of each lake.

However, Tohopekaliga’s mud stations were significantly higher in bulk density

compared to the mud sediments of Hatchineha; and Kissimmee (P<0.007). Lake

Kissimmee’s mud stations were significantly higher in LOI, total C and N compared to

the mud sediments of Tohopekaliga (P<0.05). The mud stations (n=24) were

34 significantly higher in bulk density, LOI, and total C, N, and P compared the sand stations (n=26) for all lakes combined (P<0.05).

Total P, C, and N were highly correlated to LOI with R2 = 0.87, 0.99, and 0.98 respectively for the mud sediments (Figure 2-10 to Figure 2-12). However, total P, C, N were not highly correlated with LOI for the sand sediments with R2=0.24, 0.57 and 0.48 respectively. A strong positive correlation between sediment total P and LOI suggests that organics are important as a P reservoir (Oui and McComb 2000). Total N and C were well correlated to P with R2= 0.84 and 0.87, respectively, indicating that the P source in these mud sediments may be related to organic matter (Figure 2-13 and Figure

2-14). However, there was not a strong relationship found between total C and N to P with R2=0.54 and 0.55, respectively. The strong correlation of nutrient content with organic matter demonstrates the importance of organic matter in nutrient cycling in lake sediments.

Table 2-4. Mean and standard deviations for P forms for sand sediments: bulk density (BD), mass loss on ignition (LOI), total carbon (TC), total nitrogen (TN), total phosphorus (TP) per lake in mg kg-1 for all P forms.

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga n=7 n=4 n=5 n=4 n=6 Sand BD 1.0 ± 0.1 0.9 ± 0.3 0.9 ± 0.2 0.9 ± 0.02 1.0 ± 0.2 LOI 1.2 ± 0.4 2.9 ± 1.9 1.7 ± 0.7 1.7 ± 1.7 2.4 ± 1.0 TC 5.8 ± 1.2 9.8 ± 7.6 9.0 ± 4.0 6.5 ± 1.0 9.9 ± 5.1 TN 0.6 ± 0.2 0.9 ± 0.7 0.8 ± 0.3 0.7 ± 0.2 0.7 ± 0.4 TP 66 ± 16 81 ± 49 69 ± 29 48 ± 10 68 ± 30

Table 2-5. Mean and standard deviations for P forms for mud sediments: bulk density (BD), mass loss on ignition (LOI), total carbon (TC), total nitrogen (TN), total phosphorus (TP) per lake in mg kg-1 for all P forms.

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga n=3 n=6 n=5 n=6 n=4 mud BD 0.4 ± 0.1 0.2 ± 0.2 0.1 ± 0.05 0.1 ± 0.1 0.2 ± 0.1 LOI 7.8 ± 3.4 27 ± 17 34 ± 11 42.7 ± 18 23 ± 12 TC 41 ± 18 127 ± 81 153 ± 52 203 ± 88 115 ± 52 TN 3.2 ± 1.3 12 ± 8.0 15 ± 5.0 19 ± 8.0 9.0 ± 4.0 TP 307 ± 104 1016 ± 679 1092 ± 371 1139 ± 523 587 ± 217

400 y = 4.70x + 0.03

) 2

-1 300 R = 0.99

200

100 Total (g C kg

0 0 10203040506070 Loss on Ignition (%)

25 y = 2.65x + 3.00 R2 = 0.57

) 20 -1

Total C (g kg (g C Total 5

0 0123456 Loss on Ignition (%)

Figure 2-10. Regression between concentrations of total C (g kg-1) to loss on ignition (%). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

30 y = 0.44x - 0.63 2

) R = 0.98

-1 25 20 15 10 Total (g N kg 5 0 0 10203040506070 Loss on Ignition (%)

3 y = 0.21x + 0.34 2

) R = 0.48 -1 2

1 Total (g N kg

0 0123456 Loss on Ignition (%)

Figure 2-11. Regression between concentrations of total N (g kg-1) to loss on ignition (%). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

2000 y = 28.8x + 52.7

) R2 = 0.87 -1 1600

1200

800

400 Total P kg (mg Total 0 0 10203040506070 Loss on Ignition (%)

y = 11.2x + 44.7 200 R2 = 0.24 ) -1 150

100

50 Total P kg (mg Total

0 0246 Loss on Ignition (%)

Figure 2-12. Regression between concentrations of total P (g kg-1) to loss on ignition (%). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

2000 y = 6.02x + 69.1 R2 = 0.84

) 1600 -1

1200

800

Total P (mg kg 400

0 0 50 100 150 200 250 300 350 Total C (g kg-1)

400 y = 4.83x + 27.28 2

) R = 0.54 -1 300

200

100 Total P ( mg P kg ( Total

0 0 5 10 15 20 25 Total C (g kg-1)

Figure 2-13. Regression between concentrations of total P (mg kg-1)and with total C (g kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

2000 y = 64.0x + 98.2 2 ) R = 0.87 -1 1600

1200

800

400 Total P(mg kg 0 0 5 10 15 20 25 30 Total N (g kg -1)

y = 55.9x + 24.3 200 R2 = 0.55 ) -1 150

100

50 TotalP (mg kg 0 0123 Total N (g kg -1)

Figure 2-14. Regression between concentrations of total P (mg kg-1) and with total N (g kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

Metals

Metals may increase the capacity of sediments to retain P under certain

conditions. The ability of P to be retained by Fe/Al and Ca/Mg depends on the pH and/or

redox conditions of the sediments. Phosphorus is retained by Fe/Al compounds under

acidic conditions and therefore is more stable under low pH conditions. Depending on

redox conditions, the reduction of insoluble ferric iron (Fe3+) to a more soluble ferrous

iron (Fe2+) compound can lead to P released from the sediment. When there is a

dominance of Ca/Mg P in the sediments, P is more stable under high pH or alkaline

40 conditions. Organic acids from settling or deposited decomposing organic matter can lower the pH short term and lead to dissolution of Ca.

The sandier lakes, such as Lake Tohopekaliga and Istokpoga had lower amounts of Ca, Mg, Fe, and Al, compared to the muddier sediments of Cypress, Kissimmee, and

Hatchineha (refer to Figure 2-10). Phosphorus accretion in these lakes is significantly associated with Ca, Mg, Fe, and Al; thus the presences of these metals play a very important role in inorganic P retention in lake sediments (Table 2-6).

Table 2-6. Pearson correlations for selected metals and total P

Total P Ca Mg Fe Ca 0.924 (<0.001) Mg 0.924 0.962 (<0.001) (<0.001) Fe 0.969 0.887 0.879 (<0.001) (<0.001) (<0.001) Al 0.943 0.929 0.970 0.908 (<0.001) (<0.001) (<0.001) (<0.001)

Samples were again divided into muds and sands to look at the difference in the relationship between metals with total P amongst the mud and sand sediments (Table 2-7 and Table 2-8). The mud sediments in each of the five lakes contain greater amounts of

Ca, Mg, Fe and Al compared to the sand sediments. Total phosphorus concentrations were regressed against Ca, Mg, Fe and Al for the mud sediments Both Ca, Mg, and Al were significantly correlated with phosphorus with a R2=0.72, 0.68 and 0.77 respectively

(P<0.001) (Figure 2-18 to Figure 2-21). Oxalate-Fe was highly correlated with phosphorus with R2=0.88, which suggest that Fe plays a greater role in inorganic P stability. Calcium, Mg, Fe and Al were also regressed against total P for the sand

41 sediments and did not correlate well with phosphorus with a R2=0.01, 0.68, 0.58 and 0.39 respectively (Figure 2-15 to Figure 2-18).

There were no significant differences in metals found between the sand stations of each lake. However, there was a difference found in the mud stations in Mg between

Tohopekaliga and Hatchineha (P<.05). There was also a significant difference found in the mud stations in Fe content between Lake Kissimmee and Tohopekaliga (P<0.03).

There were also significant differences found between the mud and sand sediments within each lake for all metals (Ca, Mg, Fe, Al) (P<0.05).

Table 2-7. Mean and standard deviations for P forms for sand sediments: HCl-Ca and Mg and Oxalate Fe and Al mg kg-1 for all lakes

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga n=7 n=4 n=5 n=4 n=6 Sand Ca 470 ± 375 1041 ±846 669 ± 164 237 ± 42.8 1403 ± 1080 Mg 14.9 ± 17.7 42.2 ± 53.4 46.7 ± 30.2 2.7 ± 3.5 49.7 ± 39.4 Fe 800 ± 114 1070 ± 579 971 ± 458 1182 ± 195 727 ± 324.2 Al 1060 ± 616 1343 ± 824 1131 ± 376 632 ± 122 851 ± 404

Table 2-8. Mean and standard deviations for P forms for mud sediments: HCl-Ca and Mg and Oxalate Fe and Al mg kg-1 for all lakes

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga n=3 n=6 n=5 n=6 n=4 mud Ca 1946 ± 1042 5165 ± 3288 9511± 3186 6774 ± 2802 4834 ± 2527 Mg 304 ± 234 1098 ± 745 1825 ± 7795 1063 ± 456 902 ± 416 Fe 3185 ± 1409 13325 ± 8899 13947 ± 5617 18772 ± 8328 6193 ± 2609 Al 61117 ± 4137 19010 ± 12828 24335 ± 10423 16569 ± 8093 7366 ± 3360

y = 17.8x - 140

) 40000 2

-1 R = 0.77 32000 24000 16000 8000

oxalate-Al (mg kg 0 0 500 1000 1500 2000 Total P (mg kg-1)

y = 14.6x + 33.6

) 3000 2

-1 R = 0.58

2000

1000

oxalate-Al (mg kg 0 0 50 100 150 200 Total P (mg kg-1)

Figure 2-15. Regression between concentrations of oxalate-Al (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

y = 14.6x - 835

) 30000 2 -1 R = 0.88 24000 18000 12000 6000

oxalate- Fe (mg kg 0 0 500 1000 1500 2000 Total P (mg kg-1)

y = 8.1832x + 373.97 ) 3000 -1 R2 = 0.3928

2000

1000

oxalate- Fe (mgkg 0 0 50 100 150 200 Total P (mg kg-1)

Figure 2-16. Regression between concentrations of oxalate-Fe (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

16000 y = 5.58x + 968 2

) R = 0.72 -1 12000

8000

4000 HCl-Ca (mg kg

0 0 500 1000 1500 2000 Total P (mg kg-1)

4000 y = 2.78x + 590 R2 = 0.01 ) -1 3000

2000

1000 HCl-Ca (mg kg (mg HCl-Ca

0 0 50 100 150 200 Total P (mg kg-1)

Figure 2-17. Regression between concentrations of HCl-Ca (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

3000 y = 1.11x + 105

) 2

-1 2500 R = 0.68 2000 1500 1000 500 HCl-Mg (mg kg 0 0 500 1000 1500 2000 Total P (mg kg-1)

160 y = 1.05x - 38.1 2 ) R = 0.68 -1 120

40 HCl-Mg (mg kg 0 0 50 100 150 200 Total P (mg kg-1)

Figure 2-18. Regression between concentrations of HCl-Mg (mg kg-1) with total P (mg kg-1). The mud sediments values are located at top graph and the sand sediments are located at the bottom graph.

Inorganic P Fractionation

The sandier lakes, such as Tohopekaliga and Istokpoga had less inorganic and

organic P compared to the lakes characterized as muds (Kissimmee, Hatchineha, and

Istokpoga). There were no differences found between these any of these lakes due to a

high standard deviation, an artifact of different sediment types. The sample data was

divided into sand and mud sediment type to compare the distribution of P between the

two types (Table 2-9 and Table 2-10).

The proportions of P fractions were relatively the same for both sediment type

(Figure 2-19). However, the mean total P concentrations for the sand sediments were

much less than for the mud sediment 61 ± 30 and 855 ± 459 mg kg-1, respectively.

Although, the sand sediments had the greater percentage of available P (KCl-Pi) than was

found in the mud sediments, the muddier sediments may release more P, due to their greater amount of total P. These results are similar to those found in Lake Okeechobee

for these major sediment types, in which greater concentrations of total P was found in

the muds compared to the sands (Olila and Reddy 1993).

Sand sediment had a slightly greater percent of NaOH-Pi (Fe and Al-P) fraction

(31%) than the mud sediments (29%). A similar trend was found for HCl-Pi (Ca and

Mg-P) and NaOH-Po (humic and fulvic acids ) fractions. Residue P distribution was

greater in the mud sediments than in the sand sediments.

There were no significant differences found between the sand stations of each lake

for each P fractions. For the mud sediments of Lake Istokpoga, concentration of KCl-Pi

(labile P) fraction was significantly higher than Tohopekaliga and Kissimmee (P<0.05).

Total organic P was found to be significant higher in Kissimmee compared to

Tohopekaliga for the muds (P<0.05). There were also significant differences found between the mud and sand sediments within each lake for all parameters (P<0.05).

Table 2-9. Mean and standard deviations for P forms for sand sediments: KCl- Pi, NaOH Pi, HCl-Pi, TPi, NaOH Pi, residue P, total Po and total P per lake in mg kg-1 for all P forms.

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga Sand n=7 n=4 n=5 n=4 n=6 P forms

KCl-Pi 1.2 ± 0.9 0.7 ± 0.3 0.6 ± 0.1 0.6 ± 0.04 1.3 ± 0.8 NaOH-Pi 17.7 ± 5.6 24.9 ± 21.2 15.5 ± 4.5 11.4 ± 3.4 26.1 ± 19.1 HCl-Pi 6.3 ± 2.4 8.7 ± 5.8 9.2 ± 5.0 3.3 ± 1.2 5.9 ± 3.9 TPi 25.2 ± 8.0 34.3 ± 25.3 25.3 ± 7.1 15.2 ± 4.5 33.2 ± 21.0 NaOH-Po 14.6 ± 4.6 17.6 ± 14.5 21.9 ± 7.3 9.3 ± 3.4 14 ± 13.8 Residue P 19.7 ± 5.5 28.3 ± 18.2 12.8 ± 6.1 13.2 ± 3.1 18.9 ± 14.3 Total Po 34.4 ± 7.2 45.8 ± 32.1 34.7 ± 9.3 22.5 ± 5.9 32.9 ± 22.4 Total P 59.6 ± 3.3 80.2 ± 56.8 60.0 ± 12.2 37.8 ± 10.4 66.1 ± 40.4

Table 2-10. Mean and standard deviations for P forms for mud sediments: KCl- Pi, NaOH Pi, HCl-Pi, TPi, NaOH Pi, residue P, total Po and total P .

Tohopekaliga Cypress Hatchineha Kissimmee Istokpoga mud n=3 n=6 n=5 n=6 n=4 P forms KCl-Pi 1.5 ± 0.4 1.4 ± 0.3 1.8 ± 0.3 1.5 ± 0.4 2.1 ± 0.8 NaOH-Pi 234 ± 175 352 ± 248 285 ± 119 234 ± 175 179 ± 82.9 HCl-Pi 43.9 ± 58.3 34 ± 23.6 69.7 ± 27.9 43.9 ± 58.3 35.2 ± 12.9 TPi 279 ± 145 384 ± 263 356 ± 112 280 ± 145 216 ± 95.1 NaOH-Po 351 ± 214 163 ± 80.0 230 ± 97.1 352 ± 214 209 ± 94.0 Residue P 478 ± 235 418 ± 234 375 ± 181 478 ± 235 161 ± 68.4 Total Po 191 ± 145 553 ± 350 605 ± 175 829 ± 392 370 ± 155 Total P 1109 ± 483 948 ± 591 962 ± 281 1109 ± 483 586 ± 220

Sand Sediments

30% 33% KCL-Pi NaOH-Pi HCL-Pi NaOH-Po Residue P 11% 25% TP = 61 ± 30 mg kg-1

Mud Sediment

0.2%

29% KCL-Pi 40% NaOH-Pi HCL-Pi NaOH-Po 5% Residue P

26% TP = 855 ± 459 mg kg-1

Figure 2-19. The mean percent of mean TP (mg kg-1) of each P fractions (KCl-Pi, NaOH-Pi, HCl-Pi, NaOH-Po, and Residue P) for both mud and sand sediments for all the lakes

Conclusion

Lake sediments can function as a source or sink for dissolved P coming from

nonpoint and point sources. Chemical, physical, and microbial processes control the

exchange of P between the sediment and water column. For any planned restoration to

occur in these lakes, it is important to understand the forms and properties of P in lake

sediments to identify the factors that control P release from the sediment to the overlying

water column.

The sediments of each of the five lakes were characterized for bulk density, mass

loss on ignition (LOI), total C, N, and P, as well as selected metals (Ca, Mg, Fe and Al).

The bulk density ranged from 0.06-1.18 g cm-3 with sediment texture varying from

organic mud to sand. The LOI values ranged from 0-55% with the highest values

representing the greatest content of organic matter. The sand stations tended to have low organic matter and high bulk density and the mud stations typically had greater organic matter and low bulk density. The lakes characterized as sandy lakes (Tohopekaliga and

Istokpoga) exhibit the characteristics of low organic matter and high bulk density while the muddier lakes had the greater amount of organic matter and low bulk density

The lakes characterized as muds, primarily had high nutrient levels (total P, total N, and total C) and organic matter content. The sandy lakes typically had less nutrients

(total P, total N and total C) and organic matter. There were strong correlations of total

P, N, C and bulk density to LOI for the mud station within each lake. Total C and total N are generally found to be related to organic matter in sediments. A strong positive correlation between total P and LOI were found, which suggest the importance of organics as a P reservoir.

The muddier lakes also contained greater amounts of Ca, Mg, Al, and Fe than the sandier lakes and are well correlated with total P. The mud stations of each lake contained the greatest amount of iron compared to the sand stations and is significantly and positively correlated with total P, which indicates that Fe plays a greater role in inorganic P stability. The sand stations were not well correlated with any of the metals, suggesting these selected metals may not play a great role in inorganic P stability.

The inorganic P results suggest that the greatest portion of inorganic P was in the form most associated with Fe and Al (NaOH-Pi). The total organic P was proportionally

greater in each lake than total inorganic P. The mud stations contained the greatest

amount of TP and P associated with organics and also had greater amounts of available or

easily exchangeable P than the sands. The sand and mud stations were not at all different

in their distribution of P; however, the muds contained greater amounts of total P, so this

sediment type may contribute more to P release to the overlying water column of a lake.

CHAPTER 3 PHOSPHORUS FLUX OF SEDIMENTS UNDER DIFFERENT SIMULATED LOADING CONDITIONS

Introduction

Phosphorus is essential for plant growth, but excessive amounts entering lakes can lead to eutrophic conditions resulting in harm to the quality of water in many freshwater systems such as Lake Okeechobee and Lake Apopka. Harm to fisheries, changes in vegetation, and recreation can be some of the results of excessive quantities of P entering into lakes. Phosphorus enters the surface water of freshwater lakes primarily by way of nonpoint and point source pollutions from entities such as wastewater treatment plants and from surface runoff from agricultural and urban areas.

Reducing nutrient inputs from nonpoint and point sources of pollution are essential to restoring lake water quality. However, even after external P load to lakes have been curtailed, internal P flux from the sediment to the water column can occur, contributing heavily to the degradation of water quality in lakes (Welch and Cooke 1995). The idea of internal loading is based on the recycling of nutrients from bottom sediments in lakes to the overlying water column (Carpenter 1983). After load reduction, the internal load of sediments will determine the trophic status of a lake and the amount of lag time for recovery (Petterson 1998).

The equilibrium phosphorus concentration (EPC) can be used to determine the extent of which the internal load will be released during restoration of a lake after

external load reductions. The EPC is defined as the P in solution that is in equilibrium

51 52 with P in the solid phase or the point where P is neither being retained nor released from the sediment to the water column (Olila and Reddy 1993). At water column SRP concentrations above the EPC, P is retained by the sediments and at concentrations below, the sediments serve as a P source. The EPC can be a useful tool for water managers to determine the water column SRP concentration for which sediments may act as a potential source of P to the overlying water column of a lake. Water managers can manage for the internal sediment P load by determining the EPC of aquatic systems. For example, water managers may consider dredging a lake as a component of a restoration plan; however dredging is very cost and labor intensive. Therefore, it is important to look at the EPC of a lake to determine if this lake should be dredged or if focus should be aimed at other activities during restoration.

There are four pathways for the exchange of P from the sediment to water column of a lake: i) settling of insoluble (particulate) inorganic and organic P, ii) uptake of soluble reactive P (SRP) by primary producers (algae) and its subsequent settling, iii) sorption of soluble inorganic or organic P onto particles that settle onto the sediments, and iv) sorption of soluble inorganic or organic P directly onto sediment particles (Reddy et al. 1999). Sediments act as a net sink of P; however, when porewater P concentration exceed the overlying water column concentration, SRP can be released from the sediment

(Moore et al. 1991).

The flux of P from the sediment to the water column can depend on processes such as: i) diffusion and advection ( wind/wave action, flow, and bioturbation), ii) processes within the water column (biotic uptake and release, mineralization, and sorption by particulate matter), iii) diagenetic processes (mineralization, sorption, precipitation, and

53 dissolution) in bottom sediments, and iv) redox conditions (oxygen content), organic matter content, pH, temperature and the presence of metal bound to P (Fe, Al, Ca, and

Mg) (Bostrom and Pettersson 1982, Holdren and Armstrong 1980, Moore et al 1991,

Wetzel 2001).

Wind/wave action can induce sediment resuspension and cause event driven large P release from the sediment to the water column and thereby available for uptake by primary producers (Pettersson and Bostrom 1985). Bioturbation can also increase the release of P. However, P release may not occur over the entire lake sediment surface, thus bioturbation may not be sufficient to perpeturate eutrophic conditions (Holdren and

Armstrong 1980). Diagenetic processes such as sorption (P release from soil mineral surfaces or retention of P onto soil mineral surfaces), precipitation (formation of amorphous precipitates), dissolution (solubilization of the precipitates), and mineralization (breakdown of organic matter) can also mediate the release of P from the sediments.

A decrease in dissolved oxygen of the water column can result in an increase in P release from the sediments in freshwater lakes. However, oxygenation of the sediments can result in a decrease in P release to the water column (Holdren and Armstrong 1980,

Patrick and Khalid 1974). It is important to note that for shallow and eutrophic lakes that are well mixed, anaerobic conditions rarely persist for any extended periods of time

(Welch and Cooke 1995). However, these ephemeral anaerobic events can significantly after water quality.

The release of P may result from the reduction of ferric iron (Fe3+) to ferrous iron

(Fe2+) in sediments or from the decomposition of organic matter (Holdren and Armstrong

1980). The ability of P to be retained by Fe/Al and Ca/Mg depends on pH. Phosphorus

is retained by Fe/Al compounds under low pH or acidic conditions (Patrick and Khalid

1974). When there is a dominance of Ca/Mg P in sediments, P is more stable under high

pH or alkaline conditions (Patrick and Khalid 1974). Organic acids from settling or

deposited decomposing organic matter can lower pH short term and lead to dissolution of

Ca bound P (Marsden 1989). Studies have also shown that temperature plays an

important role in P release from sediments, in which P release increased with increases in

temperature due in part to increased mineralization rates (Holdren and Armstrong 1980).

Hypothesis

The equilibrium P concentration will be higher in sediments with higher TP and

therefore provide a greater internal release of P during lake restoration as water quality

continues to improve.

Objectives

The objectives of this study were to: i) determine the release rate of P from the

sediments to the water column and ii) determine the equilibrium P concentration of the

sediments.

Site Selection

Data collected from the P characterization study provided the information for

selection of each site for the phosphorus flux study. Two stations per lake were chosen

from the P characterization study based on a range of sediment TP concentrations and

organic matter content (Figure 3-1 to Figure 3-5). Geographical Positioning Satellite

(GPS) equipment was used to locate each site within +/-5m of the true coordinates for the

stations chosen. The sampling location and latitude/longitude were documented at each

station (Table 3-1).

2 #Y

10 Y#

0 2 4 6 8 Kilometers

L. Tohopekaliga

Figure 3-1. Location of sampling stations for Lake Tohopekaliga.

16 Y# 15 Y#

01234Kilometers

Cypress Lake

Figure 3-2. Location of sampling station for Cypress Lake.

103 Y#

107 Y#

01234Kilometers

L. Hatchineha

Figure 3-3. Location of sampling stations for Lake Hatchineha.

1012 Y#

1004 Y#

0 1 2 3 4 Kilometers

L. Kissimmee

Figure 3-4. Location of sampling stations for Lake Kissimmee.

Y# 10004

Y# 10007

01234Kilometers

L. Istokpoga

Figure 3-5. Location of sampling stations for Lake Istokpoga.

Table 3-1. X and Y coordinates of each station. All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Lake Station x_coord y_coord Toho 2 460252 3125825 Toho 10 461809 3116800 Cypress 15 468261 3105828 Cypress 16 469875 3106370 Hatch 103 458082 3100650 Hatch 107 461341 3098421 Kissimmee 1004 472394 3084179 Kissimmee 1012 473188 3088426 Istokpoga 10004 469916 3030750 Istokpoga 10007 472779 3026915

Materials and Methods

Intact sediment cores were taken from two stations per lake (10 station total) by a

SCUBA diver using 7.5 cm wide plexiglas tube to collect 15 cores per site (~30 cores per

lake; ~150 cores total). The cores were carefully driven approximately 30 cm into the

sediment with minimal impact to the sediment-water interface. Stoppers were inserted into both ends of the cores and secured with tape for transport back to Gainesville,

Florida. Surface water from each lake was collected in 30 L containers for purposes of re-flooding each core with lake water.

Upon arrival to the laboratory, the surface water was filtered with 0.45 um

Whatman filter paper to remove any particulates. The water column of each core was slowly drained and replaced with 1 L of filtered lake surface water for a 30 cm water column. The SRP concentration of the surface water was determined during analysis using the Murphy and Riley Method (1962). All cores were spiked with SRP to yield concentrations of 0, 15, 30, 60, 120 ug L-1 at the beginning of the experiment. Three

replicates per loading concentration for each site and flux measurements were

determined.

Water columns in each core were constantly aerated with room air using aquarium

pumps to maintain dissolved oxygen levels close to 5 mg L-1 for 25 days. Aluminum

shrouds were placed over the cores so that light could not penetrate and the cores were

incubated in a water bath to maintain a constant temperature (22 ± 0.34°C).

Water was periodically removed for analysis with a 10 mL plastic syringe fitted

with tubing to withdraw samples from the middle of the water column, in which, 10 ml

were taken and filtered with a 0.45 um syringe filter and analyzed for SRP using a

segmented flow colorimetric analyzer (USEPA 1993, Method 365.4). The water column

levels (1 L or 30 cm) were maintained after sampling by adding 10 ml of lake water back

into each core. Background water column SRP concentrations were an average of 6 ± 4

ug L-1. Filtered water samples were immediately frozen until analysis.

Data Analysis

Data were analyzed using a one way analysis of variance (ANOVA) with a p value

of 0.05. The Tukey-Kramer test was used to evaluate differences between means. Data

were analyzed using JMP statistics version 4. Microsoft excel (Microsoft 2000) was used

to perform regression analyses and correlations.

Results

No P Addition

Water column SRP concentrations. In general, water column SRP

concentrations (filtered water with no P addition) tended to increase over time,

suggesting P flux from the sediment. The initial site water was 0.002, 0.003, 0.005,

0.009 and 0.011 for Lakes Kissimmee, Istokpoga, Tohopekaliga, Cypress and

Hatchineha, respectively.

Water column SRP concentrations increased over the first 2 days in all lakes,

except Lake Hatchineha, in which concentrations declined slightly at a rate of -36.4%

(Table 3-2). Concentrations increased in all the other lakes between 22% in Lake

Cypress to 400% in Lake Kissimmee. The mean water column SRP concentrations at

day 2 ranged from a low in Lake Hatchineha (0.007 ± 0.002 mg L-1) to a high in Lake

Istokpoga (0.014 ± 0.003 mg L-1) at day 2.

Mean water column SRP concentrations ranged from a low of 0.013 ± 0.006 mg L-1

in Cypress Lake to higher concentrations in Lake Istokpoga at 0.022 ± 0.007 mg L-1 at

day 7 (Table 3-2). Between day 2 and 7 water column SRP concentrations increased for

all lakes, however, Lake Cypress and Hatchineha values were close to their initial water

column SRP concentration at day 7. The change in water column SRP concentrations

ranged from a high of 650%in Lake Kissimmee to 27% in Lake Hatchineha.

After 7 days, the SRP concentrations, for the most part, increased over the course

of the experiment (Table 3-2). Water column SRP concentrations ranged from a high in

Lake Tohopekaliga (0.045 ± 0.059 mg L-1) to 0.015 ± 0.003 mg L-1 in Lake Kissimmee

by the end of the study (~25 days). The change in concentration increased between

1233% from the initial concentration in Lake Istokpoga to 100% in Cypress Lake.

P flux rates. The SRP flux rate was determined based on the slope of the curve

of water column SRP concentration over time. At 2 days, the mean P flux ranged from a

rate of -1.668 ± 0.885 (mg m-2 d-1) in Lake Hatchineha to a positive rate of 0.784 ± 0.458(

mg m-2 d-1) in Lake Istokpoga (Table 3-3). The positive P flux rates of Lakes

Tohopekaliga, Kissimmee and Istokpoga suggest that the lakes are releasing phosphorus

to the water column, while the negative flux rates of Lake Cypress and Hatchineha

suggest P retention by sediments. There was a difference in P flux rates at day 2, in

which, rates were lower in Lake Hatchineha compared to the other lakes (Istokopoga,

Tohopekaliga, Kissimmee and Cypress P<0.0001). This difference may be due to

differences in the sediment characteristics of the lakes (sediment type) or past nutrient

loading (Table 3-4 and Table 3-5).

The mean 7 day P flux rate for the lakes ranged from -0.036 ± 0.168 mg m-2 d-1 in

Lake Hatchineha to a high of 0.439 ± 0.296 mg m-2 d-1 in Lake Istokpoga (Table 3-3).

Table 3-2. Percent change in Water Column SRP (mg L-1) under no P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6 for all lakes except Cypress in which n=4.

Initial ------SRP (mg L-1)------Percent Change (%)------SRP Lake (mg L-1) 2 d 7 d 25 d 2 d 7 d 25 d Tohopekaliga 0.005 0.008 ± 0.002 0.017 ± 0.012 0.045 ± 0.059 60 240 800 Cypress 0.009 0.011 ± 0.003 0.013 ± 0.006 0.018 ± 0.015 22 44 100 Hatchineha 0.011 0.007 ± 0.002 0.014 ± 0.007 0.033 ± 0.033 -36 27 200 Kissimmee 0.002 0.010 ± 0.001 0.015 ± 0.002 0.015 ± 0.003 400 650 650 Istokpoga 0.003 0.014 ± 0.003 0.022 ± 0.007 0.040 ± 0.036 367 633 1233

63 Table 3-3. Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at no P additions at 2, 7, and 25 days. n=6 for all lakes except Cypress (n=4).

------P flux mg m-2 d-1------Lakes 2 day 7 day 25 day Tohopekaliga 0.103 ± 0.430 0.311 ± 0.255 0.418 ± 0.734 Cypress -0.003 ± 0.520 0.085 ± 0.180 0.070 ± 0.142 Hatchineha -1.67 ± 0.885 -0.036 ± 0.168 0.298 ± 0.412 Kissimmee 0.192 ± 0.271 0.249 ± 0.255 0.065 ± 0.019 Istokpoga 0.784 ± 0.458 0.439 ± 0.296 0.295 ± 0.403

Table 3-4. Sediment characteristics of all stations for each lake for bulk density, mass loss on ignition (LOI), and total C, N, and P (mg kg-1). N=10

Sediment Bulk DensityLOI TC TN TP Lake Station Type G cm-3 % g kg-1 g kg-1 mg kg-1 Tohopekaliga T2 organic mud 0.25 11.2 57.9 4.54 423 Tohopekaliga T10 sand 1.06 1.4 5.41 0.57 61.8 Cypress C15 organic mud 0.08 32.6 140 12.4 1036 Cypress C16 organic mud 0.06 42.7 201 19.4 1694 Hatchineha H103 organic mud 0.17 15.0 72.8 6.81 494 Hatchineha H107 organic mud 0.06 38.8 180 17.8 1126 Kissimmee K1004 sand 0.57 1.94 7.59 1.09 60.6 Kissimmee K1012 organic mud 0.05 51.9 245 22.1 1333 Istokpoga I10004 organic mud 0.13 25.8 127 8.51 721 64 Istokpoga I10007 organic mud 0.13 19.7 95.7 7.68 555

Table 3-5. Sediment characteristics of all stations for each lake for oxalate-Fe and Al and HCl-Ca and Mg. n=10

Lake Station Fe Al Ca Mg Tohopekaliga T2 4800 10529 3088 563 Tohopekaliga T10 760.3 721.3 288.4 0.0 Cypress C15 17844 23532 6686 1360 Cypress C16 19970 28238 8221 1649 Hatchineha H103 5510 8813 4214 680 Hatchineha H107 13641 21335 9619 1636 Kissimmee K1004 1403 801 274 7 Kissimmee K1012 24150 20218 7303 1252 Istokpoga I10004 8238 10925 6257 1152 Istokpoga I10007 5653 6189 3977 796 65

The positive P flux values of Lakes Istokpoga, Kissimmee, Tohopekaliga and

Cypress suggest P release to the overlying water column, while the negative P flux rates

of Lake Hatchineha suggest retention by the sediments. The P flux rates were

significantly lower in Lake Hatchineha compared to Lake Istokpoga (P<0.05). This

dissimilarity may be due to differences in sediment characteristics. Lake Istokpoga

sediments are characterized mostly by sand compared to the muddier sediments of Lake

Hatchineha, with greater potential binding sites.

There were no significant correlations between P flux and any of the sediment

characteristics, however, TP was significantly and negatively correlated to bulk density

and significantly and positively correlated to Ca, Mg, Fe, and Al (Table 3-6 and Table 3-

7).

At day 25, the mean P flux ranged from a low rate of 0.065 ± 0.019 mg m-2 d-1 in

Lake Kissimmee to a high of 0.418 ± 0.734 mg m-2 d-1 in Lake Tohopekaliga (Table 3-3).

The positive P flux rates of all these lakes suggest P release from the sediments. There

were no significant differences in P flux rates at day 25 at no P additions.

Table 3-6. Correlation between sediment properties with the Pearson correlation on top and the P-value on the bottom in parentheses. All correlations are significant to P<0.05. n=10

Bulk Density LOI total C total N total P Fe Al Ca Mg

LOI -0.76 (<0.05) total C -0.77 1.00 (<0.05) (<0.001) total N -0.73 0.99 0.99 (<0.05) (<0.001) (<0.001) total P -0.74 0.95 0.95 0.96 (<0.05) (<0.001) (<0.001)(<0.001) 67 Fe -0.67 0.96 0.95 0.95 0.94 (<0.05) (<0.001) (<0.001)(<0.001) (<0.001) Al -0.72 0.89 0.88 0.90 0.96 0.92 (<0.05) (<0.001) (<0.001)(<0.001) (<0.001)(<0.001) Ca -0.82 0.92 0.92 0.91 0.91 0.83 0.90 (<0.001) (<0.001) (<0.001) (<0.001) (<0.001) (<0.001) (<0.001) Mg -0.83 0.92 0.91 0.90 0.93 0.84 0.93 0.99 (<0.001) (<0.001) (<0.001) (<0.001) (<0.001) (<0.001) (<0.001) (<0.001)

Table 3-7. . Correlation between P flux and EPCw with sediment properties with the Pearson correlation on top and the P-value on the bottom in parentheses. All correlations are significant to P<0.05. n=10

Bulk Density LOI total C total N total P EPCw Fe Al Ca Mg P Flux No P 0.184 -0.307 -0.274 -0.329 -0.314 0.488 -0.357 0.465 -0.437 -0.385 (0.611) (0.388) (0.444) (0.353) (0.377) (0.153) (0.312) (0.176) (0.207) (0.272) 15 -0.014 0.046 0.081 -0.006 -0.079 0.423 -0.136 -0.291 -0.003 -0.010 (0.968) (0.899) (0.823) (0.987) (0.828) (0.223) (0.707) (0.415) (0.994) (0.977) 30 0.568 -0.426 -0.422 -0.439 -0.464 0.105 -0.480 -0.559 -0.425 -0.435 (0.087) (0.220) (0.225) (0.204) (0.176) (0.773) (0.161) (0.093) (0.220) (0.208) 60 0.221 -0.360 -0.358 -0.390 -0.247 0.208 -0.396 -0.261 -0.256 -0.168 (0.540) (0.306) (0.309) (0.266) (0.491) (0.563) (0.258) (0.467) (0.475) (0.643) 68 120 -0.010 -0.041 -0.064 0.023 0.155 -0.410 -0.008 0.252 0.128 0.174 (0.979) (0.910) (0.861) (0.949) (0.668) (0.239) (0.982) (0.483) (0.726) (0.631)

Phosphorus Addition (15 ug L-1)

Water column SRP concentrations. The initial SRP concentrations ranged from

0.017 mg L-1 in Lake Kissimmee to a high of 0.026 mg L-1 in Lake Hatchineha (Table 3-

8). The mean water column SRP concentrations at day 2 ranged from a low in Lake

Kissimmee (0.010±0.001 mg L-1) to a high in Cypress Lake (0.023±0.003 mg L-1).

Concentrations decreased in all lakes, except, Lake Tohopekaliga, in which concentrations increased at a rate of 8% and declined in all other lakes at a rate between

6% in Cypress Lake to 41% in Lake Kissimmee. These results suggest P retention by sediments in all lakes, except Lake Tohopekaliga .

The mean SRP concentration ranged from a high in Lake Istokpoga (0.024 ± 0.008

mg L-1) to a low concentration in Lake Kissimmee (0.015 ± 0.002 mg L-1) at day 7 (Table

3-8). Water column SRP concentrations increased in Lake Tohopekaliga and Istokpoga

over a 7 day period, even after the initial spike, suggesting P release from the sediments

at a rate of 5 and 33%, respectively. In Lake Kissimmee, Cypress Lake and Lake

Hatchineha water column SRP concentrations decreased at a rate less than 45%,

suggesting P retention by the sediments.

After 7 days, the water column SRP concentrations continued to increase over the

course of the experiment for all lakes at a rate between 0% in Lake Kissimmee to 75% in

Lake Tohopekaliga. The mean water column SRP concentrations at day 25 ranged from

a low in Lake Kissimmee (0.017±0.002 mg L-1) to a high in Lake Tohopekaliga

(0.035±0.019 mg L-1) (Table 3-8). These results suggest that all the lakes all releasing P

from the sediments at this P addition (15 ug L-1).

Table 3-8. Percent change in SRP mg L-1 at 15 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6 for all lakes except Cypress in which n=5.

Initial ------SRP (mg L-1)------Percent Change (%)---- Conc. Lake (mg L-1) 2 d 7 d 25 d 2 d 7 d 25 d Tohopekaliga 0.020 0.022 ±0.002 0.021±0.010 0.035±0.019 8 5 75 Cypress 0.024 0.023±0.003 0.018±0.0050.032±0.020 -6 -25 33 Hatchineha 0.026 0.022±0.002 0.018±0.004 0.030±0.026 -15 -31 15 Kissimmee 0.017 0.010±0.001 0.015±0.002 0.017±0.002 -41 -12 0 Istokpoga 0.018 0.013±0.003 0.024±0.008 0.029±0.016 -28 33 61

P Flux rates. At 2 days, the mean SRP flux ranged from a rate of -0.64 ±1.094

(mg m-2 d-1) in Lake Tohopekaliga to a rate of -2.32 ± 0.237 (mg m-2 d-1) in Lake

Istokpoga (Table 3-9). The negative P flux rates of all the lakes suggest that the

sediments are retaining phosphorus. Phosphorus flux rates were significantly higher for

Lake Kissimmee with Lake Tohopekaliga and Cypress at day 2 (P<0.001). The dissimilarities may be due to differences in sediment type and physical and chemical properties of the sediment. For example, Lake Tohopekaliga is a sandier lake with lower total C, N, and P (16.3 ± 18.8, 1.37 ± 1.38, and 138 ± 127 mg kg-1 compared to Lake

Kissimmee C, N, P (124 ± 121, 11.7 ± 11.3, and 703 ± 685 mg kg-1 (see chapter 2, Table

2-1).

The mean 7 day SRP flux rates ranged from -0.061 ± 0.270 mg m-2 d-1 in Lake

Kissimmee to 0.367± 0.228 mg m-2 d-1 in Lake Istokpoga. The positive P flux rates of

Lake Istokpoga suggest P release from the sediments, while the negative P flux rate of all the other lakes indicate P retention by the sediments. This data suggests that Lake

Istokpoga may be the only lake functioning as a source of P to the overlying water column at this water column P level (15 ug L-1). Phosphorus flux rates were significantly

lower for Lake Istokpoga compared with Kissimmee, Tohopekaliga, Cypress, and

Hatchineha (P<0.05). Phosphorus flux was not significantly correlated with any of the sediments characteristic, however, TP was significantly and positively correlated with

LOI, Ca, Mg, Fe, and Al.

At 25 days, the mean P flux ranged from a rate of 0.137 ± 0.146 mg m-2 d-1in Lake

Istokpoga to a rate of 0.027 ± 0.232 mg m-2 d-1 in Lake Hatchineha. The positive P flux

rates of all the lakes suggest that the lakes are releasing phosphorus to the water column.

There were no significant differences in P flux rates at day 25 at this P addition.

Table 3-9. Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 15 ug L-1 P additions at 2, 7, and 25 days. n=6 for all lakes except Lake Cypress n=5

------P flux mg m-2 d-1------Lakes 2 day 7 day 25 day Tohopekaliga -0.64 ±1.094 -0.081 ± 0.0.285 0.112 ± 0.208 Cypress -0.96 ± 0.621 -0.235 ± 0.164 0.024 ± 0.139 Hatchineha -1.17± 0.687 -0.237 ± 0.160 0.027 ± 0.232 Kissimmee -2.32 ± 0.237 -0.061 ± 0.270 0.028 ± 0.030 Istokpoga -0.61 ± 0.421 0.367 ± 0.228 0.137 ± 0.146

Phosphorus additions (30 ug L-1)

Water column SRP concentrations. The site water ranged from 0.002-0.011 mg

L-1 plus the P addition which increased the concentration to 32, 33, 35, 39 and 41 ug L-1 for Lake Kissimmee, Istokpoga, Tohopekaliga, Cypress, and Hatchineha, respectively.

The mean water column SRP concentrations at day 2 ranged from a low in Lake

Kissimmee (0.021±0.002 mg L-1) to a high in Cypress Lake (0.036±0.003 mg L-1) and

Lake Tohopekaliga (0.036±0.005 mg L-1) (Table 3-10). Lake Tohopekaliga water column SRP concentrations increased at a rate of 2% while all other lakes concentrations declined in rates ranging from 8% in Cypress Lake to 30% in Lake Kissimmee at day 2.

The mean water column SRP concentrations ranged from (0.039 ± 0.005 mg L-1) in

Lake Tohopekaliga to (0.017 ± 0.003 mg L-1) Lake Kissimmee on day 7. Water column

SRP concentrations decreased in Lakes Cypress, Hatchineha, Kissimmee and Istokpoga

at day 7 at a rate between 15% in Lake Hatchineha and Istokpoga to 47% in Lake

Kissimmee, which suggests P retention by the sediments in these lakes. Lake

Tohopekaliga was the only lake to increase in water column SRP concentration at a rate of 11%, which suggests P release from the sediments at day 7.

The mean water column SRP concentrations ranged from (0.052±0.031 mg L-1) in

Lake Tohopekaliga to (0.014±0.003 mg L-1) Lake Kissimmee on day 25. The SRP concentrations increased in Lake Tohopekaliga, Cypress, Hatchineha, and Istokpoga over the course of the experiment for all lakes at day 25 at a rate between 13% in Cypress

Lake to 63% in Lake Hatchineha. Water column SRP concentrations on day 25 for Lake

Tohopekaliga were much higher in one core at 0.106 mg L-1. This may be due to heterogeneity of the sediment in the lake or biological release from organisms in the core.

Water column concentrations decreased in Lake Kissimmee at a rate of 56%, respectively at this P addition (30 ug L-1).

Table 3-10. Percent change in SRP mg L-1 at 30 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicate a decrease in SRP concentration while a positive (+) percent change indicate an increase in SRP concentrations. n=6 .

Initial ------SRP (mg L-1)------Percent Change (%)--- Conc. Lake (mg L-1) 2 d 7 d 25 d 2 d 7 d 25 d Tohopekaliga 0.035 0.036±0.005 0.039±0.023 0.052±0.031 2 11 49 Cypress 0.039 0.036±0.003 0.029±0.007 0.044±0.0027 -7 -26 13 Hatchineha 0.041 0.034±0.003 0.035±0.013 0.067±0.060 -17 -15 63 Kissimmee 0.032 0.021±0.002 0.017±0.003 0.014±0.003 -34 -47 -56 Istokpoga 0.033 0.024±0.003 0.028±0.011 0.040±0.027 -27 -15 21

P flux rates. At 2 days, the mean P flux ranged from a rate of -0.339 ± 0.977 (mg

m-2 d-1) in Lake Tohopekaliga to a rate of -3.12 ± 0.425 (mg m-2 d-1) in Lake Kissimmee

(Table 3-11). The negative P flux rates of all the lakes suggest that the sediments are

retaining phosphorus at day 2. Phosphorus flux rates were significantly higher in Lake

Hatchineha than Tohopekaliga. Flux rates were significantly higher in Lake Kissimmee

compare to Lakes Tohopekaliga, Cypress and Istokpoga (P<0.001). The differences may

be related to the different physical and chemical properties of the sediment.

The average P flux rate ranged from a negative rate of -0.381 ± 0.174 (mg m-2 d-) in

Cypress Lake to a positive rate of 0.007 ± 0.839 (mg m-2 d-1) in Lake Tohopekaliga at

day 7. The positive P flux values for Lake Tohopekaliga and Lake Istokpoga suggest that

the lakes are functioning as a P source to water column while the negative P flux rate of

the other lakes suggest P retention. There were no significant differences in P flux rates

between the lakes at day 7. This variability in P flux rates may be due to wide sediment

variability within the lakes, due to the presence of both sands and muds.

The mean P flux rate ranged from a negative rate of -0.117± 0.202 mg m-2 d-1 in

Lake Istokpoga to a positive rate of 0.295± 0.554 mg m-2 d-1 in Lake Hatchineha at day

25. The positive P flux values for Lake Hatchineha Tohopekaliga and Cypress suggest

that the lakes are functioning as a P source to water column while Lake Istokpoga and

Kissimmee negative P flux rates suggest P retention by the sediments. There were no

significant differences in P flux rates between lakes.

Table 3-11. Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 30 ug L-1 P additions at 2, 7, and 25 days.

------P flux mg m-2 d-1------Lakes 2 day 7 day 25 day Tohopekaliga -0.339 ± 0.977 0.007 ± 0.839 0.207± 0.326 Cypress -1.04 ± 0.920 -0.381 ± 0.174 0.045± 0.251 Hatchineha -1.80 ± 1.064 -0.117 ± 0.453 0.295± 0.554 Kissimmee -3.12 ± 0.425 -0.373 ± 0.132 -0.109± 0.041 Istokpoga -1.23 ± 0.681 0.073 ± 0.365 -0.117± 0.202

Phosphorus additions (60 ug L-1)

Water column SRP concentrations. Water column SRP concentrations tended to

decrease in all the lakes over the course of the study, leading to P retention by the

sediments (Figure 3-6). At 2 days, the mean water column SRP concentrations ranged

from a low of 0.045 ± 0.002 (mg L-1) in Lake Kissimmee to a high of 0.061 ± 0.005 (mg

L-1) in Cypress Lake and 0.061 ± 0.002 (mg L-1) Lake Tohopkeliga, respectively (Table

3-12). Concentrations declined at a rate between 6 % in Lake Tohopekaliga to 38% in

Lake Kissimmee.

At day 7, the mean water column SRP concentration ranged between (0.046 ±

0.007 mg L-1) in Lake Tohopekaliga to (0.018 ± 0.007 mg L-1) in Lake Kissimmee. The

SRP concentrations in the water column declined at a rate between 29% in Lake

Tohopekaliga to 75% in Lake Kisimmee.

The mean water column SRP concentrations at day 25 ranged from a low in Lake

Kissimmee (0.011 ± 0.004 mg L-1) to a high in Lake Hatchineha (0.065 ± 0.050 mg L-1).

The concentrations in the water column declined at a rate of 8% in Lake Hatchineha to a rate of 85% in Lake Kissimmee at day 25.

0.08

0.06

0.04 SRP (mg/l) SRP 0.02

0.00 0 5 10 15 20 25 Time (days)

Figure 3-6. Phosphorus retention by sediments from station T2 of Lake Tohopekaliga at 60 ug L-1 P additions.

Table 3-12. Percent change in SRP mg L-1 at 60 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6.

Initial ------SRP (mg L-1)------Percent Change %------Conc. Lake (mg L-1) 2 d 7 d 25 d 2 d 7 d 25 d Tohopekaliga 0.065 0.061±0.002 0.046±0.007 0.030±0.020 -6 -29 -54 Cypress 0.069 0.061±0.005 0.045±0.012 0.061±0.033 -12 -35 -12 Hatchineha 0.071 0.057±0.004 0.037±0.011 0.065±0.050 -19 -48 -8 Kissimmee 0.072 0.045±0.002 0.018±0.007 0.011±0.004 -38 -75 -85 Istokpoga 0.073 0.047±0.008 0.037±0.013 0.037±0.022 -36 -49 -49

P flux rates. At 2 days, the mean P flux ranged from a rate low of -0.937 ± 0.923

(mg m-2 d-1) in Lake Tohopekaliga to high rate of -3.615 ± 0.518 (mg m-2 d-1) in Lake

Kissimmee (Table 3-13). The negative P flux rates of all the lakes suggest that the

sediments are retaining phosphorus at day 2 at P additions of 60 ug L-1. Phosphorus flux

rates were significantly higher in Lake Kissimmee compare to Lake Tohopekaliga

(P<0.05) at day 2.

The average P flux rate at day 7 ranged from a low of -0.543 ± 0.420 (mg m-2 d-1)

in Lake Istokpoga to a high of -1.31 ± 0.227 (mg m-2 d-1) in Lake Kissimmee. These

negative P flux rates suggest P retention by sediments for all five lakes. Phosphorus flux

rates were significantly higher in Lake Kissimmee with Lakes Tohopekaliga and

Istokpoga at day 7.

At day 25, the mean P flux ranged from a rate low of -0.081 ± 0.471 (mg m-2 d-1) in

Lake Istokpoga to high rate of -0.399 ± 0.269 (mg m-2 d-1) in Lake Tohopekaliga. The

negative P flux rates of all the lakes suggest that the sediments are retaining phosphorus

at day 25. There were no significant differences in P flux rates at day 25 at this P

addition.

Phosphorus additions (120 ug L-1)

Water column SRP concentration. Water column SRP concentrations decreased in all the lakes over the course of the study, suggesting P retention by the sediments

(Figure 3-7). At 2 days, the mean water column SRP concentration ranged from a low of

0.088±0.001 (mg L-1) in Lake Kissimmee to a high of 0.123±0.023 (mg L-1) in Lake

Hatchineha (Table 3-14). Concentrations declined at a rate between 7% in Lake

Hatchineha to 89% in Lake Kissimmee at day 2.

Table 3-13. Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 60 ug L-1 P additions at 2, 7, and 25 days.

------P flux mg m-2 d-1------

Lakes 2 day 7 day 25 day Tohopekaliga -0.937 ± 0.923 -0.675 ± 0.281 -0.399 ± 0.269 Cypress -1.969 ± 1.429 -0.771 ± 0.371 -0.354 ± 0.048 Hatchineha -2.669 ± 0.749 -1.00 ± 0.384 -0.346 ± 0.286 Kissimmee -3.615 ± 0.518 -1.31 ± 0.227 -0.116 ± 0.220 Istokpoga -2.648 ± 1.854 -0.543 ± 0.420 -0.081 ± 0.471

At day 7, the mean water column SRP concentration ranged between (0.013±0.014

mg L-1) in Lake Kissimmee to (0.120 ± 0.040 mg L-1) in Lake Hatchineha. The SRP

concentrations in the water column declined at a rate between 8% in Lake Hatchineha to

94% in Lake Kissimmee at day 7.

The mean water column SRP concentrations at day 25 ranged from a low in Lake

Kissimmee (0.007±0.010 mg L-1) to a high in Lake Hatchineha (0.129±0.065 mg L-1).

The concentrations in the water column declined at a rate of 2% in Lake Hatchineha to a rate of 94% in Lake Kissimmee at day 25.

Phosphorus additions (120 ug L-1)

P flux rates. At 2 days, the mean P flux ranged from a rate low of -2.443 ± 1.149

(mg m-2 d-1) in Cypress Lake to high rate of -6.821 ± 1.032 (mg m-2 d-1) in Lake

Kissimmee (Table 3-15). The negative P flux rates of all the lakes suggest that the

sediments are retaining phosphorus at day 2. The P flux rate for Cypress Lake was significantly lower than Lakes Istokpoga and Kissimmee (P<0.001). Phosphorus flux rates were also significantly higher in Lakes Kissimmee compared to Lake Hatchineha

and Lake Tohopekaliga (P<0.001) at day 2.

0.12 )

-1 0.09

0.06

0.03 SRP (mg L (mg SRP

0.00 0 6 12 18 24 Time (days)

Figure 3-7. Phosphorus retention by sediments from station I10007 of Lake Istokpoga at 120 ug L-1 P additions.

The mean P flux rate at day 7 ranged from -0.87 ± 0.419 (mg m-2 d-1) in Lake

Cypress to -2.91 ± 0.494 (mg m-2 d-1) in Lake Kissimmee (Table 3-13). All lakes appear

to be retaining P (negative flux rates) at this P addition (120 ug L-1). These results imply

that none of the sediments in the lakes are net releasers of P to the water column at this P addition.

. However, even though sediments are taking up P, they still may not be taking out enough P to lower the P concentrations in the water column. Flux rates were significantly lower in Cypress Lake compared to Lakes Istokpoga (P<0.05). Lake

Kissimmee P flux rates were significantly higher than Cypress Lake, Lake Hatchineha, and Lake Tohopekaliga (p<0.05).

At day 25, the mean P flux ranged from a rate low of -0.006 ± 0.656 (mg m-2 d-1) in

Lake Hatchineha to high rate of -0.808 ± 0.069 (mg m-2 d-1) in Lake Istokpoga (Table 3-

11). The negative P flux rates of all the lakes suggest that the sediments are retaining

Table 3-14. Percent change in SRP mg L-1 at 120 ug L-1 P additions, for all lakes, at day 2, 7, and 25. A negative (-) percent (%) change indicates a decrease in SRP concentration while a positive (+) percent change indicates an increase in SRP concentrations. n=6.

Initial ------SRP (mg L-1)------Percent Change %----- Conc. Lake (mg L-1) 2 d 7 d 25 d 2 d 7 d 25 d Tohopekaliga 0.125 0.113 ± 0.002 0.081 ± 0.015 0.062 ± 0.014 -9.3 -35.2 -50.4 Cypress 0.129 0.115 ± 0.006 0.097 ± 0.012 0.097 ± 0.074 -11.0 -24.8 -24.8 Hatchineha 0.131 0.123 ± 0.023 0.120 ± 0.040 0.129 ± 0.065 -6.5 -8.4 -1.5 Kissimmee 0.122 0.088 ± 0.001 0.013 ± 0.014 0.007 ± 0.010 -27.9 -89.3 -94.3 Istokpoga 0.123 0.090 ± 0.005 0.043 ± 0.026 0.028 ± 0.033 -26.8 -65.0 -77.2

83 phosphorus at day 25. Phosphorus flux rates were significantly lower in Lake Hatchineha compared to Lakes Istokpoga, Tohopekaliga, and Kissimmee (P<0.01).

Table 3-15. Mean phosphorus flux rate (mg m-2 d-1) for Lakes Tohopekaliga, Kissimmee, Istokpoga, Cypress, and Hatchineha at 120 ug L-1 P additions at 2, 7, and 25 days.

------P flux mg m-2 d-1------Lakes 2 day 7 day 25 day Tohopekaliga -3.364 ± 2.145 -1.54 ± 0.499 -0.700 ± 0.207 Cypress -2.443 ± 1.149 -0.87 ± 0.419 -0.527 ± 0.262 Hatchineha -2.896 ± 0.257 -1.05 ± 1.07 -0.006 ± 0.656 Kissimmee -6.821 ± 1.032 -2.91 ± 0.494 -0.817 ± 0.077 Istokpoga -5.055 ± 1.380 -2.20 ± 0.884 -0.808 ± 0.069

Discussion

In general, the water column SRP concentration increased over time at no P additions, showing P release from the sediment and decreased at high P additions (60 and

120 ug L-1), showing P retention by the sediment for all the lakes. Despite, retention by the sediments at high P additions, water column SRP levels remained high (Figure 3-9).

This trend was observed for all lakes at day 2, 7, and 25, except on day 7 and 25 for

Kissimmee.

For Lake Kissimmee, the water column SRP concentration was much lower at high

P additions (120 ug L-1) than at no P additions, which may be due to the trapping of P at the aerobic sediment surface to which P adsorption by iron occurs under oxidized conditions (Gachter and Meyer 1993, Keizer and Sinke 1992, Patrick and Khalid 1974).

For example, Lake Kissimmee has a great concentration of Fe and Al in the sediment compared to any other metals (refer to chapter 2; Table 2-2). This is important because

Fe can either trap P at the aerobic sediment surface, preventing diffusive P release or bind

P at the anaerobic sediment surface, resulting in P release from the sediments. In Lake

Kissimmee, at P additions of 120 ug L-1, the mean water column SRP concentrations was lower at 0.013 ± 0.014 (mg L-1) compared to 0.015± 0.002 mg L-1 at no P additions at day

Day 2 0.18 ) -1

0.12 Tohopekaliga Cypress Hatchineha 0.06 Kissimmee

WC SRP (mg L Istokpoga 0 060120

Spike (ug L-1)

Day 7 Tohopekaliga ) 0.16 -1 Cypress 0.12 Hatchineha 0.08 Kissimmee 0.04 Istokpoga

WC SRP (mg L 0 060120 Spike ( ug L-1)

Day 25

0.16 ) -1 Tohopekaliga 0.12 Cypress 0.08 Hatchineha Kissimmee 0.04 Istokpoga

WC SRP (mg WC SRP L 0 060120

Spike (ug L-1)

Figure 3-8. Water Column SRP (mg L-1) versus spike concentration ug L-1 for each lake. at day 2, 7, and 25.

Although these lake sediments may have some capacity to retain P at high P loads

(120 ug L-1), the lakes may still be a significant source of P to downstream Lake

Okeechobee due to high water column SRP concentrations. Studies have shown that despite sediment P retention by lakes under high P loads, a high water column SRP concentration was maintained (Reddy et al. 2002). In efforts to restore water quality in the Upper Chain of Lakes and reduce P export to downstream Lake Okeechobee, the concentration of P in the water column should be taken into consideration.

The sediment P flux rates showed that as the P load increased, there was a decrease in sediment P release. The minimum average P flux rate were (-0.011) to a maximum of

(-1.714) for the range of P additions. These P flux rates are comparable to other P flux studies found in aquatic systems throughout the world for both sand and mud sediment types (Holdren and Armstrong 1980, Lofgren and Bostrom, 1989, Moore et al. 1998)

(Table 3-16). The sands P flux rate had a minimum average P retention of -0.073 ± 0.173 and a maximum flux rate of -2.00 ± 1.06 mg m-2 d-1 for stations T10 and K1004; however, P release ranged between 0.091 ± 0.701 to 0.269 ± 0.021 mg m-2 d-1. All other station were mud and had a minimum average P flux of 0.005 ± 0.293 and a maximum flux of -1.643 ± 0.929 mg m-2 d-1. The stations characterized as mud had less than 62 um of clay and silt in the sediments of the lakes and all other lakes were defined as sand (>63 um) (Oui and McComb 2000).

From the results, we found some differences in P flux rates between each lake; however, no significant correlations between P flux and any of the sediment P characteristics were found (i.e., nutrients, organic matter, bulk density, metals, EPCw).

So, porewater equilibration data, not previously mentioned, was collected and regressed

86 against the P flux rate at all P additions to see if a relationship could be found between P flux and porewater to maybe explain some of the differences found between each lake.

There was a significant and negative relationship found between P flux and porewater SRP at no P and 15 ug L-1 additions (Table 3-17). Some studies have shown that lakes dominated by Fe, as in the Upper Chain of Lakes, may not show a relationship

Table 3-16. Ranges of sediment-water SRP fluxes (mg m-2 d-1)

Study Area Sediment Type Min Max Author Kissimmee River sand -0.26 3.35 Moore et al.1998 Taylor Creek sand -0.08 1.86 Moore et al.1998 Lake Vallentunasjon -1.80 22.5 Lofgren and Bostrom 1989 Lake Ontario 0.03 0.8 Holdren and Armstrong 1980 Lake Ontario 0.03 0.8 Holdren and Armstrong 1980 Lake Balaton 0.20 10.0 Lijklema et al. 1983 Lake Okeechobee mud -0.37 0.40 Moore et al.1998 Lake Okeechobee sand -0.02 0.11 Moore et al.1998

between porewater SRP gradient and P flux into aerobic water column (Premazzi and

Provini 1985). At high P additions (120 ug L-1) there were a significant and negative relationship found at depth from 1-6, which suggest that adsorption and precipitation in the oxidized zone, rather than diffusion from the reduced zone, was the process governing P exchange between the sediment and water column (Moore et al. 1998).

The equilibrium water column phosphorus concentration (EPCw) can be used to determine the extent of which the internal load will be released during restoration of a lake after external load reductions. The EPCw can be a useful tool for water managers to determine the water column SRP concentration for which sediments may act as a potential source of P to the overlying water column of a lake. The EPCw can predict P movement between the sediment and the interstitial water (Olila and Reddy 1993).

Table 3-17.Correlation between Porewater Equilbrators (Peepers) and P flux rate with the Pearson correlation on top and the P-value on the bottom in parentheses. All correlations are significant to P<0.05. n=10

Spike Levels No P added 15 ug L-1 30 ug L-1 60 ug L-1 120 ug L-1

Peeper (1-3 cm depth) 0.284 0.502 0.393 -0.184 -0.747 (0.427) (0.140) (0.261) (0.611) (0.013) Peeper (4-6 cm depth) 0.484 0.004 -0.170 -0.196 -0.643 (.157) (0.991) (0.639) (0.587) (<0.05) Peeper (7-10 cm depth) -0.719 -0.631 -0.186 -0.540 0.063 (0.01) (0.05) (0.606) (0.107) (0.863)

Equilibrium Phosphorus Concentration

Water managers can manage for the internal sediment P load by determining the

EPCw of aquatic systems. For example, water managers may consider dredging a lake as

a component of a restoration plan; however dredging can be cost and labor intensive.

Therefore, the EPCw can be used to determine which of these lakes should be dredged or

if focus should be aimed at other activities during restoration.

The SRP flux rates gave an idea of which lake sediments were releasing or

retaining P under the five water column concentrations added (0, 15, 30, 60, 120 ug L-1).

-2 -1 The EPCw was calculated by plotting the SRP flux rate (mg m d ) against the initial water column SRP concentration (mg L-1) and taking the regression of those data points.

The EPCw is the point that intercepts the x-axis, where x = 0. The EPCw is defined as the

P in solution that is in equilibrium with P in the solid phase (Olila and Reddy 1993).

Sediments function as a net source of P at water column concentrations less than the

EPCw and as a sink of P to the overlying water column at values greater than the EPCw.

Phosphorus fluxed from the sediment to the water column in Lake Tohopekaliga

-1 for the sand station (T10) and mud station (T2) at EPCw less than 0.037 and 0.013 mg L , respectively (Table 3-18). This data suggest that the sandier station (T10) will release P

-1 first at an EPCw less than 0.037 mg L compared to the muddier station (T2) at 0.013 mg

L-1 (Figures 3-9). A study done on Lake Okeechobee found similar results in that the

sand station had a higher EPCw than the mud station (Olila and Reddy 1993).

There were no significant differences found between these two stations, maybe

due to a small sample size. However, the sand station had less amounts of metals (Ca,

Mg, Fe, and Al), total C, N, and P, as well as organic matter compared to the muds of

Lake Tohopekaliga There were no significant correlations found between EPCw with P

flux or any sediment characteristic (see Table 3-6 and Table 3-7).

Table 3-18. Equilibrium Water Column Phosphorus Concentrations (EPCw) values determined at two stations in each lake. Water column concentrations below these concentrations indicate conditions favorable for release of P n=3.

-1 Lake Station EPCw (mg L ) Tohopekaliga T10 0.030 Tohopekaliga T2 0.013 Kissimmee K1004 0.013 Kissimmee K1012 0.015 Istokpoga I10007 0.044 Istokpoga I10004 0.024 Cypress C16 ~0 Cypress C15 0.007 Hatchineha H107 0.003 Hatchineha H103 0.004

-1 The EPCw for the mud stations of Cypress Lake were ~0 and 0.007 (mg L ) for stations C16 and C15, respectively (Figure 3-10). The mud stations of C15 will release P

-1 first at an EPCw less than 0.007 (mg L ); while station C16 appears to be retaining P at

almost all water column SRP concentrations. There were not any significant differences

found in EPCw between the stations of Cypress Lake, maybe due to small sample size.

0.6 -1 EPCw=0.030 mg L 0.4 )

-1 0.2 d -2 0.0 -0.20.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 -0.4 -0.6 -0.8 y = -12.884x + 0.3765 R2 = 0.9685 -1.0 Phosphorus flux (mg m (mg flux Phosphorus -1.2 -1.4 Water colum n SRP (m g L-1)

1.0 EPCw=0.013 (mg/L) ) -1

d 0.5 -2 0.0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 -0.5

-1.0

-1.5

-2.0 y = -16.925x + 0.2277 R2 = 0.9602

P retention / P release (mg m (mg release P / retention P -2.5

-3.0 Water column SRP (mg L-1)

Figure 3-9. Release/retention of P related to water column concentration for Lake Tohopekaliga-stations-T10 (top) and T2 (bottom).

-1 The EPCw for Lake Hatchineha were 0.003 and 0.004 (mg L ) for stations H107

and H103, respectively (Figure 3-11). The mud station of H103, EPCw is slightly higher

-1 than the mud station of H103 and will release P first at an EPCw less than 0.004(mg L )

compared to station H107. There were no significant differences found between the

stations of Lake Hatchineha.

-1 EPCw =~0 mg L ) -1 d

-2 1

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1 y = -6.6443x - 0.0006 R2 = 0.6402 P retention /P release (mgm

-2 Water column SRP (mg L-1)

2 -1 EPCw = 0.007 mg L ) 1 d-

-2 1

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1 y = -8.3402x - 0.0586 2

P retention / P release (mg m R = 0.9334

-2 Water column SRP (mg L-1)

Figure 3-10. Release/retention of P related to water column concentration for Lake Cypress- station C16 (top) and C15 (bottom).

0.5 -1 EPCw=0.003 mg L )

-1 0.0 d

-2 0.000 0.020 0.040 0.060 0.080 0.100 0.120 0.140

-0.5

-1.0 y = -11.547x + 0.0328 R2 = 0.9027 -1.5

-2.0 P retention/P release (mg m

-2.5 Water column SRP (mg L-1)

2 -1 ) EPCW=0.004 mg L -1 d -2 1

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1 y = -6.8991x + 0.0253 R2 = 0.5536 P retention/ P release (mg m PP release retention/

-2 Water column SRP (mg L-1)

Figure 3-11. Release/retention of P related to water column concentration for Lake Hatchineha-station H107 (top) and H103 (bottom).

Phosphorus fluxed from the sediment in Lake Kissimmee to the water column at

-1 EPCw less than 0.013 and 0.015 mg L for stations (K1004) and (K1012), respectively

(Figure 3-12). The mud station of K1012 of Lake Kissimmee released P first compared

to the sand station of K1004 at water column SRP concentrations less than their

respective EPCw. There were no statistical differences found between the stations of

Lake Kissimmee, maybe due to small sample size. However, the mud station had greater

amounts of metals, nutrients, and organic matter compared to the sand station of this lake.

Phosphorus was released from the sediments in Lake Istokpoga at EPCw less than

0.044 mg L-1 and 0.024 mg L-1 at the mud station of I10007 and I10004, respectively

(Figure 3-13). The mud station of I10007 had greater amounts of organic matter, metals,

and nutrients compared to the station I10004.

2 -1 EPCw = 0.013 mg L ) 1 1 d- -2

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1

-2

y = -25.062x + 0.3237 -3 R2 = 0.9979 P retention / P release (mg m

-4 Water column SRP (mg L-1)

2 -1 EPCw = 0.015 mg L )

-1 1 d -2

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1

-2

-3 y = -28.683x + 0.4425 P retention/ P release (mg m R2 = 0.9912

-4 Water column SRP (mg L-1)

Figure 3-12. Release/retention of P related to water column concentration for Lake Kissimmee-stations K1004 (top) and K1012 (bottom).

-1 2 EPCw = 0.044 mg L ) -1 d

-2 1

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1

-2 y = -17.585x + 0.7722 2

P retention / Prelease (mgm R = 0.9936

-3 Water column SRP (mg L-1)

2 -1 EPCw = 0.024 mg L )

-1 1 d -2

0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14

-1

-2 y = -28.023x + 0.6703 2 -3 R = 0.9642 Pretention / P release (mg m

-4 Water column SRP (mg L-1)

Figure 3-13. Release/retention of P related to water column concentration for Lake Istokpoga-station 10007 (top) and 10004 (bottom).

In general, the stations with either low organic matter, low concentrations of metals or high bulk density tended to have a higher EPCw, in which the stations that met those characteristics were typically sand sediments. However, Lake Kissimmee was the exception, in which the sand station had a lower EPCw compared to the mud station. This

may be due to the trapping of P at the aerobic-anaerobic sediment water interface for the

sand station (Keizer and Sinke 1992). The mud station had high amounts of metal in the

sediment, but greater amounts of phosphorus, suggesting that sediment TP plays a major

role.

It appears that Lake Hatchineha, Kissimmee and Cypress Lake have a low potential to release P to the water column at almost all water column concentrations; while Lakes

Tohopekaliga and Istokpoga appear to be releasing P less than an average EPCw of 0.030 mg L-1.

Overall Conclusion

Internal sediment P load contributes heavily to the degradation of water quality in

lakes even after external sources have been reduced. Lake Tohopekaliga, Cypress,

Hatchineha, Kissimmee, and Istokpoga are shallow well mixed lakes that have been impacted by nonpoint and point sources of pollution since the 1970’s. Impacts in water quality within the Upper Chain of Lakes have influenced water quality levels in the downstream Lake Okeechobee.

The sediments of each of the five lakes were characterized for bulk density, mass loss on ignition (LOI), total C, N, and P, as well as selected metals (Ca, Mg, Fe and Al).

The bulk density ranged from 0.06-1.18 g cm-3 with sediment texture varying from

organic mud to sand. The LOI values ranged from 0-55% with the highest values

representing the greatest content of organic matter. The sands tended to have low organic

matter and the muds typically had greater organic matter.

The sites characterized as mud sediments, primarily had high nutrient levels (total

P, total N, and total C) and organic matter content. The sand sites typically had less

nutrients (total P, total N and total C) and organic matter content. There were strong

correlations of total P, N, C and bulk density to LOI. Total C and total N are generally

found to be related to organic matter in sediments. A strong positive correlation between

total P and LOI were found, but are generally not seen in lake sediments. This

relationship suggests the importance of organics as a P reservoir and that the P source

may be related to organic matter.

Total P was well correlated with total N and total C, which also indicates that the P

source may be related to organic matter. The mud sediments in each lake also contained

greater amounts of Ca, Mg, Al, and Fe than the sands and are well correlated with total P.

These selected metals are important to inorganic P stability in many lake sediments.

The inorganic P results suggest that the greatest portion of inorganic P was in the form most associated with Fe and Al (NaOH-Pi). The total organic P was proportionally

greater in each lake than total inorganic P. The mud sediments contained the greatest

amount of TP and P associated with organics and also had greater amounts of available or

easily exchangeable P than the sands. The sand and mud sediments were not at all

different in their distribution of P; however, the muds contained greater amounts of total

P, so this sediment type may contribute more to P release to the overlying water column of a lake as shown from the P characterization study.

Phosphorus flux, at all P additions and the EPCw, were not significantly correlated with sediment characteristics, such as total P, N, and C, organic matter, bulk density, iron, aluminum, calcium, and magnesium. However, significant differences were found

between some lakes. This difference may be due to the variability between the lakes due

to both the mud and sand sediments.

In general, the aerobic SRP flux rates suggest that P release was highest at ambient

water column SRP levels and decreased with an increase in P loading. However, an

increase in P loading also maintained higher water column SRP concentrations. Aerobic

SRP flux rates indicate that sediments in all lakes, except Lake Hatchineha were releasing

P to the water column at ambient water column SRP concentrations and retaining P at

higher concentrations at day 7 and all lake were releasing P by the completion of the

study (~25 days). Also, Lake Hatchineha and Cypress maintained a relatively low water

column SRP concentration at no P additions at day 7 around 0.015 mg L-1 compared to

concentrations greater than 0.095 mg L-1 at 120 ug L-1 P addition.

The Equilibrium Water Column Phosphorus Concentration suggests that Cypress

and Hatchineha have a low potential for release of SRP from the sediments as the water

column SRP concentrations decrease over time and therefore may not be a potential

source of P to downstream Lake Okeechobee. Therefore, the EPCw is a useful tool to determine which of these five lakes should be dredged or if focus should be aimed at other activities during restoration.

It is important to note from the aerobic SRP flux and EPCw results that the stations with lower sediment TP were releasing P and had higher EPCw than the stations with higher sediment TP. The stations with the higher sediment TP and lower EPCw had a low

potential to release SRP and tended to be the muddier sediments. Therefore, just going

out and measuring sediment TP does not give a good indication of which sediments have

potential to release P. So the EPCw can be a great tool to determine where future

restoration activities should be focused.

In general, the sandier lakes have the greatest potential to release P compared to the muddier lakes. It should be recognized that the muddier lakes contained the greater amounts of organic matter, total C, N and P, as well as Ca, Mg, Fe, and Al.

APPENDIX A PHOSPHORUS FRACTIONATION DATA

Table A-1. Characterization of inorganic P forms (mg kg-1) in Tohopekaliga, Cypress, and Hatchineha raw data for sand sediments.

Lake Station Labile-P Fe/Al-P Ca/Mg-P HA/FA-P Residue P Tohopekaliga 1 0.881 20.24 9.76 15.51 25.15 Tohopekaliga 4 0.421 12.04 5.30 6.61 20.36 Tohopekaliga 5 0.561 16.06 5.43 16.11 23.64 Tohopekaliga 6 1.647 15.52 4.87 19.85 13.62 Tohopekaliga 7 0.705 24.92 6.69 17.85 26.20 Tohopekaliga 9 3.057 24.29 9.15 16.38 13.47 Tohopekaliga 10 0.799 11.10 3.16 10.21 15.57 Cypress 11 0.587 12.57 13.33 5.26 17.48 Cypress 12 0.600 11.89 3.35 8.13 18.64 Cypress 14 0.544 18.71 4.03 19.81 21.51 Cypress 19 1.115 56.33 14.20 37.12 55.43 Hatchineha 102 0.660 16.03 9.12 24.20 21.08 Hatchineha 104 0.656 9.98 3.36 13.63 13.23 Hatchineha 105 0.742 14.36 9.03 24.60 15.87 Hatchineha 106 0.425 14.59 17.14 15.67 7.54 Hatchineha 108 0.504 22.45 7.49 31.44 6.08

HA=Humic Acid FA=Fulvic Acid

98 99

Table A-2. Characterization of inorganic P (mg kg-1) forms in Kissimmee and Istokpoga raw data for sand sediments.

Lake Station Labile-P Fe/Al-P Ca/Mg-P HA/FA-P Residue P Kissimmee 1002 0.596 6.94 1.79 4.70 9.66 Kissimmee 1004 0.572 13.67 4.75 10.12 17.20 Kissimmee 1005 0.501 10.76 2.91 9.59 12.37 Kissimmee 1010 0.545 14.36 3.57 12.82 13.69 Istokpoga 10001 0.801 15.55 2.77 11.48 11.31 Istokpoga 10002 1.151 36.83 5.74 41.59 29.19 Istokpoga 10003 3.145 60.70 7.39 6.33 43.50 Istokpoga 10005 1.311 14.97 3.41 8.18 11.95 Istokpoga 10008 0.901 13.40 2.98 5.23 8.78 Istokpoga 10010 0.318 15.17 12.97 11.07 8.69

HA=Humic Acid FA=Fulvic Acid

Table A-3. Characterization of inorganic P (mg kg-1) forms in Tohopekaliga, Cypress and Hatchineha raw data for mud sediments.

Lake Labile-P Fe/Al-P Ca/Mg-P HA/FA-P Residue P Tohopekaliga 2 0.580 58.63 12.34 93.91 248.90 Tohopekaliga 3 1.381 151.23 42.75 150.29 202.02 Tohopekaliga 8 0.923 61.74 16.71 72.59 76.14 Cypress 13 1.322 67.53 19.88 92.47 99.07 Cypress 15 1.523 347.08 66.08 142.80 483.30 Cypress 16 1.622 571.77 9.95 238.13 705.06 Cypress 17 1.458 431.46 46.80 180.46 497.71 Cypress 18 0.858 52.44 10.85 62.53 172.65 Cypress 20 1.649 640.51 50.38 265.27 550.74 Hatch 101 2.168 274.50 106.72 357.25 360.87 Hatch 103 1.649 111.12 60.18 216.64 86.46 Hatch 107 1.574 375.71 62.10 233.68 498.17 Hatch 109 1.979 249.73 86.14 255.83 374.12 Hatch 110 1.609 414.77 33.29 86.25 555.43

HA=Humic Acid FA=Fulvic Acid

100

Table A-4. Characterization of inorganic P (mg kg-1) forms in Kissimmee and Istokpoga raw data for mud sediments.

Lake Station Labile-P Fe/Al-P Ca/Mg-P HA/FA-P Residue P Kissimmee 1001 0.935 45.00 16.65 80.39 74.66 Kissimmee 1003 1.802 76.18 150.10 710.79 640.27 Kissimmee 1006 1.794 112.28 71.21 460.86 363.96 Kissimmee 1007 1.550 352.20 26.24 305.51 462.21 Kissimmee 1011 1.813 442.15 0.69 303.83 711.18 Kissimmee 1012 1.339 377.84 -1.27 248.10 614.24 Istokpoga 10004 1.197 281.44 51.19 174.76 191.21 Istokpoga 10006 2.126 78.92 20.88 116.14 65.16 Istokpoga 10007 3.175 169.96 30.17 206.56 164.72 Istokpoga 10009 1.784 185.15 38.37 338.19 223.52

HA=Humic Acid FA=Fulvic Acid

APPENDIX B METALS DATA

Table B-1. Characterization of metals (mg kg-1) for Tohopekaliga, Cypress, Hatchineha raw data for sand sediments.

Lake Station Ca Mg Fe Al Tohopekaliga 1 11585 1684 12451 24320 Tohopekaliga 4 951 17 672 774 Tohopekaliga 5 563 22 623 850 Tohopekaliga 6 547 42 1012 1071 Tohopekaliga 7 9619 1636 13641 21335 Tohopekaliga 9 12367 2756 18696 36135 Tohopekaliga 10 9770 2369 19436 31072 Cypress 11 988 19 993 1099 Cypress 12 242 0 705 780 Cypress 14 2222 30 672 929 Cypress 19 712 120 1911 2563 Hatchineha 102 641 63 801 1245 Hatchineha 104 951 17 672 774 Hatchineha 105 563 22 623 850 Hatchineha 106 547 42 1012 1071 Hatchineha 108 641 90 1745 1716

Table B-2. Characterization of metals (mg kg-1) for Kissimmee and Istokpoga raw data for sand sediments.

Lake Station Ca Mg Fe Al Kissimmee 1002 204 0 1267 579 Kissimmee 1004 274 7 1403 801 Kissimmee 1005 196 0 954 517 Kissimmee 1010 273.5 3.6 1102.45 630.2 Istokpoga 10001 1300 39 548 928 Istokpoga 10002 751 120 1195 1612 Istokpoga 10003 1255 19 930 683 Istokpoga 10005 1404 72 880 817 Istokpoga 10008 278 20 424 539 Istokpoga 10010 3430 29 383 527

101 102

Table B-3. Characterization of metals (mg kg-1) for Tohopekaliga, Cypress, Hatchineha raw data for mud sediments.

Lake Station Ca Mg Fe Al Tohopekaliga 2 3088 563 4800 10529 Tohopekaliga 3 1701 240 2549 5498 Tohopekaliga 8 1048 108 2207 2325 Cypress 13 1010 171 1988 2671 Cypress 15 6686 1360 17844 23532 Cypress 16 8221 1649 19970 28238 Cypress 17 7012 1590 18302 27209 Cypress 18 7125 1694 20049 29755 Cypress 20 935 127 1797 2653 Hatchineha 101 11585 1684 12451 24320 Hatchineha 103 4214 680 5510 8813 Hatchineha 107 9619 1636 13641 21335 Hatchineha 109 12367 2756 18696 36135 Hatchineha 110 9770 2369 19436 31072

Table B-4. Characterization of metals (mg kg-1) for Kissimmee and Istokpoga raw data for mud sediments.

Lake Station Ca Mg Fe Al Kissimmee 1001 1631 206 3245 2597 Kissimmee 1003 8816 1225 26473 19372 Kissimmee 1006 5669 928 20217 13527 Kissimmee 1007 8180 1481 16544 26650 Kissimmee 1011 9044 1288 22000 17049 Kissimmee 1012 7303 1252 24150 20218 Istokpoga 10004 6257 1152 8238 10925 Istokpoga 10006 1702 363 2719 3262 Istokpoga 10007 3977 796 5653 6189 Istokpoga 10009 7400 1295 8161 9090

APPENDIX C NUTRIENTS

Table C-1. Characterization of nutrients (mg kg-1) in Tohopekaliga, Cypress, and Hatchineha raw data for sand sediments.

Lake Station Total C Total N Total P Tohopekaliga 1 6.97 0.65 86.4 Tohopekaliga 4 4.08 0.32 52.8 Tohopekaliga 5 5.44 0.59 61.6 Tohopekaliga 6 6.20 0.63 48.2 Tohopekaliga 7 5.18 0.60 61.0 Tohopekaliga 9 7.56 0.83 88.5 Tohopekaliga 10 5.41 0.57 61.8 Cypress 11 7.87 0.79 59.1 Cypress 12 4.33 0.44 44.9 Cypress 14 6.09 0.63 64.2 Cypress 19 21.02 1.91 153.6 Hatchineha 102 7.84 0.72 84.8 Hatchineha 104 4.31 0.40 51.3 Hatchineha 105 12.95 1.29 40.2 Hatchineha 106 7.56 0.72 55.2 Hatchineha 108 11.99 1.02 111.0

103 104

Table C-2. Characterization of nutrients (mg kg-1) in Kissimmee and Istokpoga raw data for sand sediments.

Lake Station Total C Total N Total P Kissimmee 1002 5.6 0.6 43.8 Kissimmee 1004 7.6 1.1 60.6 Kissimmee 1005 5.8 0.6 38.1 Kissimmee 1010 7.0 0.7 50.2 Istokpoga 10001 5.10 0.39 54.8 Istokpoga 10002 17.07 1.53 127.5 Istokpoga 10003 6.69 0.42 50.0 Istokpoga 10005 14.97 0.91 55.8 Istokpoga 10008 5.73 0.49 48.6 Istokpoga 10010 9.69 0.65 68.8

Table C-3. Characterization of nutrients (mg kg-1) in Tohopekaliga, Cypress and Hatchineha raw data for mud sediments.

Lake Station Total C Total N Total P Tohopekaliga 2 57.87 4.54 422.9 Tohopekaliga 3 41.71 2.92 273.8 Tohopekaliga 8 22.07 2.01 224.2 Cypress 13 31.29 2.90 216.5 Cypress 15 139.9 12.43 1036.5 Cypress 16 200.52 19.43 1693.54 Cypress 17 164.7 14.57 1304.1 Cypress 18 201.6 18.36 1669.7 Cypress 20 21.37 2.19 181.0 Hatchineha 101 187.70 16.10 1121.3 Hatchineha 103 72.80 6.81 494.3 Hatchineha 107 180.5 17.77 1126.5 Hatchineha 109 127.5 13.67 1205.7 Hatchineha 110 197.1 19.60 1514.4

105

Table C-4. Characterization of nutrients (mg kg-1) in Kissimmee and Istokpoga raw data for mud sediments.

Lake Station Total C Total N Total P Kissimmee 1001 51.77 4.32 225.3 Kissimmee 1003 272.5 26.52 1641.0 Kissimmee 1006 175.8 17.64 866.2 Kissimmee 1007 176.8 17.08 1232.03 Kissimmee 1011 293.6 26.42 1539.0 Kissimmee 1012 244.8 22.10 1332.9 Istokpoga 10004 127 8.51 721.37 Istokpoga 10006 56.67 4.51 294.8 Istokpoga 10007 95.66 7.68 555.23 Istokpoga 10009 179.3 13.69 778.4

APPENDIX D AEROBIC WATER COLUMN SRP DATA

Table D-1. Water Column SRP for Lake Tohopekaliga under aerobic conditions for 25 days for station T10 (Coordinate x (461809 meters), y (3116800 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------Station level ug L-1 0 0.1 1 4 7 12 18 25 106 T10 0 0.005 0.008 0.009 0.013 0.014 0.031 0.015 0.018 T10 0 0.005 0.007 0.008 0.013 0.017 0.030 0.023 0.037 T10 0 0.005 0.007 0.007 0.010 0.010 0.016 0.012 0.026 T10 15 0.020 0.024 0.023 0.018 0.014 0.023 0.015 0.018 T10 15 0.020 0.034 0.024 0.030 0.035 0.042 0.023 0.050 T10 15 0.020 0.024 0.025 0.029 0.032 0.037 0.012 0.038 T10 30 0.035 0.041 0.045 0.064 0.080 0.104 0.105 0.106 T10 30 0.035 0.034 0.033 0.032 0.033 0.042 0.035 0.036 T10 30 0.035 0.034 0.032 0.028 0.043 0.046 0.038 0.040 T10 60 0.065 0.064 0.061 0.061 0.055 0.066 0.065 0.065 T10 60 0.065 0.063 0.061 0.052 0.051 0.048 0.041 0.042 T10 60 0.065 0.062 0.059 0.049 0.042 0.036 0.028 0.028 T10 120 0.125 0.129 0.116 0.103 0.094 0.086 0.069 0.069 T10 120 0.125 0.126 0.112 0.101 0.091 0.084 0.067 0.070 T10 120 0.125 0.124 0.115 0.102 0.088 0.088 0.074 0.075

Table D-2. Water Column SRP for Lake Tohopekaliga under aerobic conditions for 25 days for station T2. (Coordinate x (460252 meters), y (3125825 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------Station level ug L-1 0 0.1 1 4 7 12 18 25 T2 0 0.005 0.009 0.006 0.011 0.018 0.088 0.165 0.153 T2 0 0.005 0.008 0.010 0.020 0.027 0.026 0.008 0.013 T2 0 0.005 0.006 0.005 0.004 0.006 0.023 0.004 0.006 T2 15 0.020 0.020 0.019 0.011 0.015 0.021 0.005 0.009 T2 15 0.020 0.021 0.020 0.021 0.020 0.027 0.060 0.058

T2 15 0.020 0.020 0.020 0.013 0.012 0.019 0.024 0.035 107 T2 30 0.035 0.042 0.036 0.011 0.035 0.044 0.052 0.063 T2 30 0.035 0.034 0.033 0.021 0.012 0.010 0.011 0.014 T2 30 0.035 0.034 0.034 0.013 0.028 0.035 0.049 0.051 T2 60 0.065 0.059 0.060 0.052 0.039 0.023 0.009 0.012 T2 60 0.065 0.067 0.064 0.050 0.039 0.031 0.005 0.017 T2 60 0.065 0.072 0.063 0.057 0.053 0.041 0.014 0.015 T2 120 0.125 0.138 0.113 0.095 0.078 0.065 0.059 0.060 T2 120 0.125 0.115 0.111 0.111 0.081 0.089 0.049 0.065 T2 120 0.125 0.117 0.112 0.098 0.054 0.035 0.002 0.037

Table D-3. Water Column SRP for Cypress Lake under aerobic conditions for 25 days for station C16. Coordinate x (469875 meters), y (3106370 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------Station level ug L-1 0 0.1 1 4 7 12 18 25 C16 0 0.009 0.017 0.014 0.019 0.023 0.035 0.031 0.041 C16 0 0.009 0.009 0.010 0.012 0.012 0.012 0.011 0.010 C16 15 0.024 0.023 0.022 0.021 0.017 0.015 0.013 0.014 C16 15 0.024 0.029 0.025 0.033 0.027 0.020 0.022 0.053 C16 15 0.024 0.026 0.025 0.024 0.017 0.015 0.019 0.054 C16 30 0.039 0.043 0.034 0.030 0.022 0.023 0.052 0.049 C16 30 0.039 0.044 0.037 0.036 0.035 0.032 0.032 0.037

C16 30 0.039 0.042 0.041 0.033 0.036 0.031 0.056 0.096 108 C16 60 0.069 0.076 0.063 0.068 0.056 0.058 0.052 0.040 C16 60 0.069 0.069 0.062 0.050 0.043 0.038 0.043 0.041 C16 60 0.069 0.069 0.062 0.054 0.047 0.042 0.039 0.082 C16 120 0.120 0.126 0.116 0.110 0.105 0.097 0.091 0.116 C16 120 0.120 0.128 0.122 0.128 0.108 0.102 0.097 0.083 C16 120 0.120 0.124 0.119 0.119 0.104 0.098 0.088 0.085

Table D-4. Water Column SRP for Cypress Lake under aerobic conditions for 25 days for station C15. Coordinate x (468261 meters), y (3105828 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------Station level ug L-1 0 0.1 1 4 7 12 18 25 C15 0 0.009 0.008 0.007 0.010 0.009 0.009 0.009 0.011 C15 0 0.009 0.011 0.013 0.015 0.007 0.006 0.009 0.010 C15 15 0.024 0.028 0.022 0.018 0.016 0.015 0.012 0.026 C15 15 0.024 0.023 0.019 0.015 0.015 0.015 0.014 0.013 C15 30 0.039 0.037 0.035 0.037 0.030 0.028 0.034 0.025 C15 30 0.039 0.036 0.035 0.039 0.032 0.032 0.030 0.036 C15 30 0.039 0.038 0.036 0.039 0.019 0.021 0.018 0.025 C15 60 0.069 0.060 0.050 0.037 0.024 0.023 0.026 0.024

C15 60 0.069 0.067 0.062 0.066 0.040 0.024 0.034 0.114 109 C15 60 0.069 0.063 0.064 0.064 0.058 0.056 0.053 0.065 C15 120 0.120 0.122 0.107 0.091 0.074 0.054 0.040 0.037 C15 120 0.120 0.120 0.109 0.109 0.098 0.095 0.089 0.072 C15 120 0.120 0.120 0.115 0.111 0.097 0.084 0.068 0.050

Table D-5. Water Column SRP for Lake Hatchineha under aerobic conditions for 25 days for station H107. Coordinate x (461341 meters), y (3098421 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------level Station ug L-1 0 0.1 1 4 7 12 18 25 H107 0 0.011 0.013 0.009 0.012 0.008 0.006 0.010 0.006 H107 0 0.011 0.014 0.006 0.010 0.005 0.005 0.005 0.034 H107 0 0.011 0.012 0.004 0.011 0.015 0.041 0.092 0.082 H107 15 0.026 0.028 0.020 0.023 0.019 0.015 0.015 0.059 H107 15 0.026 0.025 0.023 0.026 0.021 0.035 0.034 0.067 H107 15 0.026 0.026 0.019 0.015 0.014 0.021 0.016 0.015 H107 30 0.041 0.041 0.033 0.036 0.029 0.029 0.040 0.148

H107 30 0.041 0.042 0.030 0.031 0.023 0.017 0.011 0.004 110 H107 30 0.041 0.039 0.034 0.036 0.034 0.042 0.065 0.126 H107 60 0.071 0.067 0.062 0.048 0.039 0.039 0.050 0.127 H107 60 0.071 0.066 0.054 0.044 0.033 0.028 0.032 0.092 H107 60 0.071 0.064 0.054 0.047 0.033 0.025 0.023 0.030 H107 120 0.131 0.124 0.115 0.113 0.120 0.127 0.147 0.148 H107 120 0.131 0.180 0.169 0.162 0.154 0.141 0.159 0.143 H107 120 0.131 0.120 0.110 0.091 0.034 0.067 0.064 0.058

Table D-6. Water Column SRP for Lake Hatchineha under aerobic conditions for 25 days for station H103. Coordinate x (458082 meters), y (3100650 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------Station level -1 ug L 0 0.1 1 4 7 12 18 25 H103 0 0.011 0.012 0.011 0.013 0.014 0.016 0.045 0.075 H103 0 0.011 0.011 0.006 0.011 0.006 0.006 0.007 0.003 H103 0 0.011 0.017 0.008 0.013 0.010 0.011 0.028 0.022 H103 15 0.026 0.025 0.022 0.018 0.012 0.014 0.016 0.015 H103 15 0.026 0.027 0.025 0.029 0.022 0.020 0.016 0.012 H103 15 0.026 0.026 0.024 0.027 0.022 0.017 0.016 0.011 H103 30 0.041 0.038 0.036 0.037 0.052 0.079 0.058 0.041

H103 30 0.041 0.041 0.034 0.032 0.024 0.022 0.014 0.008 111 H103 30 0.041 0.041 0.037 0.035 0.051 0.080 0.103 0.074 H103 60 0.071 0.068 0.060 0.068 0.056 0.060 0.074 0.110 H103 60 0.071 0.069 0.061 0.064 0.039 0.030 0.024 0.016 H103 60 0.071 0.066 0.055 0.047 0.024 0.018 0.014 0.014 H103 120 0.131 0.120 0.109 0.104 0.093 0.076 0.060 0.043 H103 120 0.131 0.122 0.113 0.114 0.108 0.112 0.118 0.177 H103 120 0.131 0.129 0.119 0.117 0.102 0.090 0.177 0.207

Table D-7. Water Column SRP for Lake Kissimmee under aerobic conditions for 25 days for station K1004. Coordinate x (472394 meters), y (3084179 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------Station level ug L-1 0 0.1 1 4 7 12 18 25 33 K1004 0 0.002 0.009 0.010 0.008 0.015 0.013 0.013 0.015 0.012 K1004 0 0.002 0.010 0.009 0.010 0.015 0.013 0.016 0.014 0.017 K1004 0 0.002 0.009 0.010 0.010 0.016 0.014 0.013 0.012 0.015 K1004 15 0.017 0.019 0.010 0.012 0.015 0.013 0.016 0.024 0.027 K1004 15 0.017 0.018 0.009 0.015 0.015 0.014 0.012 0.018 0.029 K1004 15 0,017 0.020 0.011 0.012 0.019 0.019 0.018 0.017 0.014 K1004 30 0.032 0.033 0.023 0.018 0.018 0.018 0.018 0.014 0.012

K1004 30 0.032 0.031 0.019 0.020 0.021 0.019 0.016 0.015 0.012 112 K1004 30 0.032 0.030 0.022 0.019 0.020 0.019 0.016 0.025 0.018 K1004 60 0.062 0.059 0.045 0.031 0.029 0.021 0.020 0.019 0.021 K1004 60 0.062 0.058 0.047 0.029 0.025 0.020 0.025 0.024 0.020 K1004 60 0.062 0.059 0.048 0.038 0.035 0.023 0.017 0.017 0.017 K1004 120 0.120 0.112 0.086 0.067 0.051 0.041 0.040 0.038 0.033 K1004 120 0.120 0.116 0.087 0.048 0.034 0.024 0.018 0.017 0.015 K1004 120 0.120 0.111 0.086 0.065 0.047 0.034 0.024 0.022 0.019

Table D-8. Water Column SRP for Lake Kissimmee under aerobic conditions for 25 days for station K1012. Coordinate x (473188 meters), y (3088426 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------level Station ug L-1 0 0.1 1 4 7 12 18 25 33 K1012 0 0.002 0.011 0.013 0.011 0.015 0.016 0.016 0.019 0.020 K1012 0 0.002 0.010 0.010 0.011 0.017 0.014 0.014 0.016 0.020 K1012 0 0.002 0.008 0.010 0.008 0.012 0.015 0.014 0.015 0.017 K1012 15 0.017 0.017 0.010 0.015 0.018 0.019 0.015 0.015 0.016 K1012 15 0.017 0.019 0.011 0.009 0.015 0.014 0.015 0.014 0.009 K1012 15 0,017 0.018 0.010 0.015 0.018 0.015 0.016 0.016 0.013 K1012 30 0.032 0.034 0.020 0.015 0.020 0.016 0.013 0.014 0.010

K1012 30 0.032 0.031 0.021 0.019 0.022 0.021 0.018 0.017 0.018 113 K1012 30 0.032 0.031 0.021 0.019 0.023 0.018 0.014 0.014 0.016 K1012 60 0.062 0.055 0.043 0.022 0.019 0.017 0.015 0.016 0.014 K1012 60 0.062 0.058 0.043 0.031 0.029 0.020 0.015 0.014 0.012 K1012 60 0.062 0.060 0.047 0.027 0.026 0.024 0.021 0.019 0.017 K1012 120 0.120 0.108 0.089 0.062 0.052 0.040 0.028 0.020 0.014 K1012 120 0.120 0.110 0.090 0.055 0.038 0.026 0.023 0.020 0.017 K1012 120 0.120 0.108 0.088 0.033 0.029 0.019 0.018 0.018 0.016

Table D-9. Water Column SRP for Lake Istokpoga under aerobic conditions for 25 days for station I10007. Coordinate x (472779 meters), y (3026915 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------level Station ug L-1 0 0.1 1 4 7 12 18 25 33 I10007 0 0.003 0.011 0.012 0.016 0.030 0.064 0.074 0.101 0.098 I10007 0 0.003 0.009 0.012 0.014 0.027 0.040 0.053 0.054 0.042 I10007 0 0.003 0.008 0.010 0.010 0.015 0.020 0.022 0.022 0.025 I10007 15 0.018 0.018 0.015 0.022 0.032 0.048 0.052 0.050 0.037 I10007 15 0.018 0.014 0.009 0.011 0.016 0.018 0.019 0.019 0.015 I10007 15 0.018 0.019 0.018 0.027 0.032 0.023 0.032 0.038 0.028 I10007 30 0.033 0.027 0.025 0.024 0.026 0.031 0.035 0.042 0.035

I10007 30 0.033 0.030 0.029 0.034 0.046 0.062 0.074 0.077 0.088 114 I10007 30 0.033 0.029 0.024 0.024 0.026 0.033 0.040 0.033 0.028 I10007 60 0.063 0.059 0.058 0.044 0.050 0.061 0.073 0.078 0.062 I10007 60 0.063 0.056 0.047 0.046 0.045 0.043 0.039 0.029 0.022 I10007 60 0.063 0.054 0.048 0.049 0.055 0.051 0.049 0.043 0.037 I10007 120 0.123 0.108 0.093 0.082 0.072 0.053 0.043 0.026 0.032 I10007 120 0.123 0.110 0.097 0.083 0.078 0.075 0.074 0.107 0.118 I10007 120 0.123 0.108 0.093 0.075 0.074 0.075 0.063 0.043 0.024

Table D-10. Water Column SRP for Lake Istokpoga under aerobic conditions for 25 days for station I10004. Coordinate x (469916 meters), y (3030750 meters). All coordinates are Universal Mercator, North American Datum 1983, Units meters, UTM Zone 17.

Spike ------Water Column SRP (mg L-1)------level Station ug L-1 0 0.1 1 4 7 12 18 25 33 I10004 0 0.003 0.014 0.018 0.017 0.021 0.018 0.013 0.016 0.019 I10004 0 0.003 0.012 0.017 0.014 0.017 0.016 0.015 0.016 0.014 I10004 0 0.003 0.012 0.013 0.014 0.018 0.019 0.015 0.018 0.014 I10004 15 0.018 0.013 0.012 0.017 0.020 0.024 0.020 0.018 0.017 I10004 15 0.018 0.016 0.014 0.015 0.019 0.018 0.015 0.018 0.017 I10004 15 0.018 0.013 0.012 0.015 0.018 0.015 0.017 0.017 0.024 I10004 30 0.033 0.025 0.018 0.020 0.022 0.020 0.019 0.020 0.017

I10004 30 0.033 0.031 0.024 0.027 0.032 0.035 0.039 0.045 0.063 115 I10004 30 0.033 0.029 0.024 0.019 0.022 0.018 0.017 0.020 0.021 I10004 60 0.063 0.058 0.050 0.047 0.045 0.042 0.035 0.043 0.036 I10004 60 0.063 0.052 0.041 0.034 0.029 0.031 0.024 0.021 0.011 I10004 60 0.063 0.055 0.035 0.029 0.027 0.017 0.019 0.025 0.024 I10004 120 0.123 0.107 0.090 0.062 0.051 0.029 0.021 0.020 0.019 I10004 120 0.123 0.106 0.088 0.051 0.037 0.028 0.026 0.027 0.028 I10004 120 0.123 0.108 0.082 0.041 0.031 0.021 0.019 0.016 0.013

APPENDIX E PRELIMINARY SURVEY

Figure E-1. Sediment thickness map for Cypress Lake.

116 117

Figure E-2. Sediment thickness map for Lake Hatchineha.

118

Figure E-3. Sediment thickness map for Lake Istokpoga.

119

Figure E-4. Sediment thickness map for Lake Kissimmee.

120

Figure E-5. Sediment thickness map for Lake Tohopekaliga.

121

Table E-1. Coordinates (x and y), water depth, sediment depth and thickness for Cypress Lake. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17.

LAKE POINT_ID x y WATER_DEPT SED_DEPTH THICKNESS Cypress 1 468394 3107936 1.7 1.8 0.17 Cypress 2 468124 3107392 1.5 1.5 0.00 Cypress 3 468319 3107604 1.8 1.9 0.06 Cypress 4 468903 3107592 1.7 1.7 0.00 Cypress 6 467786 3107020 1.3 1.3 0.00 Cypress 7 468319 3106995 2.0 2.0 0.00 Cypress 8 468764 3106995 2.2 2.2 0.00 Cypress 9 469272 3106995 2.0 2.0 0.00 Cypress 11 467646 3106588 1.6 1.6 0.00 Cypress 12 468306 3106563 2.1 2.3 0.20 Cypress 13 468776 3106576 2.0 2.5 0.41 Cypress 14 469272 3106576 2.0 2.3 0.27 Cypress 15 469754 3106588 1.8 3.2 1.39 Cypress 17 466973 3106068 1.7 1.9 0.16 Cypress 18 467582 3106068 2.0 2.0 0.00 Cypress 19 468306 3106106 2.1 2.6 0.46 Cypress 20 468891 3106093 2.1 2.8 0.69 Cypress 21 469437 3106118 2.1 2.5 0.42 Cypress 22 466504 3105594 1.3 1.3 0.00 Cypress 23 467052 3105606 1.6 1.7 0.13 Cypress 24 467720 3105679 2.1 2.4 0.29 Cypress 25 468306 3105661 1.9 2.5 0.67 Cypress 26 468751 3105674 2.1 2.5 0.36 Cypress 27 469246 3105674 2.6 3.0 0.39 Cypress 28 469792 3105699 2.0 2.2 0.16 Cypress 30 467350 3105305 2.0 2.1 0.12 Cypress 31 468294 3105090 2.2 2.6 0.40 Cypress 32 469259 3105090 2.1 3.1 0.97 Cypress 33 470224 3105128 2.1 2.7 0.56 Cypress 34 466760 3104640 1.4 1.4 0.00 Cypress 35 467430 3104632 1.9 1.9 0.00 Cypress 36 468306 3104645 2.0 2.1 0.06 Cypress 37 469132 3104632 2.2 2.2 0.00 Cypress 38 469945 3104658 2.1 3.6 1.51 Cypress 39 467204 3104346 1.6 1.6 0.00 Cypress 40 468294 3104163 1.6 1.6 0.00 Cypress 41 468916 3104239 1.6 1.6 0.00 Cypress 42 469653 3104277 1.7 1.7 0.00

122

Table E-2. Coordinates (x and y), water depth, sediment depth and thickness for Lake Hatchineha. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17.

LAKE POINT_ID x y WATER_DEPT SED_DEPTH THICKNESS Hatchineha 43 455556 3102621 2.3 2.6 0.31 Hatchineha 44 455638 3101536 1.7 1.8 0.02 Hatchineha 45 455851 3101856 1.5 2.2 0.66 Hatchineha 46 456065 3102222 1.3 3.6 2.22 Hatchineha 47 456354 3102709 2.6 3.5 0.90 Hatchineha 48 456629 3103197 2.3 2.8 0.44 Hatchineha 49 457156 3100995 1.6 1.6 0.00 Hatchineha 50 457620 3101555 1.9 1.9 0.00 Hatchineha 51 457391 3101216 2.7 2.8 0.07 Hatchineha 52 457756 3100286 1.7 1.7 0.00 Hatchineha 53 458305 3100728 2.6 2.6 0.06 Hatchineha 54 458752 3101186 1.6 1.6 0.00 Hatchineha 55 458305 3099463 2.7 2.7 0.00 Hatchineha 56 458778 3099753 1.9 1.9 0.00 Hatchineha 57 459296 3100042 1.9 1.9 0.00 Hatchineha 58 459691 3100236 1.4 1.4 0.00 Hatchineha 59 458747 3098503 2.0 2.5 0.47 Hatchineha 60 459174 3098777 2.0 2.0 0.00 Hatchineha 61 459661 3099113 2.5 3.0 0.51 Hatchineha 62 460119 3099494 2.6 3.2 0.60 Hatchineha 63 460454 3099783 0.8 2.3 1.46 Hatchineha 64 460848 3100033 1.1 1.7 0.63 Hatchineha 65 459373 3097829 1.4 1.4 0.00 Hatchineha 66 459890 3098031 2.1 2.6 0.47 Hatchineha 67 460362 3098473 2.3 4.0 1.76 Hatchineha 68 460820 3099021 2.5 3.2 0.67 Hatchineha 69 461109 3099311 1.6 1.9 0.27 Hatchineha 70 461216 3098183 2.5 3.5 0.95 Hatchineha 71 461536 3098564 2.6 4.0 1.41 Hatchineha 72 461780 3098823 2.3 3.3 0.91 Hatchineha 73 462463 3097855 2.2 2.4 0.18 Hatchineha 74 462923 3098366 2.1 2.1 0.00 Hatchineha 75 463837 3098427 2.8 5.9 3.10 Hatchineha 76 463426 3098808 3.1 5.5 2.43 Hatchineha 78 463909 3099344 1.9 2.3 0.41 Hatchineha 79 463959 3099799 1.8 2.3 0.48 Hatchineha 81 464556 3100131 1.8 3.3 1.47 Hatchineha 82 456370 3101429 1.9 1.9 0.00 Hatchineha 83 456796 3102298 2.5 2.5 0.00

123

Table E-3. Coordinates (x and y), water depth, sediment depth and thickness for Lake Istopokga. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17.

LAKE POINT_ID x y WATER_DEPT SED_DEPTH THICKNESS Istokpoga 84 473078 3035417 1.0 1.0 0.02 Istokpoga 85 472897 3034454 1.1 1.2 0.10 Istokpoga 86 471814 3033592 1.3 1.4 0.04 Istokpoga 87 472697 3033552 1.7 1.8 0.14 Istokpoga 88 473539 3033532 1.5 1.6 0.07 Istokpoga 89 474281 3033532 1.4 1.9 0.44 Istokpoga 90 469990 3032489 2.0 2.3 0.36 Istokpoga 91 471153 3032489 1.7 2.4 0.70 Istokpoga 92 472456 3032629 1.8 1.9 0.07 Istokpoga 93 473774 3032152 2.0 2.2 0.21 Istokpoga 94 472236 3031667 0.7 0.7 0.00 Istokpoga 95 467543 3031085 2.0 2.3 0.35 Istokpoga 96 469148 3030985 2.0 3.7 1.70 Istokpoga 97 470712 3030905 2.1 2.6 0.59 Istokpoga 98 472075 3030845 1.5 1.6 0.08 Istokpoga 99 473419 3030845 1.4 1.5 0.03 Istokpoga 100 474602 3030824 1.5 1.6 0.05 Istokpoga 101 471835 3029882 2.1 2.2 0.10 Istokpoga 102 469316 3028875 1.5 1.8 0.30 Istokpoga 103 470459 3028913 2.1 2.5 0.38 Istokpoga 104 471554 3028959 2.1 2.2 0.12 Istokpoga 105 472974 3029028 2.1 2.1 0.01 Istokpoga 106 474193 3029104 1.1 1.1 0.02 Istokpoga 107 471313 3028017 1.9 1.9 0.04 Istokpoga 108 471454 3027074 2.4 2.7 0.30 Istokpoga 109 470090 3026513 1.5 1.6 0.07 Istokpoga 110 471514 3026272 2.4 3.4 1.05 Istokpoga 111 473118 3025972 1.2 1.3 0.06 Istokpoga 112 474450 3025598 2.0 2.1 0.19 Istokpoga 113 475785 3025410 1.6 1.6 0.07 Istokpoga 114 471566 3025789 1.3 1.7 0.42 Istokpoga 115 469767 3024829 2.5 3.1 0.53 Istokpoga 116 474155 3024151 1.0 1.0 0.00 Istokpoga 117 471066 3023704 2.0 2.7 0.71 Istokpoga 118 473126 3023312 2.1 2.3 0.20 Istokpoga 119 471333 3022763 2.2 2.7 0.46 Istokpoga 120 469308 3021881 2.5 2.7 0.24 Istokpoga 121 470319 3021619 2.0 2.1 0.10 Istokpoga 122 471113 3021821 2.0 2.1 0.10 Istokpoga 123 472075 3021780 2.4 3.1 0.70 Istokpoga 124 470932 3020717 2.1 3.1 0.98

124

Table E-4. Coordinates (x and y), water depth, sediment depth and thickness for Lake Kissimmee. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17.

LAKE POINT_ID x y WATER_DEPT SED_DEPTH THICKNESS Kissimmee 125 466885 3092614 1.6 1.8 0.20 Kissimmee 126 467751 3092117 2.5 2.7 0.22 Kissimmee 127 467337 3090009 2.2 2.4 0.21 Kissimmee 128 467955 3090834 2.6 2.9 0.30 Kissimmee 129 469123 3091164 2.7 3.7 0.98 Kissimmee 130 469148 3091961 2.7 3.6 0.92 Kissimmee 131 469761 3092623 2.7 2.9 0.21 Kissimmee 132 470493 3090191 2.0 2.0 0.04 Kissimmee 133 472885 3090012 3.1 3.2 0.10 Kissimmee 134 475676 3090011 2.9 2.9 0.00 Kissimmee 135 471859 3088226 2.3 2.3 0.06 Kissimmee 136 473171 3088393 3.8 5.0 1.27 Kissimmee 137 474532 3088570 3.2 3.9 0.67 Kissimmee 138 476611 3087923 3.3 3.3 0.00 Kissimmee 139 472285 3087011 3.1 3.1 0.00 Kissimmee 140 477283 3086160 4.1 4.4 0.30 Kissimmee 141 470218 3086059 4.2 6.5 2.25 Kissimmee 142 472077 3085831 4.1 7.6 3.56 Kissimmee 143 473257 3085659 3.8 5.4 1.59 Kissimmee 144 474686 3085478 4.2 5.7 1.45 Kissimmee 145 476235 3085236 5.4 6.2 0.77 Kissimmee 146 477552 3085059 3.8 4.6 0.78 Kissimmee 147 470790 3084821 3.4 3.7 0.26 Kissimmee 148 471695 3084287 4.1 6.0 1.92 Kissimmee 149 473123 3084582 3.8 5.8 1.98 Kissimmee 150 471457 3083011 4.0 4.4 0.35 Kissimmee 151 477810 3084249 4.4 5.1 0.75 Kissimmee 152 478152 3083335 4.4 4.7 0.31 Kissimmee 153 478476 3082382 3.9 3.9 0.00 Kissimmee 155 479143 3080496 3.2 3.3 0.09 Kissimmee 156 478755 3078961 2.7 2.8 0.09 Kissimmee 157 477731 3080796 3.0 3.1 0.03 Kissimmee 158 476838 3091203 3.5 4.3 0.80 Kissimmee 159 475989 3091795 3.6 5.6 2.05 Kissimmee 160 475078 3092491 2.7 4.8 2.15 Kissimmee 161 474382 3093312 1.8 4.3 2.58 Kissimmee 162 473495 3093945 2.3 3.1 0.80 Kissimmee 163 472382 3094668 2.4 2.8 0.39 Kissimmee 164 471467 3095158 3.1 5.0 1.94 Kissimmee 165 470599 3095775 2.8 6.0 3.18

125

Table E-5. Coordinates (x and y), water depth, sediment depth and thickness for Lake Tohopekaliga. Units Meters. All coordinates are Universal Transverse Mercator, North American Datum 1983, UTM Zone 17.

LAKE POINT_ID x y WATER_DEPT SED_DEPTH THICKNESS Tohopekaliga 166 460511 3128715 2.3 2.7 0.41 Tohopekaliga 167 460966 3129050 1.8 1.8 0.00 Tohopekaliga 168 462024 3128594 1.4 2.6 1.23 Tohopekaliga 169 460627 3127155 3.0 3.4 0.35 Tohopekaliga 170 461781 3126352 2.6 3.5 0.92 Tohopekaliga 171 459865 3125631 2.7 2.8 0.12 Tohopekaliga 172 461347 3125038 2.8 2.8 0.02 Tohopekaliga 173 459250 3124176 2.5 2.8 0.26 Tohopekaliga 174 461601 3124191 2.7 2.7 0.00 Tohopekaliga 175 459759 3123696 2.2 2.2 0.00 Tohopekaliga 176 460621 3123639 2.3 2.3 0.00 Tohopekaliga 177 461516 3123472 2.3 2.3 0.00 Tohopekaliga 178 462621 3124422 2.5 2.8 0.29 Tohopekaliga 179 463900 3124294 2.6 3.0 0.40 Tohopekaliga 180 464463 3123579 2.9 3.1 0.15 Tohopekaliga 181 465244 3123220 2.3 2.3 0.00 Tohopekaliga 182 461431 3122710 2.2 2.2 0.00 Tohopekaliga 183 460366 3122075 3.5 3.6 0.16 Tohopekaliga 184 461377 3121896 3.4 3.4 0.00 Tohopekaliga 185 462417 3121800 2.4 2.4 0.00 Tohopekaliga 186 461304 3121016 2.5 2.5 0.00 Tohopekaliga 187 459992 3120127 3.3 3.5 0.21 Tohopekaliga 188 461220 3120127 2.8 2.8 0.00 Tohopekaliga 189 462363 3120127 2.6 2.6 0.00 Tohopekaliga 190 461220 3119154 3.5 4.2 0.74 Tohopekaliga 191 462278 3118519 2.9 2.9 0.00 Tohopekaliga 192 461389 3118265 3.2 3.2 0.00 Tohopekaliga 193 460500 3118053 3.2 3.2 0.00 Tohopekaliga 194 461897 3117460 2.9 2.9 0.00 Tohopekaliga 195 462490 3116867 3.0 3.0 0.00 Tohopekaliga 196 464183 3116825 2.7 2.7 0.05 Tohopekaliga 197 463297 3116263 3.0 3.0 0.00 Tohopekaliga 198 462827 3115015 2.5 2.6 0.05 Tohopekaliga 199 463844 3115682 3.4 3.5 0.13 Tohopekaliga 200 465856 3116942 2.3 2.3 0.01 Tohopekaliga 201 465538 3116275 2.8 3.0 0.17 Tohopekaliga 202 465241 3115682 3.0 4.3 1.29 Tohopekaliga 203 464733 3115089 3.0 4.8 1.75 Tohopekaliga 204 464268 3114497 2.9 4.0 1.01 Tohopekaliga 205 463675 3113819 2.6 2.8 0.14 Tohopekaliga 206 465834 3114624 2.8 4.3 1.49

APPENDIX F SEDIMENT TYPE AND COORDINATES

Table F-1. Coordinates (x and y) and sediment type for stations chosen to sample for Lake Tohopekaliga and Cypress Lake. n=10. All coordinates are Universal Transverse Mercator, North American Datum 1983, units meters, UTM zone 17.

x_coordy_coord Sediment Lake Station m m Type Tohopekaliga 1 460428 3128014 sand Tohopekaliga 2 460252 3125825 mud Tohopekaliga 3 463507 3124122 sand Tohopekaliga 4 465599 3122677 muddy sand Tohopekaliga 5 461210 3120234 muddy sand Tohopekaliga 6 462578 3115288 sand Tohopekaliga 7 467040 3116082 sand Tohopekaliga 8 465283 3113566 sand Tohopekaliga 9 464884 3116960 N/A Tohopekaliga 10 461809 3116800 sand Cypress 11 466763 3105596 muddy sand Cypress 12 467652 3106625 sand Cypress 13 468416 3108126 organic floc Cypress 14 469384 3107171 organic sand Cypress 15 468261 3105828 organic Cypress 16 469875 3106370 organic Cypress 17 469281 3105777 organic Cypress 18 469875 3104912 organic sand Cypress 19 468454 3104563 organic sand Cypress 20 467125 3104718 organic sand

126 127

Table F-2. Coordinates (x and y) and sediment type for stations chosen to sample for Lake Hatchineha and Kissimmee Lake. n=10. All coordinates are Universal Transverse Mercator, North American Datum 1983, units meters, UTM zone 17.

x_coord y_coord Sediment Lake Station m m Type Hatchineha 101 456093 3102454 organic Hatchineha 102 456867 3101718 muddy sand Hatchineha 103 458082 3100650 organic/sand Hatchineha 104 459555 3098090 sand Hatchineha 105 459997 3099084 sand Hatchineha 106 460421 3099802 muddy sand Hatchineha 107 461341 3098421 organic Hatchineha 108 462305 3098079 muddysand Hatchineha 109 464275 3100018 organic Hatchineha 110 463478 3098587 organic Kissimmee 1001 479734 3078286 organic sand Kissimmee 1002 478183 3081336 muddy sand Kissimmee 1003 477253 3084902 organic floc Kissimmee 1004 472394 3084179 organic floc Kissimmee 1005 474410 3086763 muddy sand Kissimmee 1006 476219 3088882 organic Kissimmee 1009 468156 3091828 organic Kissimmee 1010 471937 3094508 muddy sand Kissimmee 1011 474824 3092707 organic Kissimmee 1012 473188 3088426 organic

128

Table F-3. Coordinates (x and y) and sediment type for stations chosen to sample for Lake Istokpoga Lake. n=10. All coordinates are Universal Transverse Mercator, North American Datum 1983, units meters, UTM zone

x_coord y_coord Sediment Lake Station m m Type Istokpoga 10001 472488 3033861 muddy sand Istokpoga 10002 474604 3032492 organic sand Istokpoga 10003 466847 3030833 muddy sand Istokpoga 10004 469916 3030750 organic Istokpoga 10005 473484 3030211 muddy sand Istokpoga 10006 476553 3028469 organic Istokpoga 10007 472779 3026915 organic Istokpoga 10008 470858 3024780 organic/sand Istokpoga 10009 471368 3021417 organic floc Istokpoga 10010 474147 3024196 muddy sand

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BIOGRAPHICAL SKETCH

Chakesha S. Martin was born in Pine Bluff, AR, in 1979. After graduating high school in 1997, she moved to Fayetteville, AR, to attend the University of Arkansas. She graduated with a degree in environmental science in May 2001. While at the University of Arkansas, she interned at the United States Environmental Protection Agency in the

Clean Water Act Enforcement Section, working with the stormwater team. After graduation, she worked for Walmart Corporate Office in Bentonville, AR, for a few months. Shortly thereafter, she entered the master’s program in environmental science with the Wetlands Biogeochemistry Laboratory in January 2002 to work with research related to lake restoration. In the future, she hopes to work to shape the environmental policies of the United States.

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