tailieunhanh - Lake Trout Ecosystems in a Changing Environment - Chapter 9

Ô nhiễm thủy ngân của các hệ sinh thái hồ cá hồi Thủy ngân là một chất gây ô nhiễm phổ biến rộng rãi trong các loại cá nước ngọt và hiện đang gây ra mối quan tâm lớn bởi vì tác động tiềm năng của nó đối với sức khỏe của con người và động vật hoang dã. Hầu hết thủy ngân (Hg) trong thịt cá như methyl thủy ngân (MeHg) (Bloom, 1992). Đây là hình thức hữu cơ của thủy ngân là một chất độc thần kinh mạnh mẽ và với liều lượng lớn gây ra động cơ, cảm. | chapter nine Mercury contamination of lake trout ecosystems . Drew Bodaly Department of Fisheries and Oceans Freshwater Institute Karen A. Kidd Department of Fisheries and Oceans Freshwater Institute Contents Introduction Mercury concentrations in lake trout populations in small Boreal lakes Factors affecting mercury concentrations in lake trout Management of mercury exposure from consumption of lake trout Effects of mercury on fish Possible future trends Summary References Introduction Mercury is a widespread contaminant in freshwater fish and is currently causing great concern because of its potential impact on the health of humans and wildlife. Most mercury Hg in fish flesh is present as methyl mercury MeHg Bloom 1992 . This organic form of mercury is a powerful neurotoxin and in large doses causes motor sensory and developmental problems in humans and other vertebrate animals Clarkson 1992 . Because of the concerns over human health impacts Canadian provincial and federal agencies monitor Hg concentrations in fish from lakes with important fisheries and in commercial shipments. If total Hg both methyl mercury and inorganic Hg concentrations exceed the Canadian limit for commercial sale pg g-1 consumption advisories are issued and commercial sales are restricted. Though high concentrations of persistent pesticides have occasionally been the cause mercury is by far the most common reason for fish consumption advisories in North American freshwaters . Quebec Ministère de l Environnement et de la Faune 1995 United States Environmental Protection Agency 1998 Ontario Ministry of the Environment 2003 . For example in Ontario 95 of fish consumption 2004 by CRC Press LLC advisories in lakes were related to mercury and consumption advisories for this contaminant applied to 1206 of the 1595 lakes tested Ontario Ministry of the Environment 2003 . In the United States in 1997 mercury accounted for 78 of the fish consumption advisories in freshwaters United States