Metal and metalloid contaminant availability in Yundang Lagoon sediments, Xiamen Bay, China, after 20 years continuous rehabilitation.

This study is focused on the pollutant level of sediments after 20 years continuous rehabilitation in Yundang Lagoon, Xiamen Bay, one of the most developed harbors in China. The modified BCR fractionation scheme was employed in sediments for the partition of particulating metals and metalloids. Moreover, the potential environment risks of these pollutants were evaluated by using Håkanson indexes. The results showed that the sediments were slightly contaminated by Cu, Pb, Zn, Cr, Ni, Mn, Ag, As and Se. A major portion (30-46%) of Mn was strongly associated with the acid soluble fraction. Copper (Cu), Cr and Ni exhibit significant oxidisable fraction (from 22 to 32%), Pb, Cr, As, Zn, Se and Ag showed considerable concentration (>50%) in the residual phase. Environment risk evaluation showed that the pollution in Yundang Lagoon is moderate and the ranking of the contaminants followed the order: As>Ni>Pb>Cu>Cr>Zn. Importantly, though these results indicate that the concentrations of heavy metals in sediments here are also higher than the sediment quality guidelines and may pose a potential threat to these areas and so the efforts in remediation should be continued. (c) 2009 Elsevier B.V. All rights reserved.