Trace metals in surface sediments of the Taiwan Strait: geochemical characteristics and environmental indication
The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd > Pb > Ni > Zn > Cu > Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd > Pb > Ni > Cu > Zn > Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.
KeywordsSequential extraction Chemical fractionation Environmental assessment Marginal sea Marine pollution
This study was co-supported by the Ministry of Science and Technology of Taiwan (MOST 103-2611-M-110-010, NSC 101-2611-M-110-010-MY3), the Taiwan’s Aim for the Top University Program (04C030204), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA11020102), and the National Natural Science Foundation of China (41376083). The assistance of Ms. Hui Gao in the sample preparation is greatly appreciated. Our thanks also go to three anonymous reviewers who provided constructive comments which helped improve the manuscript.
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