Screening of Atrazine Distribution in Groundwater and Modeling of Leaching Potential to the Unconfined Aquifer in the Pampean Plain of Cordoba, Argentina

LUTRI, VERÓNICA F.; BLARASIN, MÓNICA T.; MATTEODA, EDEL M.; CURRELL, MATTHEW; GIACOBONE, DANIELA B.; QUINODÓZ, FÁTIMA BÉCHER; CABRERA, ADRIANA E.

Environmental Processes

Springer Nature

Año: 2022 vol. 9

2198-7491

The objective of this study was to analyze atrazine (ATZ) spatial distribution in groundwater and present the factors related to its leaching potential in an area under intensiveagricultural activity within the fuvio-Aeolian plain of the province of Córdoba, Argentina.Using tools such as soil and groundwater sampling and analysis, batch tests and numericalmodeling, the variables that control the atrazine sorption and leaching potential were evaluated. The herbicide was detected in 14.7% of groundwater samples (0.14 to 1.26 μg L−1)becoming a leachable herbicide with moderate potential for groundwater pollution according to the calculated GUS (Groundwater Ubiquity Score) index. Hydrogeological characteristics infuenced its distribution in the unconfned aquifer. Areas with a thin vadose zone(VZ) showed the highest atrazine levels, while the lithology of the vadose zone was alsocritical. In areas with a predominance of coarse-textured sediments (sands and gravels),low clay percentages and lower Koc, atrazine exhibits high mobility, which makes possibleits transport to the unconfned aquifer at sites with a deep water table (≈25 m below surface). Herbicide spray application generally coincides with the rainy seasons, which contributes to high leaching rates. Numerical modeling indicated that transport of water andATZ occurs both through micropores continuously, and macropores episodically. Groundwater has become a secondary environmental subsystem afected by the presence of ATZdue to advective, dispersive and reactive processes which allow its transport through theVZ. Even at relatively low concentrations, the presence of atrazine in groundwater requireslong-term planning to monitor and control.