Chemical Speciation and Toxicity of Nickel Species in Natural Waters from the Sudbury Area (Canada)

• Published in: Environmental science & technology 2002-04, Vol.36 (7), p.1477-1484
• Main Authors: Mandal, Rupasri, Hassan, Nouri M, Murimboh, John, Chakrabarti, Chuni L, Back, Margaret H, Rahayu, Ucu, Lean, David R. S
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Applied sciences; Biological and medical sciences; Biological and physicochemical phenomena; Canada, Sudbury; Carbon - chemistry; Cladocera; Daphnia; Daphnia magna; Earth sciences; Earth, ocean, space; Ecotoxicology, biological effects of pollution; Engineering and environment geology. Geothermics; Eukaryota; Exact sciences and technology; Fresh water environment; Fundamental and applied biological sciences. Psychology; Hydra; Hydra attenuata; Kinetics; Ligands; Metals; Natural water pollution; Nickel - chemistry; Nickel - toxicity; Ontario; Pollution; Pollution, environment geology; Pseudokirchneriella subcapitata; Solubility; Toxicity; Toxicity Tests; Trace elements; Water Pollutants - toxicity; Water pollution; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es015622e

Metal complexation properties of dissolved organic carbon (DOC) in freshwaters are recognized but poorly understood. Here, we investigated the release of free nickel from Ni−DOC complexes using nickel-polluted freshwaters from Sudbury (Canada). We used the Competing Ligand Exchange Method with Chelex-100 as the competing ligand to measure the rate of free Ni2+ ion released by the dissociation of Ni−DOC complexes. The kinetic studies showed that the fastest kinetically distinguishable component representing ∼30−95% of the total nickel had a dissociation rate coefficient similar to that reported for [Ni(H2O)6]2+. High concentrations of Ca2+ and Mg2+ caused a larger amount of the DOC-bound nickel to be released as free Ni2+ ion. Growth inhibition of the freshwater alga Pseudokirchneriella subcapitata was highly correlated with the Ni/DOC ratio, the free plus labile nickel concentration, and the dissociation rate coefficient. While the levels of metals were not sufficient to kill Daphnia magna, these test organisms were immobilized in the same samples that showed algal growth inhibition. Only one sample caused 22% death of Hydra attenuata. The algal toxicity tests were consistent with the kinetic speciation results and are consistent with the hypothesis that dissolved [Ni(H2O)6]2+ plus other labile nickel species are toxic forms of Ni present.