| Description |
1 online resource (v, 90 pages) : color illustrations, color maps. |
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text txt rdacontent |
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computer c rdamedia |
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online resource cr rdacarrier |
| Series |
Circular / U.S. Geological Survey ; 1395 |
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U.S. Geological Survey circular ; 1395.
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| Summary |
"Mercury is a potent neurotoxin that accumulates in fish to levels of concern for human health and the health of fish-eating wildlife. Mercury contamination of fish is the primary reason for issuing fish consumption advisories, which exist in every State in the Nation. Much of the mercury originates from combustion of coal and can travel long distances in the atmosphere before being deposited. This can result in mercury-contaminated fish in areas with no obvious source of mercury pollution. Three key factors determine the level of mercury contamination in fish--the amount of inorganic mercury available to an ecosystem, the conversion of inorganic mercury to methylmercury, and the bioaccumulation of methylmercury through the food web. Inorganic mercury originates from both natural sources (such as volcanoes, geologic deposits of mercury, geothermal springs, and volatilization from the ocean) and anthropogenic sources (such as coal combustion, mining, and use of mercury in products and industrial processes). Humans have doubled the amount of inorganic mercury in the global atmosphere since pre-industrial times, with substantially greater increases occurring at locations closer to major urban areas. In aquatic ecosystems, some inorganic mercury is converted to methylmercury, the form that ultimately accumulates in fish. The rate of mercury methylation, thus the amount of methylmercury produced, varies greatly in time and space, and depends on numerous environmental factors, including temperature and the amounts of oxygen, organic matter, and sulfate that are present. Methylmercury enters aquatic food webs when it is taken up from water by algae and other microorganisms. Methylmercury concentrations increase with successively higher trophic levels in the food web--a process known as bioaccumulation. In general, fish at the top of the food web consume other fish and tend to accumulate the highest methylmercury concentrations. This report summarizes selected stream studies conducted by the U.S. Geological Survey (USGS) since the late 1990s, while also drawing on scientific literature and datasets from other sources. Previous national mercury assessments by other agencies have focused largely on lakes. Although numerous studies of mercury in streams have been conducted at local and regional scales, recent USGS studies provide the most comprehensive, multimedia assessment of streams across the United States, and yield insights about the importance of watershed characteristics relative to mercury inputs. Information from other environments (lakes, wetlands, soil, atmosphere, glacial ice) also is summarized to help understand how mercury varies in space and time."--Major Findings and Implications. |
| Bibliography |
Includes bibliographical references (pages 73-84). |
| Note |
Print version record. |
| Contents |
Major findings and implications -- Why is mercury in fish a concern? -- How does mercury cycle through aquatic ecosystems? -- Where are environmental mercury concentrations highest across the nation? -- How do environmental mercury levels vary over time? |
| Subject |
Mercury -- Environmental aspects -- United States.
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Methylmercury.
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Soils -- Mercury content -- United States.
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Water -- Pollution -- United States -- Measurement.
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Mercury -- Environmental aspects.
(OCoLC)fst01017089
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Methylmercury. (OCoLC)fst01018768
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Soils -- Mercury content.
(OCoLC)fst01124763
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Water -- Pollution -- Measurement.
(OCoLC)fst01171315
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United States. (OCoLC)fst01204155
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| Added Author |
Brigham, Mark E.
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Chasar, Lia C.
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Lutz, Michelle A.
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Krabbenhoft, David P. (David Perry)
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Geological Survey (U.S.), issuing body.
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| Note |
At head of title: Quality of our Nation's waters |
| Other Form: |
Print version: Wentz, Dennis A. Mercury in the Nation's streams. Reston, Virginia : U.S. Geological Survey, 2014 9781411337862 (OCoLC)894116818 |
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Print version: Wentz, Dennis A. Quality of our nation's water (DLC) 2014019008 (OCoLC)880689777 |
| ISBN |
9781411337862 |
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1411337867 |
| Gpo Item No. |
0620-A (online) |
| Sudoc No. |
I 19.4/2:1395 |
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