Toxicities of total and chelex-labile cadmium to salmon in solutions of natural water
By James A. Buckley, Gary A. Yoshida, Norman R. Wells, Romeo T. Aquino
Water Research, Volume 19, Issue 12, 1985, Pages 1549-1554, ISSN 0043-1354, DOI: 10.1016/0043-1354(85)90400-2.
The LC50 for total Cd averaged 4.8 and 8.0 [mu]g1-1 in river water and 33% sewage-treatment-plant effluent (STPE), respectively, and for Chelex-labile Cd, 3.9 and 5.6 [mu]g1-1, respectively. The LC50 values for total Cd were significantly (P < 0.05) different, indicating a reduction in toxicity of Cd in the presence of 33% STPE, presumably due to complexation of Cd2+. The similarity of LC50 values for Chelex-labile Cd indicates that that fraction contained toxic species of Cd at approximately the same concentration(s) in both river water and 33% STPE; it is therefore considered a better measure of Cd toxicity than total Cd. Furthermore, mortality was correlated with the concentration of Chelex-labile Cd but not with that of Chelex-nonlabile Cd. Measurements of Cd2+-complexing capacity by the Chelex method indicated that toxicity was due, at least in part, to Cd2+. Values were less than those obtained by the ion-selective-electrode method; these indicated that toxicity was due only to complexed Cd. Values from both methods were uncorrelated with LC50 values.
Keywords: cadmium; complexing capacity; Chelex 100 resin; sewage; river water; LC50; ion-selective electrode; salmon