Studies of the occurrence of

Selenium (Se) is an essential element for human and animal health and plant growth (Hamilton et al., 1990, Rayman, 2000 and Germ et al., 2007). However, over- and underexposure of safe dietary Se intake (17 ~ 1600 μg Se/day) can cause significant health problems, such as selenosis and chronic Keshan disease. (Yang and Xia, 1995 and Moreno-Reyes et al., 2003). Because of toxicity, Se has been widely studied since the 1960s in various environmental samples (Anderson et al., 1961, Mosher and Duce, 1983, Cutter and Church, 1986 and De Gregori et al., 2002). It is now known that the AMG-47A plays an important role in the global biogeochemical cycle of Se (Wen and Carignan, 2007). In particular, atmospheric deposition of Se is considered to be an important source of contamination, because elevated concentrations of Se have been observed in remote aquatic environments and other habitats far from anthropogenic sources (Cutter and Church, 1986, Bennett, 1995, Kagawa et al., 2003 and Beavington et al., 2004). As a result, significant attention has been paid to the emission, transport, and deposition of atmospheric Se (Ross, 1985, Atkinson et al., 1990, Dudzinska-Huczuk et al., 2000 and Wen and Carignan, 2007).