Assessment of Ecotoxicity of Topsoils from a Wood Treatment Site

A series of 9 soil samples were taken at a timber treatment site in SW France where Cu sulphate and chromated copper arsenate （CCA） have been used as wood preservatives （Sites P1 to P9） and one soil sample was collected at an adjacent site on the same soil type （Site P10）. Copper was a major contaminant in all topsoils, varying from 65 （Soil P5） to 2600 mg Cu kg^-1 （Soil P7）, exceeding background values for French sandy soils. As and Cr did not accumulate in soil, except at Site P8 （52 mg As kg^-1 and 87 mg Cr kg^-1） where CCA-treated posts were stacked. Soil ecotoxicity was assessed with bioassays using radish, lettuce, slug Arion rufus L., and earthworm Dendrobaena octaedra （Savigny）. There were significantly differences in lettuce germination rate, lettuce leaf yield, radish root and leaf yields, slug herbivory, and earthworm avoidance. An additional bioassay showed higher negative impacts on bean shoot and root yields, Rhizobium nodule counts on Bean roots, and guaiacol peroxidase activity in primary Bean leaves for soil from Site PT, with and without fertilisation, than for soil from Site P10, despite both soils having a similar value for computed free ion Cu2＋ activity in the soil solution （pCu^2＋）. Beans grown in soil from Site P7 that had been fertilised showed elevated foliar Cu content and phytotoxic symptoms. Soils from Sites P7 （treatment plant） and P6 （storage of treated utility poles） had the highest ecotoxicity, whereas soil from Site P10 （high organic matter content and cation exchange capacity） had the lowest. Except at Site P10, the soil factor pCu^2＋ computed with soil pH and total soil Cu could be used to predict soil ecotoxicity.

Soil compression influences the avoidance behavior of Allonychiurus kimi(Collembola)to cadmium and copper

The behavior of soil organisms inhabiting soil pore spaces can be influenced by soil compression,which can affect their avoidance behavior to pollutants.In this study,we aimed to evaluate the effect of soil compression on the avoidance behavior of Allonychiurus kimi(Collembola)to heavy metals cadmium and copper.Initially,to assess the applicability of the avoidance test guideline of the International Organization for Standardization(ISO)developed for Folsomia candida,we investigated the avoidance behavior of A.kimi to cadmium and copper in an artificial soil with a loose structure(bulk density of 0.25 g cm^(-3)),the porous texture of which was sufficiently loose to enable A.kimi to move between pore spaces.The effect of soil compression on the avoidance behavior of A.kimi to both metals was evaluated in compressed soil(bulk density of 0.64 g cm^(-3))with a uniformly compressed soil surface,and avoidance behavior was investigated at 24-h intervals over a 120-h period.Given that A.kimi is unable to burrow into compressed soil,the compressed soil test can minimize the effects of differences in soil factors,such as soil porosity and bulk density,on the behavior of this collembolan.In the artificial soil,a statistically significant avoidance behavior of A.kimi was observed at cadmium and copper concentrations greater than 50 and 200 mg kg^(-1),respectively,thereby indicating the applicability of the ISO avoidance test guidelines for A.kimi.When compared at the same exposure time point,the avoidance response to both metals in compressed soil was less sensitive than that in uncompressed soil.In addition,we observed differences in the effects of metals on avoidance response in the compressed soil over time,with the effect of cadmium increasing with time and the effect of copper showing the opposite trend.Overall,we found that soil compression can affect the avoidance behavior of A.kimi to cadmium and copper,and we discussed the advantages and limitations of using compressed soil for assessments of pollutant toxicity.