CADMIUM BIOCONCENTRATION IN THE ECHINOID PARACENTROTUS-LIVIDUS - INFLUENCE OF THE CADMIUM CONCENTRATION IN SEAWATER

Uptake and loss kinetics of cadmium were studied in Paracentrotus livi dus exposed for 24 d to different stable Cd concentrations (0 to 1.14 mu g Cd l(-1)) and Cd-109 tracer added to seawater. The whole-body upt ake kinetics were linear over the time course of the experiment. The w hole-body Cd-109 concentration factor was independent of the stable Cd concentration in ambient seawater. Bioconcentration of Cd in whole in dividuals and their body compartments was directly proportional to the Cd concentration added to the seawater. The echinoid digestive tract wall showed the highest degree of Cd uptake. Whole-body loss kinetics were described by a 2-component exponential equation. The loss kinetic s were similar for each of the treatments examined. Cadmium was found to display a long biological half-life in echinoid tissues; the major fraction (73 to 85%) of the Cd taken up by echinoids was eliminated fo llowing a loss component whose biological half-life was of the order o f 1 year, regardless of the absolute Cd concentration accumulated by t he echinoid. Paracentrotus lividus is suggested as a valuable biomonit or of Cd, particularly where knowledge of Cd concentration variations over long-term is of interest. Copyright (C) 1996 Elsevier Science Ltd .