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

Abstract

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 (epsilon350) 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.

The effectiveness of conventional trickling filter treatment plants at reducing concentrations of copper in wastewaters

“…Copper is one of the metals that are of particular concern in relation to water quality, because although an essential element, elevated concentrations in the aquatic environment may result in toxicological effects (de Oliveira-Filho et al, 2004;de Schamphelaere et al, 2004). Copper has been classified under the Water Framework Directive as a potential main pollutant (Annex VIII) for which an environmental quality standard (EQS), if required, should be established at the national level (European Commission, 2000).…”

The impact of tertiary wastewater treatment on copper and zinc complexation

“…Dissolved organic carbon (DOC) was quantified using a TOC-V CPN total organic carbon analyser (Shimadzu, UK). A number of studies [21][22] have demonstrated that Specific UltraViolet Absorbance (SUVA) characteristics may provide a relatively straight-forward method for assessing the content of aromatic substances (e.g. carboxylates) in organic matter that have traditionally been considered to represent the substance category that is most significant with regard to ion binding.…”

“…carboxylates) in organic matter that have traditionally been considered to represent the substance category that is most significant with regard to ion binding. Indeed, SUVA has been proposed as an alternative to DOC as a BLM input [22]. SUVA was determined for all samples at 350 nm in 1 cm quartz cell using a UV-VIS 200 spectrophotometer (Perkin Elmer, UK).…”

The effect of natural dissolved organic carbon on the acute toxicity of copper to larval freshwater mussels (glochidia)

“…Additions of DOC have also been shown to reduce Cu toxicity in a number of aquatic species. In cladocerans, Giesy et al [20] reported that the presence of organic matter reduced the accumulation of Cu in Simocephalus serrulatus, and De Schamphelaere and Janssen [21], as well as De Schamphelaere et al [22] demonstrated the protective effect of natural DOC additions on the copper toxicity in Daphnia magna. Similarly, in fish (rainbow trout [24]; fathead minnow [18]) acute Cu toxicity has been shown to decrease when the concentration of DOC in the exposure water was increased.…”