Abstract
In order to evaluate the background abundance and anthropogenic contamination of chemical constituents, a total of 810 samples such as soils and stream sediments from the Kanto district, and marine sediments from the Tokyo Bay were analyzed for major and minor constituents. The background abundance of constituents are controlled mainly by the mode of occurrence, distribution of grain size, concentration and diffusion during the process of weathering and diagenesis, and biogenic enrichment. The effect of recent anthropogenic contamination in the studied natural forest soils is estimated to be negligible. However, significant amounts of P2O5, Cd and U which derived mainly from the phosphatic feltilizer are detected in the cultivated and paddy field soils. High concentrations over background abundance are found for As, Cu, Hg, Pb, Sb, Sn and Zn in the soils from parks and residential lands indicating the contamination by the anthropogenic source constituents. The stream sediments obtained around the old mineral deposits such as Ashio, Takatori and Hitachi are much dominant in several constituents. The high concentrations of Cr and Ni in the sediments from the Kanto Mountain are caused by clastic materials derived from the basement ultramafic rocks. The sediments collected around the urban industrial areas are generally abundant significantly in some elements of anthropogenic source constituents such as Zn, Sn, Pb, As, P2O5, Hg, Cd, Bi, Cu and/or Sb. The upper layer sediments in the middle to northern region of the Tokyo Bay are mostly dominant in Pb, Zn, Sn, Cd, Bi, Sb and Cr by the recent environmental contamination, whereas the sediments in the southern region have lower background abundances. The average background abundances of Al2O3,TiO2 and most heavy metals are clearly higher in the soils than the Tokyo Bay sediments, with the stream sediments showing intermediate abundance. The different concentrations of chemical constituents among the studied soils, stream sediments and Tokyo Bay sediments may be formed mainly during the process of weathering and diagenesis of parent materials.
