Spatial and temporal variation of total mercury and methylmercury in lacustrine wetland in Korea

The spatial and temporal variations of total mercury (THg) and methylmercury (MeHg) concentrations (n = 120, respectively) in water and sediments of the Yangsuri lacustrine wetland in Korea were measured. The average concentrations of THg and MeHg in surface water were 2.04 +/- 1.97 and 0.05 +/- 0.05 ng L-1, respectively. The concentrations of THg and MeHg in sediments ranged from 1.28 to 85.83 and <= 0.01 to 0.35 ng g(-1), respectively, and varied depending on the location. In the vegetated zone located near residential areas, the highest concentrations of THg and MeHg in both surface water and sediments were obtained near the residential areas, especially during the fall season. This result might be due to increased methylation rate of Hg by water turnover in the fall season. While THg and MeHg concentrations in water were not correlated, they were significantly correlated in sediment (r = 0.75; P < 0.01). Log-transformed Hg concentrations in sediments were highly correlated with log-transformed organic matter (OM) and acid volatile sulfide (AVS) concentrations (P < 0.01). We also collected five species of fish near the output point of the wetland, and MeHg concentrations in fish tissue varied from 21.30 to 154.66 mu g kg(-1) w/w, which was significantly dependent on fish species (P < 0.05). This is the first reported study which measured the levels of mercury, especially MeHg in the wetlands, and freshwater fish species in Korea.