Distribution characteristic of AVS and SEM and toxicity to benthic organism of heavy metal in surface sediments of Lake Taihu

34 points of surface sediments in Taihu Lake were observed on the distribution of Acid Volatile Sulfide (AVS) and Simultaneously Extracted Metal (SEM), and the relativity was analyzed between contents of AVS, AEM and the physical and chemical indices of the surface sediments. Results show that there is a significant difference on the spatial distribution of AVS and SEM contents in the whole lake of Taihu. Among these, AVS concentrations were higher in Meiliang Bay, northern Zhushan Bay, estuary of Gonghu Bay, especially in Eastern Taihu Lake (with the content value of 33.80~43.76μmol/g), and SEM concentrations were higher in the Meiliang Bay, Zhushan Bay and Gonghu Bay. The analysis of relativity shows that AVS concentrations were higher in sediments with higher water content, higher organic matter, higher organic carbon and lower oxidation-reduction potential. Meanwhile, by using two indices of SEM/AVS and SEM-AVS to evaluate the quality of surface sediments (heavy metal of sediments will toxic when SEM/AVS>;9 or SEM-AVS>; 2), it indicates that heavy metals in sediments of 6, 12 and 32 points could generate remarkable toxicity on creatures, and heavy metals in sediments of 3, 5, 14, 15, 20 and 21 points could generate a toxicity on creatures, but not significant. In general, our results could give supports and data base for current evaluation on sediment quality and ecolgical security for Taihu Lake.