Matthieu DESCOUT

High Nitrates concentration in rivers is one of the main issue concerning water pollution and raises big concerns about human health and eutrophication. The agricultural sector is often targeted as being the main source of this water degradation, due to the use of mineral fertilizers. But Nitrates concentration fluctuates aver time because nutrients transfers from agricultural landscapes result from changing hydrological and biogeochemical processes (discharge, retention rate, residence time of nutrients, etc.) controlling their mobilization and delivery in the terrestrial and aquatic compartments of catchments.
During this internship, me and my colleagues focus on 37 selected watersheds that present a significant share of water coming from agricultural drainage – i.e. with low influence of large subsurface waterbodies – and try to investigate the impact of extreme climatic events – i.e. extremely dry years with low waterflow – and agricultural yields on this Nitrates concentration in water coming from drained areas. Our objective is to observe if extreme climate events have an influence on the different hydrological and biogeochemical processes controlling Nitrates leaching from drained agricultural surfaces and contribute to higher/lower levels of water pollution.