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Heavy metal (HM) pollution in agricultural fields reduces crop productivity and quality, and poses a risk for human health. On these areas, the cultivation of crops devoted to biomaterial and bioenergy production thus constitutes an attractive alternative to food crop production. To maintain the soil productivity and to obtain a biomass compatible with the requirements of industry, the use of the beneficial metalloid silicon, applied on leaves during plant growth, has been considered. A field study using Cannabis sativa L. (cv. Futura 75) was performed during 2 consecutive years on two sites (one soil parcel contaminated with Cd, Zn and Pb, and one taken as uncontaminated control) in the North of France. One half of the plants received weekly foliar spray of Si (2 mM). Photosynthesis-related parameters were analysed in situ, while mineral concentration and fibre properties were determined after 4 months of culture. Our results suggest that Si application improves and preserves the mechanical properties of fibres when plants are exposed to HM stress. Si was also shown to increase by 27% the Cd concentration in leaves and by 30% the Zn concentration in stems. Contaminated fibres and shives containing immobilized HM could be used for specific purposes such as inclusion in cement aglomerates.

The positive impact on restoring soil functionality, decreasing toxic elements (TE) bioaccessibility, and enhancing soil physicochemical and biological parameters established a consensus on considering a

This study was designed to assess the impact of the mixture of cadmium (Cd) and zinc (Zn) on the bioaccumulation and the ultrastructural changes in the hepatopancreas of Porcellio laevis (Latreille, 1804) after 4 weeks of exposure to contaminated Quercus leaves under laboratory conditions. For each metal, four concentrations were used with four replicates for each concentration. Metal concentrations in the hepatopancreas and the rest of the body were determined using atomic absorption spectrometry. From the first week until the end of the experiment, a weight gain in P. laevis was observed particularly between the first and the end of exposure from 93.3 ± 18.22 mg fw to 105.22 ± 16.16 mg fw and from 106.4 ± 22.67 mg fw to 125.9 ± 23.9 mg fw for Mix1 and Mix4, respectively. Additionally, the determined metal trace elements (MTE) concentrations in the hepatopancreas were considerably higher compared to those in the rest of the body and seem to be dose-dependent. Using transmission electron microscopy (TEM), some alterations were highlighted in the hepatopancreas. The main observed alterations were (a) the destruction of the microvilli border in a considerable portion of cells, (b) the increase of the lipid droplets with different shapes and sizes, (c) the increase in the number of the mitochondria, and (d) the appearance of TE in the form of B-type granules. The obtained results confirmed the ability of P. laevis to deal with high amounts of MTE, suggesting its possible use in future soil's biomonitoring programs.

ACL; The present study experimented five biochars, one made from wood (400 °C, 12 h) and four made from miscanthus cultivated on contaminated soils (temperature 400/600 °C, duration 45/90 min). They were used as amendments at a 2% application rate on soil, cultivated or not cultivated with ryegrass, contaminated with (i) metals (Cd, Pb, and Zn), (ii) eight polycyclic aromatic hydrocarbons (PAHs), and (iii) a mix of metals and PAHs. The objectives were (i) to compare the effectiveness of the five biochars on soil parameters and pollutant availability and (ii) to determine the influence of soil multicontamination and ryegrass cultivation on biochar effectiveness. The results showed that biochar application did not necessarily lead to lower pollutant extractability and metal bioaccessibility. However, differences were highlighted between the biochars. The miscanthus biochars produced at 600 °C (BM600) showed higher effectiveness at decreasing metal extractability than the miscanthus biochars produced at 400 °C (BM400) due to its better sorption characteristics. In addition, ryegrass cultivation did not impact pollutant availability but modified metal bioaccessibility, especially for the soil amended with the BM600 and the woody biochar. Moreover, the presence of PAHs also negatively impacted the metal bioaccessibility in the soil amended with the BM600, and, on the contrary, positively impacted it in the soil amended with the BM400. Complementary studies are therefore necessary to understand the mechanisms involved, particularly in a context where soils requiring remediation operations are often multicontaminated and vegetated.

International audience; Miscanthus × giganteus demonstrated good phytostabilization potentials in toxic element (TE) contaminated soils. However, information about its tolerance to elevated concentrations is still scarce. Therefore, an ex-situ pot experiment was launched using three cultivars (termed B, U, and A) grown in soils with a gradient Cd, Pb and Zn concentrations. Control plants were also cultivated in non-contaminated soil. Results show that the number of tillers per plant, stem diameter as well as leaf photosynthetic pigments (chlorophyll a, b and carotenoids) were negatively impacted by soil contamination. On the other hand, phenolic compounds, flavonoids, tannins, and anthocyanins levels along with the antioxidant enzymatic activities of superoxide dismutase, ascorbate peroxidase and glutathione reductase increased in the plants grown on contaminated soils. Altogether, these data demonstrate that miscanthus is impacted by concentrations of toxic elements yet is able to tolerate high levels of soil contamination. These results may contribute to clarifying the miscanthus tolerance strategy against high contamination levels and its efficiency in phytoremediation.

We assessed the relationship between the diffusive gradient in thin film (DGT) technique using the new ion-exchange resin Ambersep GT74 and the uptake of mercury (Hg) by a model plant cultivated on metal-contaminated agricultural soils under greenhouse conditions. Based on the total Hg content, 0.37 to 1.17% of the Hg passed to the soil porewater from the solid phase, and 2.18 to 9.18% of the Hg is DGT-available. These results were confirmed by calculating the R value (the ratio of the concentrations of bioavailable Hg measured by DGT and soil solution), which illustrated the strong bonding of Hg to the solid phase of soil and its extremely low mobility. Only inorganic Hg2+ species were found in the metal-contaminated agricultural soils, as determined by a high-performance liquid chromatography-cold vapor atomic fluorescence spectrometry speciation analysis. The Hg was distributed in Miscanthus × giganteus organs in the following order for all sampling sites: roots (55-82%) >> leaves (8-27%) > stems (7-16%) > rhizomes (4-7%). Environ Toxicol Chem 2019;38:321-328. © 2018 SETAC.

Phytomanagement is proposed as a cost-effective and environmentally-friendly suggestion for sustainable use of large metal-contaminated areas. In the current work, the energy crop miscanthus (Miscanthus × giganteus) was grown in ex situ conditions on agricultural soils presenting a Cd, Pb and Zn contamination gradient. After 93 days of culture, shoot and root growth parameters were measured. Soils and plants were sampled as well to study the TE accumulation in miscanthus and the effects of this plant on TE mobility in soils. Results demonstrated that miscanthus growth depended more on the soils silt content rather than TE-contamination level. Moreover, soil organic carbon at T93 increased in the soils after miscanthus cultivation by 25.5–45.3%, whereas CaCl2-extractible TEs decreased due to complex rhizosphere processes driving plant mineral uptake, and organic carbon inputs into the rhizosphere. In the contaminated soils, miscanthus accumulated Cd, Pb and Zn mainly in roots (BCF in roots: Cd '' Zn > Pb), while strongly reducing the transfer of these elements from soil to all organs and from roots to rhizomes, stems and leaves (average TFs: 0.01–0.06, 0.11–1.15 and 0.09–0.79 corresponding to Cd, Pb and Zn respectively). Therefore, miscanthus could be considered a TE-excluder, hence a potential candidate crop for coupling phytostabilization and biomass production on the studied Metaleurop TE-contaminated soils.

International audience; Incidental ingestion of polluted soil particles exposes the population to toxic metal(loid)s. To refine the methods of exposure and risk assessment, it is relevant to use bioaccessible concentrations of metal(loid)s determined via in vitro digestion methods. However, some validated methods are complex and costly, involving high technical skills and numerous reagents. The objective of the present study was to evaluate the suitability of four simple chemical extractions to mimic the bioaccessible fraction of As, Cd, and Pb in the gastric (G) and gastrointestinal (GI) phases obtained using the validated UBM (unified bioaccessibility method) test. Acetic acid (0.11 M), citric acid (0.11 M), EDTA (0.16 M), and hydrochloric acid (HCl, 0.65%) were separately tested in 201 soil samples with a wide range of physicochemical parameters and metal(loid)s concentrations. Significant linear relationships were observed with HCl, EDTA, and to a lesser extent with citric acid. For the cheaper HCl method, correlations with the UBM ranged from 0.91 to 0.99 for the G phase and from 0.72 to 0.97 for the GI phase. This test can be used at least as a first-tier screening to assess the oral bioaccessibility of As, Cd, and Pb.

International audience; Human health risk assessment (HHRA) and ecotoxicological risk assessment (ERA) of contaminated soils are frequently performed separately and based on total soil concentrations without considering the concepts of mobility, bioaccessibility and bioavailability. However, some chemical and biological assays rarely used in combination can be applied to more accurately assess the exposure of organisms to metal(loid)s and thus to better estimate the links between soil contamination and effects. For humans, the unified bioaccessibility method (UBM) assesses oral bioaccessibility, while for soil fauna such as land snails, the bioaccumulation test reflects the bioavailability of contaminants. The aim of this study is to explore the relationship between oral bioaccessibility and the bioavailability of arsenic, cadmium and lead in twenty-nine contaminated soils. The results show a modulation of bioaccumulation and bioaccessibility of metal(loid)s by soil physicochemical parameters (organic matter especially). For the three metal(loid)s studied, strong relationships were modelled between the UBM and snail tests (0.77

Miscanthus x giganteus is suggested as a good candidate for phytostabilization of metal-polluted soils. Its late harvest in winter generates large amounts of leaf litter on the soil surface. However, little is known about the mobility and the bioavailability of metals following leaf decomposition and the consequences on the succeeding culture. Ex situ artificial aging for 1, 3, and 6 months was conducted with miscanthus leaf fragments incorporated into three agricultural soils displaying a gradient concentration in Cd (0.6, 3.1 and 7.9 mg kg−1), Pb (32.0, 194.6 and 468.6 mg kg−1), and Zn (48.4, 276.3 and 490.2 mg kg−1) to simulate the leaf litter input over 20 years of miscanthus culture. We investigated the impacts on physicochemical and biological soil parameters, CaCl2-extractable metal, and their subsequent ryegrass shoot concentrations, and hence on ryegrass health. The results showed that the amended soils possessed higher pH along with greater available phosphorous and soil organic carbon values. The respiratory activity and microbial biomass carbon in the amended soils increased mainly after 1 month of aging, and decreased afterwards. Despite the higher Pb- and Zn–CaCl2 extractability in the amended soils, the phytoavailability slightly increased only in the most contaminated soils. Moreover, leaf incorporation did not affect the ryegrass biomass, photosynthetic pigment contents, nor the antioxidative enzyme activities. Conclusively, leaf incorporation induced slight variations in soil physicochemical and biological parameters, as well as metal extractability, but not to an extent that might cause a considerable threat to the subsequent culture. Nevertheless, these results are preliminary data that require confirmation by long-term in-situ experimentations as they reflect the modelization of long-term impact of leaf decomposition on soil-plant system.

COM; International audience

Le jardinage se pratique de plus en plus souvent en milieu peri-urbain ou urbain. Se pose alors la question de la qualite des sols, des productions cultivees et des composts autoproduits au regard des pollutions resultant des activites industrielles actuelles et/ou passees. En partenariat avec les services sanitaires, des investigations ont ete menees dans des jardins privatifs urbains en vue de mieux evaluer l’exposition aux polluants metalliques, et plus particulierement au cadmium et au plomb, des jardiniers et leur famille. Dans cet article est presente le retour d’experience d’une demarche originale basee sur l’acquisition d’un grand jeu de donnees environnementales et sociales.

The C18 column (250 mm × 4.6 mm) packed with 5 μm core-shell particles was used in an effort to optimize the separation of 8 polycyclic aromatic hydrocarbons under very low pressure values (44–52 bars), low temperature (16 °C) and in 13 min. Chromatogram and peaks of each polycyclic aromatic hydrocarbon studied, obtained using an ultra fast liquid chromatography fitted with this column and equipped with a diode array detector, were compared with those obtained using two other traditional C18 columns, packed with fully porous 5 μm particles, usually used in our laboratory and specifically designed for the separation of polycyclic aromatic hydrocarbons. Thinnest peaks, highest sensitivity and efficiency are the main results related to the core-shell technology of the recent Kinetex column compared to more common C18 columns due to the bed uniformity and packing quality of the recent core-shell column. On the other hand, reduced retention time was highlighted for each polycyclic aromatic hydrocarbon using the column packed with core-shell particles resulting from the lower surface area of these particles compared to the totally porous particles of the both other columns used. Limits of detection and quantification, linearity range and repeatability were determined for the method developed with the core-shell column. A practical application was realized by evaluating the sorption capacity of the 8 polycyclic aromatic hydrocarbons studied in mixture using a biochar made from woody plants. To this end, the biochar was mixed with aqueous solution spiked with the mixture of polycyclic aromatic hydrocarbons and a kinetic study of their sorption was conducted. Sorption percentage was higher than 89% for each polycyclic aromatic hydrocarbon studied showing that the studied biochar could be good and low cost alternative products for the sorption of this type of pollutants.

Phytostabilization can be an appropriate choice for managing soils contaminated by diverse metals. Miscanthus x giganteus was selected to phytostabilize polluted soils surrounding the former lead smelter Metaleurop Nord, in Northern France. The aim of the current study was to determine the impact of miscanthus plants on restoring the corresponding soil functionality. Ex situ experiments revealed that soil biological activities (basal respiration, fluorescein diacetate hydrolytic activity, acid phosphatases, laccases and ureases) as well as microbial biomass carbon increased in contaminated soils cultivated with miscanthus, compared to unplanted soils. These results verify the capacity of miscanthus to restore polluted soil functionalities, indicating the positive effect of phytostabilization on soil biological activities. In conclusion, revegetating polluted soils with miscanthus plants can restore their capacity to perform biochemically and biologically.

The objective of this study was to evaluate the sorption efficiency of eight biochars, made from Miscanthus x giganteus cultivated on contaminated agricultural soil, in aqueous solutions contaminated with metals alone or mixed with polycyclic aromatic hydrocarbons. These biochars were produced in different pyrolysis conditions (temperature, 400/600 °C; heating rate, 5/10 °C min−1; duration, 45/90 min) and compared with an uncontaminated commercialized biochar made of wood. The physicochemical characterization of the Miscanthus biochars confirmed the impact of the pyrolysis on the biochar parameters with substantial differences between the biochars in terms of pH, cation exchange capacity, and specific surface area. The sorption experiment showed higher sorption efficiency of Cd, Pb, and Zn for the Miscanthus biochars produced at 600 °C compared with the biochars produced at 400 °C when the aqueous solutions were mono- or multicontaminated. Furthermore, the desorption study showed that the sorption process was largely irreversible. Therefore, the high sorption capacity of Miscanthus biochars and the low sorption reversibility confirmed that these biochars are a suitable sorbent for metals.

The behaviour of metals mainly depends on soil pH, carbonate contents and contamination level, which should be considered for the management of contaminated soils. In this study, kitchen garden topsoils (0–25 cm) were sampled from the area around three smelters in France, with different Cd and Pb contamination levels. Effect of a phosphate amendment (a mixture of diammonium phosphate and hydroxyapatite) on the environmental availability and phytoavailability of Cd and Pb was evaluated by different chemical extractions and cultivating lettuce (Lactuca sativa L.), respectively. Changes in the distribution of Cd and Pb were found in most contaminated soils after phosphate amendment. An increase of Cd and Pb in the residual phase was highlighted in almost all carbonated contaminated soils, whereas a decrease of Pb in the exchangeable, water and acid-soluble phase was observed in most contaminated soils with the lowest carbonate contents. The concentrations of extractable Cd and Pb using calcium chloride and acetic and citric acids generally decreased after the soil amendment. Lettuces grown on amended soils were acceptable for human consumption as regard to Pb concentration. In contrast, some lettuces were unacceptable for human consumption, since the concentrations of Cd in the leaves were higher than the European legislation limit. Surprisingly, in carbonated soils with very low concentration of Cd, the Cd concentrations in lettuce reached up to the European legislation limit, making the lettuce unacceptable for human consumption. Our study highlighted the fact that the total metal concentration in soils does not always allow to predict the metal accumulation in the edible parts of vegetables in order to make a judgement about their acceptability or unacceptability for human consumption.

The most recent in vitro tests used to determine metal bioaccessiblility are generally time-consuming and expensive. This study aimed at determining potential relationships between the concentrations of metals extracted using single-extraction methods and the concentrations of bioaccessible metals assessed by a harmonised in vitro test, the Unified BARGE Method (UBM). A total number of 27 soil samples were collected from kitchen gardens and lawns with various physicochemical parameters and contamination levels. Significant relationships were obtained between Cd, Pb and Zn extracted in gastric and gastrointestinal phases and using single extractions. The best relationhips were established using acetic and citric acids for Cd, whereas for Pb, citric acid and ethylenediaminetetraacetic acid (EDTA) were identified as the best extractants. These relationships were improved by means of a linear multiple regression with a downward stepwise procedure involving agronomic parameters (soil cation exchange capacity and assimilated P). This method highlighted the fact that the cation exchange capacity and P contents in soils were the two main parameters that controlled the human bioaccessibility of Cd, Pb and Zn in the gastric phase. Besides, the metal concentrations extracted with the acetic and citric acids correlated well with the metal concentrations in the gastric and gastrointestinal phases, suggesting that the bioaccessible metals were mainly in a soluble form, weakly bound to the organic matter and associated with the carbonates and the Fe and Mn oxides/hydroxides in soils.

Dredging and disposal of sediments onto land sites is a common practice in urban and industrial areas that can present environmental and health risks when the sediments contain metallic elements. The aim of this study was to characterise and study the environmental and toxicological availability of Cd and Pb in anthroposols from dredged river sediments. To do this, 67 surface samples spread over 12 sediment disposal sites in northern France were studied. The results showed substantial heterogeneity for this matrix in terms of physicochemical parameters and contamination degree; however, ascending hierarchical clustering made it possible to classify the samples into eight groups. For each group, the mobile fraction of Cd and Pb was studied using single EDTA extraction, solid-phase distribution was analysed with sequential extractions and toxicological availability was assessed with the oral bioaccessibility test. The results showed that (i) Cd had a higher environmental and toxicological availability than Pb; (ii) this availability depends on the physicochemical characteristics of the matrix; and (iii) it is necessary to take into account the environmental and toxicological availability of contaminants when requalifying these sites in order to propose appropriate management measures. In the first years after sediment disposal, it would appear that the environmental and toxicological availability of Cd and Pb increased (from 52.5 to 71.8% and from 28.9 to 48.9%, respectively, by using EDTA and from 50.2 to 68.5% for Cd with the bioaccessibility test). Further studies would therefore be required to confirm this trend and understand the mechanisms involved. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

ACTN; International audience

ACL; This study aimed at determining the competition of cadmium (Cd), lead (Pb), zinc (Zn) and copper (Cu) on their assimilation, on the food consumption and the growth of terrestrial isopod Porcellio laevis. Individuals were exposed to artificially contaminated litter of Quercus for 4 weeks and were weekly weighed. At the end of the experiment, the concentration of Cd, Pb, Zn and Cu in individuals were measured by atomic absorption spectrometry. Biological parameters such as growth, and bioaccumulation factor (BAF) were calculated and results from the various treatments were compared. Depending on metals, weight loss or gain were recorded for isopods during the four weeks of exposure. A weight loss was measured on individuals exposed to Cd-contaminated litter whereas a weight gain was highlighted for those exposed to the Zn-contaminated litter. BAF values revealed that P. laevis was macroconcentrator of Zn and Cu and deconcentrator of Cd and Pb

ACL; To evaluate the influence of soil contamination on the distribution of terrestrial isopods, species richness, relative abundance, and diversity, various indices were studied in 20 sampling sites from five industrial areas located in Sfax (SE Tunisia). The following hypotheses were tested: (1) is isopod diversity affected by soil properties? (2) What are the environmental factors that influence the isopod distribution? A total of 445 individuals were sampled and eight species of terrestrial isopods were identified. Porcellionides pruinosus was the most abundant species (38%); however, the highest specific richness per area was equal to four species. To evaluate the impact of metal contamination on isopod distribution, cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), and iron (Fe) concentrations were measured in soils and terrestrial isopods. Moreover, multivariate analyses revealed a negative correlation between heavy metal concentrations and ecological parameters suggesting an impact of the contamination degree on biodiversity. In addition, to characterize the heavy metal accumulation in isopods, the bioaccumulation factor (BAF) was determined and revealed that Cu and Zn were the most accumulated elements. Results showed that for all species, the order of the BAF values is as follows: Cu ≫ Zn ≫ Cd > Pb > Fe. On the contrary, all species seemed to be deconcentrators of Fe and Cd, with some exceptions.

This study aimed at evaluating the impact of the use of fly ash-aided phytostabilisation as a method to manage highly metal-contaminated soils on soil functionality taking into account the soil and the litter qualities, the Diptera larvae communities and the microbial activity. To reach this goal, 70 parameters were studied. The main results showed that the two studied fly ashes Soproline® and Sodeline® had a positive influence on soil characteristics especially the availability of metals, nearly 14 years after amendment. Regarding biological parameters, no positive or negative effects were found by adding fly ashes to the soil concerning soil basal respiration and urease activity. The fungal activity was even enhanced. In the same way, the fly ashes had no negative effect on the Diptera larvae community and a greater richness of larvae was even found in amended soils. Thus, this study confirmed that aided-phytostabilisation using these fly ashes should be an advantageous technique to manage metal-polluted soils and to recycle industrial wastes.

ACTN; International audience; La reconquête des friches industrielles présente des enjeux environnementaux et sanitaires d’envergure. Dans cet objectif, les phytotechnologies sont présentées dans la littérature comme un mode de gestion innovant, transitoire ou pérenne, et limitant la dispersion des polluants en protégeant les sols de l’érosion. Elles peuvent réduire la disponibilité des polluants. Néanmoins, ces techniques manquent encore de recul opérationnel [1]. Le projet MisChar, soutenu par l’ADEME, vise à apporter un regard scientifique, technique et économique sur différents modes de gestion appliqués sur des sols multicontaminés par des activités industrielles passées. Une expérimentation a été mise en place avec pour objectif d’étudier les effets de modes de gestion basés sur l’utilisation d’un amendement des sols, l’installation de communautés végétales et des pratiques usuelles d’entretien des espaces verts. Elle concerne une parcelle située dans l’ancien Bassin minier du Nord – Pas de Calais sur laquelle ont été déposés des matériaux multicontaminés issus de la carbochimie (usines de Mazingarbe). Au printemps 2018, 20 placettes d’une surface de 20 m² ont été définies. Le sol de 10 de ces placettes a été amendé au moyen d’un mélange de biochar de miscanthus et de compost de déchets verts. Les 10 autres placettes ont été utilisées comme témoin. A chacune de ces placettes correspond un type d’ensemencement particulier et un mode de gestion distinct. Ainsi, diverses essences végétales ont été semées. Il s’agit (1) d’un mélange d’espèces classiquement mis en oeuvre sur les espaces verts (ray-grass anglais, fétuque rouge gazonnante, fétuque rouge traçante et pâturin des prés), (2) d’un mélange d’espèces sélectionnées pour leurs comportements présumés vis-à-vis des polluants (stabilisation des polluants métalliques, rhizo/phytodégradation de certains polluants organiques (ray-grass anglais, agrostide stolonifère, fétuque rouge, trèfle blanc), et des mêmes espèces en implantation monospécifique avec (3) un ray-grass, (4) une agrostis stolonifère, (5) un trèfle blanc, et (6) une fétuque rouge. Une septième modalité correspond à l’installation d’une végétation spontanée. Aux espèces implantées en mélange et à la végétation spontanée, correspondent deux modes de gestion (tonte ou pas du couvert végétal). Durant les trois années d’expérimentation seront étudiés le comportement des polluants des sols, les effets des modes de gestion sur les communautés végétales et d’une façon globale, sur la fonctionnalité des sols.

ACTN; International audience

ACTN; International audience

ACTN; International audience; L’épandage de digestats de méthanisation, issus d’intrants agricoles provenant d’une zone contaminée en métaux, interroge sur le devenir des polluants et le comportement des cultures. Pour apporter des éléments de réponse, des digestats de méthanisation ont été élaborés à partir de productions issues ou non de la zone affectée massivement par les émissions passées de Metaleurop Nord (Noyelles-Godault). Une culture de ray-grass a été réalisée en serre sur deux terres prélevées dans l’horizon labouré de deux parcelles situées ou non sous l’influence de l’ancienne fonderie de plomb et de zinc. Ce protocole expérimental a été complété avec une modalité comportant une fertilisation minérale NPK et un témoin (eau). Sur la terre non contaminée, l’ajout des digestats solides contaminés ou non n’a pas eu d’effet sur le rendement des feuilles de ray-grass alors que sur la terre contaminée a été constaté un accroissement notable de la biomasse. La contamination de la terre contaminée a été soulignée par la modalité témoin (eau) ; les concentrations en Cd, Pb et Zn dans les parties aériennes du ray-grass cultivé sur la terre contaminée sont respectivement près de 5, 2 et 5 fois plus élevées que celles se rapportant au ray-grass récolté sur la terre non contaminée. Les concentrations en Cd et Zn du ray-grass cultivé sur la terre non contaminée amendée n’ont pas montré de différence avec celles du témoin. L’apport de digestat issu des productions de la zone Metaleurop a augmenté les concentrations en Cd et Zn dans les feuilles de ray-grass cultivé sur la terre contaminée par rapport au témoin. Toutefois, cet accroissement n’a pas été significativement différent de celui constaté avec l’apport de digestat issu de végétaux non contaminés ou de fertilisants minéraux. Ceci laisse donc penser que l’accroissement des concentrations en métaux dans le ray-grass est davantage lié à la contamination des sols qu’aux contaminants apportés avec les digestats.

The ultrastructural changes on the hepatopancreas of Porcellio laevis individuals were investigated after their exposure to a mixture of cadmium (Cd) and zinc (Zn) during four weeks. At the end of the experiment, trace element (TE) concentrations were determined using atomic absorption spectrometry (AAS). The growth of individuals was calculated and compared among the treatments. From the first week until the end of the experiment, a weight gain was observed in P. laevis individuals. Additionally, the TE concentrations in the hepatopancreas and in the rest of the body were considerable and seem to be dose dependent. Moreover, our results confirmed the role of the hepatopancreas as the main storage organ. Thus, the conducted transmission electron microscopy highlighted remarkable alterations on the hepatopancreas cells resulting from the Cd and Zn bioaccumulation. The displayed alterations are principally the disorganization of the S- and B-cells leading to a destruction of the microvilli border, an increase of the lipid droplets and mitochondria as well as the appearance of trace elements in the form of B-type granules. Based on the obtained results herein, we can conclude that Porcellio laevis might be a good candidate in the prevention of TE pollution in the terrestrial ecosystems.

ACL; The immobilizing effects of wood biochar (BW2%) and iron grit (Z1%) applied alone or in combination (BW2% + Z1%) to agricultural (M750) and brownfield (MAZ) soils highly contaminated by metals were assessed in a greenhouse experiment. The results showed that Z1% and BW2% + Z1% were the most efficient amendments to reduce Cd, Cu, Pb, and Zn mobility, environmental availability, and phytoavailability in the M750 soil. The oxidation of Z1% allowed part of the Cu and Zn pools present in exchangeable or carbonate-bound forms (labile fraction) to complex in less mobile forms. In this soil, the metal chemical extractions (0.01 M CaCl2 and 0.05 M EDTA) and the DGT (diffusive gradient in thin films) devices to assess metal in soil solution and soil pore water (SPW) also highlighted the immobilizing characteristic of Z1%. In most cases, the addition of BW2% to Z1% (BW2% + Z1%) did not improve this effect, except for the dissolved Pb and Zn concentrations in the M750 soil solution. It was also observed that Cd, Pb, and Zn passed throughout DGT mimicking the biological cell membrane were reduced by all amendments of the M750 soil corroborating metal concentrations measured in rye grass shoots. In the MAZ soil, metals were less available as shown by their low extractability rate, low capacity of metal resupply from the solid phase to pore water, and low phytoavailability. The poor metal availability could be explained by the high levels of carbonate and organic matter contents in this soil. Nevertheless, a decrease of the Cu environmental availability and the Cu concentrations in rye grass shoots grown on the MAZ soil was also observed in the soil amended with Z1% alone or in combination with BW2%. From a health point of view, the most effective amendment to reduce human exposure through ingestion of soil particles for the M750 and MAZ soils was BW2% for Cd and BW2% + Z1% for Pb. However, the presence of rye grass minimized the amendments’ beneficial effects.

ACTI; International audience

ACL; The current study reports the effects of heavy metals issued from the emissions of phosphate and their bioaccumulation in the soils, leaf litter, and the terrestrial isopod Porcellionides pruinosus in the vicinity of Gabes-Ghannouch industrial complex. Cd, Pb, Zn, and Cu concentrations were measured in soils, leaf litter, and P. pruinosus individuals, collected from four stations located at different distances from the factory. Results showed that heavy metal concentrations in soils varied from one site to another and did not reflect those measured in individuals. In contrast, a positive correlation was found between the isopods’ body length and the distance from the pollution source, revealing the isopod sensitivity to the soil metal concentrations. The bioaccumulation factor was calculated using soil and leaf litter as a solid support with the aim of ordering the metal accumulation in P. pruinosus for each site. Overall, P. pruinosus could be defined as a macroconcentrator of Cd, Zn, and Cu (BAF>2) and as a deconcentrator of Pb (BAF

ACL; Phytomanagement used on soils contaminated with metals aims to stabilize them in the soil. It generally uses less demanding tree species such as maple, poplar, and black locust. However, it is important to consider the rate of accumulation of metals in the leaves as well as their location (leaf blade/petiole) together with the contents of cell wall compounds (hemicelluloses, cellulose, lignin). These two aspects are likely not only to have repercussions on the decomposition of litter but also to lead to a possible transfer ofmetal contamination into the food chain via soil decomposers/detritivorous. A successful phytoremediation is therefore the result of compromise: no tree species can meet all these criteria. The results obtained show that poplar is not recommended due to a high accumulation of Cd and Zn. The most appropriate species among our 3 studied species, which seem the most suitable in terms of remediation of metal polluted soils, could be the black locust and the maple which are less susceptible to contribute to the transfer of exogenous metals such as Cd to the trophic chain. However, maple strongly accumulates Pb in the leaf blade and it is susceptible to degrade quickly due to its high hemicelluloses and cellulose contents and low lignin content. The black locust accumulates metals mainly in the petiole (little consumed by detritivorous). However, its exotic character and high lignin content may limit the interest of its use.

ACTN; International audience; La reconquête des friches industrielles en coeur des métropoles est un enjeu majeur dans le cadre du renouvellement urbain. La période de transition vers un nouvel usage des sites peut s’échelonner sur plusieurs années. Pendant ce laps de temps, il est important de répondre aux attentes environnementales (confinement des contaminants sur le site…) et sociétale (amélioration du cadre de vie des riverains…). Les couvertures végétales peuvent apporter une réponse à ces contraintes. La diversité des espèces végétales couramment utilisées est cependant restreinte. Une expérimentation de phytomanagement on-site a été mise en place de 2015 à 2018 sur un ancien site industriel lié à la chimie minérale et ceci, en vue d’évaluer l’aptitude de différents couverts végétaux à se développer sur des matériaux multi-contaminés (fortes anomalies en As, Hg et Pb). Une plateforme expérimentale comportant 14 placettes a été créée pour être dédiée à l’étude de 12 espèces végétales sélectionnées au regard de leur comportement vis-à-vis des polluants métalliques et de leur aptitude à les accumuler dans leurs organes aériens (Medicago lupulina, Brassica juncea, Agrostis capillaris, Salix alba, Lolium perenne, Anthyllis vulneraria, Festuca rubra, Festuca ovina, Achillea millefolium, Deschampsia cespitosa, Valeriana officinalis, Miscanthus x giganteus). Lolium perenne a été semé seul ou en association avec Salix alba. Après trois années de suivi, seules quatre espèces initialement installées étaient encore présentes se sont adaptées aux conditions expérimentales. Les teneurs en contaminants inorganiques (As, Cd, Cr, Zn) dans les parties aériennes ont été supérieures dans le Miscanthus x giganteus par rapport à celles mesurées dans Agrostis capillaris, Festuca ovina et Festuca rubra.

Many studies were interested in the assessment and the monitoring of soil contamination with heavy metals. This study aimed to evaluate the effects of emissions from the Tunisian Steel Company El Fouladh in Bizerte (Tunisia). In this context, we measured Zinc (Zn), Copper (Cu), Lead (Pb) and Cadmium (Cd) soil’s concentrations from 8 sites along a contamination gradient. Besides, physicochemical parameters, pH, organic carbon, CEC, and CaCO3 were measured. Heavy metals were determined using an atomic absorption spectrometry. The results revealed a high concentration of heavy metals in the sampled soils. The contamination factor (CF) was determined to assess the soil contamination of the sampling sites, and revealed that the level of contamination varied along a contamination gradient, which may be due to the mobility of metals.

Dans le cadre de la prévention du saturnisme infantile, le Haut Conseil de la Santé Publique (HCSP) a fixé en 2014 des seuils de gestion liés aux concentrations en plomb dans les sols. En effet, au regard des risques liés à l’ingestion de particules de terre liée au portée main-bouche pour les enfants de moins de 6 ans, un seuil de vigilance de 100 mg de plomb par kg de terre a été fixé dans les sols des espaces verts. Suite à la parution de ces nouveaux objectifs de gestion, la Ville de Paris a amorcé un travail de caractérisation des sols de ses 500 ha d’espaces verts (EV). Ainsi, des analyses d’éléments traces métalliques (ETM), d’hydrocarbures et de paramètres agronomiques ont été réalisées sur 102 premiers EV. Ces mesures de qualité des sols, confrontées à la reconstitution de l’histoire des espaces verts, ont permis de dresser un certain nombre d’hypothèses quant à l’origine des terres végétales qui ont été utilisées depuis 200 ans. Alors que les efforts pour passer à une économie circulaire aboutissent à privilégier les circuits courts et l’approvisionnement local, il s’agit de s’interroger sur les pollutions potentielles des terres d’apports qui ont transité et qui transitent encore de la proche banlieue vers les centres urbains pour l’aménagement des espaces verts accueillant de plus en plus des potagers urbains. Dans ce contexte, il n’est pas inutile de réinterroger les principes et les rouages complexes de l’économie circulaire appliquée aux flux de terres végétales dans une démarche à la fois historique et spatiale., As part of the measures taken to prevent infantile saturnism, the French Higher Council for Public Health (Haut Conseil de la Santé Publique – HCSP) set thresholds values in 2014 for lead concentrations in the soil. Considering the risks linked to the ingestion of particles of soil by children under the age of six, who tend to put their hands in their mouth, a vigilance threshold value of 100 mg of lead per kilogram of soil was set for green spaces. Following the publication of these new objectives, the City of Paris initiated a program intended to characterize the soil of its102 green spaces representing 500 ha. Analyses of metallic trace elements, of hydrocarbons and of agronomic parameters were carried out to assess soil quality. Related to the history of the green spaces, they provided the basis for several hypotheses on the origins of the topsoil that has been used in vegetable gardens over the past 200 years. Considering the efforts made to shift to a circular economy, that favour short circuits and local supplies, this paper critically examines the potential pollution of soils which move from the close suburbs to the green spaces of urban centres, where more and more vegetable gardens are developed. In this context, it is interesting to re-examine the principles and complex workings of the circular economy applied to the evolution of vegetable gardens from a historical and spatial point of view.

The study focused on the attractiveness of mulches (consisting of the addition of a layer material to the soil surface) and their efficiency to promote recolonization by pedofauna of isolated and degraded areas. The experimental study was set up in the former coal mining area of Northern France. This area is particularly disturbed and fragmented by land-use change, urbanization, industry, intensive agriculture and metal pollution. To examine the movements of pedofauna, four kinds of mulches were applied: (i) Ramial Chipped Wood (RCW), (ii) chopped Miscanthus, (iii) dead leaves and (iv) wheat straw as well as plastic sheeting, a material often used in green spaces. A negative control consisted in soil without mulch addition. The experimental set-up consisted of a set of 18 bands of mulch (6 m long x 0.5 m width x 8 cm thick, i.e. a volume of 0.04 m3 per band) installed on three adjacent plots on a surface area which stretch on 4400 m2: (i) plot F1, a mixed plantation, (ii) plot M consisted of three rows of maples (both considered to be the reservoir of biodiversity) and (iii) plot BF, an ash plantation (with lower biodiversity). Faunistic communities of soil present within the mulches were monitoring using pitfall traps for four months (April to July), at a rate of eight surveys for each of the 90 traps installed, i.e. 720 samples. Different life traits and indices of diversity were studied, more specifically on carabid beetles. The main objective of the study was first to check whether mulches could or not reconnect different planted plots in a peri-urban landscape highly modified by human activities. The second aim was to find which type of mulch had the best efficiency in the recovery of the connectivity between plots. The last questions were which type of zoological groups could be favoured by the use of mulches and which benefits for ecosystem functioning. The main hypotheses of this study were: (i) Organic mulches would act as dispersal corridors and refuge zones to the soil organisms; (ii) organic mulches would be attractive to many organisms with various ecological needs. This study highlighted the potential benefits of using the mulching technique to support ecological connectivity in disturbed environment since this method highlighted the presence of individuals with different diets (saprophagous, predators, phytophagous and so forth), small and large size species which do not have the same dispersal capacities as well as species that are more dependent on forest environments and others that depend on more open environments. The study concluded that organic mulches are more favourable to pedofauna than soil without mulch or plastic sheeting. With regard to organic mulches, no difference was noted, either in terms of cumulative abundance or monthly monitoring. However, for carabids, it should be noted that dead leaves and wheat straw have higher specific richness than Miscanthus and RCW.

International audience; Accumulation of heavy metals in soils poses a potential risk to plant production, which is related to availability of the metals in soil. The phytoavailability of metals is usually evaluated using extracting solutions such as salts, acids or chelates. The purpose of this study was to identify the most significant soil parameters that can be used to predict the concentrations of acetic and citric acid-extractable cadmium (Cd), lead (Pb) and zinc (Zn) in contaminated woody habitat topsoils. Multiple linear regression models were established using two analysis strategies and three sets of variables based on a dataset of 260 soil samples. The performance of these models was evaluated using statistical parameters. Cation exchange capacity, CaCO3, organic matter, assimilated P, free Al oxide, sand and the total metal concentrations appeared to be the main soil parameters governing the solubility of Cd, Pb and Zn in acetic and citric acid solutions. The results strongly suggest that the metal solubility in extracting solutions is extractable concentration-dependent since models were overall improved by incorporating a change point. This change point detection method was a powerful tool for predicting extractable Cd, Pb and Zn. Suitable predictions of extractable Cd, Pb and Zn concentrations were obtained, with correlation coefficient (adjusted r) ranging from 0.80 to 0.99, given the high complexity of the woody habitat soils studied. Therefore, the predictive models can constitute a decision-making support tool for managing phytoremediation of contaminated soils, making recommendations to control the potential bioavailability of metals. The relationships between acetic and/or citric acid-extractable concentrations and the concentrations of metals into the aboveground parts of plants need to be predicted, in order to make their temporal monitoring easier.

The choice of agronomic practices for phytomanagement of metal-contaminated soils is of crucial importance to optimize plant biomass yields and to mitigate both environmental and health risks due to metal exposure. The present study aimed to assess the effects of agronomic practices on shoot yield and on metal (Cd, Pb, and Zn) accumulation in the organs of the energy crop miscanthus ( Miscanthus × giganteus ) during the first three years since the plantation on metal-contaminated agricultural soils. Three miscanthus cultivars, hereafter named Mis-A, Mis-B and Mis-I, were planted at low and high density. An inoculum of arbuscular mycorrhizal fungi-AMF ( Glomus LPA Val 1) was added during plantation, and nitrogen fertilization was applied during the third growing season. Metal accumulation in miscanthus organs was determined during the second growing season, whereas shoot yields and their metal concentrations were determined during both the second and the third growing seasons. Based on metal concentrations and bioconcentration factors, the three cultivars mainly accumulated metals in their roots. The shoot yields increased from 3.7 to 10.3 t DW ha −1 in the second growing season to 15.8–23.3 t DW ha −1 in third growing season. There were no or very few significant differences in metal concentrations and shoot yields within treatments comprising the same cultivar. The addition of AMF inoculum increased metal (mainly Cd and Zn) accumulation in miscanthus organs and in the shoot yields and this was more observed in both Mis-B and Mis-I which presented a higher root mycorrhization level than in Mis-A. Shoot yields in treatments comprising different cultivars depended not on fertilization but on the interactions between cultivar and planting density, and between cultivar, planting density and AMF inoculum. Whatever the treatment and the sampling period, Pb concentrations did not significantly differ in shoot yields. The interaction between cultivar and planting density resulted in higher Cd concentrations in the yields of Mis-B planted at low density during the third growing season. Zn concentrations increased with fertilization in all treatments, and with the addition of the AMF inoculum in Mis-B and in Mis-I. Overall, the results demonstrated that the three cultivars could be potential candidates for coupling phytostabilization and biomass production on metal-contaminated soils.

Biochars are products that are rich in carbon obtained by pyrolysis processes that consist in introducing a biomass (such as wood or manure) in a closed container and heating it with little or no available air. This paper reports the impacts of pyrolysis parameters on biochar characteristics. A preliminary examination of the scientific literature revealed that the type of feedstock, the temperature, the heating rate and the gas flow were the major parameters influencing the biochar characteristics. This review highlights the multitude of biochars that can be made and shows the importance of characterizing them before their use in soils. Then we assess how the input of biochars in soils can affect soil parameters. A review of the literature showed modifications on: i) the physical properties of soils (i.e. the modification in soil structure and water retention), ii) the chemical properties of soils (i.e. the modification of pH, cation exchange capacity, nutrient availability, the organic matter content) and iii) the biological properties (i.e. the changes in microbial and faunal communities). All these modifications can lead to an increase in crop productivity, which confirms the value of biochars as a soil amendment. Moreover, biochars can also provide an advantage for soil remediation. Indeed, biochars efficiently reduce the bioavailability of organic and inorganic pollutants. In addition, this review focuses on a specific plant that can be used to produce biochars: Miscanthus, a non-wood rhizomatous C4 perennial grass. Miscanthus presents advantages for biochar production due to: i) its lignocellulosic content, ii) its silicon content, which can mitigate environmental stresses (notably for plants grown on contaminated sites) and iii) the greater surface area of the Miscanthus biochars compared to the biochars produced with other feedstock.

ACL; This study aimed to observe the type of asymmetry exhibited by Porcellio laevis sampled from 15 sites belonging to Tunisian industrialized areas. Physicochemical parameters such as pH, organic matter and CaCO3 contents were measured in soils. Moreover, Cd, Pb, Zn, and Cu concentrations were determined in both soils and woodlice. Additionally, 10 metrical traits were measured to evaluate the type of asymmetry on individuals: the basis, the second and the third articles of the antenna, the first article of the flagellum of the antenna and the merus, the carpus, and the propodus of the sixth and the seventh pereopods. Among the 531 measured individuals, 432 exhibited fluctuating asymmetry (FA) while the remaining individuals exhibited antisymmetry or directional asymmetry. The data obtained were analyzed using a multivariate statistical analysis. Contrary to our hypothesis, the results showed that individuals from contaminated sites have a low FA level, whereas those from uncontaminated sites have a high FA level, particularly females but with some exceptions. Variations in FA level in the traits and populations studied and its usefulness as a stress indicator were discussed.

ACL; Although growing vegetables in urban gardens has several benefits, some questions in relation with the safety of foods remain when the self-production is carried out on highly contaminated garden soils. To better assess the local population's exposure to Cd and Pb induced by the past activities of a lead smelter, a participatory program was initiated in 115 private kitchen gardens located in northern France to assist gardeners in understanding their soil environment. The challenge included contributing to the database of urban garden soils with the collection of a large number of samples: 1525 crops grouped into 12 types (leaf, fruiting, root, stem and bulbous vegetables, tubers, cabbages, leguminous plants, celeriac, fresh herbs, fruits, and berries), 708 topsoils, and 52 samples of self-produced compost. The main results were as follows: (i) topsoils were strongly contaminated by Cd and Pb compared to regional reference values; (ii) great variability in physicochemical parameters and metal concentrations in topsoils; (iii) the highest concentrations of Cd and Pb for celeriac and fresh herbs and the lowest for fruits and fruiting vegetables; (iv) a high percentage of vegetables that did not comply with the European foodstuff legislation; and (v) most self-produced compost samples were strongly contaminated. This study aimed to raise awareness and generate functional recommendations to reduce human exposure and to provide useful data that could be considered in other environmental contexts.

COM; International audience; Soil is an essential and non-renewable resource which can perform a high number of economic, social and environmental functions as biomass production, source of raw materials or protection of humans and environment (Blum, 2005). However, the soil functionality becomes increasingly compromised due to contaminations caused by human activities. In 2006 and in 39 countries, the European Environmental Agency inventoried approximately 3 million of sites where pollutant activities occurred with more than 1 .8 million potentially contaminated sites (CGDD 2013). In 2012, the most frequently identified contaminants were metals (35 %), hydrocarbons (24 %) and polycyclic aromatic hydrocarbons (11 %). Until recently, the most common remediation technique was the excavation of contaminated soil and its disposal as landfill. However, this kind of method is considered inappropriate because it generates considerable disturbances, is expensive and economically unfeasible on a large scale . Thus, other remediation techniques (ex and in situ) have been developed to overcome these disadvantages . Among them, a technique consists in adding inorganic or organic amendments to the contaminated soils in order to decrease the mobility and bioavailability of pollutants in soils (Kumpiene et al., 2008; Vangronsveld et al., 2009; Bolan et al., 2014; Nejad et al., 2017) . The most often used amendments are phosphate compounds, liming materials, metal oxides and biochars, used alone or in combination (Waterlot et al., 2017; Lahori et al., 2017; Oustrière et al., 2017). The goal of the present work consists in evaluating the ability of two amendments (woody biochar and iron grit, used alone or in combination) to immobilize Cd, Cu, Pb, and Zn in contaminated soils under greenhouse conditions

ACL; The main objective of the study was to assess the efficiency of phytoremediation methods implemented for 14 years on highly metal contaminated soils. The different experimental strategies were plots planted with a tree mix or with a single tree species coupled or not with the use of fly-ashes as an amendment to limit metals mobility in soil. The breakdown of poplar litter on the four plots was monitored during 10 months. In parallel, colonization of litter bags by functional groups of mesofauna (Collembola and Acari) was followed. Two mesh sized litter-bags were used to allow distinguishing microbial and mesofaunal actions on the litter breakdown. We observed the breakdown of litter in four studied plots. Litter breakdown occurred faster in 3 mm litter bags than 250 µm ones during summer demonstrating the importance of mesofauna. Mixed plantation allowed faster litter breakdown than mono-specific plantation. A higher abundance of mesofauna and/or better abiotic conditions (moisture, shading…) could explain this result. Regarding litter breakdown and mesofauna, no significant difference was observed between the amended plots and those subjected to soil phytomanagement. However, communities of the studied area are disturbed since a low abundance of detritivores was observed. This could explain also the slower litter breakdown than expected in our study. To conclude, among the phytomanagement methods tested, mixed plantations could provide a benefit for the restoration of degraded soils. By contrast, the use of fly-ashes does not seem to have any effect on the functionality of ecosystem neither on the litter breakdown process nor on the abundance of mesofauna.

ACL; Different remediation techniques have been used to restore metal-contaminated sites, including stabilizing metals by adding amendments to the soils. This study experimented three biochars, made from wood and miscanthus, cultivated on contaminated and uncontaminated soils, used as amendments at a 2% application rate on a metal-contaminated soil for 9 months in laboratory-controlled conditions. The objective was to evaluate whether biochars were able to decrease the availability and human oral bioaccessibility of metals in an alkaline soil. To meet this goal, the modifications of the soil’s physicochemical parameters, metal distribution in soil, and human bioaccessibility were evaluated at different sampling times. The results showed that biochar application to the alkaline soil did not always decrease the soil metal availability, which challenges the value of using biochars in already slightly alkaline soils at a low application rate. However, differences in efficiency between the three biochars tested were highlighted. The biochar produced with miscanthus cultivated on uncontaminated soil led to higher soil metal bioaccessibility. Moreover, because of the absence of any increase in soil metal availability with the biochar produced from biomass cultivated on contaminated soil, the use of such biochars can be recommended for the remediation of contaminated soil.