Comparing acute toxicity testing and extensive targeted chemical screening for risk assessment of urban stormwater pond sediments.

32 urban stormwater pond sediment samples were analyzed for 259 organic substances, 13 trace elements, physico-chemical parameters and acute toxicity of eluates to the bioluminescent bacteria Aliivibrio fischeri according to the Microtox® method. Five of these samples showed some toxicity to Aliivibrio fischeri. Statistical analysis was conducted to identify substances with significantly different concentrations between toxic and non-toxic samples, as well as differences in contaminant patterns between these sets. Results showed no significant differences in trace element, organic contaminant concentrations or overall contaminant patterns between toxic and non-toxic samples. However, dissolved oxygen was significantly lower in toxic than in non-toxic samples, likely due to an influence on the lability of contaminants. This work highlights the difficulty of conducting a pertinent and robust environmental hazard assessment for complex matrices composed of a large number of substances present at low concentrations and discusses the advantages and limitations of both chemical and biological approaches to environmental hazard assessment for urban stormwater sediments. Because the evaluation of urban stormwater sediments is so complex, to comprehensively and accurately analyse its risks, it is very important to consider both biological and chemical factors. Considering both will provide an accurate identification of possible risks and enhanced control of environmental risks in urban areas.