Computation of the index of pollution caused by heavy metals in river sediment

Abstract

To set up an index of the degree of pollution by a number of heavy metals in river sediment, we have proposed the quantity, t = Σ j = 1 n y 2 j n Our method is based on the simple idea that the upper 10% of the distribution of t for a standard group of rivers could be considered polluted. As the standard group we have used data on hydrochloric acid-soluble Cu, Zn, Pb and Cd in the upstream sediment of first-class rivers in Japan, and we have obtained a value of 2·57 as the critical point of pollution for the four heavy metals. Application of the critical point to estuary sediment showed a satisfactory result.