Thesis
Patterns of mercury in aquatic biota in Twin Lakes, Washington
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/101462
Abstract
Recent health concerns regarding mercury contamination have spurred investigations into strategies to abate the bioaccumulation of toxic methylmercury (meHg) in fish that may be consumed by humans and wildlife. Hypolimnetic lake oxygenation systems have been shown to improve overall water quality, ameliorate hypoxia, and enhance fish habitat, as well as potentially decrease the concentration of meHg present throughout the water column. However, recent research at Twin Lakes, Washington has indicated that zooplankton in the oxygenated environment of North Twin have higher levels of meHg than those inhabiting South Twin, the non-oxygenated reference lake. The objectives of this study were: (1) to test if concentrations of total mercury in zooplankton and fish collected in both lakes in 2011 would reflect the same trends as previously documented in zooplankton in 2009 and 2010, and (2) to determine if trends in mercury levels in biota correlate with observed patterns of pH and DOC in the lakes, two key parameters that affect mercury uptake into biota. Water quality profiles and zooplankton samples were collected twice-monthly from both North and South Twin during the 2011 field season. Also, in cooperation with the Colville Tribes Fish and Wildlife Department, fish were captured each month in both lakes for total mercury analysis. Substantial increases in the magnitude of mercury were evident in zooplankton and rainbow trout analyzed from North Twin, compared to South Twin in 2011. This pattern of bioaccumulation may result from increased meHg bioavailability, enhanced by the lower pH, decreased quantity of DOC, and increased DOC aromaticity observed within North Twin. Lower pH can be attributed to increased rates of respiration and carbon dioxide production in the bottom waters of oxygenated North Twin. Oxygenation may also decrease internal loading of DOC, while stimulating the consumption of less recalcitrant, non-aromatic compounds by heterotrophic bacteria. Thus, while oxygenation may reduce the quantity of mercury being methylated, it may inadvertently influence other parameters which increase the bioavailability of meHg present.
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Details
- Title
- Patterns of mercury in aquatic biota in Twin Lakes, Washington
- Creators
- Piper Elizabeth Marshall
- Contributors
- Marc W. Beutel (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525051001842
- Language
- English
- Resource Type
- Thesis