W6 PM Environmental Changes in Response to China's Economic Expansion
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 324-326

(FAN-1117-696089) Metal pollution and speciation in surface sediments from two Chinese bays.

fan, W.H¹, Wang, W.X², ¹ Beihang University, beijing, china² HKUST, HongKong, China

ABSTRACT- A total of 35 sediment samples were collected from two highly contaminated bays in China. The sediments were analyzed for the total concentrations of Cd, Cu, Pb, Ni, and Zn, and their associations with different geochemical phases using Tessier's extraction methods. The total metal concentrations in sediments were significantly correlated with the Fe-Mn oxide and organic matter contents. Metal speciation in contaminated sediments was significantly dependent on the metal concentrations in sediments, as well as on the sediment geochemical compositions (Fe-Mn oxide and organic matter). However, such influence was largely metal-specific. The percentages of Cu in the Fe-Mn oxide and residue phases decreased while in the organic matter increased with increasing sediment Cu concentration. The percentage of Ni in the Fe-Mn oxide phase decreased while in the residue increased with increasing total Ni concentration. Metal concentrations in the dominant geochemical phases increased with increasing total metal concentration, but the degree of such increase was different among the five metals. The most important geochemical phase was the organic matter for Cu, Fe-Mn oxide for Pb, residue for Ni, carbonate and Fe-Mn oxide for Zn. Such difference in metal speciation has major impact on the bioavailability of metals to benthic invertebrates.

Key words: Metals, Contamination, Sediment, Sediment-bound metals