Abstract
Heavy metals in the bottom mud at the mouth of 91 rivers in Japan were analyzed and the data were published in a paper. In order to compare with these data, the distribution of heavy metals in the bottom mud up the river was studied in the present work. Samples of the mud were collected from the upper stream near the mountain, not polluted with waste water. It was concluded from these data that the concentration of the heavy metals among 193 mud samples up the river dispersed in a narrow limited range, compared with that of the river-mouth, i. e., the range of Ni and Cr concentration was 1-25ppm, that of Cu and Pb, 4-50ppm, Zn 10-200ppm, Cd 0.08-2.00 ppm, and Hg 0.0-1.0 ppm. The value of the mean of heavy metal concentration up the river decreased to 1/2 or 1/3 of those at the mouth of the river.
