A Study On Environmental Geochemistry Of Trace Mercury In Poyang Lake

Environmental pollution is one of several essential problems faced from the global. There is numerous lakes in China, however the Poyang lake is the unique and famous for its largest area in our country. Although total mercury concentration in lake is in trace or even ultra-trace level, it is greatly harmful to human health through food chain by the enrichment of fish, etc.. Based on the investigation of geological and hydrologic feature in the Poyang Lake, three zones corresponding to Ruihong in Yugan county , Kangshan in Poyang county and Hukou in Hukou county were choosed in our research works. The aim of this study through the speciation analysis was to carry out the distributions and the behaviors of trace mercury in lake, which is not reported in literatures.A novel procedure on speciation analysis of trace and ultratrace mercury in natural water system using hydride generation atomic fluorescence spectrometry was established in the study, then the mercury speies in porewaters and sediments in the mentioned three fields of Poyang Lake were measured successfully after the novel procedure established.The species of mercury and its vertical distributions in porewaters and sediments in Poyang lake are studied in the first time. Based on those series data, regulative behaviors of removement and enrichment of mercury in porewaters and sediments were revealed. It is demonstrated that the vertical distributions of mercury in the sediments in the three regions studied have good corelation in the surfaces of water-sediment, and the specie of dissolved mercury was diffused from sediments to lakewater with a concentration gradient. The horizontal distribution feature of mercury concentration is that outflow of Poyang Lake > stream outlet > the lake center.The two usually evaluation methods, i.e. enrichment factor (EF) and geoaccumulation (Igeo) were used as an efficient environmental evaluation. The results clearly demonstrated that there is almost without mercury contamination in Kangshan region whereas the Hukou adjoined Changjiang River and the Ruihong adjoined stream outlet are affected by extrinsic mercury.