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.

[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

International audience | The objective of this study was to assess the time variation of mineral and water stress levels across the life of a declining, Mg-deficient, spruce stand, in order to clarify the factors that caused the decline. Since 1985, strong soil acidification linked to a large leaching of nitrate and base cations was measured at the study site. In 1994, 5 trees were felled and tree rings were measured and analysed for Ca, Mg, K, Sr, 13 C/ 12 C and 87 Sr/ 86 Sr isotopic ratios. Strontium pools and fluxes as well as root Sr isotope ratio in relation to depth were also measured. Wood chemical concentrations and isotope ratios were strongly related to the dominance status of each tree. On average during the study period, the 87 Sr/ 86 Sr ratio of spruce wood decreased. Using a mechanistic model computing long term variations of 87 Sr/ 86 Sr ratio in trees and soils, we reproduced the observed trend by simulating soil acidification-increasing Sr drainage from the whole profile, and particularly from the organic horizon-, and root uptake becoming more superficial with time. Between 1952 and 1976, tree ring 13 C decreased strongly and continuously, which, in addition to other factors, might be related to an increase in water stress. Thus, a decrease in rooting depth, possibly related to soil acidification, appeared as a possible cause for the long term increase in water stress. The extreme drought event of 1976 appears to have revealed and triggered the decline.

International audience | Calcium dissolved deposition shows an unusual spatial structure in France, probably due to the contribution of southern air masses from Mediterranean Sea and Saharan desert. These masses are often loaded with terrigenous particles that contain carbonates. However, no precise relationship has been quantified between dissolved Ca and mineral dust deposition (MDD). The database of the French network RENECOFOR, gathering atmospheric deposition <0.45 mu m in 27 sites near forests during 18 years, was used to determine the non-sea-salt atmospheric deposition over France. This study (1) explores the relationship between dissolved components to decipher their origin in atmospheric deposition nearby forests and (2) tests the use of dissolved Ca and Mg as proxies for MDD. In the RENECOFOR database, non-sea-salt Ca (nssCa) preferentially deposited between May and August. MDD observed in RENECOFOR was synchronic with high nssCa deposition, particularly in June 2008, when air mass highly loaded with Saharan dust covered France. The dissolution of this mineral dust likely contributed to the nssCa deposition of this period and suggested a relationship between the depositions of nssCa and MDD. Then, MDD was specifically sampled with dissolved deposition in four sampling sites. Encouraging relationships were found between MDD and the depositions of nssMg and nssCa, suggesting that the latter could be used as a proxy for MDD in regions where it is not monitored, and in a retrospective approach in order to calculate nutrient fluxes.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [Axe_IRSTEA]TED-EPURE | International audience | 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.