Abstract
It was observed from the analysis of Cr and Ni in the bottom mud of Japanese rivers that mud normally contained 1-50 ppm of total Ni and 1-80 ppm of total Cr. Chromium content was plentiful in the lower stream mud.
The bottom mud of rivers flowing through Hokkaido, Shikoku, and the Pacific coast districts was high in total Ni and Cr compared with those of other districts. These districts geologically belong to the serpentine belt or Outer zone.
The correlation coefficient between total Ni and Cr was 0.91 for the mud of serpentine rock areas and 0.54 for the mud of urban rivers polluted artificially.
