The Geochemical Characteristics Of Heavy Metals For Water-Sediment System In Hulun Lake

Hulun Lake is the highest latitude lake, which is the Chinese northeastern important habitat of fishery production and rare and endangered birds. In recent years, the water level and the water area reduced year by year, and then the ecology deteriorated sharply. There are the most typical deposits of hydrothermal type lead-zinc-silver deposit and porphyry copper-molybdenum deposit In the basin, and this two deposits related to Mesozoic volcanic activity, which is more concentrated on both sides of the Kelulun river and Eerguna river. Relatively high background of heavy metal and its migration and transformation into Hulun Lake may affect the function of lake ecosystems.In this paper, To the Chinese high-latitude lakes-Hulun lake as the research object, carry out the content and distribution of heavy metals fraction, Acid Volatile Sulfide-Simultaneous extract metals(AVS-SEM) and environmental geochemical behavior in lake water and sediments to discuss the migration and transformation of heavy metals at the water-sediments interface, utilize different evaluation methods to evaluate the environmental quality and ecological risk assessment in study area, to predict and determined the possibly potentially risk of heavy metals in sediments of Hulun Lake and combined with the data of pore water, fraction and AVS-SEM to initially establish sediment quality criteria (SQC) of Hulun Lake. The main conclusions are as follows:1. Cu and Cd had the trend from the sediment upward into overlying water. Zn stayed dynamic equilibrium between the overlying water and pore water. Pb maybe migrate from the overlying water to sediment by pore water bridge.2. According to fraction research, the main bio-availability fraction of Cu is organic sulfides fraction, the Zn, Cd, Hg were the Fe-Mn oxides fraction, and the Pb were carbonate fraction and Fe-Mn oxides fraction. The horizontal distribution of bio-available fraction contents of Cu, Pb, Zn, Cd and As in surface sediments decreased from the north west to south east.3. According to the distribution of AVS-SEM, that the horizontal distribution of AVS in surface sediments decreased from southeast to northwest and showed the opposite trend with sulfate-reducing bacteria (SRB), organic matter and the horizontal distribution of SSEM and had the same distribution of Fe/Mn. AVS in sediment cores showed a gradual increase with increasing depth trend, same as the vertical distribution of ESEM.4. Based on this research data established the sediment quality criteria (SQC) of Hulun Lake, according to SQC lake sediments at each sampling point has not been polluted by Cu, Cd, Pb, and Zn, and the sediment in the security level. The results of speciation analysis, ∑SEM/AVS ratio and a variety of comprehensive assessment show that Cd and Pb in Hulun lake sediments have a certain potential ecological risks and they are priority control pollutants in heavy metal pollution of watery environment.Because of the different assessment method in the selected standard and the different theoretical basis and get a different evaluation results.