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International audience; Evaluation of liming and fertility properties of biochar on acid soil was studied in this work. Selected soil properties such as pH, electrical conductivity (EC), exchangeable acidity (Ex Ac), exchangeable Al (Ex Al), exchangeable Fe (Ex Fe), available P and, soil organic carbon (SOC) were examined under the effect of biochar amendments. The acid soil was treated with biochar issued from coffee husk (CH) and cocoa pods (CP) pyrolyzed at 350°C and 550°C for 4 hours at amendment rate of 0, 20, 40 and 80 g kg−1 and an incubation time of 7, 14, 30, 40 and 60 d. Biochar amendments significantly increased soil pH, soil EC with respect to control and decrease in exchangeable acidity was observed. Results show that biochar improved available P in acid soil, though re-adsorption occurred with increasing incubation time. A significant increase in SOC is observed as compared to control. The impact of biochar on these acid soil chemical properties is due to the properties which are dependent on the biochar type and pyrolysis temperature. Thus, biochar can play the dual role of a liming agent and a source of P fertilizer nutrients.

International audience; This work proposes a suitable treatment for the leachates from a sewage sludge composting process using a specific windrow (biopile). The biopile's evolution and organic content degradation were followed for 2 months with regular leachate spraying to assess the physico-chemical and biological impacts, and determine the risk of enrichment with certain monitored pollutants. The final objective was the valorization of the biopile substrates in the composting process, while respecting the quality standards of use in a circular economy way. Classical physico-chemical parameters (pH, conductivity, dissolved organic carbon (DOC), total dissolved nitrogen (TDN), etc.) were measured in the leachates and in the water-extractable and dry-solid fractions of the biopile, and the catabolic evolution of the microorganisms (diversity and activities), as well as the enrichment with persistent organic pollutants (POPs) (prioritized PAHs (polycyclic aromatic hydrocarbons) and PCBs (polychlorinated biphenyls)), were determined. The results showed that the microbial populations that were already present in the biopile, and that are responsible for biodegradation, were not affected by leachate spraying. Even when the studied compost leachate was highly concentrated with ammonium nitrogen (10.4 gN L −1 on average), it significantly decreased in the biopile after 2 weeks. A study on the evolution of the isotopic signature (δ 15 N) confirmed the loss of leachate nitrogen in its ammoniacal form. The bio-physico-chemical characteristics of the biopile at the end of the experiment were similar to those before the first spraying with leachate. Moreover, no significant enrichment with contaminants (metal trace elements, volatile fatty acids, or persistent organic pollutants) was observed. The results show that it would be possible for composting platforms to implement this inexpensive and sustainable process for the treatment of leachates.

The occurrence and contamination level of seven important toxic metals (Cd, Cu, Co, Cr, Hg, Pb, and Zn) and three additional metals (Al, Fe, and Mn) in the water, sediment, and shrimp muscle in aquaculture areas located in Central Java, Indonesia, were investigated. The results suggest that the majority of metals have higher concentrations in the inlet followed by the outlet and ponds. Cd dissolved in the waters exhibited the highest level in Pekalongan (3.15 ± 0.33 μg L−1). Although Pb was not detected in the water, it was detected in the sediment, and the concentration ranged from 7.6 to 15.40 mg kg−1 dw. In general, the heavy metal concentrations in the sediments were found to decrease in the sequence Al > Fe > Mn > Zn > Cr > Cu > Co > Pb. Concentrations below the effects range low level based on the Canadian sediment quality guidelines were found for Cr, Cu, Pb, and Zn, whereas moderate sediment pollution (25–75 mg kg−1 dw) was observed for Cr (all regions), Cu (except in the Pekalongan region), and Zn (Brebes and Tegal regions) according to the US EPA standard. The status of the waters was evaluated by calculating a pollution index derived mostly from Mn and Zn. The ecological risk (geoaccumulation index (Igeo), contamination factor (CF), pollution load index (PLI), and potential ecological risk index (ERI)) determined in the sediments indicated that all studied areas had low to moderate contamination. The concentrations of all metals in shrimp were generally below the maximum limits for seafood, except for Zn (in all stations), Pb, and Cr (Tegal and Pekalongan). The hazard index values for metals indicated that consuming shrimp would not have adverse effects on human health.

The selection of plant species at mine sites is mostly based on metal content in plant parts. Recent works have proposed referring to certain ecological aspects. However, plant traits for plant metal-tolerance still need to be accurately assessed in the field. An abandoned Zn-Pb mine site in Gard (France) offered the opportunity to test a set of ecological criteria. The diversity of micro-habitats was first recorded through floristic relev&eacute, s and selected categorical and measured plant traits were compared for plant species selection. The floristic composition of the study site consisted in 61 plant species from 31 plant families. This approach enabled us to focus on seven wild plant species naturally growing at the mining site. Their ability to form root symbioses was then observed with a view to phytostabilization management. Four species were considered for phytoextraction: Noccaea caerulescens (J. et C. Presl) FK Meyer, Biscutella laevigata L., Armeria arenaria (Pers.) Schult. and Plantago lanceolata L. The metal content of their aerial and root parts was then determined and compared with that of soil samples collected at the same site. This general approach may lead to the development of a knowledge base for assessment of the ecological restoration trajectory of the site and can help in plant selection for remediation of other metal-rich soils in the Mediterranean area based not only on metal removal but on ecological restoration principles.

International audience; In polluted protected areas, using phytoremediation raises the question of the choice of the plant species to select. As an example, Atriplex halimus has been identified as a proliferative plant species that needs to be eradicated in the Calanques National Park (PNCal). Since it has been proven that the spontaneous populations of this plant species could phytostabilize shore waste deposits generated by past industrial activities within the PNCal territory, its status seems controversial, presenting a dilemma between biodiversity management of a protected area and ecological solutions for pollution management. To address this issue, we assessed the ability of A. halimus to grow on different soils from this territory, in order to estimate the potential invasiveness of this plant in this territory. Petri dish germinations and pot-growth experiments showed 50% germination of seeds collected on local individuals from the most polluted PNCal soil and 20% growth reduction of seedlings. Soil analysis showed that limitation of growth was caused by high pH value and sparsely available micronutrients as well as metal and metalloid contamination. Our results suggested that local populations of A. halimus may stabilize the highly metal and metalloid polluted salt-affected soils of the PNCal, with low seed germination potential lowering the eventuality of a propagation over the PNCal territory. As a consequence of this study, the administration of the PNCal decided not to remove A. halimus populations along the polluted coastline until another solution to prevent pollution dispersal had been found. This laboratory approach may be extended to other similar situations where plant species may be evaluated not only in term of phytoremediation potential but also in term of biodiversity preservation.

International audience; This study highlights the trace metal and metalloid (TMM) accumulation in Rosmarinus officinalis L. and its chemical responses when exposed to high levels of contamination. R. officinalis individuals growing along a gradient of mixed TMM soil pollution, resulting from past industrial activities, were analysed. Several plant secondary metabolites, known to be involved in plant tolerance to TMM or as a plant health indicator, were investigated. The levels of thiol compounds and phytochelatin precursors (cysteine and glutathione) in the shoots were measured in the laboratory, while a portable non-destructive instrument was used to determine the level of phenolic compounds and chlorophylls directly on site. The level of Pb, As, Sb and Zn contaminations within the soil and plants was also determined.The results highlighted a decrease of TMM translocation with increases of soil contamination. The concentration of TMM in the shoots followed the Mitscherlich equation and reached a plateau at 0.41, 7.9, 0.37, 51.3 mg kg−1 for As, Pb, Sb and Zn, respectively. In the shoots, the levels of thiols and phenols were correlated to concentrations of TMM. Glutathione seems to be the main thiol compounds involved in the tolerance to As, Pb and Sb. Phenols indices, using non-destructive measurements, may be considered as an easy way to establish a proxy to estimate the TMM contamination level of the R. officinalis shoots. The study highlights metabolic processes that contribute to the high potential of R. officinalis for phytostabilisation of TMM in contaminated areas in the Mediterranean.

International audience; Recent studies consider the native flora as a potential source of plant candidates for phytostabilization of metal and metalloid (MM) contaminated soils, but ecological restoration is not the main objective of these researches. However, in contaminated areas, phytostabilization should be considered as a useful tool for ecological restoration. The present study takes stock of 3 years of a Mediterranean pilot site implementation using native plant species to recover plant and microbial communities (diversity and functions) together with soil re-mediation in the Calanques National Park. To determine the success of this operation, three in situ treatments were compared: ecological restoration plots characterized by the handling of physical environment (creation of cultivation terraces) and plants, negative control plots without vegetation but with the same physical environment handling as ecological restoration plots, and positive control plots with natural vegetation and no handling. The results suggest that an ecological restoration trajectory is initiated in the ecological restoration plots, characterized by a partial permanent plant cover. However, there is no evidence of a significant improvement of soil quality (evaluated by soil texture, pH, nutrients and organic carbon contents, cation exchange capacity, microbial biomass and activities) and phytostabilization efficiency after 3 years. Native plant communities and their associated microorganisms may need more time before improving soil quality and MM stabilization under the drastic Mediterranean conditions. Any amendment addition to accelerate restoration and MM immobilization was forbidden in this protected area. Under such conditions, an active restoration need to be carried out in this contaminated area even if resilient dynamics of the native plant communities may sporadically occur over a long period of time.

International audience; Sewage sludges are problematic due to the constant increase of urban population. The high level of organic matter in sludges can be valorized by co-composting with green waste. Many chemical changes occur in the compost maturation process, resulting on stabilized organic matter by humification which is recoverable as soil amendment. In this way, the knowledge of organic matter stability and maturity of compost is essential. However, estimation of chemical parameters allowing the management of compost quality usually need complex time consuming laboratory measurements. Indeed, there is not yet rapid, simple and robust method for their on site assessment at the moment. Among usual parameters used to monitor compost evolution, the C/N 2 ratio is a fundamental chemical parameter. The aim of this work is the estimation of the C/N ratio using a Partial Least Squares regression based on UV and fluorescence spectroscopic data and pH from compost water extracts at various steps of composting process and measured on site. A mathematical linear model is established based on selected data (pH, spectroscopic indices) resulting on average relative error for C/N estimation of 5.26 % (range between 0.5 % min. and 9.5 % max.). This tool leads to a rapid and simple on site estimation of the compost stabilization, allowing qualification of the end-product resulting on a global spectroscopic index of stability.

International audience; The creation of pit lakes is usually an acceptable solution from the landscaping point of view for voids left by discontinued open-pit mines. However, without rehabilitation, these voids represent a potential environmental risk. The aim of the present work was to assess, for the first time, the water quality i.e. physico-chemical characteristics, metal and metalloid (MM) content and ecotoxicity of the waters of the El Cobre Blue Lagoon, a pit lake formed in an open-pit copper mine in Cuba. Potential effects of rainy season vs. dry season and spatial location (different depths) on water characteristics were considered. Results revealed that water contained was moderately acidic (pH = 4.6±0.2), with high lectrical conductivity (EC = 3.02±0.03 mS.cm-1), whatever the season. Dissolved oxygen (DO = 9.9±2.0 mg.L-1), Total Dissolved Solid (TDS = 7003±245 mg.L-1) and sulfate concentration (6556±1410 mg.L-1) in the El Cobre Blue Lagoon water were above acceptable limits for sources of surface water as recommended by Cuban standard (NC 1021:2014). High copper (43.6±1.7 mg.L-1) and manganese (24.1±1.1 mg.L-1) contents were detected. Except for EC, sulfates, chlorides, TDS, nitrates and phosphates, other physico-chemical parameters were stable between dry and rainy seasons (p

International audience; Astragalus tragacantha is a protected plant species in France that grows even in the trace metal and metalloid (TMM) polluted soils of the Calanques National Park (PNCal). Soils are mainly contaminated by lead, copper, zinc and arsenic. An ex situ experiment was conducted, firstly to determine the molecular responses and root traits involved in the TMM tolerance of this plant species by growing individuals in a soil from the surroundings of one of the brownfields of the PNCal, known as l’Escalette, where this plant species grows spontaneously. Secondly, in order to determine the plasticity of these responses, seeds were collected from three different populations, one at l’Escalette (polluted site), one from the Frioul archipelago (non-polluted, insular site) and one from La Seyne (non-polluted, littoral site). The results of this study confirmed the capacity of A. tragacantha to germinate and grow in TMM contaminated soils. Only moderate significant variations in chlorophyll and flavonol indices, proline content and antioxidant activities were detected between polluted and control soil conditions for all populations. The main driver for A. tragacantha TMM tolerance seemed to be its ability to be associated with root symbionts i.e. arbuscular mycorrhizal fungi and dark septate endophytes, corresponding to a nutrient-uptake strategy trait. This work provides support for the challenge of A. tragacantha conservation along the littoral of the PNCal, because increasing the number of A. tragacantha individuals would both increase vegetation cover of the polluted soils to reduce the pollution transfer and reinforce the populations of this species.

International audience; The spatial distribution patterns, origins and environmental and health risks of metal trace elements (As, Cd, Co, Cr, Cu, Ni, Pb, Zn) have been analyzed through the spiking and the analysis of 84 soils sampled in the region of Arzew (Algeria). This city gathers one of the biggest petroleum harbors of Algeria and gathers in the same platform several industries, coexisting with residential and agricultural areas. The mean concentration of all the metals studied exceed their corresponding backgrounds levels and/or exceed the ecological Predicted No effect Concentration (PNEC) values. The geo-accumulation and the potential ecological risk indices indicate a low to moderate risk for As, Co, Cu, Ni and Zn, and a moderate to considerable risk for Cr and Pb. According to the health risk assessment results, the carcinogenic risks due to Cr exceed the acceptable level in all the functional areas, and when considering combined effects of metals, the hazard index obtained show a high potential carcinogenic risk to the local children.

Moanda region in Southeastern Gabon is rich in manganese (Mn) ores. This study aimed to determine the physico-chemical properties of cultivated and uncultivated soils and the metal content in edible parts of 9 plants cultivated in this area. The studied soils had a sandy loam clay texture. Cultural practices induced a significant acidification, decrease in fertility and loss of metals from soils. Mn contents in soils varied from 8,672 to 17,956 mg.kg-1, and were significantly higher in uncultivated than in cultivated soils. Concentration of metals in plants seemed to depend on the type of plant more than the concerned part. Except for Nkoumou (Gnetuma fricanum), Ca, Mg and K contents were in large amounts in all plants so they could be good sources of macronutrients for humans and animals. Mn levels in leaves of cassava and sorrel and Fe levels in the red sorrel leaves exceeded 1 g.kg-1. Sorrel and amaranth showed the highest daily intake of nutrients. Key words: Manganese-rich soil, metal nutrients, food plants, bioconcentration factor (BCF), daily nutrient intake.

International audience; This is an in natura study aimed to determine the potential of Rosmarinus officinalis for phytostabilization of trace metal and metalloid (TMM)-contaminated soils in the Calanques National Park (Marseille, southeast of France). The link between rosemary tolerance/accumulation of As, Pb, Sb, and Zn and root symbioses with arbuscular mycorrhizal (AM) fungi and/or dark septate endophytes (DSE) was examined. Eight sites along a gradient of contamination were selected for soil and root collections. TMM concentrations were analyzed in all the samples and root symbioses were observed. Moreover, in the roots of various diameters collected in the most contaminated site, X-ray microfluorescence methods were used to determine TMM localization in tissues. Rosemary accumulated, in its roots, the most labile TMM fraction in the soil. The positive linear correlation between TMM concentrations in soil and endophyte root colonization rates suggests the involvement of AM fungi and DSE in rosemary tolerance to TMM. Moreover, a typical TMM localization in root peripheral tissues of thin roots containing endophytes forming AM and DSE development was observed using X-ray microfluorescence. Rosemary and its root symbioses appeared as a potential candidate for a phytostabilization process of metal-contaminated soils in Mediterranean area.

Background In central Africa, studies on the transfer of metals from soil to food crops, the composition of foods and the dietary intake of cultivated vegetables are scarce. In this study, aluminium (Al), iron (Fe), manganese (Mn) and zinc (Zn) transfer from naturally (pedogeochemically) contaminated soils into ten edible plants and human exposure to these metals via edible parts of the plants were investigated. Results The fertility of the soils studied was still satisfactory. Soil Al (33 029–40 031 mg kg−1), Fe (20 869 ± 1124 mg kg−1) and Zn (248.3 ± 37.9 mg kg−1) concentrations were consistent with those found in agricultural soils, but Mn concentrations were above those normally encountered in arable fields (10 000 mg kg−1). The results indicated a substantial accumulation of Fe in red roselle leaves and of Al, Mn and Zn in some leafy plants and okra (fruits). The present study highlights that adults consuming vegetables grown on naturally Mn-rich soils ingest significant amounts of Al, Mn and Zn. However, Zn amounts were below the recommended maximum tolerable levels for hazard risk. Conclusion The study indicated that Al and Mn accumulation in food crops cultivated in the Moanda area of Gabon may represent a health hazard. However, the high levels of Zn in vegetables could be a pathway for Zn supplementation in human nutrition to reduce Zn deficiency in developing countries. © 2013 Society of Chemical Industry

International audience; The aim of this study was to develop an effective and non-destructive method for the selection of native Mediterranean plants with phytoremediation potential based on their spontaneous recovery capacities. The study site consisted in a mixed contaminated soils (As, Cu, Pb, Sb, Zn) in the vicinity of a former lead smelting factory abandoned since 1925 in the Calanques National Park (Marseille, southeastern France). We developed an integrated characterization approach that takes into account topsoil metal(loid)s (MM) contamination, plant community composition and structure and mesologic parameters without using destructive methods. From a statistical selection of significant environmental descriptors, plant communities were described and interpreted as the result of spontaneous recovery under multiple stresses and local conditions (both natural and anthropogenic). We collected phytoecological and MM topsoil data using field monitoring and geographic information system (GIS) on a pollution hotspot where natural plant communities occur. The results of the multivariate analysis performed between species and descriptors indicated that a century of MM pollution pressure produced a significant correlation with plant community dynamics in terms of composition, diversity and structure, leading to the co-occurrence of different plant succession stages. Thus, these successions seemed linked to the variability of anthropogenic disturbance regimes within the study site. We recorded high topsoil contamination heterogeneity at the scale both of the plot and of the whole study area that suggested a heterogeneous MM distribution pattern dependent on the source of contaminants and site environmental variability. We identified 4 spontaneous plant communities co-occurring through a MM contamination gradient that could be used later from degraded to reference communities to define ecological restoration target combined to phytoremediation applications with respect to local conditions. Our results suggested that some of the native plant species such as Coronilla juncea and Globularia alypum might be tolerant to high mixed MM soil concentrations and they could thus be used for phytostabilization purposes in polluted Mediterranean areas in regard to their life-traits. Our non-destructive methodology led both to the selection of tolerant native plant species and communities and identification of highly polluted priority intervention areas through the study site where phytostabilization should be implemented. Furthermore, by analyzing succession dynamics linked to contamination patterns throughout the area and spontaneous recovery of native tolerant vegetation, our methodology opens up broad perspectives and research fields for ecological restoration for Mediterranean protected and contaminated areas based on ecosystem trajectories and new approaches for the integrative management of polluted soils. (C) 2016 Elsevier Ltd. All rights reserved.

The aim of this study was to investigate the properties of cultivated urban soils and metal concentrations in these soils and in roots and leaves of the crops Amaranthus cruentus (amaranth) and Hibiscus sabdariffa(roselle). The soil physicochemical properties showed a poor fertility rate of cultivated soils. The metal concentrations in soils were in the range of concentrations for uncontaminated agricultural soils. The ranges of concentrations of metals were as follows: Aluminium (Al), 239-1222 mg/kg; cadmium (Cd), Al > Mn > Zn > Cu >Pb; in roots, Al > Fe > Zn > Mn > Cu > Pb. Al and Fe were weakly bioaccumulated but their concentrations were high. Cu and Mn were more accumulated in leaves than roots for amaranth and roselle. The leaves of amaranth were found to accumulate soil Cu and Zn more efficiently than other tissues of both vegetables. The translocation factor was in the order: Mn > Cu > Fe > Zn > Al, and when this value was compared between amaranth and roselle, it was observed to be higher in amaranth than in roselle. The concentrations of the essential elements Cu and Mn in roselle, and Cu, Fe, Mn and Zn in amaranth indicate that these leafy vegetable are a good nutrient sources. Key words: Soil, edible vegetables, metals, bioconcentration factor (BCF), translocation factor (TF).

We performed a mesocosms experiment using a vertical-flow wetland system to treat liquid sludge in the Mediterranean region. Three common helophyte species, common reed ( Phragmites australis Cav.), broadleaf cattail ( Typha latifolia L.), and yellow flag ( Iris pseudacorus L.), were planted as monoculture and irrigated with a liquid sewage sludge from a food industry, characterised by very high organic concentrations (COD > 8000 mg/L). We studied the benefits of plants by comparing unplanted to planted mesocosms. Results showed the high performance of such vertical-flow wetland systems. Removal efficiency was more than 98% for total suspended solids (TSS) and chemical oxygen demand (COD), and more than 87% for total Kjeldahl nitrogen (TKN). The main removal process was physical filtration by the substrate due to the high proportion of particulate elements in the sludge. Planted mesocosms were more efficient than those unplanted, confirming the positive role of the plants. Mesocosms planted with Phragmites or Typha showed better performances in TKN removal than those planted with Iris . Only in mesocosms planted with Phragmites was there no outflow in summer due to high evapotranspiration.

Among compostable matrices, green wastes represent a significant fraction which can be used as an amendment after composting. Several indicators, e.g. CHA/CFA or C/N ratios give information on evolution of the organic matrix during composting. However, measurement of these parameters is complex and requires laboratory conditions. The aim of this study was to propose on site easy-to-measure parameters to monitor composting process, such as redox potential (Eh), related to complex indices such as CHA/CFA, C/N, A210 nm/A280 nm, NH 4 + / NO 3 - ratios, and total organic matter (OM). Windrows were consisting in a mixture of green wastes such as palm, olive, cypress, pine, mimosa, and bay residues. By using covariance analysis, an opposite correlation between Eh and CHA/CFA ratio was found. Linear regression of this parameter with Eh was chosen to monitor the composting process. Therefore, Eh can be used to monitor green wastes composting.

Soil microbial activities in a reed-bed used for effluent purification of a small cheese-dairy farm under a Mediterranean climate were described and studied. This work aims to demonstrate (i) whether certain enzyme activities used as bioindicators of dairy waste degradation (beta-galactosidase and protease) vary over time, which might influence organic matter degradation and (ii) whether specific microbial communities are selected through contact with the discarded effluent using community level catabolic profiles (CLCPs). beta-galactosidase and protease activities were followed in a 14-month monitoring experiment. These enzyme activities were strongly expressed during the whey-discarding period from February to May. CLCPs using Biolog Ecoplate showed great microbial diversity, as described by Shannon-Weaver index, and no difference was observed in microbial diversity between areas at the receiving end of the reed-bed (where effluent was discarded) and those at the opposite end. This may be explained by successive environmental factors which made enzyme activities vary: whey discarded from February to May and Mediterranean climate conditions (drying-rewetting effects on summer). Microbial enumeration using epifluorescence microscopy also showed a pattern linked to Mediterranean conditions with a drastic decrease in biomass during summer drought. These results on functional biodiversity were correlated with high purification yields: the minimum decrease in Biological Demand in Oxygen was 84% and that in suspended solids was 75%.

This paper aims to improve the understanding of organic amendments distribution on different fractions of soil organic matter (SOM) and the knowledge of processes controlling the temporal evolution of organic matter (OM) in the first layer of a calcareous soil of two adjacent plots, one control and one treated with 3 kg m − 2 of organic amendment. An appropriate fractionation procedure of SOM, consisting in sequential extractions by water, hydrochloric acid, sodium hydroxide and potassium pyrophosphate extractions, was applied. Dissolved organic carbon (DOC), UV and fluorescence spectroscopic properties of organic matter reveal quantitative and qualitative aspects. Spectral indexes such as SUVA 254 (specific UV absorbance), E 2 /E 3 and FI (fluorescence index) were used to examine annual changes of SOM in the different fractions. Extractions with pyrophosphate, and in a lesser amount with sodium hydroxide, represented the major part of DOC, for both control and treated soils. Yields of sequential extractions ranged from 16.1% to 16.4% of TOC for these two soils. Compost inputs resulted in evolution of quantitative and qualitative results, especially for water extractable organic matter (WEOM) and pyrophosphate extracts mainly during the first 3 months of this field experiment. Study of annual changes of DOC, SUVA 254 and E 2 /E 3 index values in treated soil indicated a priming effect during the weeks after compost spreading, in relation with a revitalizing effect of microbial activity. Contributions of organo-mineral interactions and rainfall regulated WEOM amount throughout the year, and the activity of microbial communities in soil seemed to play a significant role on WEOM production. FI index values demonstrated microbial origin for WEOM, and for OM extracted either with acid or with sodium hydroxide. At the contrary, pyrophosphate extracts revealed that OM came essentially from terrestrial origin, which corresponds to the most complex and aromatic compounds. It was found that sodium hydroxide extracted less aromatic SOM, but higher molecular weight compounds. 3D fluorescence spectra revealed the presence of four main types of fluorophores according to the different extracts: humic, fulvic and marine-like compounds (A, C and M) common to all extracts, and lignin-like compounds (H) specific to pyrophosphate extracts only in treated soil at the beginning of the experiment due to initial compost effect. PCA on quantitative and qualitative data for WOEM fraction revealed essentially that meteorological aspects, with temperature and precipitation variations, were an important parameter over the year of experimentation, and that compost input impacted significantly WEOM amounts at the beginning of the experiment.

International audience; A field study on the capacity of spontaneous vegetation of four motorway ponds to extract four trace metals (Cd, Cu, Zn and Pb) was carried out. High biomasses (ca. 400 g m (2) DW) of freshwater macroalgae Chara spp. were found in all ponds. However, higher biomasses (ca. 900 and 1600 g m (2) DW for aerial and root parts, respectively) were found for broadleaf cattails Typha spp. with perennial structures. Biomasses of Chara were mainly controlled by seasonal variations and water level of the ponds. Metal contents in Chara vulgaris beds were higher than those in Chara globularis and, with less than half of the biomass corresponded to the same range than those found in Typha. For the latter, the highest contents of metals were found in the root system. Sediments of the ponds were moderately contaminated and the concentrations of the four metals were very low in the water (often under detection level). Translocation factors of the contaminants from sediment to plants were very low (parts per thousand) for all species and phytoextraction of metals from the sediment seemed not to be the main effect of the spontaneous vegetation. However, this latter prevent pollutant transfers provided that the dry and crumbly Chara are collected during summer before being blown outside the pond by strong winds. (C) 2015 Elsevier B.V. All rights reserved.

Composting organic matter is an interesting way to valorize waste. Compost is a product obtained after a humification process. The humification of organic matter during composting was studied by the quantification and monitoring of the evolution of humic substances. The final objective was to be able to evaluate the state of humification based on a spectrum of total humic substances using the method of UV spectral deconvolution. This study presented a new index obtained by UV spectroscopy using the deconvolution of an unknown spectrum of compost with 3 reference spectra. This index was compared to the maturity indices usually used, such as total extraction of humic substances (rate of extraction), IP (index of polymerization) or the humic acid to fulvic acid ratio. This new parameter, which was easy and quick to determine, gave precise information about the quality of the compost. It made it possible to disregard the values of aberrant concentrations caused by the classical protocol of extraction. Compared to the humic acid to fulvic acid ratio, the new index obtained by UV spectral deconvolution showed more representative results: the humic acid to fulvic acid ratio for an apparently non-mature compost was abnormally high, suggesting that the compost was mature, whereas the UV index proposed showed that the compost was really young and not yet humified.

To evaluate phytoremediation potentialities by metal accumulation in tolerant plants, trials are carried out using in vitro cultures. Organic compounds influence on metal accumulation is studied with metals supplemented media. The tested compounds on zinc and lead absorption by Brassica juncea, are chelating agents (EDTA, citric acid) and soluble organic fractions of compost. EDTA seems to enhance the transfer of lead in plant but it is the opposite in the case of zinc. Citric acid stimulates root absorption for both zinc and lead. For the aqueous extracts of compost, variable effects are obtained according to the origin of compost (green wastes and food wastes). In all tested conditions of cultures, zinc is mainly exported towards shoot while lead is stored in root.

The mobility of mercury (Hg), particularly organic Hg, has been studied in the Thur river basin using an ultra-sensitive and specific analytical equipment (High Performance Liquid Chromatography (HPLC) with on-line CVAFS detection). The Thur river, sub-tributary of the Rhine river is polluted by mercury since the beginning of the 20th century because of industrial effluents from chlorine and soda industry. This study allows to determine in different environmental compartments (soils and river sediments) the total mercury contents (THg) and, for the first time in such an industrialized catchment, the methyl mercury concentrations (MeHg). The ratio between MeHg and THg concentrations is higher in the grassland soils than in the industrial and alluvial soils even if MeHg and THg contents are higher in these latters. The highest MeHg/THg ratios can be observed for lowest C/N ratios and slightly acidic soils. MeHg/THg ratio is very low in the industrial channel despite high MeHg and THg concentrations. For river sediments, MeHg/THg ratios are higher in the suspended matters than in the bottom sediments. These first results are very helpful to better understand the transformation of Hg species in the different compartments and the processes of Hg transfer from one compartment to another.

International audience; High fluoride pollution has been detected in the surrounding soils of the coastal superphosphate industries in the Gulf of Gabes (Southeast of Tunisia). A study was conducted in vicinity of factories analysing plant functional traits combined with plant fluoride accumulation and soil metal concentrations aiming to screen more efficiently native plant species tolerant to this pollution. Aerial parts of 18 plant species out of the 10 most abundant species per site were harvested on two polluted sites of Gabes and Skhira at the vicinity of the factories and on the less polluted site of Smara. Native plant species accumulated fluoride following the gradient of soil pollution. Fluoride contents of plant aerial parts ranged from 37 mg kg(-1) to 360 mg kg(-1) and five plant species were only found in the most polluted site. However these latter had low biomass and soil cover. Crossing biological traits and fluoride contents, a selection grid for potentially restorative plant species enabled the selection of three native perennials i.e. Rhanterium suaveolens, Atractylis serratuloides and, Erodium glaucophyllum as potential candidates for an in-situ phytoremediation program on arid fluoride-polluted sites. This approach may be used in other fluoride-polluted Mediterranean environments. (C) 2014 Elsevier Ltd. All rights reserved.

International audience; Various industrial processes and anthropogenic activities in urban areas induce a release of metals, metalloids and organic pollutants. Phytoremediation of co-contaminated waters in constructed wetlands is a promising solution for reducing the impact on natural environments. In order to improve the design and management of constructed wetlands, more knowledge is needed concerning the effect of organic pollutants on plant metal and metalloid uptake. In this study, the effects of a mixture of organic pollutants commonly found in industrial effluents (hydrocarbons, polycyclic aromatic hydrocarbons, anionic detergent) on the uptake of ten metals and metalloids (MM), i.e. Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn, by five helophytes having a wide European distribution were studied. Main effects of plant species and pollutant conditions on metal uptake and interactions between factors were determined by a statistical treatment of a microcosm experiment. Overall, the order of element uptake in plants was Fe > Al > Mn > Cr, Ni, Zn, > Cu > As, Cd, Pb, which was consistent with relative concentrations in the rhizosphere environment of microcosms. Larger amounts of metals were retained in belowground biomass of plants than in aboveground parts. Statistical analysis showed that organic pollutants enhanced the accumulation of Mn in whole plants and the retention of Fe in belowground parts, while they reduced the accumulation of Cd, Ni, and Zn in whole plants and the retention of Cu in belowground parts. For the other MM (Al, As, Cr, Pb), effects were variable, depending on the plant species. Among the five plants tested, Carex cuprina generally removed the highest quantities of MM, which was the result of both a high metal accumulation capacity and high biomass production. Nevertheless, no significant proportion of the MM total loading could be removed in plants aboveground parts. (C) 2014 Elsevier Ltd. All rights reserved.

International audience; The concentrations of eight elements (Cr, Cu, Fe, Mn, Ni, Ti, V, and Zn) in surface sediments from Segara Anakan Nature Reserve (SARN), Indonesia, were determined using inductively coupled plasma-atomic emission spectroscopy following microwave-assisted acid digestion. In general, the heavy metal concentrations of the sediments were found to decrease in the sequence Fe>Ti>Mn>Zn>V>Cu>Cr>Ni. Sediment pollution assessment was carried out using a pollution status index contamination factor, pollution load index, geoaccumulation index, and enrichment factor as well as by comparing the measured values with two sediment quality guidelines, i.e., threshold effect level and probable effect level. The evaluation showed that in the refinery site stations, Cr, Ni, and Zn concentrations found in the SANR sediments may cause the adverse effect to occur over a wider range of organisms and can contribute to a more serious harmful effect.

8th International-Association-of-Hydrological-Sciences Groundwater Quality Conference (GQ), Univ Florida, Gainesville, FL, APR, 2013; International audience; After a crude oil spill caused by a broken pipeline in 2009 to a gravel aquifer in southern France, degradation processes under various redox conditions progressively established, but at rates that predict a long life-time of the source under natural attenuation after partial source removal. In this study, we aimed at identifying the rate-limiting factors for each redox condition, with special emphasis on phosphate as limiting nutrient. The study was conducted in laboratory microcosms assembled with material collected on site: sediments, water from monitoring wells, oil and microbial sludge. Redox conditions were promoted by adding electron acceptors (either oxygen, nitrate, limonite (FeO(OH)), cryptomelane (K(Mn4+, Mn2+)(8)O-16), or sulfate). For each condition, the role of phosphate was studied by repeated additions for up to 290 days. The results showed a very strong stimulation of aerobic and denitrifying rates of oil degradation by phosphate, provided that oxygen and nitrate were repeatedly supplied. Phosphate caused also a marked stimulation of methanogenic degradation, and a relatively small stimulation of metal reduction. These anaerobic processes started only after marked lag phases, and phosphate shortened the lag phase for methanogenic degradation. Degradation of aromatic and aliphatic hydrocarbons with less than 8 carbons, including benzene, was confirmed even under unstimulated conditions. It is concluded that degradation rates at the site are limited by both, availability of electron acceptors and availability of phosphate needed for promoting microbial growth. (C) 2014 Elsevier B.V. All rights reserved.

International audience; Elements uptake, histological distributions as well as mycorrhizal and physiological statuses of Atriplex halimus were determined on trace metal and metalloid polluted soils from the surrounding spray zones of a former lead smelter in the South-East coast of Marseille (France). Analyses of heavy metal and arsenic distribution in soil and plant organs showed that A. halimus tolerance is largely due to exclusion mechanisms. No specific heavy metal concentration in leaf or root tissues was observed. However, accumulation of salts (NaCl, KCl, Mg and Ca salts) on leaf bladders and peripheral tissues of roots was observed and may compete with metal element absorption. Occurrence of endomycorrhizal structures was detected in roots and may contribute to lower element transfer from root into the aerial parts of plants. The non-destructive measurements of leaf epidermal chlorophylls, flavonols and phenols showed a healthy state of the A. halimus population on the metal and metalloid polluted sites. Considering the low metal bioaccumulation and translocation factors along with a reduced metal stress diagnosis, A. halimus appeared as a good candidate for phytostabilization of trace metals and metalloids and notably arsenic in contaminated soils of the Mediterranean spray zone. However, its invasive potential has to be determined before an intensive in situ use.

International audience; The appearance of agriculture in urban areas improved the health-iness of the diet of people by enabling their consumption of fresh vegetables and fruits. This study assessed the level of fertility, and the impact of the cropping system and of the exploitation time on the physicochemical properties and the pseudo-total and EDTA-extractable metals contents of the vegetable soils of urban garden of in Libreville (Gabon). The results indicated a low fertility of the cultivated soils. The metal contents in the open field cultured soils were generally different from the soils cultured under shelters. Except Al that could be toxic for cultivated vegetables, the soil properties and metal element concentrations decreased significantly with time in the open field soil, while they did not vary in open shade cultured soils. The pseudo-total cadmium concentration was below the detection limit in all soils. Multivariate analysis showed that Al, Fe and Pb were of lithogenic origin, while Cu, Zn and Mn were of anthropogenic origin.

International audience; This study aimed at estimating exposition risks to wild rosemary used as herbs in the contaminated area of the former smelting factory of L'Escalette (South of Marseille, France). Metals and metalloids i.e. Pb, As, Sb, Zn, and Cu concentrations were analyzed in soils and in rosemary aerial parts (stems and leaves) on two sites: one heavily contaminated and the other far away from the pollution source, considered as reference, The metal and metalloid transfer into water during the brewing process of herbal tea was also determined. A mixed contamination by the above-cited contaminants was demonstrated in soils of the factory site, with average concentrations of 9253, 1127, 309, 2698 and 32 mg/kg for Pb, As, Sb, Zn and Cu, respectively. However, metals and metalloids' transfer in rosemary aerial parts was limited, as bioaccumulation factors were under 1. Thus, Pb, As and Cu concentrations in leaves were below international regulation limits concerning ingestion of medicinal herbs (no regulation values available for Sb and Zn). This study highlighted that, if contaminated rosemary leaves were ingested, health risks may be limited since acceptable daily intake (ADI) for Pb, As, Sb and Cu (no ADI value available for Zn) will only be reached if very high quantities are consumed. Furthermore, we aimed to establish if this mixed contamination could alter rosemary's essential oil quality, and thereby the compositions of essential oils obtained from individuals on the heavily contaminated soil were compared to those obtained from the reference population. An increased biosynthesis of antioxidant compounds was favored in essential oils from rosemary individuals growing in contaminated site. Although the health risk of a long-term exposition of low level of the mixed contamination by rosemary ingestion is not easy to elucidate, the use of rosemary essential oils from contaminated site appears as safe. (C) 2013 Elsevier B.V. All rights reserved.

International audience; This study aimed at identifying the extent and type of contamination of a former lead smelting site in the area of Marseille, France, dating from the industrial revolution, and to evaluate environmental hazards and opportunities for phytoremediation, a promising sustainable technology. Amongst the native plants growing in this semiarid shrub ecosystem, two perennials Globularia alypum L. and Rosmarinus officinalis L were selected. Twenty-one soil/plant couples were collected and seventeen additional soil samples were added to better characterize the soil pollution of the area. A multi-contamination by Pb, As, Sb, Zn, Cu was demonstrated, with huge variations within the contamination levels. The soils highest concentrations were encountered along the horizontal chimney and on the slag heaps area. However, both sites differed from each other. The former was characterized by the highest Pb, As and Sb concentrations that could reach 130, 7.0 and 9.0 g kg(-1) respectively, the latter, by high Cu, Fe, Mn, S concentrations, even if it was also heavily contaminated by Pb and Zn. G. alypum and R. officinalis were shown to be metal-tolerant and to accumulate trace metals and As. Due to the low bioconcentration and translocation factors determined, both species may not be used for phytoextraction, but seem to be good candidates for phytostabilization. (C) 2013 Elsevier B.V. All rights reserved.

International audience; This study was aimed at assessing the impact of urban agriculture on physicochemical properties of the soil and the metal uptake by some leafy vegetables cultivated in urban soils of Libreville, Gabon. Cultivated and uncultivated topsoil and vegetable samples were collected from two urban garden sites, and analyzed. The results showed that there was strong acidification and a decrease in the concentrations of nutrients and metals in soils due of agricultural practices. The metal transfer to plants was important, with the exception of iron. The non-essential metals cadmium and lead were not detectable in the plant tissues. Amaranth accumulated more metals than other vegetables. Amaranth and Roselle were vegetables that preferentially concentrated metals in their leaves and could, therefore, be used for metal supplementation in the food chain.

In central Africa, studies on the transfer of metals from soil to food crops, the composition of foods and the dietary intake of cultivated vegetables are scarce. In this study, aluminium (Al), iron (Fe), manganese (Mn) and zinc (Zn) transfer from naturally (pedogeochemically) contaminated soils into ten edible plants and human exposure to these metals via edible parts of the plants were investigated.The fertility of the soils studied was still satisfactory. Soil Al (33,029-40,031 mg kg(-1)), Fe (20,869 ± 1124 mg kg(-1)) and Zn (248.3 ± 37.9 mg kg(-1)) concentrations were consistent with those found in agricultural soils, but Mn concentrations were above those normally encountered in arable fields (10,000 mg kg(-1)). The results indicated a substantial accumulation of Fe in red roselle leaves and of Al, Mn and Zn in some leafy plants and okra (fruits). The present study highlights that adults consuming vegetables grown on naturally Mn-rich soils ingest significant amounts of Al, Mn and Zn. However, Zn amounts were below the recommended maximum tolerable levels for hazard risk.The study indicated that Al and Mn accumulation in food crops cultivated in the Moanda area of Gabon may represent a health hazard. However, the high levels of Zn in vegetables could be a pathway for Zn supplementation in human nutrition to reduce Zn deficiency in developing countries.

In a context of ecological restoration, the use of local source plant populations may be successful for both reclaim of areas polluted with inorganic compounds and biological conservation. Knowing that contaminated sites are generally poor in nutrients and contain a highly altered soil structure, mycorrhizal fungi and rhizobial nodulation are suspected to play an important role in vegetation establishment. The aim of our study was to evaluate the potentiality of an endemic plant species of South-Eastern France, Astragalus tragacantha L. (Fabaceae), to re-colonize an abandoned industrial polluted site. We first grew seedlings of three local populations on soil polluted by heavy metals from the surrounding factory and various growth parameters were measured, after one and two years. Second, arbuscular endomycorrhizal colonization and rhizobial nodulation were determined. Our results are promising because i) A. tragacantha appeared to be heavy metal-tolerant and ii) this is the first report on the occurrence of both endosymbioses for this plant species. This opens new perspectives for dual inoculation with selected rhizobium and arbuscular mycorrhizal strains, in a context of community ecological restoration with this key-species of phryganas from South-Eastern France. This study helps improving the connection between biodiversity conservation and restoration ecology and founding strategies for the propagation of native seeds for ecological restoration resulting in long term population viability., L’utilisation de populations locales comme source de plantes dans le cadre de processus de restauration écologique permet de parvenir à la fois à la réhabilitation de sites pollués par des composés inorganiques et à la conservation biologique. Les sols contaminés étant généralement pauvres en nutriments et présentant une structure hautement altérée, il est supposé que les associations mycorhiziennes et rhizobiennes jouent un rôle non négligeable dans la colonisation végétale. Ainsi, l’objectif de ce travail a été d’évaluer la capacité d’une espèce endémique du sud-est de la France, Astragalus tragacantha L. (Fabaceae) à recoloniser un ancien site industriel pollué. Des plantules issues de graines provenant de trois populations locales ont été transplantées dans du sol pollué prélevé aux alentours du site industriel. Des mesures de croissance ont été réalisées après une et deux années de culture. D’autre part, l’importance des colonisations endomycorhiziennes et rhizobiennes a été évaluée. Nos résultats sont prometteurs parce que 1) A. tragacantha apparaît comme tolérante aux métaux lourds et 2) c’est la première mise en évidence de la présence d’une double endosymbiose chez cette espèce. En effet, cela permet d’envisager une double inoculation de souches rhizobiennes et endomycorhiziennes sélectionnées pour favoriser la restauration écologique des phryganes du sud-est de la France en utilisant cette espèce clé sur des zones polluées par des éléments traces métalliques. Cette étude contribue également à montrer le lien étroit entre conservation de la biodiversité et restauration écologique en étudiant des stratégies de propagation des espèces natives dans un objectif de viabilité des populations à long terme., Laffont-Schwob Isabelle, Dumas Pierre-Jean, Pricop Anca, Rabier Jacques, Miché Lucie, Affre Laurence, Masotti Véronique, Prudent Pascal, Tatoni Thierry. Insights on metal-tolerance and symbionts of the rare species Astragalus tragacantha aiming at phytostabilization of polluted soils and plant conservation. In: Ecologia mediterranea, tome 37 n°2, 2011. Numéro spécial, 7e conférence européenne SER en écologie de la restauration, 23-27 août 2010, Avignon, France. pp. 57-62.

This study showed that Atriplex halimus forms endomycorrhizae on heavy metal polluted-soils. But no variation of chlorophylls content in leaves was observed. Only low concentrations of heavy metals were found in leaves compared with the high levels of pollutants in the soil. A. halimus appears as a good candidate for phytostabilization of heavy metals in brackish soils.

A vertical-flow wetland system was tested for treatment of liquid sludge with high organic concentrations using an organic substrate (peat/crushed pine bark, 1/1) as growing medium. Mesocosms (1 m 3 ) were planted with either Phragmites australis Cav . , Typha latifolia L., or Iris pseudacorus L. The aim of the work was to determine the feasibility of using an organic substrate in treatment wetlands, through the study of its temporal patterns and of its impact on the water output quality. Results confirmed that the organic substrate can be used in such wetlands treating highly organic sludge, without clogging phenomena for the experimental period. The organic substrate released soluble organic matter but few mineral elements. Over the experimental period, substrate TOC concentration did not change while N concentration increased. Plants showed positive impact on substrate temporal patterns and also on the outflow water quality. Overall, Phragmites seemed to be more beneficial than Typha and Iris .

Solid-state 13 C NMR were used to follow organic matter transformation in a subsurface wetland under the effluent of a small cheese-dairy farm under a Mediterranean climate. The results showed that the ratios commonly used to quantify humification, (aromaticity and Alkyl-C/ O- Alkyl-C ratios) can be considered as relevant chemical indicators of organic matter transformation. Polysaccharides were transformed throughout the subsurface wetland whereas aromatic, phenolic and alkyl compounds accumulated. Furthermore, Phenolic-C signal and O- Alkyl-C signal were negatively correlated to proteases and β-galactosidase activities showing that recalcitrant molecules actually accumulated. These results were correlated with high purification yields: the average decrease in chemical demand in oxygen was 90.75% and that in Total Kjeldahl Nitrogen was 75.65%. Thus subsurface wetlands can be considered as an efficient technology to purify effluents with high organic matter contents, such as cheese-dairy effluent, under drastic climate conditions. Furthermore this study highlights the fact that solid-state 13 C NMR is a suitable tool to follow organic matter transformation.

Grevillea exul var exul (Proteaceae), a tree species native to serpentine soils in New Caledonia, is a reported manganese accumulator. Since the metal tolerance of this species remains unknown, its growth and metal accumulation were studied for seven heavy metals under controlled conditions. Brassica juncea, a popular species for metal phytoremediation, was used as a reference. G. exul seedlings were more tolerant to Cr, Zn, Ni, and Cu than B. juncea. There were no differences in Hg, and Cd tolerance between both species. B. juncea seedlings concentrated more Cd, Hg, and Cr in their shoot than G. exul seedlings, while Ni, Zn, and Mn levels were similar for both species. Comparison then focused on tolerance at toxic doses of Ni and Mn using older individuals of both species. No growth inhibition for G. exul plants was observed, whereas the growth of B. juncea was significantly inhibited at the higher metal concentrations. Shoot Mn and Ni concentrations were again lower in G. exul plants as compared to B. juncea, suggesting a mechanism of partial Ni and Mn exclusion in G. exul. In a subsequent study, 1-year-old G. exul plants favored Ni accumulation in roots while Mn accumulated preferentially in shoots.

International audience; Methylmercury (MeHg) and total Hg (THg) concentrations in soil profiles were monitored in the Thur River basin (Alsace, France), where a chlor-alkali plant has been located in the city of Vieux-Thann since the 1930s. Three soil types were studied according to their characteristics and location in the catchment: industrial soil, grassland soil and alluvial soil. Contamination of MeHg and THg in soil was important in the vicinity of the plant, especially in industrial and alluvial soil. Concentrations of MeHg reached 27 ng g1 and 29,000 ng g1 for THg, exceeding the predictable no effect concentration. Significant ecotoxicological risk exists in this area and remedial actions on several soil types are suggested. In each type of soil, MeHg concentrations were highest in topsoil, which decreased with depth. Concentrations of MeHg were negatively correlated with soil organic matter and total S, particularly when MeHg concentrations exceeded 8 ng g1. Under these conditions, MeHg concentrations in soil seemed to be influenced by THg, soil organic matter and total S concentrations. It was found that high MeHg/THg ratios (near 2%) in soil were mainly related to the combined soil environmental conditions such as low THg concentrations, low organic C/N ratios (

River bottom sediments and soils were collected from the industrialized Thur River basin (north-eastern France) to assess mercury contamination. The regional geochemical background level of total mercury was evaluated to calculate mercury contamination factors (Fc) in soils and river bottom sediments. Our estimate of the mean background mercury levels in river sediments and soils, not affected by human activities, was 232 ng g −1 (range: 27–406 ng g −1 ). Sediments contaminated by the effluent from a chlor-alkali plant yielded the highest contamination factors (Fc=1784). Contamination factors of surficial soils within 1 km of the industrial site range from 6.3 to 43.6. This contamination is attributed to diffuse atmospheric deposition from this local plant. However, even upstream from this industrial area elevated contamination factors were recorded for river bottom sediments (Fc=3.2 to 26.4) and for one alluvial soil profile (Fc=10). This is possibly due to past pollution resulting from waste water discharges. Mercury contamination in the different horizons of alluvial soils is not correlated with soil organic carbon content, but may be the result of occasional accidental pollution arising from the introduction of contaminated suspended particulate matter by the Thur River during periods of flooding.

Des eaux de riviere, des sediments et des sols ont ete echantillonnes dans le bassin versant industrialise de la Thur (nord-est de la France) pour evaluer l'ampleur actuelle de la contamination en mercure total et en methylmercure (MeHg). Une methode de separation par chromatographie liquide a haute performance (CLHP) couplee a une detection par spectrometrie de fluorescence atomique en ligne apres oxydation des composes organomercuriels par irradiation UV et generation de vapeurs froides (CV-AFS) a ete developpee pour la speciation de mercure et en particulier pour la determination du methylmercure. Le fond geochimique regional en mercure a tout d'abord ete evalue pour calculer des facteurs de contamination (FC) en mercure total dans les sols et les sediments de riviere. Il a ete estime a 232 ng.g-1 a partir de sediments et de sols non perturbes par des activites anthropogeniques. Les facteurs de contamination les plus eleves sont situes dans les sediments de la riviere (FC = 1 782) recevant les effluents d'une usine chlor-alcali. Les facteurs de contamination des horizons superficiels des sols localises a 1 km autour du site industriel varient entre 6,2 a 55,3. Cette contamination est attribuee au depot atmospherique diffus de l'industrie locale. La contamination mercurielle dans les differents horizons de sols alluviaux n'est pas correlee avec leur teneur en carbone organique particulaire mais plutot avec une pollution historique de mercure provenant de sediments contamines deposes par la riviere Thur en periode de crue. Les premiers resultats sur la speciation du mercure ont montre que la proportion de MeHg par rapport au mercure total dans les sols alluviaux et industriels est en moyenne de 0,03 a 0,15 %. Le mercure organique dissous represente la composante principale du mercure total dissous dans l'eau de riviere (70-100 %) et sa proportion varie de maniere saisonniere.

National audience