Water quality and ecotoxicology in the Rampillon Artificial Wetland Buffer Zones – Seine-et-Marne (77)

Abstract

Non-point source pollution generated by the intensification of agricultural practices leads to disturbances in terrestrial and aquatic ecosystems. This article is part of the PSDR Brie'Eau project (2016-2020) aimed at sharing ecosystem services for regulating pollutant flows and maintaining biodiversity in the context of field crops in the Seine et Marne department (France - 77). In order to prevent the degradation of the aquatic ecosystem, in parallel with actions targeting agricultural practices, ecological engineering actions are set up to manage agricultural waters that are variably charged with pollutants. This is the case of the Artificial Wetland Buffer Zone (Zone Tampon Humide Artificielle, ZTHA), system that promotes natural chemical and biological reactions to improve water quality. In 2010, a pilot ZTHA was set up in the commune of Rampillon near the "Ru des Gouffres" watercourse. It is located upstream of the direct inflow of surface water to the Champigny aquifer, which supplies part of the Ile de France region with drinking water. Within the ZTHA, the INRAE and AQUI'Brie association collaborate on monitoring to measure its effects on water quality. The results speak in favour of the project, since it significantly reduces the frequency with which the drinking water threshold, set at 50 mg/L of nitrates, is exceeded. Similarly, the ZTHA promotes the abatement of metal and pesticide flows at the outlet. Notwithstanding this abatement, laboratory ecotoxicological studies show that pesticide exposure at levels as measured in the ZTHA are likely to induce sublethal impacts in ecological organisms that are key to the functioning of aquatic ecosystems, these require confirmation in situ. In conclusion, this work confirms the relevance of these artificial ecosystems for the improvement of water chemical quality and the need to reduce upstream inputs of agricultural contaminants for optimal protection of aquatic life. Additional work is nevertheless essential to assess the ecotoxicological impact on the trophic chain that develops within the ZTHA. This article is the first in a trilogy presenting the various assets of the ZTHA to address current environmental issues such as water quality, biodiversity and land use planning.