Tracing Sediment Sources Using Strontium Isotopes in a Pond Draining an Agricultural Catchment (Loire River Basin, France)

Soil erosion in agricultural catchments leads to the accelerate supply of sediment to rivers. Here, we determine the sources contributing to the siltation of a pond in the Louroux catchment (24km2, French Loire River basin), representative of lowland agricultural environments of Northwestern Europe. Strontium isotopic ratios weredetermined in potential sources and sediment core samples collected in the Louroux pond, at the outlet of the catchment. These ratios were shown to provide good discrimination between differentsediment sources (soil, suspended particulate matter, calcareous rock samples), and their respective contributions were calculated using mass balance equations. These results should be used to guide the implementation of soil conservation measures to limit sediment supply to the Louroux River.