International audience | Neonicotinoids are modern insecticides widely used in agriculture worldwide. Their impact on target (nervous system) and non-target (midgut) tissues has been well studied in beneficial insects including honeybees under controlled conditions. However, their detailed effects on pest insects on the field are missing to date. Here, we have studied the effects of the neonicotinoid imidacloprid on the midgut of the pest insect Locusta migratoria caught in the field. We found that in the midgut of imidacloprid-exposed locusts the activity of enzymes involved in reactive oxygen metabolism was perturbed. By contrast, the activity of P450 enzymes that have been shown to be activated in a detoxification response and that were also reported to produce reactive oxygen species was elevated. Probably as a consequence, markers of oxidative stress including protein carbonylation and lipid peroxidation accumulated in midgut samples of these locusts. Histological analyses revealed that their midgut epithelium is disorganized and that the brush border of the epithelial cells is markedly reduced. Indeed, microvilli are significantly shorter, misshapen and possibly non-functional in imidacloprid-treated locusts. We hypothesize that imidacloprid induces oxidative stress in the locust midgut, thereby changing the shape of midgut epithelial cells and probably in turn compromising their physiological function. Presumably, these effects reduce the survival rate of imidacloprid-treated locusts and the damage they cause in the field.

Neonicotinoids are modern insecticides widely used in agriculture worldwide. Their impact on target (nervous system) and non-target (midgut) tissues has been well studied in beneficial insects including honeybees under controlled conditions. However, their detailed effects on pest insects on the field are missing to date. Here, we have studied the effects of the neonicotinoid imidacloprid on the midgut of the pest insect Locusta migratoria caught in the field. We found that in the midgut of imidacloprid-exposed locusts the activity of enzymes involved in reactive oxygen metabolism was perturbed. By contrast, the activity of P450 enzymes that have been shown to be activated in a detoxification response and that were also reported to produce reactive oxygen species was elevated. Probably as a consequence, markers of oxidative stress including protein carbonylation and lipid peroxidation accumulated in midgut samples of these locusts. Histological analyses revealed that their midgut epithelium is disorganized and that the brush border of the epithelial cells is markedly reduced. Indeed, microvilli are significantly shorter, misshapen and possibly non-functional in imidacloprid-treated locusts. We hypothesize that imidacloprid induces oxidative stress in the locust midgut, thereby changing the shape of midgut epithelial cells and probably in turn compromising their physiological function. Presumably, these effects reduce the survival rate of imidacloprid-treated locusts and the damage they cause in the field.

International audience | The main objective of this study was to improve our knowledge on the responses of fish populations to multistress (diffuse pollution and warming waters) in estuaries. Adult flounders were caught in two estuaries in the Eastern English Channel: the heavily polluted Seine estuary vs the moderately contaminated Canche estuary. Fish samplings were conducted in January just before the reproduction period, and in July when gonads were at rest. The overall rise in coastal winter water temperatures detected over the Channel impairs the flounder's phenology of reproduction in the two estuaries, inducing a delay of maturation process and probably also spawning. The higher liver histopathology index in Seine vs Canche could be the consequence of the fish exposition to a complex cocktail of contaminants in a strongly industrialized estuary. Higher levels of neurotoxicity, gill lipid peroxidation, and liver EROD activity were observed in Seine vs Canche. Furthermore, a possible impairment in mitochondrial metabolism was suggested in the Seine flounder population. We confirmed in this study the potential role of two membrane lipids (sphingomyelin and phosphatidylserine) in the resistance towards oxidative stress in Seine and Canche. Finally, we suggest that the Seine flounder population (and possibly the connected Eastern English Channel flounder populations over the French Coast) could be seriously impacted in the future by multistress: higher winter temperatures and chemical contamination.

The main objective of this study was to improve our knowledge on the responses of fish populations to multistress (diffuse pollution and warming waters) in estuaries. Adult flounders were caught in two estuaries in the Eastern English Channel: the heavily polluted Seine estuary vs the moderately contaminated Canche estuary. Fish samplings were conducted in January just before the reproduction period, and in July when gonads were at rest. The overall rise in coastal winter water temperatures detected over the Channel impairs the flounder’s phenology of reproduction in the two estuaries, inducing a delay of maturation process and probably also spawning. The higher liver histopathology index in Seine vs Canche could be the consequence of the fish exposition to a complex cocktail of contaminants in a strongly industrialized estuary. Higher levels of neurotoxicity, gill lipid peroxidation, and liver EROD activity were observed in Seine vs Canche. Furthermore, a possible impairment in mitochondrial metabolism was suggested in the Seine flounder population. We confirmed in this study the potential role of two membrane lipids (sphingomyelin and phosphatidylserine) in the resistance towards oxidative stress in Seine and Canche. Finally, we suggest that the Seine flounder population (and possibly the connected Eastern English Channel flounder populations over the French Coast) could be seriously impacted in the future by multistress: higher winter temperatures and chemical contamination.

International audience | The purpose of this study was to assess heavy metal contamination in soil, plants, earthworms, and chicken in farmlands adjacent to an old mining site and to evaluate the potential exposure risks to humans through the consumption of chicken. For this purpose, soil, earthworms, plant, chickens, and eggs were sampled from 5 sites following a gradient of contamination. All samples were analyzed for heavy metals (Pb, Cd, Cu, and Zn). A food chain model was used in order to characterize heavy metal transfer between soil-plant-earthworm and chicken organs. Furthermore, target hazard quotient (THQ), estimated daily intake (EDI), and hazard index (HI) were employed to assess human health risks posed by heavy metal contamination. Despite the higher level of Pb, our data related to the calculation of EDI and THQ suggested that local consumers are more at risk of Cd contamination. The calculated HI showed values ranging from 2.58 to 4.74 for adults, and up to 12.34 for children, indicating a considerable risk to the health of local inhabitants, especially children. This study highlighted the crucial role of diets based on chickens grown in contaminated areas, on health risks especially for children.

The purpose of this study was to assess heavy metal contamination in soil, plants, earthworms, and chicken in farmlands adjacent to an old mining site and to evaluate the potential exposure risks to humans through the consumption of chicken. For this purpose, soil, earthworms, plant, chickens, and eggs were sampled from 5 sites following a gradient of contamination. All samples were analyzed for heavy metals (Pb, Cd, Cu, and Zn). A food chain model was used in order to characterize heavy metal transfer between soil-plant-earthworm and chicken organs. Furthermore, target hazard quotient (THQ), estimated daily intake (EDI), and hazard index (HI) were employed to assess human health risks posed by heavy metal contamination. Despite the higher level of Pb, our data related to the calculation of EDI and THQ suggested that local consumers are more at risk of Cd contamination. The calculated HI showed values ranging from 2.58 to 4.74 for adults, and up to 12.34 for children, indicating a considerable risk to the health of local inhabitants, especially children. This study highlighted the crucial role of diets based on chickens grown in contaminated areas, on health risks especially for children.

International audience | Phytomanagement manipulates the soil-plant system to lower the risk posed by contaminated soils. In this process, the addition of amendments, such as biochar, and bacteria can improve the fertility of poor contaminated soils and consequently ameliorate plant growth. A number of studies based on the inoculation of soil with microorganisms of the genus Bacillus, previously isolated from contaminated sites, revealed positive effects on soil properties and plant growth. Furthermore, when the Bacillus isolates were used in association with biochar, better results were obtained, as biochar can ameliorate soil properties and serve as habitat for microorganisms. Accordingly, a mesocosm study was set-up using a mining technosol amended with biochar and inoculated with an endogenous Bacillus isolate, to evaluate the effect of inoculation on soil properties, metal(loid) immobilization, and Salix viminalis growth. Two inoculation methods were compared: (1) direct inoculation of bacteria (Bacillus sp.) and (2) inoculation using biochar as a carrier. Results showed that the Bacillus isolate modified soil properties and ameliorated plant growth, while having a reduced effect on metal(loid) accumulation. The microbial activity was also stimulated, and the community composition was shifted, more importantly when biochar was used as a carrier. In conclusion, this research revealed an improvement of the plant growth and microbial activity after the addition of the endogenous bacterium to the analyzed former mining soil, with better results recorded when a carrier was used.

Phytomanagement manipulates the soil-plant system to lower the risk posed by contaminated soils. In this process, the addition of amendments, such as biochar, and bacteria can improve the fertility of poor contaminated soils and consequently ameliorate plant growth. A number of studies based on the inoculation of soil with microorganisms of the genus Bacillus, previously isolated from contaminated sites, revealed positive effects on soil properties and plant growth. Furthermore, when the Bacillus isolates were used in association with biochar, better results were obtained, as biochar can ameliorate soil properties and serve as habitat for microorganisms. Accordingly, a mesocosm study was set-up using a mining technosol amended with biochar and inoculated with an endogenous Bacillus isolate, to evaluate the effect of inoculation on soil properties, metal(loid) immobilization, and Salix viminalis growth. Two inoculation methods were compared: (1) direct inoculation of bacteria (Bacillus sp.) and (2) inoculation using biochar as a carrier. Results showed that the Bacillus isolate modified soil properties and ameliorated plant growth, while having a reduced effect on metal(loid) accumulation. The microbial activity was also stimulated, and the community composition was shifted, more importantly when biochar was used as a carrier. In conclusion, this research revealed an improvement of the plant growth and microbial activity after the addition of the endogenous bacterium to the analyzed former mining soil, with better results recorded when a carrier was used.

International audience | Soil pollution is a worldwide issue and has a strong impact on ecosystems. Metal(loid)s have toxic effects on plants and affect various plant life traits. That is why metal(loid) polluted soils need to be remediated. As a remediation solution, phytoremediation, which uses plants to reduce the toxicity and risk of polluted soils, has been proposed. Moreover, flax (Linum usitatissimum L.) has been suggested as a potential phytoremediation plant, due to its antioxidant systems, which can lower the production of reactive oxygen species and can also chelate metal(loid)s. However, the high metal(loid) toxicity associated with the low fertility of the polluted soils render vegetation difficult to establish. Therefore, amendments, such as biochar, need to be applied to improve soil conditions and immobilize metal(loid)s. Here, we analyzed the growth parameters and oxidative stress biomarkers (ROS production, membrane lipid peroxidation, protein carbonylation and 8-oxoGuanine formation) of five different flax cultivars when grown on a real contaminated soil condition, and in the presence of a biochar amendment. Significant correlations were observed between plant growth, tolerance to oxidative stress, and reprogramming of phytochemical accumulation. A clear genotype-dependent response to metal(loid) stress was observed. It was demonstrated that some phenylpropanoids such as benzoic acid, caffeic acid, lariciresinol, and kaempferol played a key role in the tolerance to the metal(loid)-induced oxidative stress. According to these results, it appeared that some flax genotypes, i.e., Angora and Baikal, could be well adapted for the phytoremediation of metal(loid) polluted soils as a consequence of their adaptation to oxidative stress.

Soil pollution is a worldwide issue and has a strong impact on ecosystems. Metal(loid)s have toxic effects on plants and affect various plant life traits. That is why metal(loid) polluted soils need to be remediated. As a remediation solution, phytoremediation, which uses plants to reduce the toxicity and risk of polluted soils, has been proposed. Moreover, flax (Linum usitatissimum L.) has been suggested as a potential phytoremediation plant, due to its antioxidant systems, which can lower the production of reactive oxygen species and can also chelate metal(loid)s. However, the high metal(loid) toxicity associated with the low fertility of the polluted soils render vegetation difficult to establish. Therefore, amendments, such as biochar, need to be applied to improve soil conditions and immobilize metal(loid)s. Here, we analyzed the growth parameters and oxidative stress biomarkers (ROS production, membrane lipid peroxidation, protein carbonylation and 8-oxoGuanine formation) of five different flax cultivars when grown on a real contaminated soil condition, and in the presence of a biochar amendment. Significant correlations were observed between plant growth, tolerance to oxidative stress, and reprogramming of phytochemical accumulation. A clear genotype-dependent response to metal(loid) stress was observed. It was demonstrated that some phenylpropanoids such as benzoic acid, caffeic acid, lariciresinol, and kaempferol played a key role in the tolerance to the metal(loid)-induced oxidative stress. According to these results, it appeared that some flax genotypes, i.e., Angora and Baikal, could be well adapted for the phytoremediation of metal(loid) polluted soils as a consequence of their adaptation to oxidative stress.

International audience | In recent years, recreational waterbodies are increasingly favoured in urban areas. In spite of the growing concerns for maintaining the required bathing water quality, the impacts of stormwater drainage are still poorly controlled. In this context, this study originally develops an integrated urban catchment-pipes-lake monitoring and modelling approach to simulate the impacts of microbial quality from stormwater drainage on recreational water quality. The modelling system consists of three separated components: the urban catchment component, the 3D lake hydrodynamic component and the 3D lake water quality component. A series of processes are simulated in the model, such as rainfall-discharge, build-up, wash-off of Escherichia coli (E. coli) on urban surfaces, sewer flows, hydrothermal dynamics of lake water and transport and mortality of E. coli in the lake. This integrated model is tested for an urban catchment and its related recreational lake located in the Great Paris region. Continuous monitoring and samplings were performed at the stormwater drainage outlet and three different sites in the lake. Comparing the measured data with simulation results over 20 months, the modelling system can correctly represent the E. coli dynamics in the stormwater sewer systems and in the lake. Although uncertainties related to parameter values, pollution sources and E. coli mortality processes could be further discussed, the good performance of this modelling approach emphasizes a promising potential for urban bathing water quality management.

In recent years, recreational waterbodies are increasingly favoured in urban areas. In spite of the growing concerns for maintaining the required bathing water quality, the impacts of stormwater drainage are still poorly controlled. In this context, this study originally develops an integrated urban catchment-pipes-lake monitoring and modelling approach to simulate the impacts of microbial quality from stormwater drainage on recreational water quality. The modelling system consists of three separated components: the urban catchment component, the 3D lake hydrodynamic component and the 3D lake water quality component. A series of processes are simulated in the model, such as rainfall-discharge, build-up, wash-off of Escherichia coli (E. coli) on urban surfaces, sewer flows, hydrothermal dynamics of lake water and transport and mortality of E. coli in the lake. This integrated model is tested for an urban catchment and its related recreational lake located in the Great Paris region. Continuous monitoring and samplings were performed at the stormwater drainage outlet and three different sites in the lake. Comparing the measured data with simulation results over 20 months, the modelling system can correctly represent the E. coli dynamics in the stormwater sewer systems and in the lake. Although uncertainties related to parameter values, pollution sources and E. coli mortality processes could be further discussed, the good performance of this modelling approach emphasizes a promising potential for urban bathing water quality management.

International audience | The bioaccumulation of metals (As, Cd, Co, Cr, Cu, Ni, Pb, Sb, V, Zn, Al, Fe) and organochlorine compounds (PCDD-Fs and PCBs) was assessed in soils and vegetables of 3 sites of contrasted anthropogenic influence (rural and industrial-urban areas). Cultivated soils in industrial areas exhibited diffuse pollution in organochlorine pollutants (PCBs and PCDD-Fs). The pollutant levels encountered in vegetables were always lower than the EU regulatory or recommended values. However, the contents measured in vegetables cultivated near industrialized areas were significantly higher than those observed in rural areas. This was notably the case for Co, Cd, Cr, Ni, Pb, V, NDL- and DL-PCB, PCDD, and PCDF. The leaf pathway appeared as the main absorption pathway for many contaminants. The results suggested that population exposure to pollutants was mainly caused by vegetable ingestion. In the vegetables and soils, the toxicity was mainly caused by the V, Co, Cd, and Pb contents to which can be added As and PCDD-Fs for soils. Therefore, the proximity of vegetable crops to highly anthropised areas has led to long-term exposure of vegetables and soils to air pollutants, leading to an accumulation in the food chain and thus a risk for human health.

The bioaccumulation of metals (As, Cd, Co, Cr, Cu, Ni, Pb, Sb, V, Zn, Al, Fe) and organochlorine compounds (PCDD-Fs and PCBs) was assessed in soils and vegetables of 3 sites of contrasted anthropogenic influence (rural and industrial-urban areas). Cultivated soils in industrial areas exhibited diffuse pollution in organochlorine pollutants (PCBs and PCDD-Fs). The pollutant levels encountered in vegetables were always lower than the EU regulatory or recommended values. However, the contents measured in vegetables cultivated near industrialized areas were significantly higher than those observed in rural areas. This was notably the case for Co, Cd, Cr, Ni, Pb, V, NDL- and DL-PCB, PCDD, and PCDF. The leaf pathway appeared as the main absorption pathway for many contaminants. The results suggested that population exposure to pollutants was mainly caused by vegetable ingestion. In the vegetables and soils, the toxicity was mainly caused by the V, Co, Cd, and Pb contents to which can be added As and PCDD-Fs for soils. Therefore, the proximity of vegetable crops to highly anthropised areas has led to long-term exposure of vegetables and soils to air pollutants, leading to an accumulation in the food chain and thus a risk for human health.

Abstract The bioaccumulation of metals (As, Cd, Co, Cr, Cu, Ni, Pb, Sb, V, Zn, Al, Fe) and organochlorine compounds (PCDD-Fs, and PCBs) was assessed in soils and vegetables of 3 sites of contrasted anthropogenic influence (rural and industrial-urban areas). Cultivated soils in industrial areas exhibited diffuse pollution in organochlorine pollutants (PCBs and PCDD-Fs). The pollutant levels encountered in vegetables were always lower than the regulatory or recommended values by EU. However, the contents measured in vegetables cultivated near industrialised areas were significantly higher than those observed in rural areas, this was notably the case for Co, Cd, Cr, Ni, Pb, V, NDL- and DL-PCB, PCDD and PCDF. The leaf pathway appeared as the main absorption pathway for many contaminants. The results suggested that population exposure to pollutants was mainly caused by the vegetable ingestion. In the vegetables and soils, the toxicity was mainly caused by the V, Co, Cd and Pb contents to which can be added As and PCDD-Fs for soils. Therefore, the proximity of vegetable crops to highly anthropised areas has led to long-term exposure of vegetables and soils to air pollutants, leading to an accumulation in the food-chain and thus a risk for human health.