Groundwater in the Maresme area (NE Spain) is characterised by high concentrations of nitrate, sulphate and chloride. Chemical and isotope data presented in this paper were collected in order to characterise the main sources of nitrate contamination. This study has also provided information about sources of sulphate and chloride in the area. The nitrate groundwater contamination is related to agriculture activities such as the intense use of synthetic fertilisers. The high rates of fertilisation and re-circulation of the shallow groundwater used for irrigation explain the high concentration of nitrates in the groundwater with values as high as 482 mg l-1. The isotope composition of the groundwater nitrate ranges between +6.8‰ and +9.4‰ for δ15N and from +5.1‰ to +10.2‰ for δ18O. Fertilisers used in the area show values close to 0‰ and +23‰ for δ15N and δ18O, respectively. The more enriched δ15N values in the groundwater compared to the fertilisers is associated to volatilisation of the ammonia component of the fertilisers. The 18O pattern in the groundwater implies that nitrate from nitrogenous fertilisers is recycled in the soil where it becomes 18O depleted. Based on the δ15N NO3 and δ18ONO3 data, a significant denitrification was discarded in the study site. Groundwater dissolved sulphate has δ34SSO4 values between +5.8 to +7.0‰ suggesting that the main source of sulphate might not be related to seawater intrusion, which in turn questioned the origin of chloride previously related to a seawater intrusion. © 2005 Springer-Verlag Berlin Heidelberg.
CITATION STYLE
Vitòria, L., Soler, A., Aravena, R., & Canals, À. (2005). Multi-isotopic approach (15N, 13C, 34S, 18O and D) for tracing agriculture contamination in groundwater. In Environmental Chemistry: Green Chemistry and Pollutants in Ecosystems (pp. 43–56). Springer Berlin Heidelberg. https://doi.org/10.1007/3-540-26531-7_5
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