[1] Total gaseous mercury (TGM) exchange fluxes between air and water surface were measured using a dynamic flux chamber (DFC) coupled with a gaseous mercury analyzer at two sampling sites of Hongfeng reservoir in cloudy and rainy weather conditions. The concentrations of dissolved gaseous mercury (DGM) in water were also measured and indicated that DGM was supersaturated at most time during the sampling periods, which implied that the water body acted primarily as a source of mercury to the atmosphere. In general, TGM fluxes displayed a consistent diurnal pattern with peak fluxes at noon and minimum levels at early morning or night. However, this diurnal pattern was not clear when the weather was heavily cloudy and rainy with the maximum solar radiation of less than 140 W m 2. At this specific weather condition, a significantly positive correlation between TGM flux and relative humidity was observed. The behaviors of TGM flux over Hongfeng reservoir observed at cloudy weather conditions were some what different from those observed during mostly sunny weather conditions in Northern America and Europe. The empirical model developed based on the correlation between TGM flux and solar radiation during sunny days in Northern America was not applicable for estimation of TGM flux at cloudy and rainy weather conditions.

[1]

Four measurement campaigns were carried out to monitor total gaseous mercury (TGM) at one site in Guiyang City, PR China in the following periods: April 19-30, 2000; February 26–March 14, 2001; June 26–July 20, 2001; and October 9-November 22, 2001, respectively. High temporal resolved data were obtained by using automated mercury analyzers Gardis 1A and Tekran 2537A. TGM data from all measurement periods followed the typical log normal distribution pattern. The geometric mean of TGM from different seasons were 8.56, 7.45, 5.20 and 8.33 ng m-3 in spring 2000, winter 2001, summer 2001 and autumn 2001, respectively. The overall average TGM covering the sampling periods was 7.39 ng m-3, which is significantly elevated comparing to global background of approximately 1.5-2.0 ng m-3. The major anthropogenic atmospheric mercury emission sources differed significantly among seasons, which caused the seasonal variability of TGM level.Distinct daily variability of TGM was observed among seasons.The daytime TGM concentrations were larger than that of nighttime in spring and winter seasons, while in summer and autumn the opposite daily TGM distribution pattern was observed.

[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 m3 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. INDEX TERMS: 0330 Atmospheric Composition and Structure: Geochemical cycles; 0345 Atmospheric Composition and Structure: Pollution—urban and regional (0305); 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0399 Atmospheric Composition and Structure: General or miscellaneous; 

Mercury