益田市の匹見川流域の山崎遺跡の土壌の重金属の地球化学的分析による古代人の活動の復元

Recent archaeological excavations at the Yamasaki site, Hikimi River, in Shimane prefecture of SW Japan discovered Earliest to Late Jomon pottery fragments. Based on the ages of the unearthed artifacts, sediment samples were collected from three trenches to examine their geochemical composition in relation to source composition, and to interpret past human activity and heavy metal accumulation. X-ray fluorescence analyses of 68 samples showed different concentrations of elements due to source rock type, sediment grain size fractionation, and past human activity. However, all trenches had low abundances of Cr, Ni, V and Sc relative to UCC, indicating that the sediments at the Yamasaki site were derived from highly felsic source rocks. Contents of As, Pb, Zn, Cu, Fe2O3 and P2O5 were considerably greater than UCC, and are likely to be associated with past human habitation. The northern trench (NST-1) which contained the oldest past human settlement exhibited the lowest abundances of heavy metals. Highest abundances of heavy metals occur in the eastern and western trenches, which also contained the most artifacts. Peak concentrations of phosphate and zinc were detected in the Guro-1 black layer. The geochemical and archaeological evidence indicates that people were living and producing pottery at the Yamasaki site at about 3500-3000 BP. Past human life style, activities such as cooking, heating, and firing pottery, and human wastes were probably significant contributors to the distributions of elements in the soils.