Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 435, Issue -, Pages 167-178Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2012.06.028
Keywords
Nitrogen; Groundwater; Groundwater dating; Agriculture; Nitrate modeling
Categories
Funding
- French National Research Agency (ANR) through the VMC program (project MOHINI) [ANR-07-VULN-08]
- Systerra program (Acassya project) [ANR-08-STRA-01]
- EU-RDF INTERREG IVA France (Channel) - England program, (Climawat project)
- INRA
- CNRS (Environmental Research Observatories H + and AgrHys)
Ask authors/readers for more resources
Although nitrate export in agricultural catchments has been simulated using various types of models, the role of groundwater in nitrate dynamics has rarely been fully taken into account. We used groundwater dating methods (CFC analyses) to reconstruct the original nitrate concentrations in the groundwater recharge in Brittany (Western France) from 1950 to 2009. This revealed a sharp increase in nitrate concentrations from 1977 to 1990 followed by a slight decrease. The recharge concentration curve was then compared with past chronicles of groundwater concentration. Groundwater can be interpreted as resulting from the annual dilution of recharge water in an uncontaminated aquifer. Two aquifers were considered: the weathered aquifer and the deeper fractured aquifer. The nitrate concentrations observed in the upper part of the weathered aquifer implied an annual renewal rate of 27 to 33% of the reservoir volume while those in the lower part indicated an annual renewal rate of 2-3%. The concentrations in the deep fractured aquifer showed an annual renewal rate of 0.1%. The river concentration can be simulated by combining these various groundwater reservoirs with the recharge. Winter and summer waters contain i) recharge water, or water from the variably saturated zone with rapid transfer and high nitrate concentrations, and ii) a large contribution (from 35 to 80% in winter and summer, respectively) from the lower part of the aquifer (lower weathered aquifer and deep fractured aquifer). This induces not only a relatively rapid response of the catchment to variations in agricultural pressure, but also a potential inertia which has to be taken into account. (c) 2012 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available