.[1] Total gaseous mercury (TGM) concentrations in ambient air were monitored at an urban site in Guiyang from 23 November 2001 to 30 November 2002 using a high temporal resolution 5 min mercury vapor analyzer (Tekran 2537A). TGM concentrations follow lognormal frequency distribution pattern, and the mean TGM concentration at the measurement site is 8.40 ng m À3 on the basis of 1 year observation. TGM concentrations in Guiyang are significantly elevated compared to the continental global background values. Coal combustion from both industrial and domestic uses is estimated to be the primary atmospheric source. A seasonal distribution pattern of TGM with a descending order of winter, spring, fall, and summer was observed. The highest TGM concentration in winter is attributed to household heating using coal. A consistent diurnal distribution pattern of TGM was obtained among all seasons, and the nighttime TGM concentration is elevated compared to the daytime values. Meteorological conditions are responsible for the formation of diurnal TGM distribution pattern. Tremendous efforts are needed to reduce mercury emissions from coal combustion to decrease TGM concentrations in Guiyang.

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.

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