Temporal and spatial distribution of different mercury species in precipitation of Wujiang River Basin
乌江流域大气降雨中不同形态汞的时空分布

Concentrations of mercury (Hg) species were measured in precipitation collected from five sites in the Wujiang River between January and December, 2006. The concentrations of total Hg (THg) ranged from 7.49 to 149.13 ng·L-1, dissolved Hg (DHg) from 1.23 to 10.02 ng·L-1, particulate Hg (PHg) from 5.76 to 141.92 ng·L-1, reactive Hg (RHg) from 0.56 to 2.94 ng·L-1, and methylmercury (MeHg) from 0.082 to 0.821 ng·L-1. The particulate fraction, which accounted for 67.6%~96.1% with an average of 87% of the total Hg, was dominant among the different Hg species. The ratios of RHg and MeHg were 5.1% and 0.68%, respectively. Concentrations of THg, DHg, PHg, and MeHg in samples collected in winter and spring were significantly higher than those found in summer and autumn, however, no significant spatial differences were obtained among Hg species in samples from five sites. Mercury levels in the precipitation were mainly affected by the amount of rainfall, coal combustion, and other human activities.