Current Research Projects: Link to the talk by Sonja Hausmann Climate Impact on a Drinking Water Reservoir at the North American Lake Management Society meeting Nov 2010 The talk includes climate impact on total mercury flux trends (1964 - 2007)  in NW Arkansas Mercury contamination of lakes and rivers in Arkansas has been a major concern for over 15 years. In people, exposure to ionic mercury or methylmercury results in cognitive disorders. In Arkansas the ultimate sources of mercury found in aquatic environments include natural geologic mercury and mercury from atmospheric deposition. Sediment core mercury analyses enables us to establish the historical, natural background concentrations of mercury and to distinguish between the natural background concentration and mercury added by coal-fired power plants. Our data from a Beaver Reservoir sediment core in NW Arkansas have shown significantly elevated mercury concentration and deposition rates after the commissioning of four coal-fired power plants fueled with low quality (mercury rich) coal upwind of the reservoir around 1979. However, in South Arkansas, where elevated mercury levels are of concern, natural background conditions are unclear. The overall objective of our research is to partition natural background mercury concentrations from mercury introduced by atmospheric deposition in South Arkansas. We hypothesize that South Arkansas lakes are influenced through atmospheric deposition from coal-fired plants south and west of the state. We will test this hypothesis by analyzing mercury deposition rates through time archived in lake sediments in South Arkansas. Further Links Prestbo, E., and D. Gay, 2009. Wet deposition of mercury in the US and Canada, 1996-2005: Results and analysis of the NADP mercury deposition network (MDN), Atmospheric Environment, 43, 4223-4233. link Poster by Chalmers, Argue, Gay, Brigham, Schmitt and Lorenz Mercury trends in fish from Rivers and Lakes in the United States 1969 to 2005 Talk by Jeffrey Levengood, David Soucek, Christopher Taylor Mercury in Small Fishes in Illinois:Historical Perspectives andContemporary Issues
Reconstruction of the Aleutian Low
. Greyling Lake (source: Darrell Kaufman, Northern Arizona University)	For his master's thesis at the University of Arkansas, Raymond Keveren is working in a collaborative effort with Dr. Darrell Kaufman at Northern Arizona University to examine diatom flux in a proglacial lake (Greyling Lake) in the Chugach Range of Southern Alaska. His research aims to show corroborative changes in diatom assemblages during the Younger Dryas, Holocene Thermal Maximum, onset of the Neoglacial, and climate events of the past 2,000 years (First Millennium AD Advance, Medieval Warming Period, and Little Ice Age). This is part of a series of examinations of climate records from Southern Alaskan lakes in collaboration with Northern Arizona University, the Alaska Volcano Observatory, Togiak National Wildlife Refuge, and the National Science Foundation (http://jan.ucc.nau.edu/~dsk5/S_AK/). Raymond works on understanding paleoecological interactions between organisms and climate in the Arctic through the use of biological proxies (in this case, diatoms in lacustrine sediment cores) and relating them to geomorphological (glacial), and sedimentological proxies in the same region.  The purpose of comparison is to develop and further corroborate paleoclimate reconstructions.  Diatoms are very sensitive to changes in the environment; examining their prevalence in bodies of water through preserved assemblages found in lake sediment cores contributes to our understanding of the cyclicity of climate in the Holocene. This has serious implications for current concerns of climate change, the amplified effect seen in polar regions, and possible effects on various industries ranging from tourism, to agriculture, to wildlife habitat preservation

Paleoflood reconstruction in the Mississippi Alluvial Valley

For her PhD thesis Ruchi Bhattacharya is working on the influence of natural and anthropogenic factors on flood plain dynamics. Her current research interests lie in paleo-flood reconstruction from the Lower White River, Arkansas. She uses oxbow lake sediments as archives for flooding events. Training-set lakes were sampled along a flood frequency gradient out of 300 lakes in the National Wild life refuge (map).  Past flood events archived in the sediment cores get identified by comparison with modern diatom assemblages and geochemistry. The preliminary chronology indicates an undisturbed sedimentation rate of 0.5 cm per year. In the project we collaborate with Brad Hubeny from Salem State College and Erik Brown of the Large Lake Observatory.

Taste and Odor Problems in Water Reservoir

Byron Winston, PhD candidate at the University of Arkansas,  is currently working on determining the source and environmental conditions conducive to production of the taste and odor compound 2-Methyl-Isoborneol in the drinking water reservoir in NW Arkansas. Preliminary evidence suggests that both climate and nutrient limitation may be important. Years with high rainfall lead to high Si:TP, TN:TP ratios which suppress cyanobacterial growth and allow for year-round diatom domination in the reservoir. Years with low rain fall lead to nitrogen depletion and summer cyanobacterial domination followed by taste and odour outbreaks.

Pingualuit Crater Lake

Jessica Black, a postdoc at University of Arkansas working with Dr. Hausmann, is currently analyzing the diatom assemblages from the three ice free periods in the lake sediments recovered from Pingualuit, spanning the last ~200,000 years. Using diatoms, together with other proxy measurements, the past environmental change of the lake will be reconstructed. A new extinct diatom species has been discovered that dominated the oldest interglacial period recovered, and is in the process of being formally described in collaboration with Mark Edlund. This is a collaboration with Reinhard Pienitz and many others.

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Last Update March 2009
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