Historical deposition and fluxes of mercury in Narraguinnep Reservoir,southwestern Colorado,USA |
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| Institution: | 1. US Geological Survey, P.O. Box 25046, Federal Center, MS 973, Denver, CO 80225, USA;2. US Geological Survey, 600, 4th Street South, St. Petersburg, FL 33701, USA;3. Battelle Marine Sciences Laboratory, 1529 West Sequim Bay Road, Sequim, WA 98382, USA;1. State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, Kunming, Yunnan 650093, China;2. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650093, China;3. National Local Joint Laboratory of Engineering Application of Microwave Energy and Equipment Technology, Kunming, Yunnan 650093, China;4. School of Chemistry and Environment, Yunnan Minzu University, Kunming, Yunnan 650093, China;1. Ocean Engineering and Technology Research Center, Iranian National Institute for Oceanography and Atmospheric Science, Tehran, Iran;2. Griffith School of Engineering, Gold Coast Campus, Griffith University, QLD, 4222, Australia;1. Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, School of Marine Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China;2. MOE Key Laboratory of Aquatic Product Safety, Instrumental Analysis & Research Center/School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China;3. State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center of Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, PR China;4. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, PR China |
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| Abstract: | Narraguinnep Reservoir has been identified as containing fish with elevated Hg concentrations and has been posted with an advisory recommending against consumption of fish. There are presently no point sources of significant Hg contamination to this reservoir or its supply waters. To evaluate potential historical Hg sources and deposition of Hg to Narraguinnep Reservoir, the authors measured Hg concentrations in sediment cores collected from this reservoir. The cores were dated by the 137Cs method and these dates were further refined by relating water supply basin hydrological records with core sedimentology. Rates of historical Hg flux were calculated (ng/cm2/a) based on the Hg concentrations in the cores, sediment bulk densities, and sedimentation rates. The flux of Hg found in Narraguinnep Reservoir increased by approximately a factor of 2 after about 1970. The 3 most likely sources of Hg to Narraguinnep Reservoir are surrounding bedrocks, upstream inactive Au–Ag mines, and several coal-fired electric power plants in the Four Corners region. Patterns of Hg flux do not support dominant Hg derivation from surrounding bedrocks or upstream mining sources. There are 14 coal-fired power plants within 320 km of Narraguinnep Reservoir that produce over 80 × 106 MWH of power and about 1640 kg-Hg/a are released through stack emissions, contributing significant Hg to the surrounding environment. Two of the largest power plants, located within 80 km of the reservoir, emit about 950 kg-Hg/a. Spatial and temporal patterns of Hg fluxes for sediment cores collected from Narraguinnep Reservoir suggest that the most likely source of Hg to this reservoir is from atmospheric emissions from the coal-fired electric power plants, the largest of which began operation in this region in the late-1960s and early 1970s. |
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