Water Quality Benchmarks, the Modifying Effect of Organic Matter on Uranium Toxicity and Why This Matters

Abstract

The 2011 Canadian uranium water quality guidelines (CWQGs) do not consider toxicity modifying factors. However, more recent data than considered in those CWQGs provide further evidence that dissolved organic carbon (DOC) reduces uranium bioavailability and toxicity. Determinations of site-specific uranium water quality benchmarks must consider the modifying effects of DOC as well as other factors including hardness and pH; when predictions of uranium toxicity based on water quality parameters are possible, the uranium CWQGs will need to be revised. The modifying effects of DOC (and other key physico-chemical variables) have implications for regulatory permitting, effluent management or treatment, and decommissioning.