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

(DUS-1117-716268) Impact of Thermal Shock on the Enzyme Activity of a Copper-Contaminated Soil.

Dussault, M¹, Becaert, V.¹, Sauve, S², Deschenes, L¹, ¹ NSERC Industrial Chair in Site Remediation and Management, Chemical Engineering Department, École Polytechnique de Montréal, Montreal, Quebec, Canada² Environmental Chemistry Laboratory, Chemical Department, Université de Montréal, montreal, quebec, canada

ABSTRACT- The aim of this study is to establish the relationship between soil physicochemical parameters and copper speciation and ecotoxicity to the microbial flora by monitoring the soil functional recovery capacity following a thermal stress. The recovery of protease and -glucosidase activity following a simulated heat wave perturbation (17 hrs, 60°C) was monitored over a 4-day period. Concurrently, Cu2+ activity, total dissolved Cu content, soluble anions and DOC were analyzed before thermal stress and after the recovery period. The study was conducted on a natural soil with adjusted organic matter content (% O.M. : 2, 5, 8) and pH (5, 6 and 7). In order to obtain different copper concentrations (0, 250 and 750 mg/kg), 3 wet/dry cycles followed by a lixiviation were performed. An increase in DOC from 42% to 100% was observed in the soil samples having undergone a thermal stress. Moreover, results showed that protease activity in uncontaminated soil samples was stimulated by the thermal stress, reaching an average of twice that of the baseline level after 2 days. In contrast, the recovery of contaminated soil reached just over half the activity of its corresponding thermally unperturbed soil, for any O.M. content. For glucosidase activity, a better recovery rate was observed in 750 mg Cu/kg-contaminated soils than in 250 mg Cu/kg-contaminated soils. Finally, results indicate that a significant variation in basic enzyme activity occurred in all samples over a period as short as 4 days. This observation highlights the importance of assessing the temporal evolution of enzyme activity.

Key words: thermal stress, soil functional recovery, enzyme activity, Copper