International audience | This study aimed to better understand the impact of different bauxite residues (BR) on the germination and the development of Sinapis alba (white mustard). Unamended BR from Provence, France (PRO), and Guinea (GUI) bauxite were selected, and modified bauxite residues from PRO and GUI (MBRPRO and MBR-GUI) were obtained by gypsum application and repeated leaching, in order to reduce their pH, electrical conductivity (EC), and exchangeable sodium percentage (ESP). Germination rates were monitored in soil-BR mixtures with increasing concentrations of BR. A rhizotron experiment was done, where Sinapis alba was allowed to develop in a layer of soil on the top of a layer of bauxite residue. To assess the impact of the residue on root development, the WhinRhizo (R) software was used to measure the architectural traits of roots. Peroxidase and fluorescein hydrolase activities were also assessed on the roots grown either in the soil or in the residue layers. Results showed that (i) bauxite residue origin, (ii) bauxite residue modification by gypsum, and (iii) bauxite residue concentration had significant effects on the germination, the root development and architecture, and the enzymatic activities of the roots of Sinapis alba. The PRO residue had a far stronger phytotoxic effect compared to the GUI residue on every measured variable. The toxic effect was strongly modulated by the origin of bauxite residue. The gypsum application efficiently reduced the phytotoxic effect of the residues, but significant negative effects on the different variables were still recorded.

This study aimed to better understand the impact of different bauxite residues (BR) on the germination and the development of Sinapis alba (white mustard). Unamended BR from Provence, France (PRO), and Guinea (GUI) bauxite were selected, and modified bauxite residues from PRO and GUI (MBR-PRO and MBR-GUI) were obtained by gypsum application and repeated leaching, in order to reduce their pH, electrical conductivity (EC), and exchangeable sodium percentage (ESP). Germination rates were monitored in soil-BR mixtures with increasing concentrations of BR. A rhizotron experiment was done, where Sinapis alba was allowed to develop in a layer of soil on the top of a layer of bauxite residue. To assess the impact of the residue on root development, the WhinRhizo® software was used to measure the architectural traits of roots. Peroxidase and fluorescein hydrolase activities were also assessed on the roots grown either in the soil or in the residue layers. Results showed that (i) bauxite residue origin, (ii) bauxite residue modification by gypsum, and (iii) bauxite residue concentration had significant effects on the germination, the root development and architecture, and the enzymatic activities of the roots of Sinapis alba. The PRO residue had a far stronger phytotoxic effect compared to the GUI residue on every measured variable. The toxic effect was strongly modulated by the origin of bauxite residue. The gypsum application efficiently reduced the phytotoxic effect of the residues, but significant negative effects on the different variables were still recorded.

International audience | Organic waste products (OWP) application to crop lands makes possible nutrients recycling. However, it can result in long-term accumulation of trace elements (TE) in soils. The present study aimed at (i) assessing the impact of regular applications of urban composts and manure on the TE contents of topsoils and crops in a long-term field experiment, (ii) comparing the TE mass balances with the stock variations of TE in soils, and (iii) proposing a prospective evaluation of this practice, based on estimated soil safe threshold values and simulations of soil TE accumulation for 100 years. In the long-term field experiment, physico-chemical properties and TE contents (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been measured in OWP, soils, plants and leaching waters for the period 1998–2015, and used for mass balance calculations and long-term simulations of TE accumulations. The composts of green wastes and sludge (GWS) and of municipal solid waste (MSW) were the OWP with the largest TE contents, while the farmyard manure tended to have the lowest. Repeated application of OWP led to significant accumulation of Zn and Cu in the topsoil layer (not for Cr, Cd, Hg, Ni, Pb), especially with GWS, without overpassing calculated protective threshold values. No effect of repeated application of OWP has been observed on TE contents in grains (wheat, maize, barley). The positive mass balance has been dominated by the input flux of TE through OWP and resulted in the observed increases of soil stocks for Cu and Zn. Prospective simulation of soil content evolution until 2100 showed that soil content reached 0.4 mg Cd kg−1 soil (GWS, MSW), 38 mg Cu kg−1 soil (GWS) and 109 mg Zn kg−1 soil (GWS), which remained lower than protective threshold values.

International audience | Organic waste products (OWP) application to crop lands makes possible nutrients recycling. However, it can result in long-term accumulation of trace elements (TE) in soils. The present study aimed at (i) assessing the impact of regular applications of urban composts and manure on the TE contents of topsoils and crops in a long-term field experiment, (ii) comparing the TE mass balances with the stock variations of TE in soils, and (iii) proposing a prospective evaluation of this practice, based on estimated soil safe threshold values and simulations of soil TE accumulation for 100 years. In the long-term field experiment, physico-chemical properties and TE contents (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been measured in OWP, soils, plants and leaching waters for the period 1998–2015, and used for mass balance calculations and long-term simulations of TE accumulations. The composts of green wastes and sludge (GWS) and of municipal solid waste (MSW) were the OWP with the largest TE contents, while the farmyard manure tended to have the lowest. Repeated application of OWP led to significant accumulation of Zn and Cu in the topsoil layer (not for Cr, Cd, Hg, Ni, Pb), especially with GWS, without overpassing calculated protective threshold values. No effect of repeated application of OWP has been observed on TE contents in grains (wheat, maize, barley). The positive mass balance has been dominated by the input flux of TE through OWP and resulted in the observed increases of soil stocks for Cu and Zn. Prospective simulation of soil content evolution until 2100 showed that soil content reached 0.4 mg Cd kg−1 soil (GWS, MSW), 38 mg Cu kg−1 soil (GWS) and 109 mg Zn kg−1 soil (GWS), which remained lower than protective threshold values.

Organic waste products (OWP) application to crop lands makes possible nutrients recycling. However, it can result in long-term accumulation of trace elements (TE) in soils. The present study aimed at (i) assessing the impact of regular applications of urban composts and manure on the TE contents of topsoils and crops in a long-term field experiment, (ii) comparing the TE mass balances with the stock variations of TE in soils, and (iii) proposing a prospective evaluation of this practice, based on estimated soil safe threshold values and simulations of soil TE accumulation for 100 years. In the long-term field experiment, physico-chemical properties and TE contents (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been measured in OWP, soils, plants and leaching waters for the period 1998–2015, and used for mass balance calculations and long-term simulations of TE accumulations. The composts of green wastes and sludge (GWS) and of municipal solid waste (MSW) were the OWP with the largest TE contents, while the farmyard manure tended to have the lowest. Repeated application of OWP led to significant accumulation of Zn and Cu in the topsoil layer (not for Cr, Cd, Hg, Ni, Pb), especially with GWS, without overpassing calculated protective threshold values. No effect of repeated application of OWP has been observed on TE contents in grains (wheat, maize, barley). The positive mass balance has been dominated by the input flux of TE through OWP and resulted in the observed increases of soil stocks for Cu and Zn. Prospective simulation of soil content evolution until 2100 showed that soil content reached 0.4 mg Cd kg⁻¹ soil (GWS, MSW), 38 mg Cu kg⁻¹ soil (GWS) and 109 mg Zn kg⁻¹ soil (GWS), which remained lower than protective threshold values.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [ADD1_IRSTEA]Systèmes aquatiques soumis à des pressions multiples - Trend Editorial | International audience | TheWater Framework Directive (WFD) currently supports chemical and ecological monitoring programmes in order to achieve the good water surface status. Although chemical and ecological assessments are necessary, they have some limitations. Chemical approaches focus on certain substances identified as priorities, but they do not take into account other potentially harmful substances and also ignore the hazards related to contaminant cocktails. On the other hand, while ecological approaches provide holistic information on the impairment of biological communities in ecosystems, they do not distinguish the role of contaminants in these alterations, and consequently do not allow the establishment of contaminant impact reduction plans. Consequently, ecotoxicologists suggest the use of effect-based tools such as biomarkers. Biomarkers highlight the effect of potentially harmful substances (or a cocktail), and their specificity towards the chemicalsmakes it possible to properly discriminate the role of toxicantswithin biological community impairments. Thus, the integration of such tools (besides existing chemical and ecological tools) in the WFD could considerably improve its biomonitoring strategy. The B n' B project (Biomarkers and Biodiversity) exposes key objectives that will allow to (i) establish an inventory of the biomarkers developed by French laboratories; (ii) determine their methodological advancement and limits and, on this basis, formulate recommendations for biomonitoring use and future research needs; (iii) discuss the biomarkers' ecological significance, specificity to contaminants and interpretation capacity; (iv) establish, in fine, a selection of valuable biomarkers to enter the WFD; and (iv) propose integrative tools to facilitate the decision-taking by stakeholders.

The Water Framework Directive (WFD) currently supports chemical and ecological monitoring programmes in order to achieve the good water surface status. Although chemical and ecological assessments are necessary, they have some limitations. Chemical approaches focus on certain substances identified as priorities, but they do not take into account other potentially harmful substances and also ignore the hazards related to contaminant cocktails. On the other hand, while ecological approaches provide holistic information on the impairment of biological communities in ecosystems, they do not distinguish the role of contaminants in these alterations, and consequently do not allow the establishment of contaminant impact reduction plans. Consequently, ecotoxicologists suggest the use of effect-based tools such as biomarkers. Biomarkers highlight the effect of potentially harmful substances (or a cocktail), and their specificity towards the chemicals makes it possible to properly discriminate the role of toxicants within biological community impairments. Thus, the integration of such tools (besides existing chemical and ecological tools) in the WFD could considerably improve its biomonitoring strategy. The B n’ B project (Biomarkers and Biodiversity) exposes key objectives that will allow to (i) establish an inventory of the biomarkers developed by French laboratories; (ii) determine their methodological advancement and limits and, on this basis, formulate recommendations for biomonitoring use and future research needs; (iii) discuss the biomarkers’ ecological significance, specificity to contaminants and interpretation capacity; (iv) establish, in fine, a selection of valuable biomarkers to enter the WFD; and (iv) propose integrative tools to facilitate the decision-taking by stakeholders.

The Water Framework Directive (WFD) currently supports chemical and ecological monitoring programmes in order to achieve the good water surface status. Although chemical and ecological assessments are necessary, they have some limitations. Chemical approaches focus on certain substances identified as priorities, but they do not take into account other potentially harmful substances and also ignore the hazards related to contaminant cocktails. On the other hand, while ecological approaches provide holistic information on the impairment of biological communities in ecosystems, they do not distinguish the role of contaminants in these alterations, and consequently do not allow the establishment of contaminant impact reduction plans. Consequently, ecotoxicologists suggest the use of effect-based tools such as biomarkers. Biomarkers highlight the effect of potentially harmful substances (or a cocktail), and their specificity towards the chemicals makes it possible to properly discriminate the role of toxicants within biological community impairments. Thus, the integration of such tools (besides existing chemical and ecological tools) in the WFD could considerably improve its biomonitoring strategy. The B n' B project (Biomarkers and Biodiversity) exposes key objectives that will allow to (i) establish an inventory of the biomarkers developed by French laboratories; (ii) determine their methodological advancement and limits and, on this basis, formulate recommendations for biomonitoring use and future research needs; (iii) discuss the biomarkers' ecological significance, specificity to contaminants and interpretation capacity; (iv) establish, in fine, a selection of valuable biomarkers to enter the WFD; and (iv) propose integrative tools to facilitate the decision-taking by stakeholders.

[Departement_IRSTEA]Eaux [ADD1_IRSTEA]Dynamique et fonctionnement des écosystèmes | International audience | The nutritional value and developmental variations of cultured fish were assessed for European seabass and gilthead seabream specimens reared in semi-intensive aquaculture systems in two Portuguese estuaries. Quantification of total protein and of carbohydrate and fatty acid profiles was carried out to determine differences between the composition of the same species in two development stages reared in four distinct farms. A significant influence of the rearing site on the nutritional composition of the same species was found for adult European seabass regarding saturated, monounsaturated and highly unsaturated fatty acids contents, both between estuaries and within each estuary. In gilthead seabream, saturated, monounsaturated, polyunsaturated and highly unsaturated fatty acids content were also influenced by the rearing site. Carbohydrate analysis showed a significant influence of the rearing site on free sugar and polysaccharide content in fish of both species, and there was no influence on the species' protein content. Differences in fatty acid and carbohydrate content among juvenile and adult stages were found for all the groups studied. The present study supported the existing evidence that semi-intensive rearing systems are subjected to the variability of extrinsic factors in the rearing sites, influencing the nutritional value of the same species, namely regarding lipid and carbohydrate profiles, depending on the production site. From a consumer's perspective, such differences may come as a disadvantage of the rearing method, as it is expected for a product to provide equal nutritional properties and benefits regardless its origin, especially within the same country.

The nutritional value and developmental variations of cultured fish were assessed for European seabass and gilthead seabream specimens reared in semi-intensive aquaculture systems in two Portuguese estuaries. Quantification of total protein and of carbohydrate and fatty acid profiles was carried out to determine differences between the composition of the same species in two development stages reared in four distinct farms. A significant influence of the rearing site on the nutritional composition of the same species was found for adult European seabass regarding saturated, monounsaturated and highly unsaturated fatty acids contents, both between estuaries and within each estuary. In gilthead seabream, saturated, monounsaturated, polyunsaturated and highly unsaturated fatty acids content were also influenced by the rearing site. Carbohydrate analysis showed a significant influence of the rearing site on free sugar and polysaccharide content in fish of both species, and there was no influence on the species’ protein content. Differences in fatty acid and carbohydrate content among juvenile and adult stages were found for all the groups studied. The present study supported the existing evidence that semi-intensive rearing systems are subjected to the variability of extrinsic factors in the rearing sites, influencing the nutritional value of the same species, namely regarding lipid and carbohydrate profiles, depending on the production site. From a consumer’s perspective, such differences may come as a disadvantage of the rearing method, as it is expected for a product to provide equal nutritional properties and benefits regardless its origin, especially within the same country.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | International audience | Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate community-level responses of river phototrophic biofilms from different environments to herbicide exposure. Biofilms were initially cultivated on artificial substrates placed in situ for 4 weeks at two sites, site M, located in an agricultural watershed basin and site S, located in a forested watershed basin. The biofilms were subsequently transferred to microcosms and, after an acclimatization phase of 7 days, were exposed to alachlor at 10 and 30 µg L-1 for 23 days. Alachlor effects were assessed by a combination of structural parameters, including biomass (ash free dry mass and chlorophyll a), molecular fingerprinting of the bacterial community (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and diatom species composition. Alachlor impacted the chlorophyll a and ash-free dry mass levels of phototrophic biofilms previously cultivated at site S. The structural responses of bacterial and diatom communities and diatom were difficult to distinguish from changes linked to the microcosm incubation period. Phototrophic biofilms from site S exposed at 30 µg L-1 alachlor were characterised by an increase of Achnanthidium minutissimum (K-z.) Czarnecki abundance, as well as a higher proportion of abnormal frustules. Thus, phototrophic biofilms with different histories, exhibited different responses to alachlor exposure demonstrating the importance of growth environment. These observations also confirm the problem of distinguishing changes induced by the stress of pesticide toxicity from temporal evolution of the community in the microcosm.

Ecotoxicological experiments were performed in laboratory-scale microcosms to investigate community-level structural responses of river phototrophic biofilms from different environments to herbicide exposure. Biofilms were initially cultivated on artificial supports placed in situ for 4 weeks at two sites, site M, located in an agricultural watershed basin and site S, located in a forested watershed basin. The biofilms were subsequently transferred to microcosms and, after an acclimatisation phase of 7 days were exposed to alachlor at 10 and 30 μg L⁻¹ for 23 days. Alachlor effects were assessed by a combination of structural parameters, including biomass (ash-free dry mass and chlorophyll a), molecular fingerprinting of the bacterial community (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE)) and diatom species composition. Alachlor impacted the chlorophyll a and ash-free dry mass levels of phototrophic biofilms previously cultivated at site S. The structural responses of bacterial and diatom communities were difficult to distinguish from changes linked to the microcosm incubation period. Phototrophic biofilms from site S exposed at 30 μg L⁻¹ alachlor were characterised by an increase of Achnanthidium minutissimum (K-z.) Czarnecki abundance, as well as a higher proportion of abnormal frustules. Thus, phototrophic biofilms with different histories, exhibited different responses to alachlor exposure demonstrating the importance of growth environment. These observations also confirm the problem of distinguishing changes induced by the stress of pesticide toxicity from temporal evolution of the community in the microcosm.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | International audience | In this study, the passive sampling strategy was evaluated for its ability to improve water quality monitoring in terms of concentrations and frequencies of quantification of pesticides, with a focus on flux calculation. Polar Organic Chemical Integrative Samplers (POCIS) were successively exposed and renewed at three sampling sites of an extensive French multi-agricultural watershed from January to September 2012. Grab water samples were recovered every 14 days during the same period and an automated sampler collected composite water samples from April to July 2012. 39 compounds (pesticides and metabolites) were analysed. Desethylatrazine, diuron and atrazine (banned in France for many years) likely arrived via groundwater whereas dimethanamid, imidacloprid and acetochlor (all still in use) were probably transported via leaching. The comparison of the three sampling strategies showed that the POCIS offers lower detection limits, resulting in the quantification of trace levels of compounds (acetochlor, diuron and desethylatrazine) that could not be measured in grab and composite water samples. As a consequence, the frequencies of occurrence were dramatically enhanced with the POCIS compared to spot sample data. Moreover, the integration of flood events led to a better temporal representation of the fluxes when calculated with the POCIS compared to the bimonthly grab sampling strategy. We concluded that the POCIS could be an advantageous alternative to spot sampling, offering better performance in terms of quantification limits, and more representative data.

In this study, the passive sampling strategy was evaluated for its ability to improve water quality monitoring in terms of concentrations and frequencies of quantification of pesticides, with a focus on flux calculation. Polar Organic Chemical Integrative Samplers (POCIS) were successively exposed and renewed at three sampling sites of an extensive French multi-agricultural watershed from January to September 2012. Grab water samples were recovered every 14 days during the same period and an automated sampler collected composite water samples from April to July 2012. Thirty-nine compounds (pesticides and metabolites) were analysed. DEA, diuron and atrazine (banned in France for many years) likely arrived via groundwater whereas dimethanamid, imidacloprid and acetochlor (all still in use) were probably transported via leaching. The comparison of the three sampling strategies showed that the POCIS offers lower detection limits, resulting in the quantification of trace levels of compounds (acetochlor, diuron and desethylatrazine (DEA)) that could not be measured in grab and composite water samples. As a consequence, the frequencies of occurrence were dramatically enhanced with the POCIS compared to spot sample data. Moreover, the integration of flood events led to a better temporal representation of the fluxes when calculated with the POCIS compared to the bimonthly grab sampling strategy. We conclude that the POCIS could be an advantageous alternative to spot sampling, offering better performance in terms of quantification limits and more representative data.