title: Performance of diffusion gradient in thin films to evaluate the toxic fraction of copper to Daphnia magna.
abstract: This study investigates the relevance of the diffusion gradient in thin films technique (DGT) to measure copper's induced lethality on Daphnia magna in natural water spiked with various organic ligands. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and glycine were used as artificial organic ligands in controlled solutions of mineral water. With EDTA, DGT measurement makes it possible to predict the toxicity of the mixture because Cu-EDTA complexes are inert, whereas DGT is of no help in the case of NTA, because Cu-NTA complexes are fully labile. The Cu-glycine complexes appear as partly labile and toxic. Humic acids as well as fresh and aged algae extracts also were used as models for natural dissolved organic matters. All three of them form copper complexes that are not toxic to Daphnia magna and appear as partly labile with open-pored DGT. However, the use of restricted gels in DGT greatly reduces the contribution of labile complexes, at least for humic acids and aged algae copper complexes. The DGT with restrictive gels, therefore, appears to be a powerful tool for measuring bioavailable copper in natural water bodies, especially when the dissolved organic matter mostly is of humic origin. The DGTs potential ability to mimic the lability induced by the biological uptake also is discussed.
authors.affiliation: Cemagref, UR Qualité et Fonctionnement Hydrologique des Systèmes Aquatiques, Parc de Tourvoie, BP 44, F-92163 Antony Cedex, France. marie-helene.tusseau@cemagref.fr
authors.forename: Marie-Hélène
authors.initials: MH
authors.lastname: Tusseau-Vuillemin
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Gilbin
authors.forename: Estelle
authors.initials: E
authors.lastname: Bakkaus
authors.forename: Jeanne
authors.initials: J
authors.lastname: Garric
mesh_terms: D000818:Animals; D001682:Biological Availability; D002614:Chelating Agents / Q000737:chemistry; D003300:Copper / Q000032:analysis / Q000737:chemistry / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects*; D004058:Diffusion; D004492:Edetic Acid / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D005544:Forecasting; D005618:Fresh Water / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D006812:Humic Substances; D007928:Lethal Dose 50; D008024:Ligands; D009571:Nitrilotriacetic Acid / Q000737:chemistry; D012996:Solutions / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D006812:Humic Substances; D008024:Ligands; D012996:Solutions; D003300:Copper; D004492:Edetic Acid; D009571:Nitrilotriacetic Acid; D005998:Glycine