Wet deposition flux and runoff output flux of mercury in a typical small agricultural watershed in Three Gorges Reservoir areas

In order to explore the contributions of wet deposition and runoff formed by rainfall events to the water body mercury burden in Three Gorges Reservoir (TGR), we conducted a 1-year successive study on the deposition fluxes and runoff output characteristics of total mercury (THg) and methylmercury (TMeHg) in a typical small agricultural watershed in TGR areas. The results showed that the annual volume-weighted concentration (VWC) of THg and TMeHg was 18 and 0.23 ng L-1, respectively. Particulate form was the main form of both THg and TMeHg, accounting for 61 % of THg and 59 % of TMeHg. The annual deposition fluxes of THg and TMeHg in rainfall were 13 +/- 2.4 mu g m(-2) year(-1) and 174 +/- 52 ng m(-2) year(-1), respectively. The VWCs of THg and TMeHg in runoff were 10 +/- 6.5 and 0.15 +/- 0.15 ng L-1. The annual output fluxes of THg and TMeHg to TGR from study area were 1.2 +/- 0.73 mu g m(-2) year(-1) and 17 +/- 16 ng m(-2) year(-1), respectively.