Use of environmental isotopes to assess groundwater pollution caused by agricultural activities

Arumi, Jose; Escudero, Manuel; Aguirre, Evelyn; Salgado, Juan Carlos; Aravena, Ramon

Abstract

This work applied environmental isotope techniques to validate the results of previous studies on recharge sources in a rural area in central Chile (34.3 degrees S and 71.3 degrees W) and discern the origin of nitrate contamination in wells. Stream water and groundwater samples were taken during three surveys, two during spring snowmelt and one in low-water conditions. Chemical analyses included major cations and anions, isotope analyses included(18)O-H2O;H-2-H(2)0;H-3-H(2)0;O-18-NO(3)(-)and(15)N-NO3-. The stable isotope data show that surface water and deep groundwater present depleted isotope values associated with recharge from the Andes Mountains and that shallow groundwater has more enriched isotope values that reflect the contribution of local recharge from rainwater infiltration. Depleted isotope values observed in shallow groundwater show the effect of recirculated river water used for irrigation. These results are consistent with the conceptual groundwater model developed in previous studies. Some wells have nitrate concentrations above the allowable limit for drinking water. The stable nitrogen isotopes indicate that nitrate is associated mainly with urea and ammoniacal fertilizers, and nitrate is attenuated by denitrification. The results of this study are relevant to improving management of groundwater resources used for drinking water.

Más información

Título según WOS: Use of environmental isotopes to assess groundwater pollution caused by agricultural activities
Título de la Revista: ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES
Volumen: 56
Número: 5-6
Editorial: TAYLOR & FRANCIS LTD
Fecha de publicación: 2020
Página de inicio: 673
Página final: 683
DOI:

10.1080/10256016.2020.1813124

Notas: ISI