ABSTRACT
Selenium (Se) is an essential trace element for biological systems and is a “double-edged sword” element for biological health. Excessive and deficient levels of Se in vivo may damage biological bodies (Fordyce et al. 2000). Atmospheric Se is firstly reported as a complex system and is an important part of the biogeochemical cycle of Se. The atmospheric Se speciation is classified into particulate Se and volatile Se containing volatile inorganic and organic Se that are emitted into the atmosphere at a rate of about 13,000–19,000 tons per year (Mosher & Duce 1987). The particulate Se originated mostly from natural sources, such as sea salts, wind-blown dusts, volcanic ashes, and from anthropogenic activities that may include aerosol particles (De Santiago et al. 2014). The sources of volatile inorganic Se are volcanic and anthropogenic activities (Floor & Román-Ross 2012). The volatile inorganic Se is unstable in the atmosphere and easily transforms into the particulate Se, consisting of element Se (S0), hydrogen selenide (H2Se), and Se dioxide (SeO2).
