Comparative evaluation of urban versus agricultural nitrate sources and sinks in an unconfined aquifer by isotopic and multivariate analyses

BLARASIN, MÓNICA; CABRERA, ADRIANA; MATIATOS, IOANNIS; BECHER QUINODÓZ, FÁTIMA; GIULIANO ALBO, JESICA; LUTRI, VERÓNICA; MATTEODA, EDEL; PANARELLO, HÉCTOR

THE SCIENCE OF TOTAL ENVIRONMENT

Elsevier

Lugar: Amsterdam; Año: 2020 vol. 741

0048-9697

Nitrate (NO3−) is one of themost widespread contaminants in groundwater primarily due to agriculturalactivities utilizing N-containing fertilizers and the presence of animalwastes. Hydrochemical and nitrate isotope data (δ15N-NO3 − and δ18O-NO3−) from the unconfined aquifer in the urban area of Del Campillo city andits surrounding rural area with different land-use types, i.e. individualsanitation systems, agricultural areas and livestock breeding facilities, weregenerated to investigate the impact of nitrogen pollution sources and to assessN biogeochemical processes. The Principal Component Analysis of hydrochemicaland isotopic data were used to compare the factors that control the groundwaterquality and particularly the nitrate concentrations in the urban and the ruralarea. The results showed that nitrate pollution in the urban area of DelCampillo city originatedmainly from the on-site sanitationsystems and/or animal domestic wastes, whereas in the rural area nitrate pollutionwas mostly attributed to a combination of urea-based fertilizers and manurefrom livestock breeding activities. The aquifer is under oxic to suboxicconditions in the rural area and becomes suboxic in the urban area where thehigher supply of organic matter consumes oxygen. As a result, denitrification was more significant in the urban area compared to therural area, as evidenced by the higher N and O isotope enrichment factor (ε). This work willbe used to benchmark the current nitrate contamination status in the region andevaluate effective planning of environmental measures and remediationstrategies