Background levels of trace and ultra-trace elements in soils of Japan

Five hundred and fourteen soil samples collected from 78 sites in Japan wer e analyzed for their contents of trace and ultra-trace elements. We estimat ed the background levels (natural abundance) of 57 elements in soils. The c oncentration ranges were so wide that the ratios of the highest values to t he lowest values were more than 100 for all the elements, with the exceptio n of Be, Ga, Mo, Ag, In, Sn, and Ba. While the concentrations of the first transition elements (Sc-21 to Zn-30 in atomic numbers) were higher than the concentration of the other elements, those of lighter (Li-3 and Be-4) and heavier elements tended to decrease, with an increase or decrease of atomic numbers, with the apparent exception of Pb, Th, and U. Concentrations of e lements with even atomic numbers, were, in most of the cases, higher than t he concentrations of both adjacent elements with odd atomic numbers. Freque ncy distribution of most of the elements was strongly positively skewed. Ma rkedly positive correlation coefficients (r > 0.9) were observed among the elements within the same group in the Periodic Table in many combinations. The dendrogram obtained by cluster analysis showed that the occurrence and distribution of the elements in soils were mostly controlled by the chemica l properties of each element, rather than by the nature and properties of i ndividual soil samples. The total contents of the elements in soils were st rongly dependent on the chemical composition of the parent rocks from which respective soils were derived.