Ardières-Morcille: a research catchment dedicated to the study of the
transfer and impact of diffuse agricultural pollution in rivers
The Ardières catchment, (150 km²), in Beaujolais (France), belongs to
the first European catchments where surface water contamination by
pesticides has been highlighted in the late 1980s. Research on this site
mainly aims at better understanding organic pesticides and trace
elements hydrological pathways to watercourses, and at evaluating
subsequent contamination and impact on aquatic ecosystems. Landscape as
well as instream processes are studied in order to highlight catchment
vulnerability to contaminants and possible mitigation actions. A
consistent hydrological and chemical monitoring of the Ardières River
and one of its tributaries, the Morcille River, has been taking place
since 2002. It was supplemented by biological measurements on aquatic
micro-organisms and macroinvertebrates, more particularly after 2005.
The results show the importance of long-term study to account for the
kinetics of contaminant transfer in hydro-biogeochemical systems.
Physico-chemical, ecological and ecotoxicological measurements all
showed spatial and temporal variability in water quality and a gradient
of impact on community structures and ecological functions as a function
of the pressure of human activity. Results allowed to develop indicators
of toxic impacts and resilience of communities and provided avenues for
action to improve water quality.