Evaluating the ameliorative effect of natural dissolved organic matter (DOM) quality on copper toxicity to daphnia magna: Improving the BLM

Hassan A. Al-Reasi*, D. Scott Smith, Chris M. Wood

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Citations (Scopus)


Various quality predictors of seven different natural dissolved organic matter (DOM) and humic substances were evaluated for their influence on protection of Daphnia magna neonates against copper (Cu) toxicity. Protection was examined at 3 and 6 mg l-1 of dissolved organic carbon (DOC) of each DOM isolate added to moderately hard, dechlorinated water. Other water chemistry parameters (pH, concentrations of DOC, calcium, magnesium and sodium) were kept relatively constant. Predictors included absorbance ratios Abs 254/365 (index of molecular weight) and Abs-octanol 254/Abs-water254 (index of ipophilicity), specific absorption coefficient (SAC340; index of aromaticity), and fluorescence index (FI; index of source). In addition, the fluorescent components (humic-like, fulviclike, tryptophan-like, and tyrosine-like) of the isolates were quantified by parallel factor analysis (PARAFAC). Up to 4-fold source-dependent differences in protection were observed amongst the different DOMs. Significant correlations in toxicity amelioration were found with Abs 254/365, Abs-octanol254/Abs-water254, SAC340, and with the humiclike fluorescent component. The relationships with FI were not significant and there were no relationships with the tryptophan-like or tyrosine-like fluorescent components at 3 mg C l-1, whereas a negative correlation was seen with the fulvic-like component. In general, the results indicate that larger, optically dark, more lipophilic, more aromatic DOMs of terrigenous origin, with higher humic-like content, are more protective against Cu toxicity. A method for incorporating SAC340 as a DOM quality indicator into the Biotic Ligand Model is presented; this may increase the accuracy for predicting Cu toxicity in natural waters.

Original languageEnglish
Pages (from-to)524-537
Number of pages14
Issue number2
Publication statusPublished - Mar 2012
Externally publishedYes


  • Absorbance and fluorescence quality parameters
  • Biotic ligand model
  • Copper
  • Daphnia magna
  • Dissolved organic matter

ASJC Scopus subject areas

  • Toxicology
  • Management, Monitoring, Policy and Law
  • Health, Toxicology and Mutagenesis


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