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International audience; The widespread use of pesticides in agriculture during the last several decades has contaminated soils and different Critical Zone (CZ) compartments, defined as the area extended from the top of the vegetation canopy to the groundwater table, and it integrates interactions of the atmosphere, lithosphere, biosphere, and hydrosphere. However, the long-term fate, storage, and transfer dynamics of persistent pesticides in CZ in a changing world remain poorly understood. In the French West Indies, chlordecone (CLD), a toxic organochlorine insecticide, was extensively applied to banana fields to control banana weevil from 1972 to 1993 after which it was banned. Here, to understand CZ trajectories we apply a retrospective observation based on marine sediment core analyses to monitor long-term CLD transfer, fate, and consequences in Guadeloupe and Martinique islands. Both CLD profiles show synchronous chronologies. We hypothesized that the use of glyphosate, a postemergence herbicide, from the late 1990s onward induced CZ modification with an increase in soil erosion and led to the release of the stable CLD stored in the soils of polluted fields. CLD fluxes drastically increased when glyphosate use began, leading to widespread ecosystem contamination. As glyphosate is used globally, ecotoxicological risk management strategies should consider how its application affects persistent pesticide storage in soils, transfer dynamics, and widespread contamination.

International audience; In Guadeloupe, the use between 1972 and 1993 of chlordecone, an organochlorine insecticide, has permanently contaminated the island’s soil, thus contaminating the food chain at its very beginning. There is today a strong societal requirement for an improved mapping of the contaminated zones. Given the extent of the areas to be covered, carrying out soil tests on each plot of the territory would be a long and expensive process. In this article, we explore a method of demarcating polluted areas. The approach adopted consists in carrying out, using surface water analyses, a hydrological delimitation that makes it possible to distinguish contaminated watersheds from uncontaminated ones. The selection of sampling points was based on the spatial analysis of the actual and potential contamination data existing at the beginning of the study. The approach was validated by soil analyses, after having compared the contamination data of the watersheds with the soil contamination data of the plots within them. The study thus made it possible to highlight new contaminated areas and also those at risk of contamination and to identify the plots to be targeted as a priority during future analysis campaigns by State services.

Partie B; International audience; Incidental zinc sulfide nanoparticles (nano-ZnS) are spread on soils through organic waste (OW) recycling. Here we performed soil incubations with synthetic nano-ZnS (3 nm crystallite size), representative of the form found in OW. We used an original set of techniques to reveal the fate of nano-ZnS in two soils with different properties. 68 Zn tracing and nano-DGT were combined during soil incubation to discriminate the available natural Zn from the soil, and the available Zn from the dissolved nano-68 ZnS. This combination was crucial to highlight the dissolution of nano-68 ZnS as of the third day of incubation. Based on the extended X-ray absorption fine structure, we revealed faster dissolution of nano-ZnS in clayey soil (82% within 1 month) than in sandy soil (2% within 1 month). However, the nano-DGT results showed limited availability of Zn released by nano-ZnS dissolution after 1 month in the clayey soil compared with the sandy soil. These results highlighted: (i) the key role of soil properties for nano-ZnS fate, and (ii) fast dissolution of nano-ZnS in clayey soil. Finally, the higher availability of Zn in the sandy soil despite the lower nano-ZnS dissolution rate is counterintuitive. This study demonstrated that, in addition to nanoparticle dissolution, it is also essential to take the availability of released ions into account when studying the fate of nanoparticles in soil.

In Senegal, the environmental impact of artisanal small-scale gold mining (ASGM) using mercury (Hg) is poorly documented despite its intensification over the past two decades. We report here a complete dataset including the distribution and speciation of Hg in soil, sediment, and water in pristine and ASGM impacted sites of the Gambia River ecosystem (Kedougou region - eastern Senegal). Selective extraction showed that soils surrounding ASGM activities were contaminated with elemental Hg [Hg(0)] at concentrations up to 3.9 mg kg−1. In the Gambia River, high total Hg (THg: 1.16 ± 0.80 mg kg−1) and methylmercury (MeHg: 3.2 ± 2.3 ng g−1) were also measured in sediment samples collected at ASGM sites. Along the stream, THg concentrations in sediment decrease with distance from the ASGM sites, while those of methylmercury increase downstream. The study of THg and MeHg partitioning between filtered surface water and suspended particles demonstrate that particulate transport is responsible for the downstream dissemination of the Hg contamination from ASGM sites. Sedimentation of fine particles enriched in Hg downstream ASGM sites likely favors MeHg production and accumulation in sediment. Although elemental Hg is weakly labile, surface soil erosion may also provide important and long-term Hg inputs to downstream aquatic ecosystems, where it can be oxidized and methylated. Finally, the dissemination of THg and MeHg downstream from the ASGM sites in the Gambia River may constitute a long-term source of contamination and can have a large scale impact on the aquatic ecosystem through biomagnification.

International audience

International audience; Sourcing and understanding the fate of anthropogenic metals in a historical contamination context is challenging. Here we combined elemental and isotopic (Pb, Zn, Cu) analyses with X-ray Absorption Spectroscopy (XAS) measurements (Zn) to trace the fate, in undisturbed soil profiles, of historical metal contamination emitted by a 167-year-old Pb-Ag smelter decommissioned 100 years ago located in the Calanques National Park (Marseilles, France). Lead isotopic measurements show that entire soil profiles were affected by 74 years of Pb emissions up to similar to 7 km from the smelter under the main NNW wind, and indicate particulate transfer down to 0.8 m at depth. This vertical mobility of anthropogenic Pb contrasts with previous studies where Pb was immobilized in surface horizons. The contribution of anthropogenic Pb to the total Pb concentration in soil was estimated at 95% in surface horizons, and 78% in the deepest horizons. Zinc isotopic signatures of past emissions that are enriched in light isotopes compared to the natural geological background (-0.70 +/- 0.04% and -0.15 +/- 0.02%, respectively), were detected only in the surface horizons of the studied soils. Using XAS analyses, we showed that anthropogenic Zn was transformed and immobilized in surface horizons as Zn-Layered Double Hydroxide, thus favoring the enrichment in heavy isotopes in these surface horizons. No clear evidence of copper contamination by the smelter was found and Cu isotopes point to a bedrock origin and a natural distribution of Cu concentrations.

Environmental pollution through heavy metals is an upcoming universal problem that relentlessly endangers human health, biodiversity and ecosystems. Hence remediating these heavy metal pollutants from the environment by engineering soil microbiome through metatranscriptomics is befitting reply. In the present investigation, we have constructed size fractionated cDNA libraries from eukaryotic mRNA of cadmium (Cd) contaminated soil and screened for Cd tolerant genes by yeast complementation system by using Cd sensitive ycf1Δ mutant. We are reporting one of the transformants PLCe10 (from library C, 1–4 kb) with potential tolerance towards Cd toxicity (40 μM–80 μM). Sequence analysis of PLCe10 transcript showed homology to von Willebrand factor type D domain (VWD) of vitellogenin-6 of Ascaris suum encoding 338 amino acids peptide. qPCR analysis revealed that PLCe10 induced in presence of Cd (32 fold) and also accumulated maximum amount of Cd at 60 μM Cd. This cDNA was further tested for its tolerance against other heavy metals like copper (Cu), zinc (Zn) and cobalt (Co). Heterologous complementation assays of cDNA PLCe10 showed a range of tolerance to Cu (150 μM–500 μM), Zn (10 mM–12 mM) and Co (2–4 mM). Results of the present study suggest that cDNA PLCe10 is one of the functional eukaryotic heavy metal tolerant genes present among the soil microbial community and could be exploited to rehabilitate metal contaminated sites.

International audience; Purpose Salinisation is a threat not only to arable land but also to freshwater resources. Nevertheless, salinisation impacts have been rarely and only partially included in life cycle assessment (LCA) so far. The objectives of this review paper were to give a comprehensive overview of salinisation mechanisms due to human interventions, analyse the completeness, relevance and scientific robustness of existing published methods addressing salinisation in LCA and provide recommendations towards a comprehensive integration of salinisation within the impact modelling frameworks in LCA.Methods First, with the support of salinisation experts and related literature, we highlighted multiple causes of soil and water salinisation and presented induced effects on human health, ecosystems and resources. Second, existing life cycle impact assessment (LCIA) methods addressing salinisation were analysed against the International Reference Life Cycle Data System analysis grid of the European Commission. Third, adopting a holistic approach, the modelling options for salinisation impacts were analysed in agreement with up-to-date LCIA frameworks and models.Results and discussion We proposed a categorisation of salinisation processes in four main types based on salinisation determinism: land use change, irrigation, brine disposal and overuse of a water body. For each salinisation type, key human management and biophysical factors involved were identified. Although the existing methods addressing salinisation in LCA are important and relevant contributions, they are often incomplete with regards to both the salinisation pathways they address and their geographical validity. Thus, there is a lack of a consistent framework for salinisation impact assessment in LCA. In analysing existing LCIA models, we discussed the inventory and impact assessment boundary options. The land use/land use change framework represents a good basis for the integration of salinisation impacts due to a land use change but should be completed to account for off-site impacts. Conversely, the land use/land use change framework is not appropriate to model salinisation due to irrigation, overuse of a water body and brine disposal. For all salinisation pathways, a bottom-up approach describing the environmental mechanisms (fate, exposure and effect) is recommended rather than an empirical or top-down approach because (i) salts and water are mobile and theirs effects are interconnected; (ii) water and soil characteristics vary greatly spatially; (iii) this approach allows the evaluation of both on-and off-site impacts and (iv) it is the best way to discriminate systems and support a reliable eco-design.Conclusions This paper highlights the importance of including salinisation impacts in LCA. Much research effort is still required to include salinisation impacts in a global, consistent and operational manner in LCA, and this paper provides the basis for future methodological developments.

International audience; Some volcanic soils like andosols contain short-range order nanoclays (allophane) which build aggregates with a tortuous and fractal microstructure. The aim of the work was to study the influence of the microstructure and mesoporosity of the allophane aggregates on the pesticide chlordecone retention in soils. Our study shows that the allo-phane microstructure favors pollutants accumulation and se-questration in soils. We put forth the importance of the meso-porous microstructure of the allophane aggregates for pollutant trapping in andosols. We show that the soil contamination increases with the allophane content but also with the mesopore volume, the tortuosity, and the size of the fractal aggregate. Moreover, the pore structure of the allophane aggregates at nanoscale favors the pesticide retention. The fractal and tortuous aggregates of nanoparticles play the role of nanolabyrinths. It is suggested that chlordecone storage in allophanic soils could be the result of the low transport properties (permeability and diffusion) in the allophane aggregates. The poor accessibility to the pesticide trapped in the mesopore of allophane aggregates could explain the lower pollutant release in the environment.

International audience; The root system anchors the plant to the soil and contributes to plant autotrophy by taking up nutrients and water. In relation with this nutritional function, root development is largely impacted by availability of nutrients and water. Due to human activity, plants, in particular crops, can also be exposed to pollutants which can be absorbed and incorporated into the food chain. Cesium in soils is present at non-toxic concentrations for the plant (micromolar or less), even in soils highly polluted with radioactive cesium due to nuclear accidents. Here, we report on the morphological response of rice roots to Cs+ at micromolar concentrations. It is shown that Cs+ reduces root elongation without affecting root dry weight. Noteworthy, inactivation of the Cs+-permeable K+ transporter OsHAK1 prevents such effect of Cs+, suggesting that internal Cs+ triggers the modification of the root system.

Human populations are threatened by chronic exposure to the Cd accumulated in foods after being taken up from soils by crops. To decide whether and to what extent it is necessary to reduce the Cd content in cultivated soils, one needs to understand and predict its evolution. We therefore simulated the Cd mass balance in the soils under annual crops in France and in its 22 regions for the next century, following six scenarios of agricultural practices or regulatory conditions. If current cultivation practices are maintained, the average Cd content would increase by about 15% after a century, due to the input of Cd with P fertilizer applications. This represents around 85% of the soil Cd inputs and is nearly twice the Cd output caused by leaching and crop offtake. These results conflict with those recently obtained at the European level, due to three factors: the higher rate of P application in France than in Europe, a higher Cd content in the P fertilizers applied in France and a lower Cd leaching in French soils. Strict application of the good practices for P fertilization would stabilize the future soil Cd content at its present level. Assuming the current excessive P fertilization, the enforcement of a regulation limiting Cd content in the P fertilizers, as proposed by the European Union, would lead to a lesser increase in soil Cd, by 1.6% to 3.9% after a century. The combination of P fertilization good practices and Cd content limitation in P fertilizers would lead to a decrease in soil Cd content of between 3.0% to 5.2%. Organic agriculture would lead to an evolution of soil Cd content similar to that of conventional agriculture applying good practices. The accuracy of the mass balances could be ameliorated by a better assessment of Cd leaching.

International audience; Nickel (Ni), an essential micronutrient, is toxic to plants and animals at elevated levels. Fewer data are available on the dynamics of Ni than for trace metals such as Cu and Zn. Dietary intake is the major source of Ni, but almost no information is available on dietary intake for Asian populations whose diet contains much less animal products and processed foods than in Western countries. In south-eastern China, most food is grown on peri-urban agricultural land and thus, food crops from these areas should be the major source of dietary Ni. A large-scale survey of Ni in soils and edible crops, including 515 sites and 24 crop species from 10 crop groups, was conducted in Fujian Province, SE China, to assess Ni intake for a typical SE Asian diet. Correlation, principal component analysis (PCA) and data mining were used to identify soil and plant factors that determine Ni accumulation in crops. Both soil Ni content and plant species contributed to Ni accumulation. Crop Ni (Ni-crop) was positively correlated with soil Ni DTPA-extractible (diethylenetriaminepentaacetic acid) (Ni-DTPA) for many crops. PCA did not identify strong relations between soil-to-crop transfer factors and any soil properties. Stepwise linear correlations found positive correlations between Ni-crop and Ni-DTPA; however, relationships between Ni-crop and both silt content and pH varied between crops. Dietary intake of foods containing mean Ni content could lead to health risks, especially for children. It was concluded that sandy soils, rich in organic matter with a large Ni content, are unsuitable for the production of rice and legumes.

The former use of chlordecone (CLD) in the French West Indies has resulted in long-term pollution of soils. CLD is known to be potentially transferred towards animal products of animals reared outdoors, mainly through accidental soil ingestion. Several studies indicate that soil bound CLD is bioavailable when administered to farm animals. Currently there is a need to quantify the level of CLD absorption and its toxicokinetic characteristics in the ruminant and particularly in the goat. These are considered as important farm species in the French West Indies. The objective of this study was to evaluate the absorption rate and the half-life of CLD in the non-lactating goat. The goats were administered either intravenously (i.v., n = 6) or orally (p.o., n = 6) one dose (1 mg kg −1 body weight) of CLD. Blood samples were collected at defined times up to 160 days post-dosing. CLD was analyzed in serum by high-resolution gas chromatography. A comparison of the area under the serum concentration-time curves (AUC) showed that the i.v. route is equivalent to the oral route. Thus, CLD is considered almost completely absorbed after p.o. administration, as shown by the mean absolute bioavailability. The comparison between the pharmacokinetic profiles of CLD following oral and intravenous dose showed a difference during the first 14 days and a similar kinetic after this period. The half-life of CLD in serum was close to 20 days. These results highlight a possible strategy of decontamination due to the short half-life of CLD, obtained in dry goats that did not excrete fat matter.

Evaluate the efficiency of Populus alba clone Villafranca in the uptake and translocation of Zn from contaminated soils. The effects of 48 days of zinc treatment (Zn t ) on the growth and the photosynthetic activities of P. alba L. clone Villafranca were studied using ZnSO4 (375 ppm per unit of soil dry weight) added in sand and peat moss substrate at the beginning of the treatment (T 0) and again after 30 days (T 1) in order to reach a target Zn concentration of 375 ppm at T 0 and 750 ppm at T 1 per unit of soil dry weight. Zn uptake in the different organs was analyzed after 30 (T 1) and 48 days (T 2) from the beginning of treatment, showing the following order: root ≫ leaves ≥ woody cutting = stem. The leaf area increased by 12 % in comparison to control plants at the end of second treatment (48 days). Cutting radial growth showed a high synchronicity in the growth rate fluctuation among control and Zn t plants, but a higher increase in radial diameter of Zn t cutting was observed starting from day 38 (after 8 days of second Zn t ) reaching after 48 days 38 % higher than control plants. Although our data of leaf Zn concentration were in the range usually reported as toxic for plants, Villafranca clone in Zn t substrate were unaffected in terms of net CO2 assimilation and stomatal conductance to water vapor.

International audience; 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 Lum-bricus terrestris). The combination of behavioural factors measurements (cast production and biomass) and physico-chemical 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.

Background: Chemical soil factors play an important role in generating and maintaining plant diversity. Naturally metal-enriched habitats support highly distinctive plant communities consisting of many rare and endemic species. Species of these plant communities possess remarkable physiological adaptations and are now being considered key elements in the implementation of green technologies aimed at phytoremediation of contaminated soils and post-mined soils. Several studies have emphasised that industrial mineral extraction results in serious damage to ecosystems and serious threats to human health and leads to the extinction of metallophyte species. In the southeastern Democratic Republic of the Congo (DRC), mining activities represent a threat to the long-term persistence of communities located on metalliferous copper and cobalt outcrops and their associated endemic metallophytes, which are currently considered some of the most critically endangered plants in the world. Scope: Plant diversity conservation of metal-rich soils must assess soil-plant relationships at different scales (ecosystems, communities, and populations) to define in-situ and ex-situ conservation and restoration projects. This paper proposes a review of soil-plant relationships involved in plant diversity and endemism and their implications for biodiversity conservation and restoration., SCOPUS: ar.j, info:eu-repo/semantics/published

Insecticidal Cry, or Bt, proteins are produced by the soil-endemic bacterium, Bacillus thuringiensis and some genetically modified crops. Their environmental fate depends on interactions with soil. Little is known about the toxicity of adsorbed proteins and the change in toxicity over time. We incubated Cry1Ac and Cry2A in contrasting soils subjected to different treatments to inhibit microbial activity. The toxin was chemically extracted and immunoassayed. Manduca sexta was the target insect for biotests. Extractable toxin decreased during incubation for up to four weeks. Toxicity of Cry1Ac was maintained in the adsorbed state, but lost after 2 weeks incubation at 25 °C. The decline in extractable protein and toxicity were much slower at 4 °C with no significant effect of soil sterilization. The major driving force for decline may be time-dependent fixation of adsorbed protein, leading to a decrease in the extraction yield in vitro, paralleled by decreasing solubilisation in the larval gut.

The aim of this study was to identify primary flow paths involved in the chlordecone (CLD) river contamination and quantify the CLD fluxes to assess CLD pollution levels and duration according to a typical catchment of the banana cropping area in the French Indies (Guadeloupe): the Perou Catchment (12 km(2)) characterized by heavy rainfall (5686 mm year(-1)). Three sub-catchments (SC1, SC2 and SC3) were studied during the hydrological year 2009-2010: a pedological survey combined with a spatialized hydrochemical approach was conducted. The average soil concentration is higher in the Perou Catchment (3400 mu g kg(-1)) than in the entire banana cropping area in Guadeloupe (2100 mu g kg(-1)). The results showed that CLD stocks in soils vary largely among soil types and farming systems: the weakest stocks are located upstream in SC1 (5 kg ha(-1)), where a majority of the area is non-cultivated; medium stocks are located in Nitisols downstream in SC3 (9 kg ha(-1)); and the greatest stocks are observed in SC2 on Andosols (12 kg ha(-1)) characterized by large farms. The annual water balance and the hydro-chemical analysis revealed that the three sub-catchments exhibited different behaviors. Perou River contamination was high during low flows, which highlighted that contamination primarily originated from groundwater contributions. The results showed that only a small part of the catchment (SC2), contributing little to the water flow, comprises a major CLD contribution, which is in agreement with the highly contaminated andosol soils observed there. Another significant result considers that at least 50 years would be required to export the totality of the actual CLD soil stocks retained in the topsoil layer. The actual time for soil remediation will however be much longer considering (i) the necessary time for the chlordecone to percolate and be stored in the shallow aquifers and (ii) its travel time to reach the river.rights reserved.

A batch experiment was conducted to assess the impact of chemical oxidation using modified Fenton reaction on PAH content and on physico-chemical and biological parameters of an industrial PAH contaminated soil in unsaturated condition. Two levels of oxidant (H2O2, 6 and 65 g kg(-1)) and FeSO4 were applied. Agronomic parameters, bacterial and fungal density, microbial activity, seed germination and ryegrass growth were assessed. Partial removal of PAHs (14% and 22%) was obtained with the addition of oxidant. The impact of chemical oxidation on PAH removal and soil physico-chemical and biological parameters differed depending on the level of reagent. The treatment with the highest concentration of oxidant decreased soil pH, cation exchange capacity and extractable phosphorus content. Bacterial, fungal. and PAH degrading bacteria densities were also lower in oxidized soil. However a rebound of microbial populations and an increased microbial activity in oxidized soil were measured after 5 weeks of incubation. Plant growth on soil treated by the highest level of oxidant was negatively affected. (C) 2011 Elsevier Ltd. All rights reserved.

Spreading of urban wastewater on agricultural land may lead to concomitant input of organic and inorganic pollutants. Such multiple pollution sites offer unique opportunities to study the fate of both heavy metals and pharmaceuticals. We examined the occurrence and fate of selected antibiotics in sandy-textured soils, sampled four years after cessation of 100 years irrigation with urban wastewater from the Paris agglomeration. Previous studies on heavy metal contamination of these soils guided our sampling strategy. Six antibiotics were studied, including quinolones, with a strong affinity for organic and mineral soil components, and sulfonamides, a group of more mobile molecules. Bulk samples were collected from surface horizons in different irrigation fields, but also in subsurface horizons in two selected profiles. In surface horizons, three quinolones (oxolinic acid, nalidixic acid, and flumequine) were present in eight samples out of nine. Their contents varied spatially, but were well-correlated one to another. Their distributions showed great similarities regarding spatial distribution of total organic carbon and heavy metal contents, consistent with a common origin by wastewater irrigation. Highest concentrations were observed for sampling sites close to irrigation water outlets, reaching 22 μg kg(-1) for nalidixic acid. Within soil profiles, the two antibiotic groups demonstrated an opposite behavior: quinolones, found only in surface horizons; sulfamethoxazole, detected in clay-rich subsurface horizons, concomitant with Zn accumulation. Such distribution patterns are consistent with chemical adsorption properties of the two antibiotic groups: immobilization of quinolones in the surface horizons ascribed to strong affinity for organic matter (OM), migration of sulfamethoxazole due to a lower affinity for OM and its interception and retention in electronegative charged clay-rich horizons. Our work suggests that antibiotics may represent a durable contamination of soils, and risks for groundwater contamination, depending on the physicochemical characteristics both of the organic molecules and of soil constituents.

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.

This work assesses relationships between characteristic aggregate microstructures related to biological activity in soils under different long-term land use and the distribution and extractability of metal pollutants. We selected two neighbouring soils contaminated with comparable metal loads by past atmospheric deposition. Currently, these soils contain similar stocks, but different distributions of zinc (Zn) and lead (Pb) concentrations with depth. One century of continuous land use as permanent pasture (PP) and conventional arable (CA) land, has led to the development of two soils with different macro- and micro-morphological characteristics. We studied distributions of organic matter, characteristic micro-structures and earthworm-worked soil by optical microscopy in thin sections from A, B and C horizons. Concentrations and amounts of total and EDTA-extractable Zn and Pb were determined on bulk samples from soil horizons and on size-fractions obtained by physical fractionation in water. Large amounts of Zn and Pb were found in 2–20-µm fractions, ascribed to stable organo-mineral micro-aggregates influenced by root and microbial activity, present in both soils. Unimodal distribution patterns of Zn, Pb and organic C in size-fractions were found in horizons of the CA soil. In contrast, bimodal patterns were observed in the PP soil, because large amounts of Zn and Pb were also demonstrated in stable larger micro-aggregates (50–100-µm fractions). Such differing distribution patterns characterized all those horizons markedly influenced by earthworm activity. Larger earthworm activity coincided with larger metal EDTA-extractability, particularly of Pb. Hence, land use-related biological activity leads to specific soil microstructures affecting metal distribution and extractability, both in surface and subsurface horizons.

International audience; Chlordecone was applied between 1972 and 1993 in banana fields of the French West Indies. This resulted in long-term pollution of soils and contamination of waters, aquatic biota, and crops. To assess pollution level and duration according to soil type, WISORCH, a leaching model based on first-order desorption kinetics, was developed and run. Its input parameters are soil organic carbon content (SOC) and SOC/water partitioning coefficient (Koc). It accounts for current chlordecone soil contents and drainage water concentrations. The model was valid for andosol, which indicates that neither physicochemical nor microbial degradation occurred. Dilution by previous deep tillages makes soil scrapping unrealistic.Lixiviation appeared the main way to reduce pollution. Besides the SOC and rainfall increases, Koc increased from nitisol to ferralsol and then andosol while lixiviation efficiency decreased. Consequently, pollution is bound to last for several decades for nitisol, centuries for ferralsol, and half a millennium for andosol.

[Departement_IRSTEA]RE [TR1_IRSTEA]RIE / TRANSFEAU; International audience; Grassed buffer strips are one way to reduce pesticide transfer by surface runoff from farmed fields to streams. Numerous experimental studies have demonstrated that this type of development is very effective in various conditions. The results are nevertheless very variable. This variability is partially explained by the multiplicity of processes and contributive factors and by the fact that the latter are dynamic in nature and site-specific. Several results also show that the intercepted products are not systematically immobilized within the strip but can move in the subsurface, thus affecting the overall effectiveness of the system. As a consequence of this complexity, the present guidelines for the sizing and siting of grassed strips are still only qualitative or are the result of empirical approaches. The present review analyses the available results and defines needs for further research. This concern several basic processes determining the pesticide interception by grassed strip and numerical models necessary to integrate the complexity of interacting processes and formulate reliable managing guidelines.

International audience; The environmental fate of organic waste-derived trace organic contaminants is a recent focus of research. Public awareness of this issue and concern about the potential risks are increasing, partly as a result of this research. Knowledge remains sparse but, due to growing waste volumes and contaminant concentrations, situations are arising where decisions are urgently needed and the stakes are high. We present an approach to provide stakeholders with the soundest possible information on relevant risks in specific situations where local experimental data are scarce or inexistent. With accuracy taking precedence over precision in such situations, the quantitative fate assessment aspect of the approach considers uncertainty at all levels in order to estimate best-to-worst-case (cumulative uncertainty) fuzzy fate ranges. The approach was applied to conditions that prevail on the island of Reunion. Contrasting possible organic residue recycling scenarios are considered in which trace organic contaminants originate either from pig slurry or sewage sludge. The stakeholders' concerns targeted are leaching, soil persistence and crop (sugarcane) shoot translocation. The fate assessment results in soil removal dynamics that vary over a wide range, even for a particular chemical in a particular scenario. For 3 out of 27 chemicals residual soil concentrations after one sugarcane crop cycle could possibly exceed the 100 ng/g dry weight mass fraction range, only in a worst case situation. Substances predicted to be of the highest mobility (erythromycin, ofloxacin, ciprofloxacin) might produce appreciable leaching only in the event of substantial rainfall shortly after a high rate decadal application. And only the higher bound sugarcane shoot concentration estimates of 17 alpha-ethinylestradiol and tris(chloropropyl)phosphate are significant. (C) 2014 Elsevier Ltd. All rights reserved.

International audience

Dealing with soil contaminated with persistent organic pollutants (POP) is an increasing concern amplified by both regulatory constraints and the dramatic impact of human activities on the soil resource. The most used management options are treatments which totally eradicate the toxic compounds targeted. When possible, environmental-friendly processes should be used, and recent years have seen the emergence of green technologies using biological energies involving microorganisms (bioremediation) and plants (phytoremediation). Research has focused on phytoremediation and many have presented this technology as the process ideally combining efficiency, low cost and environmental acceptance. However, the applicability of phytoremediation on soils contaminated by bio-recalcitrant organic compounds, such as polycyclic aromatic hydrocarbons (PAH), has not yet proved as successful as expected. We propose here a review and discussion of the overall question of PAH status in soil and their potential for treatment. The limits and applicability of bioremediation technologies are discussed, and the specific beneficial effect of plants is objectively evaluated with a special interest to processes which lead to rhizoattenuation. Given the PAH high affinity to soil organic matter, availability is the main limitation to phytoremediation. In this context, bioavailability quantification remains an issue as well as the characterization of the recalcitrant fraction.

Although soil contamination has received increased attention in the EU because of the potential consequences for human health and for both air and water pollution, soil contaminant flows are an issue in their own right. Control of pollutants has high priority and has resulted in a number of directives to reduce emissions. Pesticides pose a crucial problem because these chemicals are applied to crops across the agricultural sector and therefore, constitute a non-point source of soil contamination. This paper reconsiders the basic economics of contaminant flows from both private and public perspectives. Firstly, the microeconomics of pollution control are presented, followed by a discussion of alternative policy approaches. Then the economics of restoration of damaged natural assets are considered. The case of pesticide use in agriculture is presented to illustrate lessons drawn from more general economic theory. Estimation of costs and benefits of restoration is considered and the challenges it poses to policy design are discussed. A final section reviews the economics of public policy for the restoration of contaminated soils and highlights current EU policy.

Competing ions strongly affect heavy metal sorption onto the solid surfaces of soil. This study evaluated competitive sorption of Cd, Cu, Ni, Pb and Zn on three soils: Calcixerollic Xerochrept, Paralithic Xerorthent and Lithic Haplumbrept. Monometal and competitive sorption isotherms were obtained at 25 degrees C. The individual effect of ions on retention of the others was ascertained by a fractional factorial analysis design. Most of the sorption isotherms belonged to type L subtype 2 in the classification of Giles. In competitive sorption the initial linear part was shorter and the knee sharper when compared with monometal sorption isotherms. Parameters related to sorptive capacity, such as Point B, Langmuir monolayer and Freundlich distribution coefficient, were higher in monometal than in competitive sorption, and in basic soils than in acidic soil. Calcium desorbed at different points of the sorption isotherms indicated that cationic exchange with Ca was the main retention mechanism in calcareous soils. For Pb, the ratio Ca desorbed/Pb sorbed was close to one; for Cu, Ni and Zn the ratio ranged from 1.20 to 1.37, probably due to partial dissolution of calcium carbonates by hydrolytic processes during retention. On the other hand, Cd had a ratio around 0.6 reflecting another additional retention mechanism, probably surface complexation. Fractional factorial design confirmed that the presence of the cations investigated reduced the amount of the five metals retained, but the presence of Cu and Pb in the system depressed Ni, Cd and Zn sorption more than the inverse. Cation mobility was enhanced when equilibrium concentration increased and the effect was higher in Ca-saturated soils.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; In the French West Indies, chlordecone (CLD), an organochlorine pesticide, was applied in banana plantations from 1972 to 1993. Our study was aimed at identifying the factors that determine soil CLD contamination and that thus can describe the spatial distribution of this contamination. For each of the 1045 plots analyzed for CLD, we collected spatial information on the physical environment and agricultural activities. Then, we searched for determinants of soil contamination and used a multiple regression model to predict the spatial distribution of CLD. First, the results showed that the soil type had a strong impact. Andosols, with a high organic carbon content (up to 100 g kg−1) and a high sorption capacity (Koc 20 000 L kg−1), had the highest CLD concentrations and stocks. Nitisols had 10-fold lower sorption capacities. Second, the results showed a "farm effect" on soil contamination, due to the more or less intensive application of inputs by farmers and to the shorter or longer application times, depending on the banana land-use frequency. However, despite these effects and given the weak accuracy of the usually available information on agricultural activities, it remained difficult to predict the spatial distribution of CLD contamination by a multiple regression model. In conclusion, this study highlighted the multifactorial nature of pollution. The main perspectives are related to better assessments of agricultural activities using remote sensing strategies and designing agricultural practices observatories focusing on pesticide use.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Chlordecone, one of the most persistent organochlorine pesticides, was applied between 1972 and 1993 in banana fields in the French West Indies, which results in long-term pollution of soils and contamination of waters, aquatic biota, and crops. As human exposure to chlordecone is mainly due to food contamination, early research was focused on chlordecone transfer to crops. Field trials were conducted to investigate chlordecone contamination of yam, sweet potato, turnip, and radish grown on a Ferralic Nitisol polluted by chlordecone. We also carried out trials on yam, courgette, and tomato under greenhouse conditions with homogenized Andosol and Nitisol, polluted by chlordecone to various extents. Our results indicated that i) all tubers were contaminated in accordance with the chlordecone content of the soils; ii) the plant contamination capacity of the Nitisol was greater than that of the Andosol; and iii) whatever the soil type, tuber contamination was related to the soil volumetric content of dissolved chlordecone. Nevertheless, no tubers showed sufficient chlordecone uptake for efficient soil decontamination by means of plant extraction. Soil contact accounted for most of the root crop contamination, which was inversely proportional to the tuber size. Internal transfer might also increase root crop contamination when the root central cylinder contained raw sap flow, as in the case of turnip or radish. Courgette fruits showed high contamination without soil contact. Thus, further research is needed to explore the pattern of both below- and aboveground plant chlordecone contamination and assess the hypothesis of its correlation with sap flow. Finally, we used our results to build a decision-making tool for farmers, relating soil pollution with the maximal contamination of the harvested organs to predict crop contamination and thus assisting farmers in making crop choices at planting in order to conform with the European Union's regulations.

International audience; Predicting the transfer of contaminants in soils is often hampered by lacking validation of mathematical models. Here, we applied Hydrus-2D software to three agricultural soils for simulating the 1900-2005 changes of zinc and lead concentration profiles derived from industrial atmospheric deposition, to validate the tested models with plausible assumptions on past metal inputs to reach the 2005 situation. The models were set with data from previous studies on the geochemical background, estimated temporal metal deposition, and the 2005 metal distributions. Different hypotheses of chemical reactions of metals with the soil solution were examined: 100% equilibrium or partial equilibrium, parameterized following kinetic chemical extractions. Finally, a two-site model with kinetic constant values adjusted at 1% of EDTA extraction parameters satisfactory predicted changes in metal concentration profiles for two arable soils. For a grassland soil however, this model showed limited applicability by ignoring the role of earthworm activity in metal incorporation

A pot experiment was conducted to investigate the effect of nickel concentration on physiological characteristics of Alyssum murale when grown in a soil mixed with sewage sludge (at the rate of 2.8%). Two types of sludge were used: agricultural sewage sludge (S1) and industrial sewage sludge with an increasing nickel concentration (S2, S3, and S4). Results showed that Ni in shoots was higher than Ni in roots. A. murale is able to concentrate up to 12730 mg/kg Ni in leaves. The highest dry matter yield was observed with plants grown with agricultural sewage sludge. An addition of S2 and S3 increased shoot biomass. However, application of S4 reduced 40% shoot dry weight as compared to the control. Ni treatment did not affect all chlorophyll fluorescence parameters. The F-v/F-m ratio was stable between Ni treatments. Photosynthesis rate (A) increased with agricultural sewage sludge, but remained stable with variable Ni rates from the industrial sludge. The chlorophyll content increased with S1, S2 and S3 but it remains constant with S4 when compared to the control. Therefore, high nickel concentration did not affect the function of the photosynthetic machine of A. murale.

Due to human activities, large volumes of soils are contaminated with organic pollutants such as polycyclic aromatic hydrocarbons, and very often by metallic pollutants as well. Multipolluted soils are therefore a key concern for remediation. This work presents a long-term evaluation of the fate and environmental impact of the organic and metallic contaminants of an industrially polluted soil under natural and plant-assisted conditions. A field trial was followed for four years according to six treatments in four replicates: unplanted, planted with alfalfa with or without mycorrhizal inoculation, planted with Noccaea caerulescens, naturally colonized by indigenous plants, and thermally treated soil planted with alfalfa. Leaching water volumes and composition, PAH concentrations in soil and solutions, soil fauna and microbial diversity, soil and solution toxicity using standardized bioassays, plant biomass, mycorrhizal colonization, were monitored. Results showed that plant cover alone did not affect total contaminant concentrations in soil. However, it was most efficient in improving the contamination impact on the environment and in increasing the biological diversity. Leaching water quality remained an issue because of its high toxicity shown by micro-algae testing. In this matter, prior treatment of the soil by thermal desorption proved to be the only effective treatment.

International audience; Genetically modified crops, that produce Cry insecticidal crystal proteins (Cry) from Bacillus thuringiensis (Bt), release these toxins into soils through root exudates and upon decomposition of residues. The fate of these toxins in soil has not yet been clearly elucidated. Persistence can be influenced by biotic (degradation by microorganisms) and abiotic factors (physicochemical interactions with soil components, especially adsorption). The aim of this study was to follow the fate of Cry1Aa Bt toxin in contrasting soils subjected to different treatments to enhance or inhibit microbial activity, in order to establish the importance of biotic and abiotic processes for the fate of Bt toxin. The toxin was efficiently extracted from each soil using an alkaline buffer containing a protein, bovine serum albumin, and a nonionic surfactant, Tween 20. The marked decline of extractable toxin after incubation of weeks to months was soil-dependent. The decrease of extractable toxin with incubation time was not related to microbial degradation but mainly to physicochemical interactions with the surfaces that may decrease immunochemical detectability or enhance protein fixation. Hydrophobic interactions may play an important role in determining the interaction of the toxin with surfaces.

The excessive concentrations of toxic heavy metals in mine tailings and their very low N content make soil reclamation strategies by phytostabilization difficult. Our objective was to test if the symbiotic association between the legume Anthyllis vulneraria subsp. carpatica and the bacteria Mesorhizobium metallidurans originating from highly polluted mine tailings is able to increase N concentration in soils with contrasting Zn, Pb and Cd contents. Plants of A. vulneraria subsp. carpatica from a mine site and of a non-metallicolous subsp. praeopera from non-polluted soil were inoculated with a metallicolous or a non-metallicolous compatible Mesorhizobium spp. and grown on low and high heavy metal-contaminated soils. In contaminated soil, many nodules were observed when the metallicolous A. vulneraria was inoculated with its rhizobium species M. metallidurans, whereas the non-metallicolous A. vulneraria died after a few weeks regardless of the rhizobium inoculant. Eighty percent of the total nitrogen was derived from biological nitrogen fixation through the association between metallicolous A. vulneraria and the rhizobium grown on metal-enriched soil. The ability of the metallicolous A. vulneraria to develop a high nitrogen fixing potential opens new possibilities for promoting a low-maintenance plant cover and for stabilizing the vegetation in high heavy metal-contaminated soils.

Despite constraining legislation and increasing efficiency of pesticides (with a decrease in the applied amounts), their use still cause a contamination of environment (air, soil and water). To conciliate agricultural and environmental interests, a better understanding of the fate of pesticides is needed, in particular because it will determine the exposure and consequently the impact of pesticides on the target and non-target organisms. This goal requires new efforts of research at different scales (from molecular to field scale). Following application, most of the pesticides reach the soil either after direct application or after foliage wash-off. As a major interface between other environmental compartments, the soil plays a preponderant buffering role in the fate of pesticides. Apart volatilization, the main processes that control the fate of pesticides in soils are retention on soil particles and degradation (biotic and abiotic). These coupled bio-physico-chemical processes can lead to a transitory or permanent accumulation of pesticides in soils or, on the contrary, to their elimination from the environment. They determine the pesticide concentration in the soil solution, and have a large influence on pesticide transfer toward ground or surface waters and on their ecotoxicological impacts on soil organisms as well. The main difficulties in studying and predicting the retention and degradation of pesticides in soils are the diversity of chemical structures and reactivities of pesticides, the high diversity of soils and their heterogeneous composition and structure. In addition, the pedoclimatic conditions, in particular soil temperature and water content, have a strong influence on retention and degradation because of their effect on soil biological, chemical and physical properties. Therefore, the objective of this chapter is to provide an overview of the factors involved in the retention and degradation of pesticides in soils and to discuss and clarify the needs of new integrated approach. In particular, this work will examine (i) the pertinent scales (among elementary constituents, aggregates and mesoscopic scales) for both retention and degradation studies, (ii) the integrative properties that should be considered, such as hydrophobicity of the organo-clay granulometric fraction or soil structure, and (iii) the primordial role of water.

Article No e18875; International audience; Many factors such as poverty, ineffective institutions and environmental regulations may prevent developing countries from managing how natural resources are extracted to meet a strong market demand. Extraction for some resources has reached such proportions that evidence is measurable from space. We present recent evidence of the global demand for a single commodity and the ecosystem destruction resulting from commodity extraction, recorded by satellites for one of the most biodiverse areas of the world. We find that since 2003, recent mining deforestation in Madre de Dios, Peru is increasing nonlinearly alongside a constant annual rate of increase in international gold price (~18%/yr). We detect that the new pattern of mining deforestation (1915 ha/year, 2006–2009) is outpacing that of nearby settlement deforestation. We show that gold price is linked with exponential increases in Peruvian national mercury imports over time (R2 = 0.93, p = 0.04, 2003–2009). Given the past rates of increase we predict that mercury imports may more than double for 2011 (~500 t/year). Virtually all of Peru's mercury imports are used in artisanal gold mining. Much of the mining increase is unregulated/artisanal in nature, lacking environmental impact analysis or miner education. As a result, large quantities of mercury are being released into the atmosphere, sediments and waterways. Other developing countries endowed with gold deposits are likely experiencing similar environmental destruction in response to recent record high gold prices. The increasing availability of satellite imagery ought to evoke further studies linking economic variables with land use and cover changes on the ground.

Soil and tailings contamination in the eastern region of Morocco was investigated by determining metallic trace elements (MTE) (As, Cd, Cu, Ni, Pb and Zn) using inductively coupled plasma-atomic emission spectrometry (ICP-AES). This work revealed extensive contamination of the sites studied and also showed a great variability in the concentrations of MTE according to the element analyzed and the site. The soil index pollution is considered very high because of the simultaneous presence of these elements. This combination of MTE in soils makes the region toxic to flora, fauna and local populations. An exploration of plant species growing on these contaminated areas will be considered in the context of the implementation of a program for phytoremediation.; La contamination des sols et des résidus miniers dans la région orientale du Maroc a été évaluée par dosage des éléments-traces métalliques (ETM) (As, Cd, Cu, Ni, Pb et Zn) par ICP-AES (inductively coupled plasma-atomic emission spectrometry). Ce travail révèle une contamination importante des sites étudiés et souligne une grande variabilité dans les concentrations en ETM en fonction de l’élément analysé et du site étudié. L’index de pollution des stations étudiées est généralement très élevé du fait de la présence simultanée de plusieurs de ces éléments. Cette combinaison de différents ETM rend les sols de la région toxiques pour la flore, la faune et les populations locales. Une analyse des espèces végétales qui se développent sur ces zones polluées est envisagée dans le cadre de la mise en place d’un programme de phyto-remédiation.

This study was designed to evaluate whether sewage sludge could be recycled in crop fields in Reunion (volcanic island in the Indian Ocean). We first quantified heavy metal (HM) concentrations (Cd, Cr, Cu, Hg, Ni, Pb and Zn) in the soils. Fifty-eight sampling sites were selected to account for the entire range of soils on the island. The Ni concentration in 86% of the studied soil samples was higher than the standard thresholds beyond which spreading is not authorized (75% for Cr and 14% for Cu). We demonstrated that the high soil Cr, Cu, Ni and Zn concentrations were mainly due to the natural pedogeochemical background. Despite these high concentrations, the mobility and phytoavailability assessed by chemical extraction were low and always below the thresholds. For these soils, we also inventoried HM concentrations in sugarcane (bagasse and juice). We demonstrated that the Cd, Cr, Cu, Ni, Pb and Zn concentrations were low and not proportional to the soilborne HM concentrations. Note that the lack of correlation between the sugarcane HM contents and the phytoavailable fraction determined by chemical extraction (1 mol L?1 NH4NO3) indicated that this was ineffective in determining the HM (Cd, Cr, Cu, Ni, Pb and Zn) phytoavailability for sugarcane. However, these overall findings could enable competent authorities to issue a waiver to authorize the use of sewage sludge in agriculture in Reunion. (Resume d'auteur)

International audience; A comprehensive field study was conducted to determine the fate of nitrogen in pig (Sus scrofa) slurry applied to an acid tropical andic soil of Réunion with the aim of estimating drainage and nitrogen leaching below the root zone. Water movement and nitrate dynamics were monitored during two successive cropping seasons on a plot (PSP) treated with liquid manure, with an input of 264 kg N ha−1 the first year and 185 kg N ha−1 the second year, in comparison to levels recorded in a unfertilized control plot (CP). The field was cropped with rainfed maize (Zea mays L.) The process-based WAVE field-scale model was used to simulate water flow and nitrogen transport in the unsaturated zone and highlight the main processes controlling water and N fate. A calibration procedure was performed one year, while the prediction capability of the model was assessed during another cropping year. A sensitivity analysis was performed to address some critical parameters. Due to the high hydraulic conductivities measured in this andic soil, the drainage risk became high when the rain intensity was above 30 mm d−1 and the soil humidity was close to saturation. The time between the first slurry application on PSP and the nitrate onset in the drainage water at 135 cm depth (about 15 months) was attributed to nitrate adsorption on the soil particles (the retardation factor was estimated at 2.6 in the surface layer and 1.5 in deeper layers) and to the fact that the water stored in the 0–135 cm soil layer was slowly displaced. The nitrate migrated in this andic soil at rate of about 50 mm per 100 mm of infiltrated water. The main features of the experimental values of state variables (water content, water pressure head, NO3− concentration, natural mineralization and nitrification of the pig slurry ammonium at different depths and dates) as well as the water fluxes across boundaries were generally correctly reproduced by WAVE for both plots. The calibrated modelled budget error arising from net mineralization was +15 and +9 kg N ha−1 for CP and PSP, respectively. For the model evaluation, it was estimated at −9 and −13 kg N ha−1, respectively, which was considered as very acceptable. WAVE required refinements in some processes and parameters but was still found to be robust enough to work in conditions for which it was not primarily designed. Abbreviations: CP, control plot; DAS, day after sowing; PSP, pig slurry plot; TDR, time domain reflectometry; WAVE, Water and Agrochemicals in the Vadose Environment model

International audience; Recycling sewage sludges as fertilisers on soils for crop production has several potential benefits such as providing large amounts of phosphorous and organic matter. However, the spreading of urban sewage sludge is a constant cause of controversy because it is known to introduce potentially toxic trace metals into the soil, particularly cadmium. In order to clarify this debate, this review article presents a synthesis of the results of several studies carried out in France on the impact of sewage-sludge spreading. This article reports mainly Cd results but also some results on other trace metals such as Cr, Cu, Hg, Ni, Pb and Zn. Two kinds of data are presented: (1) soil data including total metal contents and data from partial extraction to evaluate the phytoavailable fractions, and (2) plant data including metal content of wheat, a major agricultural crop. The field experiments involved very different amounts of applied sewage sludges and Cd. Indeed, three categories of experiments stand out, the first and second involving high amounts of applied Cd, and the third involving low amounts of applied Cd: (1) during the 1970s and '80s, sludges with a high trace metal content, especially Cd, were spread at the INRA trials at Couhins experimental farm on sandy soils and in the Vexin area on silty topsoils. The quantities of applied Cd were very high, ranging from 3600 g to 641 000 g per ha. Here, the results show a notable impact on total Cd contents of topsoil and cereal grains. (2) Sludges containing high levels of industrial cadmium were spread on acid soils in the Limousin region for more than twenty years up to 1998. Topsoil Cd contents were measured in fields where the cadmium input was highest, of 300 to 600 g Cd per ha. Here, a clear increase in the Cd content of cereal grains was found. (3) During the 1990s and 2000s, numerous experiments with sewage-sludge applications compatible with the new French regulations of 1998 were implemented. The amounts of applied Cd were therefore much lower, from 0.6 to 270 g/ha. Here, no impact was detected on the composition of cereal grains. This review article concludes that the application of huge quantities of sewage sludges in the 1970s and '80s had a clear and long-lasting effect on both soil and grain Cd compositions. Nonetheless, spreading sewage sludge in accordance with the new French regulations had no significant impact on soil and cereal-grain Cd concentrations.

Correspondance auteur: Jean-Baptiste Charlier jb.charlier@gmail.com; International audience; The aim of this article is to determine how the nematicide cadusafos [S,S-di-sec-butyl O-ethyl phosphorodithioate] contaminates water and soils at two scales, subcatchment and catchment. The study site was a small banana (Musa spp.)-growing catchment on the tropical volcanic island of Guadeloupe in the Caribbean. Two application campaigns were conducted, one in 2003 on 40% of the catchment and one in 2006 on 12%. The study involved monitoring for 100 d the surface water and groundwater flows and the cadusafos concentrations in the soil and in surface and groundwaters in a 2400 m2 subcatchment and a 17.8 ha catchment. The results show that at the subcatchment scale the high retention in the A horizon of the soil limits the transport of cadusafos by runoff, whereas the lower retention of the molecule in the B horizon favors percolation toward the shallow groundwater. Comparing the losses of cadusafos at the subcatchment and at the catchment scales revealed that the nematicide re-infiltrated in the hydrographic network. Two successive phases of stream water contamination were observed, corresponding to two distinct contamination mechanisms: an event-dominated contamination phase (of

International audience; The role of land use on fate of metals in soils is poorly understood. In this work, we studied the incorporation of lead in two neighboring soils with comparable pedogenesis but under long-term different agricultural management. Distributions of anthropogenic Pb were assessed from concentrations and isotopic compositions determined on bulk horizon samples, systematical 5–10 cm increment samples, and on 24-h EDTA extracts. Minor amounts of anthropogenic lead were detected until 1-m depth under permanent grassland, linked to high earthworm activity. In arable land, exogenous Pb predominantly accumulated at depths

Kinetic EDTA and citrate extractions were used to mimic metal mobilization in a soil contaminated by metallurgical fallout. Modeling of metal removal rates vs. time distinguished two metal pools: readily labile (QM1) and less labile (QM2). In citrate extractions, total extractability (QM1 + QM2) of Zn and Cd was proportionally higher than for Pb and Cu. Proportions of Pb and Cu extracted with EDTA were three times higher than when using citrate. We observed similar QM1/QM2 ratios for Zn and Cu regardless of the extractant, suggesting comparable binding energies to soil constituents. However, for Pb and Cd, more heterogeneous binding energies were hypothesized to explain different kinetic extraction behaviors. Proportions of citrate-labile metals were found consistent with their short-term, in-situ mobility assessed in the studied soil, i.e., metal amount released in the soil solution or extracted by cultivated plants. Kinetic EDTA extractions were hypothesized to be more predictive for long-term metal migration with depth.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Abstract: In tropical humid environments under intensive banana production, pesticide transfer in waters can be of particular concern due to heavy rainfall, steep slopes, and soils with high infiltration capacities. The transfer in percolation and runoff waters of the nematicide cadusafos was investigated during a three month field experiment. The spatial heterogeneity of the banana plantation was taken into account by measuring percolation fluxes both under the banana plants and in the interrows with a specially designed lysimeter device installed at 60 cm depth. At the field scale, 0.34% of the pesticide applied was transferred in percolation, 0.13% in runoff. Forty-nine percent of cadusafos losses occurred by percolation under the banana plants, 23% by interrow percolation, and 28% by runoff. Losses were highest during the three weeks following cadusafos application, and this is also when dissipation in the soil was highest (calculated half-life in the soil: 7d). After this period, losses of cadusafos were low, both in soil and waters. Under the banana plant, saturated fluxes carried most of the pesticide, despite total percolation fluxes being at least five-times higher than saturated ones. Although overall pesticide transfer in water was low (0.5% of applied), it was not negligible due to the frequency of pesticide application in these areas

International audience; Studies relating macro- and microscopic aspects of impacts of long-term contaminative practices on soils are scarce. We performed such an approach by assessing the fate of metal pollutants in an area close to Paris, where sandy Luvisols were irrigated for 100 years with urban waste water. As a result, these soils display strong accumulation of organic matter, dissolved salts and metal pollutants in surface horizons, but also migration of metals to depth. We examined soil development and metal distribution patterns in two irrigated soils, in comparison with a non-irrigated reference soil. Soil macromorphological characteristics were studied in the field. Soil micromorphology and micro-scale metal distributions were both studied in situ in thin sections, the latter by synchrotron X-ray mapping. Microscopic study focussed on characteristic parts of the Ap and Bt horizons, mainly involved in metal retention. For Ap horizons, both large and diffuse metal concentrations were revealed, mainly associated with organic matter and dissolved components added by irrigation water. For Bt horizons, zinc accumulation was detected on clay-iron coatings. Our results suggest that with time, a double metal-filtering capacity has developed in these sandy Luvisols: in the Ap horizon, an anthropogenic filter resulted from input of metal pollutants together with highly reactive organic matter, carbonates and phosphates, thus favouring metal immobilization and limiting migration to depth. In the Bt horizon, the evidence is of a second, natural filter. However, this filtering capacity is endangered by clay destruction due to ferrolysis, as revealed by micromorphology. Ferrolysis, here initiated by intensive irrigation practices, leads to a reduction of the natural filtering potential and an increasing risk of metal transfer towards the groundwater.

The use of sewage sludge as a fertilizer and soil amendment has resulted in high concentrations of heavy metals in the soil limiting its use. The present study was carried out to find the possibility of phyto-separating toxic and beneficial elements from the sludge using suitable plants. Of the five plants tested the hyperaccumulator Sedum alfredii H achieved the greatest removal of Zn, while shoots of Alocasia marorrhiza accumulated high content of K. Co-cropping these two plants on the sludge verified the previous observations on A. marorrhiza and the shoots of this plant could accumulate more than 120 g K kg(-1) dry matter in the median growth stage. Zn hyperaccumulated in Sedum's shoots to an extent more than 10 g kg(-1) dry matter; K concentrated five to ten times in the Alocasia's shoots which could be used as a good organic-K-fertilizer. Hence, the two elements were simultaneously phytoseparated and could be recycled. Furthermore, cultivation of plants in the sludge resulted in significant decreases in total Zn but kept the favorable agronomic characteristics of the sludge material, such as pH, organic matter content, and NPK concentrations and ameliorated its biological stability. These results suggest that simultaneous phyto-separation of toxic and beneficial elements from sewage sludge are possible by co-cropping using specific plants without the input of any chemicals.

Avant-propos (foreword); International audience

Municipal solid waste incinerator (MSWI) bottom ash may be used as a road construction material; it potentially contains however a sizable quantity of heavy metals, which under the effect of rainfall infiltration through the road structure can be leached out from the material and infiltrate into the underlying soil. An eco-compatibility assessment of MSWI bottom ash reuse in road construction applications necessitates examining the solubility and retention of heavy metals in road soils. This study is dedicated to Pb transfer, sorption and desorption (NEN 7341 standard test) within various soils. These experiments yield results relative to the interaction between road soils and an MSWI bottom ash leachate representative of a “fresh” product, with a high leaching potential. For the soils investigated, the sorption of lead varies between 90% and 99%. For an extraction at pH 7, Pb release is very low (