wAbstract
@Nitrate-contaminated groundwater from an aquifer in the Osona
region (NE Spain) was chemically and isotopically (Β15NNO3, Β18ONO3, Β34SSO4, Β18OSO4, ΒD, Β18OH2O,
and Β13CDIC) characterized. Diffuse-NO3- contamination reached values of
366 mg/L. Nearly 75 of the 37 sampled sites had higher concentrations
than the 50 mg/L in NO3- limit
for drinking water. To identify the source of pollution Β15NNO3 and Β18ONO3 were used with results,
for most samples, in the range of pig manure NO3-.
Nitrification processes were evaluated by means of the Β18
of NO3- and water. Isotopic data
suggested that natural attenuation of NO3-
was taking place. This process was confirmed using the Β18ONO3 coupled with the NO3-/Cl- ratio, avoiding the
influence of continuous NO3- inputs.
A further insight on denitrification processes was obtained by
analyzing the ions involved in denitrification reactions. Although
the role of organic matter oxidation could neither be confirmed
nor discarded, this approach showed a link between denitrification
and pyrite oxidation. Therefore, in areas with no adequate infrastructure
(e.g. multipiezometers), such as the one studied, this approach
could be useful for implementing better water management.x
1. Introduction
2. Study area
3. Sampling and analysis
4. Results and discussion
@4.1. Groundwater quality
@4.2. Stable isotopes
@4.3. Evaluation of fractionation processes affecting N compounds
@4.4. Evaluation of the natural attenuation: the denitrification
5. Conclusions
Acknowledgements
References