Effects of environmental factors on radiocadmium uptake by four species of marine bivalves

Temp, salinity, bottom-sediment type, and zinc concn all influenced Cd uptake by 4 marine bivalves (Mya arenaria, Mytilus edulis, Mulinia lateralis and Nucula proxima) in short-term static assay systems using Super(109)Cd as a tracer. The experimental system consisted of aquaria containing 20l of seawater maintained under controlled light and temp conditions. The water contained either 5 or 20 {mu}g /l Cd and tracer. Distribution and kinetics of the metal were monitored in the water column and organisms. The results demonstrate that Cd uptake rates differed widely among the organisms tested. An increase in temp increased Cd uptake rate by all test organisms. A decrease in salinity increased Cd uptake by all organisms tested. The presence of bottom sediment depresses Cd accumulation in some benthic animals. Zinc in concns of 0.5 mg/l substantially decreased Cd uptake by M.edulis and M.lateralis. It is suggested that all important spp and environmental variables be considered when studying heavy-metal uptake by marine organisms or when establishing water-quality criteria.