Mercury methylation in constructed wetlands and distribution in sediments, Steamboat Creek (Nevada).

摘要

The construction of a wetland has been proposed at the confluence of the Truckee River and Steamboat Creek (SBC). The objective of this study was to assess the potential for net methyl mercury (MeHg) production in small-scale constructed wetlands; and to characterize total mercury (THg) and MeHg distribution in surface sediments in the SBC watershed. Net MeHg production was observed in spring, summer and fall in SBC water fed wetlands. Wetlands fed by water low in mercury were a source of MeHg all year round. The proposed large-scale wetland could increase the loading of MeHg from SBC by 20–75%. The wetland could also be a significant sink of THg.; THg concentrations in surface sediments showed no obvious pattern with distance downstream. At most sites along SBC, MeHg concentrations in streambank were higher than the concentrations in channel, suggesting that streambanks might be important sites of mercury methylation in this system.