Influence of Soil Properties and Aging on the Toxicity of Copper on Compost Worm and Barley
- Catherine M. Daousta,
- Christian Bastienb and
- Louise Deschênes *ac
- a CIRAIG: Interuniversity Reference Center for the Life Cycle Assessment, Interpretation and Management of Products, Processes and Services, 2500 ch. Polytechnique, Montreal, Quebec, H3C 3A7, Canada
b CEAEQ: Centre d'Expertise en Analyse Environnementale du Québec, Ministère de l'Environnement du Québec, 2700, Einstein, Sainte-Foy, Quebec, G1P 3W8, Canada
c NSERC Industrial Chair in Site Remediation, Chemical Engineering Department, École Polytechnique de Montréal, 2500 ch. Polytechnique, Montreal, Quebec, H3C 3A7, Canada
Influence of soil properties and aging on Cu partitioning and toxicity was assessed on 10 artificial soils constituted using a statistical design considering pH (5.5 and 7.5), organic matter (1–30% [w/w]), and clay content (5–35% [w/w]). Total Cu as well as water-, CaCl2–, and diethylene triamine pentaacetic acid (DTPA)–extracted Cu fractions were determined for each soil mixture. Ecotoxic effect was assessed by determining growth inhibition of barley (Hordeum vulgare L.) and compost worm (Eisenia fetida) mortality. Analyses were repeated after a 16-wk aging period of the soils at pH 7.5 (8 × 2-wk wetting and drying cycle). Results indicated that pH was the main factor controlling Cu partitioning, ahead of organic matter and clay content. Calcium chloride (0.5 M)–extracted Cu fractions showed the best correlation with toxic responses (r = 0.55–0.66; p < 0.05), while total and DTPA-extracted Cu concentrations could not explain differences in toxicity. Direct regressions between toxicity and soil properties (pH, organic matter, and clay content) provided better explanation of variance: r 2 = 0.50 (p = 0.00006) for compost worm mortality, r 2 = 0.77 (p < 0.00001) for barley shoot inhibition, and r 2 = 0.92 (p < 0.00001) for barley root inhibition. Copper toxicity was mainly influenced by pH and, to a lesser extent, by organic matter and clay content. Aging in organic soils revealed a slight reduction in ecotoxicity while an increase was observed in soils with low organic matter content. Further investigation using longer aging periods would be necessary to assess the significance of this observation.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2006.