tailieunhanh - Mercury Hazards to Living Organisms - Chapter 11

Sử trường hợp: các nguy hại của thủy ngân từ khai thác mỏ vàng Việc sử dụng chất lỏng thủy ngân (Hgo) riêng biệt microgold (Auo) hạt từ trầm tích thông qua sự hình thành của hỗn hợp (Au-Hg) sau đó phục hồi và tái sử dụng thủy ngân là một kỹ thuật mà đã có hiệu lực ít nhất 4700 năm (Lacerda, 1997a). Tuy nhiên, quá trình này thường đi kèm với ô nhiễm thủy ngân lớn của sinh quyển (Petralia, 1996). Người ta ước tính rằng khai thác vàng hiện đang chiếm khoảng 10,0% lượng phát thải thuỷ ngân. | Chapter 11 Case Histories Mercury Hazards from Gold Mining The use of liquid mercury Hgo to separate microgold Auo particles from sediments through the formation of amalgam Au-Hg with subsequent recovery and reuse of mercury is a technique that has been in force for at least 4700 years Lacerda 1997a . However this process is usually accompanied by massive mercury contamination of the biosphere Petralia 1996 . It is estimated that gold mining currently accounts for about of the global mercury emissions from human activities Lacerda 1997a . This chapter documents the history of mercury in gold production and ecotoxicological aspects of the amalgamation process in various geographic regions with emphasis on Brazil and North America. Useful general reviews on mercury and mercury amalgamation of gold include those by Montague and Montague 1971 D Itri and D Itri 1977 . National Academy of Sciences 1978 Nriagu 1979 Porcella et al. 1995 Da Rosa and Lyon 1997 Nriagu and Wong 1997 De Lacerda and Salomons 1998 Eisler 2000 2003 2004a 2004b and Fields 2001 . HISTORY The use of mercury in the mining industry to amalgamate and concentrate precious metals dates from about 2700 BCE when the Phoenicians and Carthaginians used it in Spain. The technology became widespread by the Romans in 50 CE and is similar to that employed today Lacerda 1997a Rojas et al. 2001 . In 177 CE the Romans banned elemental mercury use for gold recovery in mainland Italy possibly in response to health problems caused by this activity De Lacerda and Salomons 1998 . Gold extraction using mercury was widespread until the end of the first millennium Meech etal. 1998 . In the Americas mercury was introduced in the 16th century to amalgamate Mexican gold and silver. In 1849 during the California gold rush mercury was widely used and mercury poisoning was allegedly common among miners Meech et al. 1998 . In the 30-year period between 1854 and 1884 gold mines in California s Sierra Nevada range .