Accumulation of cadmium by Nereis virens

Cadmium concentration in Nereis virens exposed to sediment spiked with cadmium increased linearly with time, no equilibrium concentration being indicated by 24 days of exposure. The concentration with N. virens also increased with concentration of Cd in the sediment, and smaller worms accumulated higher amounts per unit weight than larger worms. With exposure to sediment containing 1 to 4 ppm Cd, accumulation rates ranged from 0.018 to 0.037 microgram Cd/g dry wt/hr for 1- to 2-g worms and from 0.014 to 0.024 microgram Cd/g dry wt/hr for 5- to 7-g worms. N. virens exposed to 0.03 to 9.2 ppm Cd in sea water for 14 days had accumulation rates of 0.019 to 2.217 microgram Cd/g dry wt/hr for 1- to 2-g worms and 0.013 to 1.327 microgram Cd/g dry wt/hr for 5- to 7-g worms. There was practically no excretion of cadmium for N. virens with initial concentrations of 5 to 20 microgram Cd/g dry wt during 75 days in clean conditions. Sediment containing 1 and 4 ppm Cd produced concentrations of about 0.03- and 0.1-ppm cd in the overlying water. The accumulation rates from sediment with 1 and 4 ppm Cd are equal to the rates from sea water with 0.03 and 0.1 ppm Cd, respectively, indicating that cadmium uptake by N. virens is primarily from the aqueous phase.