Saturation models of arsenic, cobalt, chromium and manganese bioaccumulation by Hyalella azteca

Bioaccumulation of As, Co, Cr and Mn by the benthic amphipod Hyalella azteca in Burlington City tap (Lake Ontario) water was measured in 4-week tests. Bioaccumulation increased with exposure concentration and demonstrated an excellent fit to a saturation model (r2: 0.819, 0.838, 0.895 and 0.964 for As, Co, Cr and Mn, respectively). The proportion of total body Mn eliminated during a 24-h depuration period decreased as Mn body concentration increased, apparently due to a saturation of the elimination rate. The high maximum body concentration of 116,000 nmol g−1 appears to result from the saturation of the Mn excretion which is slightly greater than the maximum Mn uptake rate. Elimination rates for As, Co and Cr were not dependent on body concentration. The four elements were not physiologically regulated in Hyalella. Their body concentrations should be good indicators of bioavailability and useful for environmental assessment.