Effect of dissolved organic matter source on acute copper toxicity to Daphnia magna

• Published in: Environmental toxicology and chemistry Vol. 23; no. 5; pp. 1248 - 1255
• Main Authors: De Schamphelaere, Karel A. C., Vasconcelos, Flavio M., Tack, Filip M. G., Allen, Herbert E., Janssen, Colin R.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Periodicals, Inc 01.05.2004; SETAC
• Subjects: Animal, plant and microbial ecology; Animals; Applied ecology; Biological and medical sciences; Biological Availability; Biotic ligand model; Cladocera; Copper - toxicity; Daphnia - drug effects; Daphnia - metabolism; Daphnia magna; Dissolved organic carbon; Drug Interactions; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on protozoa and invertebrates; Freshwater; Fundamental and applied biological sciences. Psychology; Ions - chemistry; Ions - toxicity; Lethal Dose 50; Ligands; Metal bioavailability; Metals - chemistry; Metals - toxicity; Models, Biological; Organic Chemicals - chemistry; Organic Chemicals - pharmacology; Spectrophotometry, Ultraviolet; Toxicity Tests, Acute - methods; Ultraviolet absorption; North America; Europe; dissolved organic matter; Metal bioavailability Dissolved organic carhon Ultraviolet absorption Biotic ligand model; Ecotoxicology; Ligand; Toxicity; Acute; Cladocera; Bioavailability; Metal; Toxicity test; Heavy metal; Crustacea; Prevention; Radiation absorption; Ultraviolet radiation; Arthropoda; Models; Fulvic acid; Invertebrata; Copper; Branchiopoda; Daphnia magna; Speciation
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1897/03-184

The protective effect of dissolved organic matter (DOM) on metal toxicity to aquatic organisms has been reported by numerous authors. Bioavailability models such as the biotic ligand model (BLM) thus account for this factor to predict metal toxicity to aquatic organisms. Until now, however, few attempts have been made to assess the effect of the DOM source on metal speciation and toxicity and, accordingly, on BLM predictions. The aims of this study were to investigate to what extent DOMs differ in their ability to decrease acute copper toxicity to the cladoceran Daphnia magna and to evaluate if ultraviolet (UV) absorbance measurements may be a simple and effective method to incorporate DOM variability into the acute Cu‐BLM for D. magna. Acute toxicity tests were carried out in artificial test water enriched with DOMs isolated from six locations in Europe and North America and in seven natural European surface waters. The acute Cu‐BLM for D. magna was then used to estimate the copper complexing capacity of each DOM (expressed as % active fulvic acid, %AFA). A factor of 6 difference was observed between the lowest and the highest copper complexing capacity. A significant linear relationship was observed between the UV‐absorbance coefficient at 350 nm (ε350) and the %AFA. Linking this relationship to the acute Cu‐BLM resulted in a significant improvement of the predictive capacity of this BLM. Without accounting for this relationship, 90% of the predicted 48‐h 50% effective concentrations (EC50) were within a factor of 2 of the observed EC50s; taking this relationship into account, 90% of the EC50s were predicted with an error of less than factor 1.3. The present study and other studies seem to indicate that UV absorbance may be a good measure of biologically and toxicologically relevant differences in copper binding behavior of DOM.