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International audience; This study aimed at determining, in the laboratory, the effects of poplar litter collected in woody habitats contaminated by heavy metals on growth and metal accumulation in the terrestrial isopod Porcellio scaber. Cd, Pb, and Zn pseudototal and CaCl(2)-extractable concentrations in litter types were determined using AAS. Juveniles were fed ad libitum, individually, for 28 days with four litter types presenting an increasing gradient of metal contamination. Individuals were weighed every week and metal body burdens were determined at the end of the experiment. From the first week until the end of the experiment, a decrease in P. scaber growth related to the increase of metal concentration in litter types was recorded. Significant correlations were observed between metal body burdens and metal concentrations in litter types. However, Cd accumulation in woodlice appeared to be related to the Cd/Zn concentration ratio in litter types. All these results showed the potential of weight gain in P. scaber as a suitable indicator for litter quality assessment with ecological relevance.

A multipolluted soil sampled from a former coking plant in Lorraine (France) was evaluated for its genotoxic effects on coelomocytes of the Eisenia fetida earthworm using the comet assay. The biological efficiency of thermal desorption of the contaminated soil was also investigated. The untreated polluted soil was shown to be genotoxic to earthworms. Although thermal desorption reduced the concentration of PAHs by 94% ([summation operator]16 PAHs=1846 and 101 mg/kg before and after thermal desorption, respectively), the treatment did not eliminate the genotoxicity of soil pollutants to earthworms but increased it. The concentration of non-volatile metals did not change after thermal desorption. Among metals found in the treated soil, cadmium, chromium and nickel could explain the genotoxicity of the contaminated soil after thermal desorption. The treatment could increase the bioavailability and genotoxicity of heavy metals, through a modification of the soil's organic matter, the speciation of heavy metals and their binding to organic matter. This study underlines the importance of measuring biological effects, in order to evaluate the risk associated with formerly contaminated soils and the efficiency of remediation.

Leaching of 14 C-ring-labeled technical trifluralin from the top 5 cm of soil was followed in a microlysimeter experiment under outdoor conditions. Leaching of water residues from soil was low and represented 2.2, 5.4, and 6.7% of the applied radioactivity after 6, 12, and 18 months, respectively. Two degradation products, called A and B, were clearly detected and represented about 80 and 10% of the leached radioactivity, respectively, whereas other degradation products accounted for about 10%. Trifluralin itself was detected in the leachate only between 3 and 6 months. Cumulated amounts of leached trifluralin were only 1% of the leached radioactivity after 1 year: i.e., 0.06% of the applied product. A second-year microlysimeter experiment demonstrated that the use of formulated trifluralin had no influence on leached amount and content.

Field and laboratory tests were conducted to investigate the disappearance and decrease in availability of the herbicide isoproturon in soil with time. Monitoring the fate of 14 C-labeled isoproturon gave the persistence of the herbicide under different conditions. The calculated half-life (DT 50 ) of the extractable parent product was close to 19 days for the two experiments, whereas half-lives of exhaustive extractable 14 C-residues averaged 22 days under controlled conditions versus 48 days in the field. Moreover, if nonextractable 14 C-residues were taken into account in estimating isoproturon fate, the DT 50 of radioactive residues in soil (extractable parent and degradation products + nonextractable residues) reached 1 to 1.4 years under field and controlled conditions, respectively. The variability of disappearance rates for the different kinds of residues is discussed within a wider definition of persistence.