Fractions Characteristics Of Heavy Metals In The Sediments Of Taihu Lake And Assessment

This paper in connection with concentration characters of seven heavy metals (Cr, Ni, Cu, Zn, As, Cd and Pb) and BCR three stage sequential extraction procedure was applied to examine the speciation and concentration of six heavy metals(Cr, Ni, Cu, Zn, Cd and Pb) in sediments of Taihu lake, combining the method of experimental analysis and theoretical analysis, study concentration characters, distribution characters, Chemical speciation and the concentration of AVS and SEM of heavy metals in the sediments and study its pollution assessment as the method of choosing the evaluation method which is based on heavy metal total concentration (enrichment coefficients method), AVS and SEM Ratio method, and Using Equilibrium-Partitioning Approach. The results indicated that, heavy metals concentrations in the sediments were significantly higher than the background values, a clear cumulative effect of these metals. Geostatistical analysis showed that there was moderate spatial self-correlation between heavy metals in the sediments from the studied area, which indicates that the spatial distribution of the heavy metal concentrations was influenced by human activities factors. The vertical distribution of total metal contents and their fractions decreased with depth and it is stable at the depth of 20cm. The fractions of heavy metals varied greatly in the surface sediment of Taihu lake Correlation analysis showed that Cr Ni Cu and Cd this 4 heavy metal elements have the extremely remarkable correlational dependence, possible to have the similar pollution origin. Acid volatile sulfide (AVS) and simultaneously extractable metal (SEM) analytic results showed that the concentration distribution of AVS and SEM has large differences, and SEMZn> SEMNi> SEMPb> SEMCu> SEMcd. From the toxicity point of view heavy metals in the surface sediments have potentially toxic to benthic organisms. The partitioning coefficient(Kp) of six heavy metals in sediments of Taihu Lake were:2.66×103,5.74×103,6.67×103,4.50×103, 0.96×103,10.87×103.With equilibrium partitioning approach and water quality criteria sediment quality guidelines for metals in Taihu lake were derived, which is basically situated between TEL and PEL.