Copper Accumulation in Presence of Zinc. Where copper concentrations were comparable, copper accumulation was lower in those shrimp exposed to copper-zinc mixtures than in those exposed to copper alone. Concen- tration factors were also lower. Copper Accumulation in Presence of Cadmium. For comparable concentrations, copper accumulation was lower in those shrimp exposed to copper-cadmium mixtures than in those exposed to copper alone, as were the concentration factors.