CU AND ZN CONCENTRATIONS OF NATURAL OYSTERS IN OSAKA BAY, JAPAN

Abstract

Cu and Zn concentrations found in oysters in Osaka Bay were 0.09 to 7.8 ‰ and 1.7 to
37 ‰. Particularly high Cu concentration was found in oysters at fishing ports as well as a yacht harbor and
leisure boat wharf. High Zn concentration oysters were also found at fishing ports, yacht harbor, wharf and
near food factories. Anti-fouling paint, found in large quantity at the small fishing port, contained Cu2O as a
biocide for biofouling and Zn concentrations of anti-fouling paint were also high. This anti-fouling paint was
suspected to be the main Cu and Zn contaminant for oysters. Among all oyster parts for natural and
cultivated oysters, Cu and Zn concentrations were highest in the oyster gills. Cu and Zn concentrations in the
mantle and hepatic gland were almost the same value while adductor muscle values were low. As Cu and Zn
concentrations in cultivated oysters were very low, less than 0.1 and 1.1 ‰, natural oysters are considered as
effective for getting Zn and Cu in Osaka Bay.