Due to diffuse atmospheric fallouts of process particles enriched by metals and metalloids, polluted soils concern large areas at the global scale. Useful tools to assess ecotoxicity induced by these polluted soils are therefore needed. Earthworms are currently used as biotest, however the influence of specie and earthworm behaviour, soil characteristics are poorly highlighted. Our aim was therefore to assess the toxicity of various polluted soils with process particles enriches by metals and metalloids (Pb, Cd, Cu, Zn, As and Sb) collected from a lead recycling facility on two earthworm species belonging to different ecological types and thus likely to have contrasted behavioural responses (Eiseina hortensis and Lumbricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physicochemical parameters such as metal absorption, bioaccumulation by earthworms and their localization in invertebrate tissues provided a valuable indication of pollutant bioavailability and ecotoxicity. Soil characteristics influenced ecotoxicity and metal uptake by earthworms, as well as their soil bioturbation.

The former use of chlordecone (CLD) in the French West Indies has resulted in long-term pollution of soils and of food chains. CLD may be transferred into eggs of hens reared outdoors, through polluted soil ingestion. Tropical volcanic soils display variable capacities of pollutant retention: CLD is less available and more persistent in andosol than in nitisol. The impact of soil type on CLD bioavailability to hens was tested through a relative bioavailability study. The deposition of CLD in egg yolk and in abdominal fat was measured in 42 individually housed laying hens fed with diets containing graded levels of CLD from polluted andosol, nitisol, or spiked oil during 23 days. Within each ingested matrix, the concentration of CLD in yolk and in abdominal fat linearly increased with the amount of ingested CLD (P<0.001). However, the response to andosol diets and to nitisol diets was not different from the response to oil diets (P>0.1), indicating that CLD was equally bioavailable to laying hens, irrespective of the matrix. This suggests that the hen's gastrointestinal tract efficiently extracts CLD from the two tropical volcanic soils, regardless of their retention capacity. Thus, hens reared on polluted soils with CLD may lay contaminated eggs. (Résumé d'auteur)

Due to its high growth rate and biomass production, bamboo has recently been proven to be useful in wastewater treatment. Bamboo accumulates high silicon (Si) levels in its tissues, which may improve its development and tolerance to metal toxicity. This study investigates the effect of Si supplementation on bamboo growth and copper (Cu) sensitivity. An 8-month hydroponic culture of bamboo Gigantocloa sp. "Malay Dwarf " was performed. The bamboo plants were first submitted to a range of Si supplementation (0-1.5 mM). After 6 months, a potentially toxic Cu concentration of 1.5 ?M Cu2+ was added. Contrary to many studies on other plants, bamboo growth did not depend on Si levels even though it absorbed Si up to 218 mg g?1 in leaves. The absorption of Cu by bamboo plants was not altered by the Si supplementation; Cu accumulated mainly in roots (131 mg kg?1), but was also found in leaves (16.6 mg kg?1) and stems (9.8 mg kg?1). Copper addition did not induce any toxicity symptoms. The different Cu and Si absorption mechanisms may partially explain why Si did not influence Cu repartition and concentration in bamboo. Given the high biomass and its absorption capacity, bamboo could potentially tolerate and accumulate high Cu concentrations making this plant useful for wastewater treatment. (Résumé d'auteur)

Many studies have shown the relationship between fire clearing and mercury contamination of aquatic ecosystems in the Brazilian Amazon. This study aimed at quantifying mercury content in long-time cultivated soils and at assessing the potential of a fire-free alternative clearing technique on mercury retention for long-time cultivated soils compared to traditional slash-and-burn. This case study included five land uses: one crop plot and one pasture plot cleared using slash-and-burn, one crop plot and one pasture plot cleared using chop-and-mulch, and one 40-year-old forest as a control. Low mercury concentrations were recorded in the surface horizon (24.83 to 49.48 ng g?1, 0–5 cm depth). The long-time cultivation (repeated burnings) of these soils triggered large mercury losses in the surface horizon, highlighted by high enrichment factors from surface to deeper horizons. The predominant effect of repeated burnings before the experimental implementation did not let us to distinguish a positive effect of the chop-and-mulch clearing method on soil mercury retention for crops and pastures. Moreover, some processes related to the presence of the mulch may favor mercury retention (Hg volatilization decrease, cationic sites increase), while others may contribute to mercury losses (cationic competition and dislocation, mobilization by the dissolved organic matter). (Résumé d'auteur)

The former use of chlordecone (CLD) in the French West Indies has resulted in long-term pollution of soils and of food chains. CLD may be transferred into eggs of hens reared outdoors, through polluted soil ingestion. Tropical volcanic soils display variable capacities of pollutant retention: CLD is less available and more persistent in andosol than in nitisol. The impact of soil type on CLD bioavailability to hens was tested through a relative bioavailability study. The deposition of CLD in egg yolk and in abdominal fat was measured in 42 individually housed laying hens fed with diets containing graded levels of CLD from polluted andosol, nitisol, or spiked oil during 23 days. Within each ingested matrix, the concentration of CLD in yolk and in abdominal fat linearly increased with the amount of ingested CLD (P<0.001). However, the response to andosol diets and to nitisol diets was not different from the response to oil diets (P>0.1), indicating that CLD was equally bioavailable to laying hens, irrespective of the matrix. This suggests that the hen's gastrointestinal tract efficiently extracts CLD from the two tropical volcanic soils, regardless of their retention capacity. Thus, hens reared on polluted soils with CLD may lay contaminated eggs. (Résumé d'auteur)

The objective was to describe and model varia- tion patterns in individual fish responses to contaminants among estuaries, season and gender. Two hundred twenty- seven adult European flounders were collected in two sea- sons (winter and summer) in four estuaries along the Bay of Biscay (South West France), focusing on a pristine system (the Ster), vs. three estuaries displaying contrasted levels of contaminants (the Vilaine, Loire and Gironde). Twenty-three variables were measured by fish, considering the load of contaminants (liver metals, liver and muscle persistent organic pollutants, muscle polycyclic aromatic hydrocar- bons); the gene expression (Cyt C oxydase, ATPase, BHMT, Cyt P450 1A1, ferritin); the blood genotoxicity (Comet test); and liver histology (foci of cellular alteration–tumour, steatosis, inflammation, abnormal glycogen storage). Ca- nonical redundancy analysis (RDA) was used to model these variables using gender, season and estuary of origin as explanatory variables. The results underlined the homo- geneity of fish responses within the pristine site (Ster) and more important seasonal variability within the three contam- inated systems. The complete model RDA was significant and explained 35 % of total variance. Estuary and season respectively explained 30 and 5 % of the total independent variation components, whilst gender was not a significant factor. The first axis of the RDA explains nearly 27 % of the total variance and mostly represents a gradient of contami- nation. The links between the load of contaminants, the expression of several genes and the biomarkers were ana- lysed considering different levels of chemical stress and a possible multi-stress, particularly in the Vilaine estuary.

This viewpoint paper explores the potential of genomics technology to provide accurate, rapid, and cost efficient observations of the marine environment. The use of such approaches in next generation marine monitoring programs will help achieve the goals of marine legislation implemented world-wide. Genomic methods can yield faster results from monitoring, easier and more reliable taxonomic identification, as well as quicker and better assessment of the environmental status of marine waters.

International audience | Although high PAH content and detection of PAH-degraders, the PAH biodegradation is limited in aged-contaminated soils due to low PAR availability (i.e., 1%). Here, we tried to experimentally increase the soil PAH availability by keeping both soil properties and contamination composition. Organic extract was first removed and then re-incorporated in the raw soil as fresh contaminants. Though drastic, this procedure only allowed a 6-time increase in the PAH availability suggesting that the organic constituents more than ageing were responsible for low availability. In the re-contaminated soil, the mineralization rate was twice more important, the proportion of 5-6 cycles PAH was higher indicating a preferential degradation of lower molecular weight PAH. The extraction treatment induced bacterial and fungal community structures modifications, Pseudomonas and Fusarium solani species were favoured, and the relative quantity of fungi increased. In re-contaminated soil the percentage of PAH-dioxygenase gene increased, with 10 times more Gram negative representatives.

International audience | This study addressed the relative importance of particle coating, sewage sludge amendment, and aging on aggregation and dissolution of manufactured Ag nanoparticles (Ag MNPs) in soil pore water. Ag MNPs with citrate (CIT) or polyvinylpyrrolidone (PVP) coatings were incubated with soil or municipal sewage sludge which was then amended to soil (1% or 3% sludge (w/w)). Pore waters were extracted after 1 week and 2 and 6 months and analyzed for chemical speciation, aggregation state and dissolution. Ag MNP coating had profound effects on aggregation state and partitioning to pore water in the absence of sewage sludge, but pre-incubation with sewage sludge negated these effects. This suggests that Ag MNP coating does not need to be taken into account to understand fate of AgMNPs applied to soil through biosolids amendment. Aging of soil also had profound effects that depended on Ag MNP coating and sludge amendment. (C) 2013 Elsevier Ltd. All rights reserved.