EABIOmE INRA | Misuse of pesticides in farming activities leads to contamination of drinking water sources and is responsible for animal and human health problems. The biobeds are practicable option to minimize contamination by pesticides during preparation, use and washing of equipment for pesticide treatments. This research aimed at testing substrate mixtures to optimize biobed efficiency to remove pesticides under the climate of the Yucatan (México). Agricultural soil and 11 mixtures adding vegetable compost, sisal pulp, corn stover and seaweed were tested under controlled conditions. Each biomixture was exposed to a mixture of five pesticides (2,4-diclorophenoxyacetic acid “2,4-D” [1.08 mg cm−3], atrazine [2.50 mg cm−3], carbofuran [0.23 mg cm−3], diazinon [0.34 mg cm−3], and glyphosate [0.36 mg cm−3]) in a period of 41 days. Monitoring of the dissipation of pesticide residues showed that pesticides were quickly dissipated in soil at microcosm level experiment, while at two critical times of 20 and 41 days, all mixtures of substrates (biomixtures) were efficient in dissipation of high concentrations of pesticide in a short time (>99%). Time, biomixture and type of pesticide were shown to be the main parameters influencing pesticide dissipation (P < 0.05). Several other physicochemical parameters of the biomixtures, such as organic matter (OM), lignin, water holding capacity (WHC), and pH, were also significant on pesticide dissipation (P < 0.05), being pH the most significant.

Misuse of pesticides in farming activities leads to contamination of drinking water sources and is responsible for animal and human health problems. The biobeds are practicable option to minimize contamination by pesticides during preparation, use and washing of equipment for pesticide treatments. This research aimed at testing substrate mixtures to optimize biobed efficiency to remove pesticides under the climate of the Yucatan (México). Agricultural soil and 11 mixtures adding vegetable compost, sisal pulp, corn stover and seaweed were tested under controlled conditions. Each biomixture was exposed to a mixture of five pesticides (2,4-diclorophenoxyacetic acid “2,4-D” [1.08 mg cm⁻³], atrazine [2.50 mg cm⁻³], carbofuran [0.23 mg cm⁻³], diazinon [0.34 mg cm⁻³], and glyphosate [0.36 mg cm⁻³]) in a period of 41 days. Monitoring of the dissipation of pesticide residues showed that pesticides were quickly dissipated in soil at microcosm level experiment, while at two critical times of 20 and 41 days, all mixtures of substrates (biomixtures) were efficient in dissipation of high concentrations of pesticide in a short time (>99%). Time, biomixture and type of pesticide were shown to be the main parameters influencing pesticide dissipation (P < 0.05). Several other physicochemical parameters of the biomixtures, such as organic matter (OM), lignin, water holding capacity (WHC), and pH, were also significant on pesticide dissipation (P < 0.05), being pH the most significant.

International audience

Due to their bioaccumulation and biomagnification pathways, inorganic elements can accumulate in high-level aquatic organisms in the food web. Then, this species can be used to monitor the quality of the environment. Blood concentration of nine inorganic elements, including possible toxic metals (An, Cu, Mn, Se, As, Ni, Cd, Pb, and Hg), in 20 males and 20 females from eight different locations with high industry and agriculture activities in Iran were evaluated in this work. Additionally, size, sex, condition index, and locations were also included and analyzed. Among the essential elements, Zn and Se presented very high concentrations (56.14 ± 2.66 and 8.44 ± 0.77 μg/g ww, respectively) in all locations. Regarding possible toxic elements, Pb and Cd presented concerning concentrations as well (0.52 and 0.58 μg/g ww); this is especially true for Pb, an element found in very high concentrations in tissues of turtles from the same area in a previous study. The sex and the size of the individuals also had significant differences in concentration of Pb, Cd, As, and Hg.

Co-phytoremediation of both trace elements and polycyclic aromatic hydrocarbons (PAH) is an emerging technique to treat multi-contaminated soils. In this study, root morphological and structural features of the heavy metal hyperaccumulator Noccaea caerulescens, exposed to a model PAH phenanthrene (PHE) in combination with cadmium (Cd), were observed. In vitro cultivated seedlings were exposed to 2 mM of PHE and/or 5 mu M of Cd for 1 week. Co-phytoremediation effectiveness appeared restricted because of a serious inhibition (about 40%) of root and shoot biomass production in presence of PHE, while Cd had no significant adverse effect on these parameters. The most striking effects of PHE on roots were a decreased average root diameter, the inhibition of cell and root hair elongation and the promotion of lateral root formation. Moreover, endodermal cells with suberin lamellae appeared closer to the root apex when exposed to PHE compared to control and Cd treatments, possibly due to modified lateral root formation. The stage with well-developed suberin lamellae was not influenced by PHE whereas peri-endodermal layer development was impaired in PHE-treated plants. Many of these symptoms were similar to a water-deficit response. These morphological and structural root modifications in response to PHE exposition might in turn limit Cd phytoextraction by N. caerulescens in co-contaminated soils.

Co-phytoremediation of both trace elements and polycyclic aromatic hydrocarbons (PAH) is an emerging technique to treat multi-contaminated soils. In this study, root morphological and structural features of the heavy metal hyperaccumulator Noccaea caerulescens, exposed to a model PAH phenanthrene (PHE) in combination with cadmium (Cd), were observed. In vitro cultivated seedlings were exposed to 2 mM of PHE and/or 5 μM of Cd for 1 week. Co-phytoremediation effectiveness appeared restricted because of a serious inhibition (about 40%) of root and shoot biomass production in presence of PHE, while Cd had no significant adverse effect on these parameters. The most striking effects of PHE on roots were a decreased average root diameter, the inhibition of cell and root hair elongation and the promotion of lateral root formation. Moreover, endodermal cells with suberin lamellae appeared closer to the root apex when exposed to PHE compared to control and Cd treatments, possibly due to modified lateral root formation. The stage with well-developed suberin lamellae was not influenced by PHE whereas peri-endodermal layer development was impaired in PHE-treated plants. Many of these symptoms were similar to a water-deficit response. These morphological and structural root modifications in response to PHE exposition might in turn limit Cd phytoextraction by N. caerulescens in co-contaminated soils.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA | International audience | Because of the excellent reducing capacity of nanoscale zero-valent iron (NZVI), it can be used as alternative materials for the removal of a variety of reducible water contaminants including toxic metals. The current paper reports the research results obtained for self-prepared biosorbent, Posidonia oceanica biomass, activated in alkaline medium and functionalized with NZVI particles. The structural characteristics, surface morphology, and binding properties of the resulting nanobiosorbent are presented. Batch comparative adsorption trials including adsorption kinetics and isothermals onto raw Posidonia, Posidonia-OH and Posidonia-OH-NZVI were investigated on three heavy metal ions: Cd(II), Pb(II), and Cu(II). The nanobiosorbent showed better properties, such as high reactivity and high uptake rate through the sorption process. The toxic metal removal has been monitored in terms of pseudo-first- and pseudo-second-order kinetics, and both Langmuir- and Freundlich-type isotherm models have been used to describe the sorption mechanism. The experimental data of all studied systems showed that the uptake kinetics follow the pseudo-second-order kinetic model and the equilibrium uptake can adopt the Langmuir-type isotherm model which assumes a monolayer coverage as the adsorption saturates and no further adsorption occurs. The thermodynamic results confirm that all sorption processes were feasible, spontaneous and thermodynamically favorable. Zeta potential data displayed that Cd(II), Pb(II), and Cu(II) tend to be reduced after exposure on the Posidonia-OH-NZVI surface. Furthermore, sorption competitions of the metals from binary and ternary systems were carried out onto Posidonia-OH-NZVI in order to gain further insight into the sorption efficiency of this material. Therefore, as a result, the proposed new nanobiosorbent could offer potential benefits in remediation of heavy metal-contaminated water as a green and environmentally friendly bionanocomposite.

Because of the excellent reducing capacity of nanoscale zero-valent iron (NZVI), it can be used as alternative materials for the removal of a variety of reducible water contaminants including toxic metals. The current paper reports the research results obtained for self-prepared biosorbent, Posidonia oceanica biomass, activated in alkaline medium and functionalized with NZVI particles. The structural characteristics, surface morphology, and binding properties of the resulting nanobiosorbent are presented. Batch comparative adsorption trials including adsorption kinetics and isothermals onto raw Posidonia, Posidonia–OH and Posidonia–OH–NZVI were investigated on three heavy metal ions: Cd(II), Pb(II), and Cu(II). The nanobiosorbent showed better properties, such as high reactivity and high uptake rate through the sorption process. The toxic metal removal has been monitored in terms of pseudo-first- and pseudo-second-order kinetics, and both Langmuir- and Freundlich-type isotherm models have been used to describe the sorption mechanism. The experimental data of all studied systems showed that the uptake kinetics follow the pseudo-second-order kinetic model and the equilibrium uptake can adopt the Langmuir-type isotherm model which assumes a monolayer coverage as the adsorption saturates and no further adsorption occurs. The thermodynamic results confirm that all sorption processes were feasible, spontaneous and thermodynamically favorable. Zeta potential data displayed that Cd(II), Pb(II), and Cu(II) tend to be reduced after exposure on the Posidonia–OH–NZVI surface. Furthermore, sorption competitions of the metals from binary and ternary systems were carried out onto Posidonia–OH–NZVI in order to gain further insight into the sorption efficiency of this material. Therefore, as a result, the proposed new nanobiosorbent could offer potential benefits in remediation of heavy metal-contaminated water as a green and environmentally friendly bionanocomposite.

International audience | Pyrethrino < ds are synthetic pesticides widely used in agriculture and farms to protect crops from weeds, insects, fungi, and molds. Increased and uncontrolled use of these pollutants can have harmful effects on human health via consumption of contaminated food products. In the present study, deltamethrin (DLT = 3.72 mg/kg) and Bifenthrin (BF = 2.6 mg/kg) were used during a long-term exposition in the rats to assess their effect on mitochondrial integrity and function in different brain areas (hippocampus, striatum, cortex, and cerebellum). The results of this study have shown that chronic treatment of rats by both DLT and BF, on their own or in a mixture, has induced a significant increase in mitochondrial MDA, but when quercetin (Que) was co-administered with pesticides, this enhancement has been prevented in the almost of treated rats compared to solvent and control groups. In hippocampus area, GSH has significantly increased in all treated rats, except for BF and DLT-Que.-treated groups. In striatum, GSH has been depleted in the BF and DLT-treated groups compared to control and solvent groups; in contrast, when Que. was associated with pesticides, the rate of this tripeptide has been maintained at normal levels. In the cortex and cerebellum, GSH has been depleted significantly in all treated animals but has increased in DLT-Que. and mixture-Que.-treated groups in the cerebral cortex, at the same time; it has been maintained at normal levels in BF-Que.-treated groups in the cerebellum compared to control and solvent rats. On the other side, the results of this study have shown a loss of catalase (CAT) and glutathione S-transferase (GST) activities in all brain regions of pesticide-treated rats, but such a fall in enzymatic activities has been prevented by Que. when it was co-administered to rats with pesticides at the dose of 5 mg/kg, except in the cerebellum. In addition, this study has shown mitochondria's swelling in almost all the brain areas with exception of the cerebellum, providing information about a loss of mitochondrial membrane integrity in brain neurons of rats exposed to pyrethrino < ds. Furthermore, preventive administration of Que., in association with pesticides (5 mg/kg) or their mixture (10 mg/kg), has prevented mitochondria swelling in almost all of the analyzed brain tissues.

Pyrethrinoïds are synthetic pesticides widely used in agriculture and farms to protect crops from weeds, insects, fungi, and molds. Increased and uncontrolled use of these pollutants can have harmful effects on human health via consumption of contaminated food products. In the present study, deltamethrin (DLT = 3.72 mg/kg) and Bifenthrin (BF = 2.6 mg/kg) were used during a long-term exposition in the rats to assess their effect on mitochondrial integrity and function in different brain areas (hippocampus, striatum, cortex, and cerebellum). The results of this study have shown that chronic treatment of rats by both DLT and BF, on their own or in a mixture, has induced a significant increase in mitochondrial MDA, but when quercetin (Que) was co-administered with pesticides, this enhancement has been prevented in the almost of treated rats compared to solvent and control groups. In hippocampus area, GSH has significantly increased in all treated rats, except for BF and DLT-Que.-treated groups. In striatum, GSH has been depleted in the BF and DLT-treated groups compared to control and solvent groups; in contrast, when Que. was associated with pesticides, the rate of this tripeptide has been maintained at normal levels. In the cortex and cerebellum, GSH has been depleted significantly in all treated animals but has increased in DLT-Que. and mixture-Que.-treated groups in the cerebral cortex, at the same time; it has been maintained at normal levels in BF-Que.-treated groups in the cerebellum compared to control and solvent rats. On the other side, the results of this study have shown a loss of catalase (CAT) and glutathione S-transferase (GST) activities in all brain regions of pesticide-treated rats, but such a fall in enzymatic activities has been prevented by Que. when it was co-administered to rats with pesticides at the dose of 5 mg/kg, except in the cerebellum. In addition, this study has shown mitochondria’s swelling in almost all the brain areas with exception of the cerebellum, providing information about a loss of mitochondrial membrane integrity in brain neurons of rats exposed to pyrethrinoïds. Furthermore, preventive administration of Que., in association with pesticides (5 mg/kg) or their mixture (10 mg/kg), has prevented mitochondria swelling in almost all of the analyzed brain tissues.

International audience | The negative impact of conventional pesticides on the environment is already extensively discussed worldwide. Although the use of chemical agents for controlling agricultural pests remains as first-line strategy for pest control, novel biorational active insecticides, such as spirotetramat, have appeared in the pesticide market during recent years in Argentina. The aim of this study was to assess the toxicity of spirotetramat on two developmental stages of a Neotropical strain of Eretmocerus mundus, with the conventional insecticide cypermethrin as a positive control, and to determine spirotetramat's side effects on parasitoid demographic parameters. Lethal effects of both insecticides on pupae and adults were evaluated by adult emergency and survival, respectively; whereas sublethal effects on both development stages were assessed by adult longevity, reproduction capacity, sex ratio, and longevity of the first progeny. Spirotetramat proved less harmful than cypermethrin at both developmental stages studied, corroborating once more the high toxicity of this pyrethroid to natural enemies. Although spirotetramat did not affect the emergence and reproductive capacity of adults surviving pupal exposure, the longevity of the first progeny was reduced as was adult survival and longevity after exposure to residues. Spirotetramat also reduced all demographic parameters in the population evaluation. This work is the first report of spirotetramat toxicity at the population level and demonstrates the need to assess the total effect of pesticides on natural enemies.

The negative impact of conventional pesticides on the environment is already extensively discussed worldwide. Although the use of chemical agents for controlling agricultural pests remains as first-line strategy for pest control, novel biorational active insecticides, such as spirotetramat, have appeared in the pesticide market during recent years in Argentina. The aim of this study was to assess the toxicity of spirotetramat on two developmental stages of a Neotropical strain of Eretmocerus mundus, with the conventional insecticide cypermethrin as a positive control, and to determine spirotetramat’s side effects on parasitoid demographic parameters. Lethal effects of both insecticides on pupae and adults were evaluated by adult emergency and survival, respectively; whereas sublethal effects on both development stages were assessed by adult longevity, reproduction capacity, sex ratio, and longevity of the first progeny. Spirotetramat proved less harmful than cypermethrin at both developmental stages studied, corroborating once more the high toxicity of this pyrethroid to natural enemies. Although spirotetramat did not affect the emergence and reproductive capacity of adults surviving pupal exposure, the longevity of the first progeny was reduced as was adult survival and longevity after exposure to residues. Spirotetramat also reduced all demographic parameters in the population evaluation. This work is the first report of spirotetramat toxicity at the population level and demonstrates the need to assess the total effect of pesticides on natural enemies.

The 2010 Deepwater Horizon (DWH) oil spill released millions of barrels of oil and dispersant into the Gulf of Mexico. The timing of the spill coincided with the spawning season of Crassostrea virginica. Consequently, gametes released in the water were likely exposed to oil and dispersant. This study aimed to (i) evaluate the cellular effects of acute exposure of spermatozoa and oocytes to surface slick oil, dispersed mechanically (HEWAF) and chemically (CEWAF), using flow-cytometric (FCM) analyses, and (ii) determine whether the observed cellular effects relate to impairments of fertilization and embryogenesis of gametes exposed to the same concentrations of CEWAF and HEWAF. Following a 30-min exposure, the number of spermatozoa and their viability were reduced due to a physical action of oil droplets (HEWAF) and a toxic action of CEWAF respectively. Additionally, reactive oxygen species (ROS) production in exposed oocytes tended to increase with increasing oil concentrations suggesting that exposure to dispersed oil resulted in an oxidative stress. The decrease in fertilization success (1-h), larval survival (24-h) and increase in abnormalities (6-h and 24-h) may be partly related to altered cellular characteristics. FCM assays are a good predictor of sublethal effects especially on fertilization success. These data suggest that oil/dispersant are cytotoxic to gametes, which may affect negatively the reproduction success and early development of oysters.

The 2010 Deepwater Horizon (DWH) oil spill released millions of barrels of oil and dispersant into the Gulf of Mexico. The timing of the spill coincided with the spawning season of Crassostrea virginica. Consequently, gametes released in the water were likely exposed to oil and dispersant. This study aimed to (i) evaluate the cellular effects of acute exposure of spermatozoa and oocytes to surface slick oil, dispersed mechanically (HEWAF) and chemically (CEWAF), using flow-cytometric (FCM) analyses, and (ii) determine whether the observed cellular effects relate to impairments of fertilization and embryogenesis of gametes exposed to the same concentrations of CEWAF and HEWAF. Following a 30-min exposure, the number of spermatozoa and their viability were reduced due to a physical action of oil droplets (HEWAF) and a toxic action of CEWAF respectively. Additionally, reactive oxygen species (ROS) production in exposed oocytes tended to increase with increasing oil concentrations suggesting that exposure to dispersed oil resulted in an oxidative stress. The decrease in fertilization success (1-h), larval survival (24-h) and increase in abnormalities (6-h and 24-h) may be partly related to altered cellular characteristics. FCM assays are a good predictor of sublethal effects especially on fertilization success. These data suggest that oil/dispersant are cytotoxic to gametes, which may affect negatively the reproduction success and early development of oysters.

The concentration and spatial distribution of microplastics in the Bay of Brest (Brittany, France) was investigated in two surveys. Surface water and sediment were sampled at nine locations in areas characterized by contrasting anthropic pressures, riverine influences or water mixing. Microplastics were categorized by their polymer type and size class. Microplastic contamination in surface water and sediment was dominated by polyethylene fragments (PE, 53–67%) followed by polypropylene (PP, 16–30%) and polystyrene (PS, 16–17%) microparticles. The presence of buoyant microplastics (PE, PP and PS) in sediment suggests the existence of physical and/or biological processes leading to vertical transfer of lightweight microplastics in the bay. In sediment (upper 5 cm), the percentage of particles identified by Raman micro-spectroscopy was lower (41%) than in surface water (79%) and may explain the apparent low concentration observed in this matrix (0.97 ± 2.08 MP kg−1 dry sediment). Mean microplastic concentration was 0.24 ± 0.35 MP m−3 in surface water. We suggest that the observed spatial MP distribution is related to proximity to urbanized areas and to hydrodynamics in the bay. A particle dispersal model was used to study the influence of hydrodynamics on surface microplastic distribution. The outputs of the model showed the presence of a transitional convergence zone in the centre of the bay during flood tide, where floating debris coming from the northern and southern parts of the bay tends to accumulate before being expelled from the bay. Further modelling work and observations integrating (i) the complex vertical motion of microplastics, and (ii) their point sources is required to better understand the fate of microplastics in such a complex coastal ecosystem.

The concentration and spatial distribution of microplastics in the Bay of Brest (Brittany, France) was investigated in two surveys. Surface water and sediment were sampled at nine locations in areas characterized by contrasting anthropic pressures, riverine influences or water mixing. Microplastics were categorized by their polymer type and size class. Microplastic contamination in surface water and sediment was dominated by polyethylene fragments (PE, 53–67%) followed by polypropylene (PP, 16–30%) and polystyrene (PS, 16–17%) microparticles. The presence of buoyant microplastics (PE, PP and PS) in sediment suggests the existence of physical and/or biological processes leading to vertical transfer of lightweight microplastics in the bay. In sediment (upper 5 cm), the percentage of particles identified by Raman micro-spectroscopy was lower (41%) than in surface water (79%) and may explain the apparent low concentration observed in this matrix (0.97 ± 2.08 MP kg−1 dry sediment). Mean microplastic concentration was 0.24 ± 0.35 MP m−3 in surface water. We suggest that the observed spatial MP distribution is related to proximity to urbanized areas and to hydrodynamics in the bay. A particle dispersal model was used to study the influence of hydrodynamics on surface microplastic distribution. The outputs of the model showed the presence of a transitional convergence zone in the centre of the bay during flood tide, where floating debris coming from the northern and southern parts of the bay tends to accumulate before being expelled from the bay. Further modelling work and observations integrating (i) the complex vertical motion of microplastics, and (ii) their point sources is required to better understand the fate of microplastics in such a complex coastal ecosystem.

International audience | Due to the increase in the use of phytosanitary products during the last few decades, the importance to study the effect of pesticide mixtures has been established. In this study, we investigated the acute toxicity of two model insecticides, chlordecone (CLD) and pyriproxyfen (PXF), alone and in mixtures, in the estuarine copepod Eurytemora affinis. After 48 h of exposure, the relative LC50 were 73.24 and 131.61 μg/L for PXF and CLD, respectively. The lower concentration tested (10 μg/L) did not affect the mortality of E. affinis whatever the considered chemical compound. To understand the interaction between compounds in mixture, the results were fitted to the concentration addition, Vølund, and Hewlett models. The best fit was obtained with the Hewlett model, suggesting a synergistic effect of the mixture.

Due to the increase in the use of phytosanitary products during the last few decades, the importance to study the effect of pesticide mixtures has been established. In this study, we investigated the acute toxicity of two model insecticides, chlordecone (CLD) and pyriproxyfen (PXF), alone and in mixtures, in the estuarine copepod Eurytemora affinis. After 48 h of exposure, the relative LC50 were 73.24 and 131.61 μg/L for PXF and CLD, respectively. The lower concentration tested (10 μg/L) did not affect the mortality of E. affinis whatever the considered chemical compound. To understand the interaction between compounds in mixture, the results were fitted to the concentration addition, Vølund, and Hewlett models. The best fit was obtained with the Hewlett model, suggesting a synergistic effect of the mixture.