SOIL POLLUTION BY HEAVY METALS IN SAKAI CITY

Abstract

Concentrations of Zn, Cu, Cd and Pb in surface soil samples collected from 76 sites (bare ground) in Sakai City near Osaka were determined. Their distribution maps indicated that the main sources of Zn, Cu and Cd existed in the coastal industrial area at the NW end of the city, from which the pollutants were distributed over the inland parts by prevailing westerly wind. The heaviest pollution of Pb was, on the other hand, found somewhat inland at the city center, suggesting that the heavy motor traffic was mainly responsible for the Pb pollution. The correlation among the concentrations of Zn, Cu and Cd was always strongly positive (r>0.8), whereas the positive correlation between Pb and one of the other elements was less close (r<0.67). This fact also suggested the difference of sources between Pb and the other metals. Mean levels of heavy metal pollution in soils of Sakai City and extremely high concentrations observed near metal-working factories showed that the soil pollution has already gone too far in Sakai and probably in other similar industrial cities of Japan.