Heavy Metals In Estuarine Sediments Of Jiaozhou Bay

A study of seven anoxic sediment cores (i.e., J1, J2, J3, J4, and B1, B2, B3) from the estuarine area of Licun River in Jiaozhou Bay has been undertaken. The contents of reactive metals,including Cd, Cu, Pb, Zn, Cr, As, Co, Ni, V, Mn, Ba, Sr,Fe, acid volatile sulfide (AVS) and the simultaneously extracted metals (SEM) in the sediments have been analyzed. It is found that the contents of reactive metals in the surface layer of sediment at J1 station are higher than those at other stations. With in a very small range, the total SEM values vary vertically in sediments, except at J1 station. The SEM/AVS ratios are lower than one at all depth at J1 station while the SEM/AVS ratios are greater than one (potentially toxic) in the surface sediments and lower than one in the deeper sediment layers at other stations. Using correlation analysis, the statistical relationships between reactive metals and AVS or reactive Fe are obtained. The results provide evidence for the role of AVS and reactive Fe in influencing reactive metal distribution in the estuarine sediments. Other factors, such as the amount of organic carbon in sediments, may also contribute to reactive heavy metal distributions. Sedimentary pyrite can be an important sink for trace metals. To better understand the pyritization of trace metals in estuarial sediments, four anoxic sediment cores from the estuarine area of Licun River in the Jiaozhou Bay have been analyzed. The degrees of trace metal pyritization (DTMP), including Ba, Cd, Cr, Cu, Fe, Mn, Pb, Sr and Zn, have been investigated and the degree of pyritization (DOP) and DTMP values have been calculated. The results show both Fe concentration and trace metal concentrations in the pyrite phase for all sites are significantly lower than their respective concentrations in the reactive fraction, except Ba. Reactive and pyrite Fe concentration profiles followed different trend with sediment burial depth at three sites. The degree of pyritization of Fe is between 11.3% and 36.2% in the Jiaozhou Bay estuarial sediments and different trace metals show quite different DTMP values.