Significant research has been dedicated to the study of copper toxicity in aquatic systems. A large body of evidence supports the claim that ionic copper is the primary form toxic to aquatic biota. However, predicting the bioavailability of copper in different water matrices has remained difficult. To establish copper water quality criteria, the US EPA adopted the Biotic Ligand Model (BLM), which utilizes several water quality parameters (pH, alkalinity, dissolved organic carbon -DOC, temperature, K+, Ca2+, Mg2+, Na+, SO42-, and Cl-) to determine the amount of bioavailable copper that would be toxic to aquatic species. Although the BLM has been shown to accurately predict copper binding by DOC of natural origins, it is unclear whether the model accurately accounts for copper binding by DOC emanating from municipal and industrial waste effluents. In these effluents DOC may consist of natural humic substances and other classes of organics added or produced during treatment. In this work, a Copper Ion Selective Electrode (CuISE) is being used to determine the copper binding characteristics of DOC from Pulp and Paper (P&P) wastewater effluents and the surface waters they discharge to. Samples collected upstream and downstream of the discharge locations are being analyzed and the results compared to evaluate any longitudinal changes in copper binding resulting from P&P effluent discharge. Using Visual MINTEQ, copper binding characteristics (ligand concentration and conditional stability constants) will be used along with water chemistry data to predict free ionic copper concentrations. These predictions will be compared to the BLM with the goal of understanding how wastewater impacted surface waters affect the BLM’s ability to predict bioavailable copper in these systems.

Quantifying copper speciation in pulp and paper wastewater effluent and implications for the biotic ligand model

255th National Meeting (2018)

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