Spatial and temporal distributions of total and methyl mercury in precipitation in core urban areas, Chongqing, China Y. M. Wang1, D. Y. Wang1,2, B. Meng3, Y. L. Peng1, L. Zhao1, and J. S. Zhu1 1Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment (Ministry of Education), College of Resources and Environment, Southwest University, Chongqing 400715, China 2Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China 3State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China
Abstract. The spatial and temporal distribution patterns of mercury (Hg) in
precipitation were investigated in the core urban areas of Chongqing, China.
During the period from July 2010 to June 2011, total mercury (THg) and
methyl mercury (MeHg) concentrations in precipitation were analysed from
three sampling sites. Our results suggested that the volume-weight mean THg
and MeHg concentrations in precipitation were 30.67 ng l−1 and
0.31 ng l−1, respectively. The proportion of MeHg in THg ranged from 0.1% to
7.6% with a mean value of 1.3%. THg and MeHg concentrations showed
seasonal variations, while the highest THg value was measured in winter.
Contrarily, the highest MeHg concentration was observed in autumn.
Additionally, a geographically gradual decline of THg concentration in
precipitation was observed from the downtown to the suburb, then to the
controlled site in the city. 5 mm rainfall might be a threshold for the full
wash-out capability. Rainfall above 5 mm may have a diluting effect for the
concentrations of THg. Moreover, the current research implies that the coal
combustion and motor vehicles could be the dominant sources for Hg in the
Citation: Wang, Y. M., Wang, D. Y., Meng, B., Peng, Y. L., Zhao, L., and Zhu, J. S.: Spatial and temporal distributions of total and methyl mercury in precipitation in core urban areas, Chongqing, China, Atmos. Chem. Phys., 12, 9417-9426, doi:10.5194/acp-12-9417-2012, 2012.