An Evaluation of the Use of Soil and Sediment Bioassays in the Assessment of Three Contaminated Sites in Atlantic Canada

Abstract

Abstract Biological tests recommended by Environment Canada (1994) for the assessment of contaminated sites were evaluated at three sites in Atlantic Canada. Soil and sediment samples from contaminated sites in Makinsons, Newfoundland, Weldon, New Brunswick, and Five Island Lake, Nova Scotia, were characterized by chemical analysis and the recommended bioassays. Contaminants in excess of federal and/or provincial guidelines included poly-chlorinated biphenyls (PCBs), total petroleum hydrocarbons (TPH) and heavy metals in Makinsons soil, TPH in Weldon soil, and PCBs and heavy metals in Five Island Lake sediment. Four soil bioassays were conducted: earthworm (Eisenia andrei) survival, lettuce seedling (Lactuca sativa) emergence, algal (Selenastrum capricornutum) population growth inhibition and inhibition of light output in Microtox® (Vibrio fischeri). Sediment bioassessment involved the following tests: midge (Chironomus tentans) growth and survival, amphi-pod (Hyalella azteca) growth and survival, algal population growth inhibition and Microtox. The study demonstrated that the toxicity of samples from contaminated sites may not necessarily be consistent with the results of chemical analyses. However, correlations were identified between soil TPH concentrations and Microtox IC50, and sediment PCB concentrations and algal IC50. Soil bioassay sensitivity was ranked (in order of increasing sensitivity) as earthworm < lettuce = algae < Microtox. Sediment bioassay sensitivity was ranked as Microtox < amphipod < midge < algae. Bioassessment as a supplement to conventional chemical testing at contaminated sites in Canada is recommended.