黄渤海典型海域DGM变化及其影响因素

采集黄渤海海域海水，研究近海、远海、河口海域溶解气态Hg（DGM）变化及其差异。结果表明，近海表、底层海水DGM浓度较高（分别为160~230 pg/L，160~250 pg/L），中层最低（50~140 pg/L），近海沉积物再悬浮导致沉积物中产生的DGM释放到上层海水，所以底层高于中层。远海站点表层、中层海水DGM浓度高（分别为140~210 pg/L，130~200 pg/L），底层最低（60~180 pg/L）。表层海水DGM主要是光还原产生，而底层海水的DGM来自上层DGM的扩散或沉积物的释放。长江、黄河河口附近海域表层海水DGM浓度高，随着深度的增加，DGM浓度减小，底层沉积物产生的DGM较少，长江口附近的低氧区未发现DGM的高浓度值，说明低氧区不能导致DGM的大量产生。

Variation and its influencing factors of DGM in typical sea area of Bohai Sea and Yellow Sea

The seawater samples were collected in Yellow Sea and Bohai Sea. The DGM of surface, middle and bottom seawater was measured. Variation and differences of DGM in the coastal, open sea and estuarine areas was studied. The results showed that DGM concentration in the surface layer and bottom layer of the nearshore site was much higher (160~230 pg/L, 160~250 pg/L) than that in the middle layer (50~140 pg/L). The DGM concentration in the bottom seawater was higher in coastal sites with high turbidity because sediment resuspension was helpful to the release of DGM from the sediments to the upper seawater. At open sea, DGM in the surface layer and middle layer was higher (140~210 pg/L, 130~200 pg/L, respectively), than that in bottom (60~180 pg/L). DGM in clean surface water was mainly produced by light reduction, while the DGM of the bottom seawater came from the diffusion of the upper DGM or the release of DGM from the sediments. The DGM concentration was high in the surface sea water near the estuary of the Yangtze River and Yellow sea, the concentration of DGM decreased following the increase of depth. The lower DGM at the bottom of the estuary indicates that less DGM produced in the bottom sediments. The high concentration of DGM was not found in the hypoxic region of the Yangtze estuary, indicating that the hypoxia might not be benefit to DGM production.