The introduction of glyphosate-tolerant (GT) crops is expected to mitigate the environmental contamination by herbicides because glyphosate is less persistent and toxic than the herbicides used on non-GT crops. Here, we compared the environmental balances of herbicide applications for both crop types in three French field trials. The dynamic of herbicides and their metabolites in soil, groundwater and air was simulated with PRZM model and compared to field measurements. The associated impacts were aggregated with toxicity potentials calculated with the fate and exposure model USES for several environmental endpoints. The impacts of GT systems were lower than those of non-GT systems, but the accumulation in soils of one glyphosate metabolite (aminomethylphosphonic acid) questions the sustainability of GT systems. The magnitude of the impacts depends on the rates and frequency of glyphosate application being highest for GT maize monoculture and lowest for combination of GT oilseed rape and non-GT sugarbeet crops. The impacts of herbicide applications on glyphosate-tolerant crops could be higher than expected due to the accumulation of a metabolite of glyphosate in soils.

Diffuse pollution is a major cause for the degradation of water quality also in the French context. Nitrates and pesticides, mostly from agricultural sources, are the main pollutants. To a lesser extent, diffuse pollution has domestic and collective sources. Nitrate rates remain high in surface waters, despite an improvement of water quality in areas where livestock farming is responsible for nitrate pollution. The contamination of groundwater by nitrates and pesticides has been worsening in the last years. The EU Nitrate Directive is the main regulatory tool for the control of nitrate diffuse pollution. Farmers in designated vulnerable zones have to comply with measures included in action programs. The implementation of the ND in France was evaluated as incomplete relating to insufficient designation of vulnerable zones and non-conformity of action programs. Two other constraints are a low awareness of requirements by farmers and difficulties in controlling and enforcing compliance. As a consequence, the implementation process of the ND was redefined in France, with an extension of vulnerable zones, now covering 55% of agricultural area. While action programs were mainly defined at the district level, now a core program defined at the national level is completed by regional programs established by State regional authorities on the basis of the work of regional technical groups. The development of action plans to protect drinking water catchments relies on cooperation between water suppliers and agricultural stakeholders. A first step is the definition of protection zone(s) in the water catchment. Then, agricultural and non-agricultural pressures are identified. Finally, an action plan is defined to be implemented voluntary by farmers. In the French context, the involvement of water suppliers is fostered by financial incentives provided by Water Agencies. Also the “Grenelle” regulation imposes the definition and implementation of action plans in priority water catchments. The participation of farmers is targeted by a number of tools: (1) mostly agri-environmental schemes funded by EU rural development policy, (2) environmental land leases, (3) the development of market outlets such as local organic supply chains. Research shows that the success of this approach depends on a number of factors. The main success factors identified are: The scale of collective action. With regard with the governance of collective action, the definition of the role of stakeholders involved the involvement of farm leaders and farm organizations and the involvement of agricultural cooperatives and agro-industries. Finally, technical support to local stakeholders (water suppliers, farmers) was identified as a crucial success factor.

In France, the number of PDA quickly increases in order to better protect receiving surface water bodies. Setting up design rules and maintenance guidelines is now urgent. | En France, l'installation de ZRV en vue de protéger davantage le milieu récepteur de surface est désormais fréquente. L'élaboration de règles de dimensionnement et de maintenance est désormais urgente.

[Departement_IRSTEA]Territoires [TR1_IRSTEA]DTAM [Axe_IRSTEA]DTAM2-ACPUB | International audience | Diffuse pollution is a major cause for the degradation of water quality also in the French context. Nitrates and pesticides, mostly from agricultural sources, are the main pollutants. To a lesser extent, diffuse pollution has domestic and collective sources. Nitrate rates remain high in surface waters, despite an improvement of water quality in areas where livestock farming is responsible for nitrate pollution. The contamination of groundwater by nitrates and pesticides has been worsening in the last years. The EU Nitrate Directive is the main regulatory tool for the control of nitrate diffuse pollution. Farmers in designated vulnerable zones have to comply with measures included in action programs. The implementation of the ND in France was evaluated as incomplete relating to insufficient designation of vulnerable zones and non-conformity of action programs. Two other constraints are a low awareness of requirements by farmers and difficulties in controlling and enforcing compliance. As a consequence, the implementation process of the ND was redefined in France, with an extension of vulnerable zones, now covering 55% of agricultural area. While action programs were mainly defined at the district level, now a core program defined at the national level is completed by regional programs established by State regional authorities on the basis of the work of regional technical groups. The development of action plans to protect drinking water catchments relies on cooperation between water suppliers and agricultural stakeholders. A first step is the definition of protection zone(s) in the water catchment. Then, agricultural and non-agricultural pressures are identified. Finally, an action plan is defined to be implemented voluntary by farmers. In the French context, the involvement of water suppliers is fostered by financial incentives provided by Water Agencies. Also the “Grenelle” regulation imposes the definition and implementation of action plans in priority water catchments. The participation of farmers is targeted by a number of tools: (1) mostly agri-environmental schemes funded by EU rural development policy, (2) environmental land leases, (3) the development of market outlets such as local organic supply chains. Research shows that the success of this approach depends on a number of factors. The main success factors identified are: The scale of collective action. With regard with the governance of collective action, the definition of the role of stakeholders involved the involvement of farm leaders and farm organizations and the involvement of agricultural cooperatives and agro-industries. Finally, technical support to local stakeholders (water suppliers, farmers) was identified as a crucial success factor.

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

Mercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments.

Exposure of the general population to airborne metals remains poorly estimated despite the potential health risks. Passive moss biomonitoring can proxy air quality at fine resolution over large areas, mainly in rural areas. We adapted the technique to urban areas to develop fine concentration maps for several metals for Constances cohort's participants. We sampled Grimmia pulvinata in 77 and 51 cemeteries within ∼50 km of Paris and Lyon city centers, respectively. We developed land-use regression models for 14 metals including cadmium, lead, and antimony; potential predictors included the amount of urban, agricultural, forest, and water around cemeteries, population density, altitude, and distance to major roads. We used both kriging with external drift and land use regression followed by residual kriging when necessary to derive concentration maps (500 × 500 m) for each metal and region. Both approaches led to similar results. The most frequent predictors were the amount of urban, agricultural, or forest areas. Depending on the metal, the models explained part of the spatial variability, from 6% for vanadium in Lyon to 84% for antimony in Paris, but mostly between 20% and 60%, with better results for metals emitted by human activities. Moss biomonitoring in cemeteries proves efficient for obtaining airborne metal exposures in urban areas for the most common metals.

Since the fifties, organochlorine pesticides (OCPs) had been used in agriculture to protect vegetables. Two decades after their ban by the Stockholm convention in 2001, OCPs are still present in agricultural soils inducing vegetable contamination with concentrations above Maximum Residue Level (MRL). This is a major concern for a 5 km² peri-urban vegetable growing valley located in the south west of France. In the present work, the sampling method was developed to clarify the spatial distribution of one OCP, Dieldrin, and its relationship with soil properties at the scale of study area. A total of 99 soil samples was collected for physicochemical analyses and Dieldrin concentrations. Results show Dieldrin concentrations in soils up to 204 μg kg⁻¹. The horizontal distribution of this pesticide is heterogeneous at the study area scale but homogeneous in each reference plot studied. About 85% of the contamination was located in the top soil layers (0–40 cm depth), but Dieldrin may still be quantified at a depth of 80 cm. Among all soil physicochemical parameters analysed, SOM was the most significantly related (P < 10⁻⁴) with Dieldrin concentrations, once different grain size fractions were considered. Moreover, results indicate a 33 times higher Dieldrin concentration and/or extractability for coarse sand than for other grain size fractions. These results show that the developed sampling method is adapted for the study area scale as it helps understanding the factors influencing the spatial distribution of Dieldrin. Historical amendments are the predominant factor for the horizontal contamination and deep ploughing for the vertical contamination. Also, the variations of coarse sand repartition in soils prevents identification of relationships between SOM and Dieldrin contamination in bulk soil. Further investigation is required to explain these relationships but these results highlight why no clear relationship between OCPs and SOM was previously identified.