Speciation of heavy metals in surface sediments from Suzhou Creek

Abstract

Nine elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in sediment samples at 7 sites (Site 1–7) from Suzhou Creek in Shanghai were analyzed with the Community Bareau of Reference (BCR) (sequential extraction (SE)) protocol and simultaneously extracted metals (SEM)/acid volatile sulfide (AVS) procedure to assess the metal bioavailability and toxicology in this area. The results showed that the BCR extraction can be utilized as an additional tool with the AVS method for assessing the potential bioavailability and toxicity of metals in sediments. Pollution from S5 (Site 5) was more severe than from other sites, especially Pb, Cu and Zn. Among all the sites, more than 80% of the total concentration of Fe existed in the residual fraction, As, Cr, Mn also dominated in the residual fraction (more than 50%). While Cd, Ni and Zn (more than 35%) were mainly in the non-stable phase. Cu had a strong affinity with oxidizable phase and Pb varied from site to site. The SEM/AVS ratio was less than one in these sediments and results implied that the majority of Zn and Ni (> 40%) were bound to AVS. In contrast, Pb, Cu and Cd were little bound to AVS due to their low ration of SEM-Pb, Cu, Cd to corresponding total concentration and relatively high porewater concentration.