tailieunhanh - Mercury Hazards to Living Organisms - Chapter 5

PART 2 Mercury Concentrations in Field Collections of Abiotic Materials, Plants, and Animals © 2006 by Taylor & Francis Group, LLC CHAPTER 5 Mercury Concentrations in Abiotic Materials Mercury burdens in sediments and other nonbiological materials are estimated to have increased up to five times prehuman levels, primarily as a result of anthropogenic activities (USNAS, 1978). Maximum increases are reported in freshwater and estuarine sediments and in freshwater lakes and rivers, but estimated increases in oceanic waters and terrestrial soils have been negligible (USNAS, 1978). Methylmercury accounts for a comparatively small fraction of the total mercury found in sediments, surface waters, and sediment. | Part 2 Mercury Concentrations in Field Collections of Abiotic Materials Plants and Animals 2006 by Taylor Francis Group LLC Chapter 5 Mercury Concentrations in Abiotic Materials Mercury burdens in sediments and other nonbiological materials are estimated to have increased up to five times prehuman levels primarily as a result of anthropogenic activities USNAS 1978 . Maximum increases are reported in freshwater and estuarine sediments and in freshwater lakes and rivers but estimated increases in oceanic waters and terrestrial soils have been negligible USNAS 1978 . Methylmercury accounts for a comparatively small fraction of the total mercury found in sediments surface waters and sediment interstitial waters of Poplar Creek Tennessee which was initially contaminated with mercury in the 1950s and 1960s. Mercury measurements in Poplar Creek from 1993 to 1994 showed that methylmercury accounted for of the total mercury in sediments in surface waters and in sediment interstitial waters Campbell etal. 1998 . The residence time of mercury in nonbiological materials is variable and depends on a number of physicochemical conditions. Estimated half-time residence values for mercury are 11 days in the atmosphere 1000 years in terrestrial soils 2100 to 3200 years in ocean waters and more than 250 million years in oceanic sediments USNAS 1978 Boudou and Ribeyre 1983 Clarkson et al. 1984 however this estimate was only 1 month to 5 years for water from the contaminated Saguenay River in Quebec Smith and Loring 1981 . This chapter documents mercury concentrations in air coal pelagic clays sediments sewage sludge snow soils suspended particulate matter seawater freshwater groundwater and sediment interstitial waters from selected geographic locales. AIR Most up to of the mercury contributed to the atmosphere each year is from anthropogenic sources such as combustion of fossil fuels from power plants with natural sources such as oceans land runoff and volcanoes

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