R7 AM Soil Ecotoxicology and Risk Assessment
Thursday, 17 November 2005: 8:00 AM - 11:40 AM in 327-329

(VAN-1117-664052) Terrestrial toxicity testing of metal contaminated soils from Sudbury, Ontario.

Van der Vliet, L¹, Princz, J¹, Gilbertson, M², Scroggins, R¹, ¹ Environment Canada, Ottawa, Ontario, Canada² C. Wren & Associates, Guelph, Ontario, Canada

ABSTRACT- An ecological risk assessment in Sudbury will examine and evaluate the possible risks associated with airborne metal particulate emissions resulting from past smelting operations. Terrestrial toxicity testing was undertaken to support decision-making in the ecological risk assessment in Sudbury. Soil was collected from two pre-selected sites within the Sudbury area. The site soil was collected from a reference site with a low background concentration of metals and from a site with a high concentration of metals; both soils were acidic. The survival, growth, and reproduction of the test species (Folsomia candida and Eisenia andrei, red clover, northern wheatgrass) were assessed in these soils, both with and without partial pH neutralization. The pH adjustment of the soils would aid in the determination of the influence of low soil pH on the toxicity of the soils. Folsomia candida were not sensitive to soil acidity or to metal contamination levels. Eisenia andrei were highly sensitive to soil pH, and the results demonstrated that even in the absence of metal contamination, earthworm reproduction was very low in the pH unadjusted reference soil. When soil pH was adjusted to reduce the effects of acidity, earthworm reproduction in the contaminated soil was significantly lower than the reference soil, showing sensitivity to elevated metal levels. Red clover and northern wheatgrass were sensitive to low pH and metal contamination levels, and root growth (root length, root dry weight) proved to be the most sensitive endpoint. Unlike earthworms, both plant species were able to emerge and grow in the low pH reference soil. However, both plants showed increased growth in soils that had been pH adjusted. Growth in reference soil was greater than in soil with elevated metals when comparing plants in the same pH treatment, demonstrating that both species of plants were sensitive to metal contamination. To focus future testing of other metal-contaminated sites, we recommend the continued use of a battery of test organisms to capture varying sensitivity as demonstrated by the test organisms.

Key words: mining activity, earthworm, plants, springtails