抄録
The concentration of heavy metals and the grain size distribution of the sediments of Edogawa and Muratagawa Rivers were measured and the mechanism of accumulation of the sediments in these rivers was considered.
From an analysis of the grain size, two sub-population groups having normal distribution were recognized. The coarser fraction was consist of resistates and the finer fraction was considered to be consist of hydrolysates.
Since the concentrations of the heavy metals in the sediments were proportional to the fine particle fractions, the total concentration of a certain metal, M, was found to be given as
M=M2×P/100+M1×(1-P/100)=(M2-M1)×P/100+M1
where P: fine particle fraction
M1: metal concentration in the coarser fraction
M2 : metal concentration in the finer fraction
The ratios of metal concentrations in the two fractions, M2/M1, decreased in the following order;
Cu>Pb>Zn>As, Cr≥Ni, Co, Mn, Fe at Edogawa and Muratagawa (St. M and St. S). This order seems to represent certain properties of the heavy metals, and these properties were conclued to be related with the adsorption capacity and the affinity of the organic matters with the metals.
