GEOCHEMISTRY AND ENVIRONMENTAL QUALITY ASSESSMENT OF HONGFENG LAKE SEDIMENTS,GUIYANG CITY

Multi-purpose geochemical survey in the Hongfeng Lake of Guiyang City shows that its pH values are between 7.3 and 7.5 suggesting an intermediate and somewhat alkaline environment.Lacustrine sediments are characterized by entrophication,high concentration and enrichment of C,Corg,N,S F and P and hidden dangers of heavy metals such as As,Cd and Hg.The concentration of As is between(34.6～52)×10-6,40.8×10-6 on average,exceeding the Grade III of Environmental Quality Standard for Soils.According to year-round monitoring and monthly sampling,the pH values of lake water are between 7.5 and 8.0,also implying an intermediate and somewhat alkaline environment,and the total N exceeds Environmental Quality Standards for Surface Water.The authors consider that the water quality of the lake may be impacted by geochemistry of lake sediments,and hence put forward some proposals for eco-environmental protection of important water source sites in Guiyang City on the basis of a comprehensive study of sediments and water in the lake.