Assessing the chronic toxicity of spreading organic amendments on agricultural soil: Tests on earthworms and plants.

Recycling organic wastes on agricultural soils improves the soil quality, but the environmental and health impact of these organic amendments closely depends on their origins, their bio-physicochemical characteristics and the considered organisms potentially affected. The aim of this study was to assess the potential chronic ecotoxicity of spreading organic amendments on agricultural soils. To do this, we characterized three different organic amendments: sewage sludge from an urban wastewater treatment plant, cow manure and liquid dairy manure. Their chronic ecotoxicity was studied through assays exposing earthworms of the species Eisenia fetida and two plants: Medicago sativa and Sinapis alba. Of the three amendments, the sewage sludge presented the highest concentrations of micropollutants and a considerable fraction of available and biodegradable organic matter. The cow manure and liquid dairy manure had lower chemical contamination and similar characteristics with lower biodegradable fractions of their organic matter. No chronic phytotoxicity was evidenced: on the contrary, particularly with sewage sludge, the germination rate and aerial and root biomass of the two plants increased. Considering earthworms, their biomass increased considerably during the reproduction assays in soil amended with sewage sludge, which contained the more bioavailable organic matter. Nonetheless, the earthworms presented an inhibition close to 78% of the production of juveniles when exposed to sewage sludge exceeding 20 g.kg-1 DW (that means 2 times the agronomic dose). This reprotoxic effect was also observed in the presence of liquid dairy manure, but not with cow manure. At the end of the assays, the glycogen and protein reserves in earthworms exposed to sewage sludge were inferior to that of control earthworms, respectively around 50% and 30%. For the earthworms exposed to liquid dairy manure, protein and lipid reserves increased. In the case of liquid dairy manure, this reprotoxic effect did not appear to be linked to the presence of micropollutants. In conclusion, our results confirm the need to use several ecotoxicity assays at different biological levels and with different biological models to assess the ecotoxic impacts of soil amendments. Indeed, although certain organic wastes present a strong nutritional potential for both plants and earthworms, a not inconsiderable risk was apparent for the reproduction of the latter. An integrated ecotoxicity criterion that takes into account a weighted sum of the different results would guide the utilization of organic amendments while ensuring the good health of agricultural ecosystems.

Combined Chemical and Ecotoxicological Measurements for River Sediment Management in an On-Land Deposit Scenario.

Sediment management along engineered river systems includes dredging operations and sediment deposition in the sea (capping) or on land. Thus, determining the ecotoxicological risk gradient associated with river sediments is critical. In this study, we investigated sediment samples along the Rhône River (France) and conducted environmental risk assessment tests with the idea to evaluate them in the future for deposit on soil. Based on an on-land deposit scenario, the capacity of the sediment samples from four sites (LDB, BER, GEC, and TRS) to support vegetation was evaluated by characterising the physical and chemical parameters (pH, conductivity, total organic carbon, grain size, C/N, potassium, nitrogen, and selected pollutants), including polychlorinated biphenyls (PCBs) and metal trace elements. All tested sediments were contaminated by metallic elements and PCBs as follows: LDB > GEC > TRS > BER, but only LDB had levels higher than the French regulatory threshold S1. Sediment ecotoxicity was then assessed using acute (plant germination and earthworm avoidance) and chronic (ostracod test and earthworm reproduction) bioassays. Two of the tested plant species, Lolium perenne (ray grass) and Cucurbita pepo (zucchini), were highly sensitive to sediment phytotoxicity. Acute tests also showed significant inhibition of germination and root growth, with avoidance by Eisenia fetida at the least contaminated sites (TRS and BER). Chronic bioassays revealed that LDB and TRS sediment were significantly toxic to E. fetida and Heterocypris incongruens (Ostracoda), and GEC sediment was toxic for the latter organism. In this on-land and spatialised deposit scenario, river sediment from the LDB site (Lake Bourget marina) presented the highest potential toxicity and required the greatest attention. However, low contamination levels can also lead to potential toxicity (as demonstrated for GEC and TRS site), underlining the importance of a multiple test approach for this scenario.

Assessing the Potential Ecotoxicological Risk of Different Organic Amendments Used in Agriculture: Approach Using Acute Toxicity Tests on Plants and Earthworms.

In Europe, spreading organic wastes to fertilize soils is an alternative commonly used instead of chemical fertilizers. Through their contributions of nutrients and organic matter, these wastes promote plant growth and thus agricultural production. However, these organic amendments can also contain mineral and organic pollutants requiring chemical and ecotoxicological analyses to guarantee their harmlessness on soil and its organisms during spreading. The purpose of this study was to assess the potential toxicity of three organic amendments from different sources (sewage sludge, dairy cow manure, dairy cow slurry) by performing chemical analyses and acute toxicity tests on three types of organism: earthworms, plants, soil microbial communities. Chemical analysis revealed a higher content of certain pharmaceuticals, polycyclic aromatic hydrocarbons and metals in sewage sludge in comparison with the two other types of organic wastes. The ecotoxicological assessment showed a dose-dependent effect on soil organisms for the three organic amendments with higher toxic effects during the exposure tests with a soil amended with dairy cow slurry. However, at realistic spreading doses (10 and 20 g kg-1 dry weight of organic amendments) on a representative exposed soil, organic amendment did not show any toxicity in the three organisms studied and had positive effects such as increased earthworm biomass, increased plant root growth and earthworm behavior showing attraction for organic amendment. On the contrary, exposure assays carried out on a limited substrate like sandy soil showed increased toxicity of organic amendments on plant germination and root growth. Overall, the ecotoxicological analysis revealed greater toxicity for soil organisms during the amendment of cow slurry, contrary to the chemical analysis which showed the potential high risk of spreading sewage sludge due to the presence of a higher quantity of pollutants. The analysis of the chemical composition and use of acute toxicity tests is the first essential step for assessing the ecotoxicological risk of spreading organic amendments on soil organisms. In addition to standard tests, the study suggests using a representative soil in acute toxicity tests to avoid overestimating the toxic effects of these organic amendments.

Metal pollution trajectories and mixture risk assessed by combining dated cores and subsurface sediments along a major European river (Rhône River, France).

In European rivers, research and monitoring programmes have targeted metal pollution from bed and floodplain sediments since the mid-20th century by using various sampling and analysis protocols. We propose to characterise metal contamination trajectories since the 1960s based on the joint use of a large amount of data from dated cores and subsurface sediments along the Rhône River (ca. 512 km, Switzerland-France). For the reconstruction of spatio-temporal trends, enrichment factors (EF) and geo-accumulation (Igeo) approaches were compared. The latter index was preferred due to the recurrent lack of grain-size and lithogenic elements in the dataset. Local geochemical backgrounds were established near (1) the Subalps and (2) the Massif Central to consider the geological variability of the watershed. A high contamination (Igeo = 3-5) was found for Cd, Cu and Zn from upstream to downstream over the period 1980-2000. This pattern is consistent with long-term emissions from major cities and the nearby industrial areas of the Upper Rhône (Geneva, Arve Valley), and Middle Rhône (Lyon, Chemical Corridor, Gier Valley). Hotspots due to Cu and Zn leaching from vineyards, mining, and highway runoff were also identified, while Pb was especially driven by industrial sources. The recovery time of pollution in sediment varied according to the metals and was shorter upstream of Lyon (15-20 years) than downstream (30-40 years). More widely, it was faster on the Rhône than along other European rivers (e.g. Seine and Rhine). Finally, the ecotoxicological mixture risk of metal with Persistent Organic Pollutants (POPs) for sediment-dwelling organisms showed a medium "cocktail risk" dominated by metals upstream of Lyon, although it is enhanced due to POPs downstream, and southward to the delta and the Mediterranean Sea. Overall, this study demonstrates the heterogeneity of the contamination trends along large fluvial corridors such as the Rhône River.

A Bayesian network approach for the identification of relationships between drivers of chlordecone bioaccumulation in plants.

Plants were sampled from four different types of chlordecone-contaminated land in Guadeloupe (West Indies). The objective was to investigate the importance of biological and agri-environmental parameters in the ability of plants to bioaccumulate chlordecone. Among the plant traits studied, only the growth habit significantly affected chlordecone transfer, since prostrate plants concentrated more chlordecone than erect plants. In addition, intensification of land use has led to a significant increase in the amount of chlordecone absorbed by plants. The use of Bayesian networks uncovers some hypothesis and identifies paths for reflection and possible studies to identify and quantify relationships that explain our data. Graphical abstract.

Past and recent state of sediment contamination by persistent organic pollutants (POPs) in the Rhône River: Overview of ecotoxicological implications.

Twenty-one sediment samples were taken from five dated sediment cores collected along the Rhône River from 2008 to 2011. A total of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 7 polychlorinated biphenyls (PCBs), 8 polybrominated diphenyl ethers (PBDEs), 3 polybrominated biphenyls (PBBs), 3 hexabromocyclododecanes (HBCD) and 31 organochlorine pesticides (OCPs) were investigated to provide information on deposition dynamics in time and space, but also regarding the ecotoxicological risks associated with these contaminants. Median concentrations of total PBDEs are nine times lower than the levels of total PCBs along the entire studied stretch of the Rhône River. The results show that total PBDEs concentrations range from 0.06 to 239 µg·kg-1 DW with a median value of 3.81 µg·kg-1 DW and a maximum concentration measured in the years 2000s. These maximum concentrations are identical to those measured for total PCBs at the end of the 1990s, but show a different pattern of distribution. Abnormal dichlorodiphenyltrichloroethane (DDT) levels were also detected in the downstream section of the river, with a peak concentration of 147.5 µg·kg-1 DW measured at the GEC site from 2005 onwards. Analyses of the enantiomeric fractions reveal a fresh input resulting from a technical formulation. Sediments from the core sampled at the most downstream site (GEC) are found to be highly toxic to organisms living nearby, particularly because of the total PCDD/Fs, DDE and DDT levels. In addition, based on available sediment quality guidelines, there may be a potential bioaccumulation risk for humans not only for these three compounds of concern but also for total PCBs and 7 out of the 8 analysed PBDEs.

Zn Speciation and Stable Isotope Fractionation in a Contaminated Urban Wetland Soil-Typha latifolia System.

Wetlands play a key role in the immobilization of metallic contaminants. In this context the mechanisms of Zn sequestration and Zn transfer and storage in Typha latifolia L. colonizing a frequently flooded contaminated soil were studied. A combination of EXAFS spectroscopy, micro X-ray fluorescence (µXRF) and Zn isotope measurements was applied to soil, plant organs and decaying biomass. Zn was present in the soil as Zn-layered double hydroxide, as tetrahedral and octahedral sorbed Zn species, and as ZnS. Octahedral and tetrahedral Zn (attributed to symplastic Zn-organic acid and apoplasmic Zn-cell wall complexes, respectively) and Zn-thiol species were observed in the roots, rhizomes and stems. Iron plaque was present on the rhizomes and roots. Enrichment in light isotopes for Zn sorbed on the plaque relative to the soil (Δ66Znplaque-soil = -0.3 to -0.1‰) suggested the dissolution of ZnS (enriched in light isotopes) in the rhizosphere with subsequent Zn2+ sorption on the root plaque. Furthermore, enrichment in light isotopes of stems relative to leaves (Δ66Znstem-leaves = -0.2‰) suggested the remobilization of Zn via the phloem, from leaves back to the stems. Overall these data highlight the role of thiols in controlling Zn speciation during its transfer and storage in T. latifolia.

Historical records, sources, and spatial trends of PCBs along the Rhône River (France).

Despite bans on PCB use since 1975 (open systems) and 1987 (closed systems), concentrations of PCBs in riverine fish in France continue to exceed regulatory levels. We present historical records of PCB concentrations in sediment cores from eight sites on the Rhône River, from Lake Geneva to the Mediterranean Sea. Maximum PCB concentrations (sum of seven indicator PCBs) increase downstream, from 11.50 µg/kg at the most upstream site to 417.1 µg/kg at the most downstream site. At some sites peak concentrations occur in sediment deposited as recently as the 2000s. Hierarchical clustering (five clusters) identified differences in PCB congener profiles within and between sites. Exponential models fit to decadal time windows indicate that rapid reductions in concentrations during about 1990-2000 have slowed, and that it might be decades before target concentrations in sediment that correspond to regulatory thresholds in fish will be reached at some sites.

Review on physical and chemical characterizations of contaminated sediments from urban stormwater infiltration basins within the framework of the French observatory for urban hydrology (SOERE URBIS).

Urban stormwater infiltration basins are designed to hold runoff from impervious surfaces and allow the settling of sediments and associated pollutants. However concerns have been expressed about the environmental impacts that may be exerted by the trapped pollutants on groundwater, soils and ecosystems. In this context, sediment characterization represents a key issue for local authorities in terms of management strategies. During the last two decades, several studies were launched including either physical or chemical characterization of stormwater sediments but without real synthesis of data and methods used. Consequently, there is an important need for reviewing the current experimental techniques devoted to the physico-chemical characterization of sediment. The review is based on the outcomes of two experimental sites for which long term monitoring and data collection have been done: the Cheviré basin (near Nantes) and the Django Reinhardt basin (near Lyon). The authors summarize the studies dealing with bulk properties, pollutant contents, their potential mobility and speciation. This paper aims at promoting the significant progresses that were made through a multidisciplinary approach involving multi-scaled and combined experimental techniques.

Influence of spontaneous vegetation in stormwater infiltration system clogging.

The paper presents the role of spontaneous vegetation on the hydraulic performance of an infiltration basin. The objective of the research was more particularly to study this role of different types of spontaneous vegetation found in situ in an infiltration basin near Lyon. The saturated hydraulic conductivity of three areas covered by Phalaris arundinacea, Polygonum mite, Rumex crispus and similar non-vegetated zones was compared. Eight field campaigns were carried out from July 2010 to May 2011 in order to compare the performance of each type of vegetation and its evolution over time. The results suggest a positive impact of vegetation on hydraulic performance in particular in summer during the growth of the plants. The hydraulic conductivity in this period was twice to four times higher than in bare areas or in vegetated zones during the plant rest periods. Some species were also found more appropriate to limit clogging (Phalaris arundinacea) likely due to its specific structure and growth process.

Thlaspi arvense binds Cu(II) as a bis-(L-histidinato) complex on root cell walls in an urban ecosystem.

Root cell walls accumulate metal cations both during acquisition from the environment and removal from the protoplast to avoid toxicity, but molecular forms of the metals under field conditions remain elusive. We have identified how copper is bound to cell walls of intact roots of native Thlaspi arvense by combining synchrotron X-ray fluorescence and absorption techniques (XANES and EXAFS) at the nano-, micro-, and bulk scales. The plants grew naturally in sediment in a stormwater runoff basin at copper concentrations typical of urban ecosystems. About 90% of acquired copper is bound in vivo to cell walls as a unique five-coordinate Cu(II)-bis(L-histidinato) complex with one L-histidine behaving as a tridentate ligand (histamine-like chelate) and the other as a bidentate ligand (glycine-like chelate). Tridentate binding of Cu(II) would provide thermodynamic stability to protect cells against copper toxicity, and bidentate binding may enable kinetic lability along the cell wall through protein-protein docking with the non-bonded imidazole group of histidine residues. EXAFS spectra are provided as ESI to facilitate further identification of Cu-histidine and distinction of Cu-N from Cu-O bonds in biomolecules.

Microbial communities of urban stormwater sediments: the phylogenetic structure of bacterial communities varies with porosity.

This study focuses on the distribution of bacterial and fungal communities within the microstructure of a multi-contaminated sedimentary layer resulting from urban stormwater infiltration. Fractionation was performed on the basis of differential porosity and aggregate grain size, resulting in five fractions: leachable fitting macroporosity, < 10, 10-160, 160-1000 µm fitting aggregates, > 1000 µm. Amounts of both bacterial and fungal biomasses are greater in the < 10 µm and leachable fractions. The aggregates contain numerous bacteria but very low amounts of fungal biomass. Single-strand conformational polymorphism molecular profiles highlighted the differences between bacterial and fungal communities of the leachable fraction and those of the aggregates. Random Sanger sequencing of ssu clones revealed that these differences were mainly because of the presence of Epsilonproteobacteria and Firmicutes in the leachable fractions, while the aggregates contained more Cyanobacteria. The Cyanobacteria phylotypes in the aggregates were dominated by the sequences related to Microcoleus vaginatus while the leachable fractions presented the sequences of chloroplastic origin. Therefore, more than 50% of the phylotypes observed were related to Proteobacteria while 40% were related to Cyanobacteria and Bacteroidetes. Preferential distribution of clades in almost all the phyla or classes detected was observed. This study provides insight into the identities of dominant members of the bacterial communities of urban sediments. Microcoleus vaginatus appeared to predominate in pioneer soils.

Structural stability, microbial biomass and community composition of sediments affected by the hydric dynamics of an urban stormwater infiltration basin. Dynamics of physical and microbial characteristics of stormwater sediment.

The sedimentary layer deposited at the surface of stormwater infiltration basins is highly organic and multicontaminated. It undergoes considerable moisture content fluctuations due to the drying and inundation cycles (called hydric dynamics) of these basins. Little is known about the microflora of the sediments and its dynamics; hence, the purpose of this study is to describe the physicochemical and biological characteristics of the sediments at different hydric statuses of the infiltration basin. Sediments were sampled at five time points following rain events and dry periods. They were characterized by physical (aggregation), chemical (nutrients and heavy metals), and biological (total, bacterial and fungal biomasses, and genotypic fingerprints of total bacterial and fungal communities) parameters. Data were processed using statistical analyses which indicated that heavy metal (1,841 µg/g dry weight (DW)) and organic matter (11%) remained stable through time. By contrast, aggregation, nutrient content (NH4⁺, 53-717 µg/g DW), pH (6.9-7.4), and biological parameters were shown to vary with sediment water content and sediment biomass, and were higher consecutive to stormwater flows into the basin (up to 7 mg C/g DW) than during dry periods (0.6 mg C/g DW). Coinertia analysis revealed that the structure of the bacterial communities is driven by the hydric dynamics of the infiltration basin, although no such trend was found for fungal communities. Hydric dynamics more than rain events appear to be more relevant for explaining variations of aggregation, microbial biomass, and shift in the microbial community composition. We concluded that the hydric dynamics of stormwater infiltration basins greatly affects the structural stability of the sedimentary layer, the biomass of the microbial community living in it and its dynamics. The decrease in aggregation consecutive to rewetting probably enhances access to organic matter (OM), explaining the consecutive release of NH4⁺, the bloom of the microbial biomass, and the change in structure of the bacterial community. These results open new perspectives for basin management since the risk of OM and pollutant transfer to the aquifer is greatly affected by alternating dry and flood periods.

Distribution of organic pollutants and natural organic matter in urban storm water sediments as a function of grain size.

The sealing of surfaces in urban areas makes storm water management compulsory. Contaminated particles carried from urban surfaces are deposited in infiltration ponds. This gives rise to a highly organic (11% DW) contaminated sedimentary layer (Zn:1.2 mg/g, Cd:15 mg/kg) that could threaten groundwater quality. During infiltration, particle arrangement impacts infiltrating water and sediment exchanges. In this context, understanding particle arrangement and leachable components is essential. This study investigates Organic Matter (OM) not only as a pollutant but also as a substrate and a structuring element. The leachable fraction was collected and grain size fractionation was performed. OM of sediments and isolated fractions were characterized by measuring organic carbon content, isolating aromatic hydrocarbons, saturated hydrocarbons and polar compounds after dichloromethane extraction, and by gas chromatography-mass spectrometry (GC-MS) molecular analyses. The organic compounds observed were petroleum byproducts (steranes and terpanes, unresolved complex mixture (UCM) and polycyclic aromatic hydrocarbons (PAH)), but plant and bacteria biomarkers were also found (phytol and derivatives, sterols). Leachable OM consisted of 6% of sediment OM (associated with particles >0.45 microm). This leachable OM is easily extractable by dichloromethane (96%) and contains fewer macromolecules than other fractions. Isolated grain size fractions showed dissimilarities (total organic carbon from 3.5 mg/g to 88.6 mg/g, extraction rate from 24 to 96%, aromatic hydrocarbon distribution) and similarities (proportions of aromatic and saturated hydrocarbons and polar compounds, molecular distribution of saturated hydrocarbons and polar compounds). The results suggest that organic macromolecules take part in the aggregation of sediments and prevent fine particles (<10 microm) from being leached. On the other hand, leachable particles (20 microm grain size mode) could carry low molecular weight organic molecules. The physical structure of the sediments and the leaching of particles containing contaminants are considerably affected by the presence of OM.

Influence of a stormwater sediment deposit on microbial and biogeochemical processes in infiltration porous media.

The purpose of this study was to test the relative influence of organic matter quantity and quality and the pollutant content of a stormwater sediment deposit on mineralization processes, microbial characteristics, and the release of solutes in infiltration sediment systems. In microcosm experiments, two other natural sediment deposits (one low and one rich particulate organic matter deposits) were studied to compare their effects with those of the stormwater deposit. The results showed that the biogeochemical processes (aerobic respiration, denitrification, fermentative processes), the microbial metabolism (enzymatic activities), and the releases of several solutes (NH(4)(+) and DOC) were stimulated in presence of the stormwater deposit and the natural particulate organic matter (POM)-rich deposit because of the quantity of the POM in these deposits. In the stormwater deposit, the high availability of the POM (indicated by its low C/N ratio and its high P content) produced a higher stimulation of the microbial metabolism than in presence of the POM-rich deposit (with a high C/N ratio). Pollutant (hydrocarbon and heavy metal) contents of the stormwater deposit did not have a significant effect on microbial processes. Thus, main effects of the stormwater sedimentary deposit on infiltration system were due to its organic matter characteristics (quantity and quality). Such organic matter characteristics need to be considered in future studies to determine the contamination potential of stormwater management practices.

Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil.

The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design.

Evaluation of the phytotoxicity of contaminated sediments deposited "on soil": II. Impact of water draining from deposits on the development and physiological status of neighbouring plants at growth stage.

As part of a study of the phytotoxic risk of spreading contaminated sediments "on soil", a laboratory experiment was carried out to assess the impact of water draining from sediments on peripheral vegetation. Drainage water was obtained in the laboratory by settling three sediments with different pollutants levels, and the supernatant solutions (respectively A1, B1, C1 drainage waters) were used as soaking water for maize (Zea maïs L.) and ryegrass (Lolium perenne L.). The physicochemical characteristics of the supernatant water, particularly metal contents, showed a pattern of contamination, with C1>A1>B1. The plants tested were grown on soil for 21 days, before being soaked for another 21-day period with drainage water (treatments) and distilled water (control). Biomass parameters (fresh weight, length, etc.), enzymatic activity [glutamine synthetase (GS), phosphoenolpyruvate carboxylase (PEPc)] and Zn, Cu, Cd and Cr contents were measured on both the shoots and roots of each plant. Biomass parameters were stimulated by C1, not affected by A1 and decreased with B1 for maize, whereas they increased for ryegrass in all the treatments. Compared to the control, GS activity was stimulated by C1 in the shoots of both plants and inhibited by treatments B1 and C1 in maize roots. PEPc activity in ryegrass was 1.5-5 times higher with contaminated water treatment, while contrasting effects were observed in maize plants. Both plants showed greater accumulation of chromium and zinc than cadmium and copper. Treatment A1 was found to be less active on plant growth and have a lower impact on the physiological status (enzymatic activities) of both plants. Treatment C1 stimulated the growth and physiological status of the plants, especially in shoots, with higher metal accumulation values in both plants. Treatment B1 was found to show more variable effects on growth indices, enzymatic activity and metal accumulation according to plant species.

Physicochemical and biological characterisation of different dredged sediment deposit sites in France.

The aim of this work is to determine sediment properties, metal contents and transfers of Cd and Zn from dredged sediments to plants. To this end 10 deposit sites with different contexts were visited in France. The main agronomic characteristics and metal contents for surface soil layers were measured, the plant species present at the sites, such as Brassicaceae and Fabaceae, were listed, and the distribution of their root systems described. Soil characteristics such as available P (Olsen) varied between sites, with values ranging from 0.01 to 0.49 g kg(-1). Total contents and enrichment factors were studied, highlighting metal contamination in most of the sites. Despite carrying out principal component analyses, it was not possible to group deposits by age or geographical localisation. However, deposits could be distinguished as a function of proximity of industrial facilities, sediment grain size and carbonate content. Associations between metals were also highlighted: (1) Cd, Pb and Zn, and (2) Al, Cr, Cu and Fe. Consequently, we propose classifying them as technogenic anthrosols.

Evaluation of the phytotoxicity of contaminated sediments deposited "on soil". I. Impact of water draining from the deposit on the germination of neighbouring plants.

As part of a study of the phytotoxic risk of spreading of contaminated sediments "on soil", we carried out a laboratory experiment assessing the impact of water draining from sediments in a deposit scenario on the peripheral vegetation. The plant tested were the Chinese cabbage (Brassica campestris L. var. chinensis), maize (Zea mays L.) and ryegrass (Lolium perenne L.). The draining water samples (A1, B1 and C1) were obtained after decantation in laboratory of the sediments. The classification of the water sampled in decreasing order of cumulative contamination was C1 > A1 > B1. The B1 and C1 water samples inhibited the germination of seeds tested to various extents. The percentage of seeds that did not germinate was 1.3-fold times higher for Chinese cabbage with B1 than for the control and 2.3-fold times higher for ryegrass with C1 than for the control. Seeds watered with B1 had lower moisture contents than the control: 10% lower for ryegrass and maize and 50% lower for Chinese cabbage. An increase (about 1.5 microg/ml) in total soluble protein (versus the control) was observed for all three plant species tested in the presence of C1. Glutamine synthetase activity was significantly (1.35 times) higher in ryegrass seeds in the presence of C1 than in the control. We also observed changes in the specific activity of phosphoenolpyruvate carboxylase, which increased for ryegrass and decreased for maize as the concentration of contaminants in the water increased. The results show (i) the necessity to use different plant species to evaluate the toxic effect of sediment deposited on soil on the vegetation, and (ii) that soon as on germination an evaluation of an impact is possible.