Late Holocene Climate Variability As Preserved In

LATE HOLOCENE CLIMATE VARIABILITY AS PRESERVED IN HIGH-RESOLUTION ESTUARINE AND LACUSTRINE SEDIMENT ARCHIVES BY JEREMIAH BRADFORD HUBENY A DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN OCEANOGRAPHY UNIVERSITY OF RHODE ISLAND 2006 DOCTOR OF PHILOSOPHY DISSERTATION OF JEREMIAH BRADFORD HUBENY APPROVED: Dissertation Committee: Major Professor__________________________ ____________________________ ____________________________ ___________________________ DEAN OF THE GRADUATE SCHOOL UNIVERSITY OF RHODE ISLAND 2006 Abstract Current concern regarding human-induced environmental and climate changes is becoming higher-profile, especially as officials become more outspoken on the topic. An important piece of the debate regarding anthropogenic change is the determination of to what degree humans are changing systems beyond natural variability. Since comprehensive instrumental records only go back 100 or fewer years, there is a demand for high-quality proxy records of environmental and climate conditions that extend past the instrumental period. One such archival source is aquatic sediment that is preserved at the bottom of a lake, estuary, or ocean. If the water column conditions are conducive to permanent stratification, then annually resolved sediment records can be preserved. This dissertation performs high- resolution proxy analyses from annually resolved sediment records in Rhode Island and central New York State to interpret the natural and anthropogenically induced changes that have occurred over the Late Holocene. The Pettaquamscutt River Estuary’s Lower Basin was studied and the post- glacial stratigraphy was interpreted. High-productivity lacustrine sedimentation started at ca. 15,500 cal BP and density-stratified estuarine conditions began about 1000 year ago. Over the last four centuries, the estuary has experienced anthropogenic influence through land clearance associated with European settlers, input of organic and non-organic pollutants, and nitrogen loading associated with domestic septic systems. Land clearance (ca. 1700 A.D.) resulted in increased sediment input and soil erosion from the watershed and increased primary productivity in the estuary. These effects lasted approximately two decades. The input of pollutants did not have a significant effect on the estuarine primary producers. Finally, the nitrogen loading (ca. 1960 A.D.) has led to cultural eutrophication in the estuary that is observed in ecologic proxies. High-resolution proxy data spanning the last millennium from the Pettaquamscutt River Estuary were used to interpret climate variability in the region. Mass accumulation rates of the photosynthetic fossil pigment bacteriochlorophyll e were linked to climate processes through water temperature limitation of bacterial production. Observed productivity/climatic cycles reveal linkages between the atmospheric-driven North Atlantic Oscillation phenomenon and the oceanic-driven Atlantic Multidecadal Oscillation at subdecadal and multidecadal periodicities. Clastic lamination thicknesses preserved in Pettaquamscutt River Estuary varved sediments record precipitation variability. This relationship was used to reconstruct precipitation variability in Rhode Island over the last millennium and to compare this record to teleconnection climate indices. A significant positive correlation was calculated between the lamination thicknesses and the Pacific/North American climate pattern at both interannual and decadal time-scales. The mechanism responsible for this linkage is driven by storm tracking associated with variability in the amplitude of the polar front jet stream. During periods of zonal atmospheric flow the region is dry due to the influence of dry continental air masses. As the amplitude of the jet stream increases, meridional atmospheric circulation becomes dominant thus increasing the influence of moist Gulf of Mexico and coastal air masses. iii Finally, a varve record was reconstructed from the sediments of Fayetteville Green Lake, New York in order to compare precipitation variability in Rhode Island and New York. The carbonate laminations were significantly correlated to precipitation conditions in the state. The positive correlation is likely caused by increased precipitation leading to increased groundwater flow. Since groundwater introduces calcium and carbonate ions to the lake, periods of higher precipitation will increase the concentrations of these ions, thus making it easier to precipitate calcium carbonate in the water column. The variability was significantly correlated to the Pacific/North American climate pattern at decadal time scales. This observation along with significant cross spectral analysis with Pettaquamscutt River data, suggests that precipitation variability between Rhode Island and New York are in phase with each other and are partially driven by the Pacific/North American pattern. iv Acknowledgements First and foremost I would like to thank John King for the opportunities that he has provided me with over the last six years. I have had the freedom to find my own directions for research after helpful initial guidance and have also had the opportunity to pursue my passion for teaching, despite the fact that it took me away from lab activities at times. The experiences that I have had in the field and with the various projects that have gone on in the lab have made me a far better scientist than simply doing my work could have offered. In addition, the lack of funding concerns during my tenure at GSO has truly been a blessing. My committee has been quite helpful over the last few years, offering help and advice when I was looking for it. Jon Boothroyd has taught me much about the Quaternary geology of southern New England, and gave me perhaps the most valuable opportunity for my career as an educator by hiring me to teach in the URI Geosciences Department during the Spring 2005 Semester. Jim Quinn has been very helpful for me in learning about chemical compounds, especially the organic ones. His prompt and thoughtful reviews have been very helpful. Scott Rutherford, although smoking me more than once on the ice, has been instrumental in my learning about spectral analysis techniques and appropriate applications for the methods. Kate Moran has pushed me to learn geophysical concepts and techniques to a level that will continue to make me a more complete geologist. As a multidisciplinary dissertation, the work presented here is in reality the result of contributions from many people. First, I would like to thank Chip Heil for all of the productive coring trips, both on and off the boat. Mark Cantwell and v Antelmo Santos have been extremely helpful in analyzing samples at EPA. Carol Gibson and Danielle Cares have been important players in getting much of this work completed in South Lab. Funding is acknowledged from the State of Rhode Island (beach survey), the National Science Foundation (GK-12; Great Lakes grant), and the NAC CESU program. Perhaps above all, thanks are due to KC who has dealt with me over the years and kept me on track. I appreciate all that you have done and continue to do! In addition, Leigh and the rest of the family have been very supportive through the whole process. Finally, thanks are in order for Doug Allen, Jim Cullen, Lindley Hanson, Jeanette Sablock, and Peter Sablock for giving me the ultimate reward for finishing the degree. vi Preface This dissertation consists of in-depth analyses of the sediment record from the Pettaquamscutt River Estuary, Rhode Island in regards to natural and anthropogenic environmental and climate change. In addition, a high-resolution paleoclimate record from Fayetteville Green Lake, New York is analyzed and compared to the Rhode Island data to examine potential regional correlation. The dissertation is written in manuscript format and consists of the following four manuscripts: Chapter 1, Late Quaternary stratigraphy and environmental history of the Pettaquamscutt River Lower Basin, evaluates the environmental conditions in the watershed since the inception of this water body after the glacial retreat. In addition, it uses a multi-proxy approach to evaluate the physical and ecological effects of anthropogenic changes in the watershed. Chapter 2, Subdecadal to multidecadal cycles of Late Holocene North Atlantic climate variability preserved by estuarine fossil pigments, uses a biennially resolved record of fossil photosynthetic pigments from the Pettaquamscutt River Estuary to reconstruct variability in climate cycles in the region and links these cycles to atmospheric and oceanic forcings. This manuscript is published in the July 2006 issue of Geology (volume 34, number 7, p. 569-572). Chapter 3, Late Holocene precipitation variability in southern New England and the relationship to Northern Hemisphere teleconnection patterns, reconstructs precipitation and drought variability from annually resolved sediment laminations preserved in the Pettaquamscutt River Estuary. The study reconstructs the vii Pacific/North American teleconnection pattern and highlights previously unresolved variability in this climate pattern. Chapter 4, Paleoclimate correlations between central New York State and Rhode Island over the last four centuries, reconstructs precipitation variability from central New York State using annually resolved sediment lamination thickness data from Fayetteville Green Lake, New York and compares the associated climate variability to the results discussed

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