Localization of heavy metals in the viscera and the muscular tissues of Haliotis discus exposed to selected metal concentration gradients.

Abstract

Black abalones were exposed to cadmium, chromium, copper, lead and manganese concentra-tion gradients of 0 (not artificially added), 5, 10, 15, 20 and 25μg/l for 120 days, and subsequently the metal concentrations in the visceral and the muscular parts were determined at the interval according to the elapsed days. Extremely high distribution rates in the viscera of the control groups were obtained for cadmium with ca. 93-96%, which was followed by the somewhat low values, ca. 77-93, for lead, ca. 76-80 for manganese and ca. 50%'s for chromium and copper. The metals were divided into three groups by the differences in the values of distribution rates and induced Localization Indices (i-LI) of the two compartments. (1) Cadmium: the rates of this metal in the viscera of the exposure groups decreased, and consequently those of the muscular tissues increased; and the i-LI values for the viscera of the control were similar to those of the exposure groups, while the values for the muscular tissues weakened about two times in the exposure groups in negative direction. (2) Lead and Copper: the rates of the two metals in the viscera increased gradually in the exposure groups according to the concentration gradi-ents, so that those of the muscular tissues decreased; and the i-LI values increased slightly in the viscera, and steadily in the muscular tissues in the negative direction. (3) Chromium and Manga-nese: there were no differences in the values of distribution rates and i-LI of the two metals in the two compartments among the control and the exposure groups regardless of the concentration gradients.