Xiamen Bay Sediments Element Geochemistry

Surface sediment samples collected from 22 stations in three regions of the Xiamen Bay, i.e., Jiulongjiang estuary, Xiamen Western Sea and Tongan Bay, were analyzed for both the major and trace elements(Al.. Fe.. Mn.. Ti.. Ca.. Mg.. Na.. Ba.. Co.. Cr.. Cu.. Li.. Ni.. P.. Sr.. V.. Zn) systemically, for the first time. The sedimentological and geochemical factors that controlled the contents, distribution patterns and the speciation of these elements were evaluated as well. The main results gained here were:Contents of most elements in the surface sediment samples from Xiamen Bay were similar with those of average coastal sediment of China and the soil of Fujian province, but were generally high in Zn and Mn, low in Ca and Sr, compared to those of changjiang estuary and huanghe estuary.Spatial distribution patterns of elements: the contents of Ca.. Sr.. Mg in Jiulongjiang estuary increased along the river towards the sea, while the distribution of Al.. Fe.. Cu.. Co showed an opposite trend. The majority of the elements in Xiamen Bay were unanimous in their distribution. The distributions of the elements in Tongan Bay exhibited two trends, Ba.. Co.. Cu.. Ni.. V had no obvious variety; while the contents of Ca.. Sr.. Mg increased from the inner part to the outer part (near the sea) of the bay.The sediment types in Xiamen bay could be divided into three groups by model R Cluster Analysis: Fe.. Al.. Cu.. Zn appeared to be enriched in mud deposits; alkaline earth elements Ca.. Mg.. Ba.. Sr wereIII7associated with the carbonate-rich sediments; P, however, did not match those two patterns but instead had a higher content in the sediments influenced by anthropogenic inputs heavily. Based on the regional distributions of elements and the hydraulic environments, the elements of sediments in Xiamen Bay could be divided into three distribution patterns and geochemical regions by model Q Cluster Analysis. The concentrations of elements near the Jiulongjiang estuary were characterized by high Fe~ Al.. Zn~. Cu; Dongzui harbor in Tongan bay had high content of P; high values of Ca.. Na.. Ni appeared in the Xunjiang of the Tongan Bay; the areas in the south of Xiamen Bay showed high values of Sr.. Ba.. Ti; the sediments of the Xiamen Western Sea had high Co.. Cr contents.A four-stage sequential extraction procedure for determination of the speciation of extractable element, proposed by the Commission of the European Communities Bureau of Reference (BCR), had been applied to the sediments in Xiamen Bay. The results obtained showed that the majority of the elements studied, such as Fe.. Ti.. Al.. Co.. Cr.. Cu.. Li.. Ni.. P.. Zn, in the sediment of Xiamen Bay, were predominate in the residual fraction. On the contrary, Ca.. Sr and Mn were similar, with the residual fraction being of lowest significance. They were extracted in the largest percentage in exchangeable and bound to carbonates fraction. The relative abundance in residual fraction for these element followed the order: Ti> Al> Ba> Fe > V> Li > Zn> Cu> Cr> Ni> Co > P> Sr> Mn> Na> Ca0The elements bound to different phases in Xiamen Bay behavedIvdifferently in the level of spatial distributions. The variations in element speciation along the Jiulongjiang estuary were considerably greater than those of Xiamen West Sea and Tongan Bay. Relative to the distribution of other element speciation, the elements, such as Mn~ P~. Ca~. Sr, showed more obvious variation.The sources, grain sizes and the currents were three major factors controlling the geochemical characteristics, such as the contents, speciation and spatial distribution patterns, of the surface sediments in Xiamen Bay.