Total gaseous mercury emissions from soil in Guiyang, Guizhou, China

摘要

Guiyang is located in the Circum-Pacific Global Mercuriferous Belt, and mercury concentrations in soil in this area are enriched. In situ total gaseous mercury (TGM) exchange fluxes between air and soil surface were intensively measured at four sampling sites in Guiyang from 21 May to 16 June 2003. Overall, net emissions were obtained from all sampling sites. Soil mercury concentration and solar radiation are proved to be the two most important parameters to control mercury emissions from soil. Meanwhile, a rain event can enhance mercury emission rate significantly. A simple model based on the linear correlation between mercury flux and solar radiation was applied to scale up mercury emissions from soil zones with different mercury concentration ranges. It is observed that mercury emission fluxes from soil in Guiyang are one order of magnitude higher than the value used in early models to represent emissions from global mercuriferous belts which is 1.1 ng m?2 h?1. The annual mercury emission from soil in Guiyang is calculated to be 408 kg, which highlights that natural emissions from soil contribute significantly to the elevated TGM concentrations in the ambient air in Guiyang.