International audience | The pesticide risk assessment for earthworms is currently performed using standardized tests, the model species Eisenia fetida, and the analyses of the data obtained are performed with ad hoc statistical tools. We assessed the impact of two fungicides on the entire growth pattern of the earthworm species Aporrectodea caliginosa, which is highly representative of agricultural fields. Individuals of three different ages (from hatching to 56 days old) were exposed to Cuprafor micro(R) (copper oxychloride) and Swing(R) Gold (dimoxystrobin and epoxiconazole). Data were analyzed with an energy-based toxicodynamic model coupled with a toxicokinetic model. The copper fungicide caused a drastic growth inhibition once the no effect concentration (NEC), estimated at 65 mg kg(-1) of copper, was exceeded. The Swing(R) Gold negatively affected the growth with NEC values estimated at 0.387 mg kg(-1) and 0.128 mg kg(-1) for the dimoxystrobin and the epoxiconazole in this fungicide formulation, respectively. The time-profile of the effects on A. caliginosa individuals was fully accounted for by the model, whatever their age of exposure. Furthermore, toxicity data analyses, supported by measurements of fungicide concentrations in earthworm at the end of the experiment, allowed bettering understanding of the mechanisms of action of the fungicides towards earthworm growth.

The pesticide risk assessment for earthworms is currently performed using standardized tests, the model species Eisenia fetida, and the analyses of the data obtained are performed with ad hoc statistical tools. We assessed the impact of two fungicides on the entire growth pattern of the earthworm species Aporrectodea caliginosa, which is highly representative of agricultural fields. Individuals of three different ages (from hatching to 56 days old) were exposed to Cuprafor micro® (copper oxychloride) and Swing® Gold (dimoxystrobin and epoxiconazole). Data were analyzed with an energy-based toxicodynamic model coupled with a toxicokinetic model. The copper fungicide caused a drastic growth inhibition once the no effect concentration (NEC), estimated at 65 mg kg⁻¹ of copper, was exceeded. The Swing® Gold negatively affected the growth with NEC values estimated at 0.387 mg kg⁻¹ and 0.128 mg kg⁻¹ for the dimoxystrobin and the epoxiconazole in this fungicide formulation, respectively. The time-profile of the effects on A. caliginosa individuals was fully accounted for by the model, whatever their age of exposure. Furthermore, toxicity data analyses, supported by measurements of fungicide concentrations in earthworm at the end of the experiment, allowed bettering understanding of the mechanisms of action of the fungicides towards earthworm growth.

International audience | Chlorpyrifos manufacturing wastewater (CMW) is characterized by complex composition, high chemical oxygen demand (COD) concentration, and toxicity. An integrated process comprising of peroxide (H2O2) promoted-catalytic wet air oxidation (PP-CWAO), struvite precipitation, and biological aerated filters (BAF) was constructed to treat CMW at a starting COD of 34000–35000 mg/L, total phosphorus (TP) of 5550–5620 mg/L, and total organophosphorus (TOP) of 4700–4840 mg/L. Firstly, PP-CWAO was used to decompose high concentrations of organic components and convert concentrated and recalcitrant TOP to inorganic phosphate. Copper citrate and ferrous citrate were used as the catalysts of PP-CWAO. Under the optimized conditions, 100% TOP was converted to inorganic phosphate with 95.6% COD removal. Then, the PP-CWAO effluent was subjected to struvite precipitation process for recovering phosphorus. At a molar ratio of Mg2+:NH4+:PO43− = 1.1:1.0:1.0, phosphate removal and recovery reached 97.2%. The effluent of struvite precipitation was further treated by the BAF system. Total removals of 99.0%, 95.2%, 97.3%, 100%, and 98.3% were obtained for COD, total suspended solids, TP, TOP, and chroma, respectively. This hybrid process has proved to be an efficient approach for organophosphate pesticide wastewater treatment and phosphorus reclamation.

Chlorpyrifos manufacturing wastewater (CMW) is characterized by complex composition, high chemical oxygen demand (COD) concentration, and toxicity. An integrated process comprising of peroxide (H₂O₂) promoted-catalytic wet air oxidation (PP-CWAO), struvite precipitation, and biological aerated filters (BAF) was constructed to treat CMW at a starting COD of 34000–35000 mg/L, total phosphorus (TP) of 5550–5620 mg/L, and total organophosphorus (TOP) of 4700–4840 mg/L. Firstly, PP-CWAO was used to decompose high concentrations of organic components and convert concentrated and recalcitrant TOP to inorganic phosphate. Copper citrate and ferrous citrate were used as the catalysts of PP-CWAO. Under the optimized conditions, 100% TOP was converted to inorganic phosphate with 95.6% COD removal. Then, the PP-CWAO effluent was subjected to struvite precipitation process for recovering phosphorus. At a molar ratio of Mg²⁺:NH₄⁺:PO₄³⁻ = 1.1:1.0:1.0, phosphate removal and recovery reached 97.2%. The effluent of struvite precipitation was further treated by the BAF system. Total removals of 99.0%, 95.2%, 97.3%, 100%, and 98.3% were obtained for COD, total suspended solids, TP, TOP, and chroma, respectively. This hybrid process has proved to be an efficient approach for organophosphate pesticide wastewater treatment and phosphorus reclamation.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]BELCA [ADD1_IRSTEA]Systèmes aquatiques soumis à des pressions multiples | International audience | Perfluorinated and polyfluorinated substances (PFASs) are widely found in freshwater ecosystems because of their resistance to degradation and their ability to accumulate in aquatic organisms. While water temperature controls many physiological processes in fish, knowledge of the effects of this factor on PFAS toxicokinetic is still limited. This study presents experimental results of internal distribution and elimination rates of two perfluorinated acid compounds, namely perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) in adult rainbow trout (Oncorhynchus mykiss) exposed to three temperatures. Dietary exposure experiments were conducted at 7 °C, 11 °C, and 19 °C and liver, blood, muscle, brain, and kidney were sampled for analysis. PFOS concentrations were comparable to or exceeded those of PFHxS, while PFHxS was eliminated faster than PFOS, whatever the temperature. Internal distribution changed significantly for both substances when fish were exposed to a range of temperatures from 7 to 19 °C. Indeed, PFOS and PFHxS relative distribution increased in blood, liver, and brain while they decreased in muscle when the water temperature rose. The water temperature variation affected the elimination half-lives, depending on the substances and organs.

Perfluorinated and polyfluorinated substances (PFASs) are widely found in freshwater ecosystems because of their resistance to degradation and their ability to accumulate in aquatic organisms. While water temperature controls many physiological processes in fish, knowledge of the effects of this factor on PFAS toxicokinetic is still limited. This study presents experimental results of internal distribution and elimination rates of two perfluorinated acid compounds, namely perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) in adult rainbow trout (Oncorhynchus mykiss) exposed to three temperatures. Dietary exposure experiments were conducted at 7 °C, 11 °C, and 19 °C and liver, blood, muscle, brain, and kidney were sampled for analysis. PFOS concentrations were comparable to or exceeded those of PFHxS, while PFHxS was eliminated faster than PFOS, whatever the temperature. Internal distribution changed significantly for both substances when fish were exposed to a range of temperatures from 7 to 19 °C. Indeed, PFOS and PFHxS relative distribution increased in blood, liver, and brain while they decreased in muscle when the water temperature rose. The water temperature variation affected the elimination half-lives, depending on the substances and organs.

International audience

Integrated hydrodynamic modelling is an efficient approach for making semi-quantitative scenarios reliable enough for groundwater management, provided that the numerical simulations are from a validated model. The model set-up, however, involves many inputs due to the complexity of both the hydrological system and the land use. The case study of a Mediterranean alluvial unconfined aquifer in the lower Var valley (Southern France) is useful to test a method to estimate lacking data on water abstraction by small farms in urban context. With this estimation of the undocumented pumping volumes, and after calibration of the exchange parameters of the stream-aquifer system with the help of a river model, the groundwater flow model shows a high goodness of fit with the measured potentiometric levels. The consistency between simulated results and real behaviour of the system, with regard to the observed effects of lowering weirs and previously published hydrochemistry data, confirms reliability of the groundwater flow model. On the other hand, accuracy of the transport model output may be influenced by many parameters, many of which are not derived from field measurements. In this case study, for which river-aquifer feeding is the main control, the partition coefficient between direct recharge and runoff does not show a significant effect on the transport model output, and therefore, uncertainty of the hydrological terms such as evapotranspiration and runoff is not a first-rank issue to the pollution propagation. The simulation of pollution scenarios with the model returns expected pessimistic outputs, with regard to hazard management. The model is now ready to be used in a decision support system by the local water supply managers.

The aim of this study was to characterize qualitatively and quantitatively the composition of the main rhizodeposits emitted from maize (Zea mays) under Cd stress, in order to discuss their role in Cd availability and tolerance. Maize was grown for 6weeks in sand at four Cd exposure levels (0, 10, 20, and 40M Cd in nutrient solution) and two types of rhizodeposits were collected at the end of cultivation period. Mucilage and other molecules adhering to rhizospheric sand were extracted with a buffer before root exudates were collected by diffusion into water. Total carbon, proteins, amino acids, and sugars were analyzed for both rhizodeposit types and about 40 molecules were identified using GC-MS and LC-MS. Cadmium effect on plant morphology and functioning was slight, but consistent with previous works on Cd toxicity. However, rhizodeposition did tend to be impacted, with a decrease in total carbon, sugars, and amino acids correlating with an increasing Cd content. Such a decrease was not noticeable for proteins in root exudates. These observations were confirmed by the same trends in individual compound contents, although the results were generally not statistically significant. Many of the molecules determined are well-known to modify, whether directly or indirectly, Cd speciation and dynamics in the soil and could play a role in Cd tolerance.

The aim of this study was to characterize qualitatively and quantitatively the composition of the main rhizodeposits emitted from maize (Zea mays) under Cd stress, in order to discuss their role in Cd availability and tolerance. Maize was grown for 6 weeks in sand at four Cd exposure levels (0, 10, 20, and 40 μM Cd in nutrient solution) and two types of rhizodeposits were collected at the end of cultivation period. Mucilage and other molecules adhering to rhizospheric sand were extracted with a buffer before root exudates were collected by diffusion into water. Total carbon, proteins, amino acids, and sugars were analyzed for both rhizodeposit types and about 40 molecules were identified using GC-MS and LC-MS. Cadmium effect on plant morphology and functioning was slight, but consistent with previous works on Cd toxicity. However, rhizodeposition did tend to be impacted, with a decrease in total carbon, sugars, and amino acids correlating with an increasing Cd content. Such a decrease was not noticeable for proteins in root exudates. These observations were confirmed by the same trends in individual compound contents, although the results were generally not statistically significant. Many of the molecules determined are well-known to modify, whether directly or indirectly, Cd speciation and dynamics in the soil and could play a role in Cd tolerance.

International audience | Pyrolysis of waste materials to produce biochar is an excellent and suitable alternative supporting a circular bio-based economy. One of the properties attributed to biochar is the capacity for sorbing organic contaminants, which is determined by its composition and physicochemical characteristics. In this study, the capacity of waste-derived biochar to retain volatile fuel organic compounds (benzene, toluene, ethylbenzene and xylene (BTEX) and fuel oxygenates (FO)) from artificially contaminated water was assessed using batch-based sorption experiments. Additionally, the sorption isotherms were established. The results showed significant differences between BTEX and FO sorption on biochar, being the most hydrophobic and non-polar contaminants those showing the highest retention. Furthermore, the sorption process reflected a multilayer behaviour and a relatively high sorption capacity of the biochar materials. Langmuir and Freundlich models were adequate to describe the experimental results and to detect general differences in the sorption behaviour of volatile fuel organic compounds. It was also observed that the feedstock material and biochar pyrolysis conditions had a significant influence in the sorption process. The highest sorption capacity was found in biochars produced at high temperature (> 400 °C) and thus rich in aromatic C, such as eucalyptus and corn cob biochars. Overall, waste-derived biochar offers a viable alternative to be used in the remediation of volatile fuel organic compounds from water due to its high sorption capacity.

Pyrolysis of waste materials to produce biochar is an excellent and suitable alternative supporting a circular bio-based economy. One of the properties attributed to biochar is the capacity for sorbing organic contaminants, which is determined by its composition and physicochemical characteristics. In this study, the capacity of waste-derived biochar to retain volatile fuel organic compounds (benzene, toluene, ethylbenzene and xylene (BTEX) and fuel oxygenates (FO)) from artificially contaminated water was assessed using batch-based sorption experiments. Additionally, the sorption isotherms were established. The results showed significant differences between BTEX and FO sorption on biochar, being the most hydrophobic and non-polar contaminants those showing the highest retention. Furthermore, the sorption process reflected a multilayer behaviour and a relatively high sorption capacity of the biochar materials. Langmuir and Freundlich models were adequate to describe the experimental results and to detect general differences in the sorption behaviour of volatile fuel organic compounds. It was also observed that the feedstock material and biochar pyrolysis conditions had a significant influence in the sorption process. The highest sorption capacity was found in biochars produced at high temperature (> 400 °C) and thus rich in aromatic C, such as eucalyptus and corn cob biochars. Overall, waste-derived biochar offers a viable alternative to be used in the remediation of volatile fuel organic compounds from water due to its high sorption capacity.

International audience | Fixation reactions reduce the concentration of soluble phosphorus (P) and affect crop growth in alkaline calcareous soils. In lab and greenhouse studies, phosphoric acid (PA) or diammonium phosphate (DAP) were evaluated at various P rates (0, 18, 36 and 54 mg kg−1 soil), either as non-mix (designated as NM-PA and NM-DAP, respectively) or after premixing with farmyard manure (FYM) at 400 mg kg−1 soil (designated as PM-PA and PM-DAP, respectively). The amended soil was incubated at 25 °C and 70% water holding capacity for 7 weeks; thereafter, 32P dynamics were measured using the Freundlich kinetic model. A greenhouse study was also conducted using the same thirteen treatments (as used in incubation experiment) and wheat cultivar (Galaxy 2013) was grown following standard agronomic practices. The results showed that application of PM-PA at the highest rate, which caused maximum change in Pr (ΔPr = 59%) in laboratory condition, also produced maximum P uptake by grain (190.3 mg pot−1) and grain yield (44.1 g pot−1) of wheat in greenhouse experiment. Similarly, regression analysis showed that an increase in Pr values caused a corresponding increase in crop parameters. The results suggested that pre-mixing P fertilizer with FYM could be a viable technique to increase P supply and enhance productivity of wheat in alkaline calcareous soils.

Fixation reactions reduce the concentration of soluble phosphorus (P) and affect crop growth in alkaline calcareous soils. In lab and greenhouse studies, phosphoric acid (PA) or diammonium phosphate (DAP) were evaluated at various P rates (0, 18, 36 and 54 mg kg⁻¹ soil), either as non-mix (designated as NM-PA and NM-DAP, respectively) or after premixing with farmyard manure (FYM) at 400 mg kg⁻¹ soil (designated as PM-PA and PM-DAP, respectively). The amended soil was incubated at 25 °C and 70% water holding capacity for 7 weeks; thereafter, ³²P dynamics were measured using the Freundlich kinetic model. A greenhouse study was also conducted using the same thirteen treatments (as used in incubation experiment) and wheat cultivar (Galaxy 2013) was grown following standard agronomic practices. The results showed that application of PM-PA at the highest rate, which caused maximum change in Pr (ΔPr = 59%) in laboratory condition, also produced maximum P uptake by grain (190.3 mg pot⁻¹) and grain yield (44.1 g pot⁻¹) of wheat in greenhouse experiment. Similarly, regression analysis showed that an increase in Pr values caused a corresponding increase in crop parameters. The results suggested that pre-mixing P fertilizer with FYM could be a viable technique to increase P supply and enhance productivity of wheat in alkaline calcareous soils.