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Effect of cation competition on cadmium uptake from solution by the earthworm Eisenia Fetida
Author(s) -
Li LianZhen,
Zhou DongMei,
Wang Peng,
Jin ShengYang,
Peijnenburg Willie J.G.M.,
Reinecke Adriaan J.,
van Gestel Cornelis A.M.
Publication year - 2009
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/09-001.1
Subject(s) - eisenia fetida , earthworm , biotic ligand model , chemistry , cadmium , environmental chemistry , metal , bioaccumulation , genetic algorithm , aqueous solution , bioavailability , competition (biology) , ecotoxicology , ecology , biology , pharmacology , organic chemistry
Metal speciation alone is insufficient to predict metal accumulation in aquatic and terrestrial organisms, because competition between cations can play an important role. In the present study, the effects of competing cations (Ca 2 +,Mg 2 +,and H+) on Cd uptake by the earthworm Eisenia fetida were quantified through short‐term experiments over a large Cd concentration range in aqueous exposure solutions. Free Cd 2+ activity was a better predictor for Cd accumulation in the earthworms than was total Cd concentration in solution, thus supporting the free ion activity model. The presence of the other cations at environmentally pertinent concentrations inhibited Cd uptake to different degrees. A competitive equilibrium model based on the biotic ligand model was developed to quantify the effect of the cations. The model parameters are the conditional constants for binding of H+ (log K = 4.97), Ca 2 + (log K = 3.00), and Mg 2 + (log K = 2.64) to the biological uptake sites of E. fetida . Autovalidation of the model with experimental results showed that 48‐h Cd accumulation in the earthworm could be successfully predicted with activities of free Cd 2 + and the major cations (Ca 2 +,Mg 2 +,and H+) as input.