tailieunhanh - Mercury Hazards to Living Organisms - Chapter 6

Thông tin về dư lượng thủy ngân trong lĩnh vực bộ sưu tập của các sinh vật sống đặc biệt là phong phú. Nồng độ thủy ngân cao xảy ra trong sinh vật thuỷ sản từ các khu vực nhận được depositions cao khí quyển của thủy ngân, hoặc khi nồng độ thủy ngân trong chế độ ăn hoặc nước cao (Sorensen et al, 1990; Wiener et al, 1990a; Fjeld và Rognerud, 1993). Hàm lượng thủy ngân tương đối cao trong các loài cá ăn cá, chim và động vật có vú (Langlois et al, 1995). Nói chung, nồng độ. | Chapter 6 Mercury Concentrations in Plants and Animals Information on mercury residues in field collections of living organisms is especially abundant. Elevated concentrations of mercury occur in aquatic biota from areas receiving high atmospheric depositions of mercury or when mercury concentrations in the diet or water are elevated Sorensen et al. 1990 Wiener et al. 1990a Fjeld and Rognerud 1993 . Mercury levels are comparatively elevated in fish-eating fishes birds and mammals Langlois et al. 1995 . In general mercury concentrations in biota were usually less than mg kg FW tissue in organisms collected from locations not directly affected by human use of the element. However concentrations exceed mg kg and are sometimes markedly higher in animals and vegetation from the vicinity of chloralkali plants agricultural users of mercury smelters mining operations pulp and paper mills factories producing mercury-containing paints fertilizers and insecticides sewer outfalls sludge disposal areas and other anthropogenic point sources of mercury Schmitt and Brumbaugh 1990 . In some Minnesota lakes mercury concentrations in fish are sufficiently elevated to be potentially hazardous when ingested by mink otters loons and raptors Swain and Helwig 1989 . An elevated concentration of mercury . mg kg FW usually as methylmercury in any biological sample is often associated with proximity to human use of mercury. The elimination of mercury point-source discharges has usually been successful in improving environmental quality however elevated levels of mercury in biota may persist in contaminated areas long after the source of pollution has been discontinued Rada et al. 1986 . For example mercury remains elevated in resident biota of Lahontan Reservoir Nevada which received about 7500 tons of mercury as a result of gold and silver mining operations during the period 1865 to 1895 Cooper 1983 . It is noteworthy that some groups of organisms with consistently elevated .