Abstract Pesticides render adverse effects on human health and ecosystems. Metalaxyl (phenylamine fungicide) is both carcinogenic and mutagenic to mammals and aquatic creatures. Considering its half-life, persistence, solubility, mobility, and widespread use in cultivation, Metalaxyl has been chosen for the subsurface transport study of pesticides. Groundwater from the Bhagirathi–Churni–Jalangi interfluvial region of the western Bengal basin, belonging to the Ca–Mg–Cl facies, has been found to be contaminated (97% of the samples exceeding 0.1 μg/L) with Metalaxyl (median concentration 2.385 μg/L). The alluvial sandy soils (average permeability 4.5 cm/h, feebly acidic pH, and low soil organic carbon) overlying the aquifers of the region were found to be free from Metalaxyl contamination, indicating a poor adsorptive capacity (KD = 0.42) of the native soil. An experimental tank was filled with such native alluvial soil and divided into parts simulating an agricultural field and a residential area. In the agricultural field, the application of 600 mg/L of Metalaxyl solution, followed by simulated rainfall, carried the pesticide to the subsurface soil–water system. Vertical migration is faster than lateral migration, as indicated by decreasing concentrations of Metalaxyl away from the agricultural field. The deeper parts of the aquifer system were found to be more vulnerable than shallower ones to the accumulation of the harmful fungicide. Graphical abstract Research Highlights <UnorderedList Mark="Bullet"> <ItemContent> Pesticides render adverse effects on human health and ecosystems. Metalaxyl (phenylamine fungicide) is both carcinogenic and mutagenic to mammals and aquatic creatures. </ItemContent> <ItemContent> Groundwater from the Bhagirathi-Churni-Jalangi interfluvial region of Western Bengal basin, belonging to the Ca-Mg-Cl facies, has been found to be contaminated (97% of the samples exceeding 0.1 μg/L) with Metalaxyl (median concentration 2.385 μg/L). </ItemContent> <ItemContent> In the agricultural field, application of Metalaxyl solution followed by rainfall carry the pesticide to the subsurface soil-water system. Vertical migration is faster than lateral migration. </ItemContent> <ItemContent> The alluvial sandy soils (average permeability 4.5 cm/hr, feebly acidic pH, and low soil organic carbon) overlying the aquifers of the region were found free from Metalaxyl contamination, hinting towards the poor adsorptive capacities (KD=0.42) of the native soil. </ItemContent> <ItemContent> The deeper parts of the aquifer system were found more vulnerable than shallower ones to the accumulation of the harmful fungicide. </ItemContent> </UnorderedList>

Pesticide contamination in lower Gangetic alluvial aquifers of the western Bengal basin: Assessment through hydrogeochemistry and laboratory-scale experiment

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发表日期：

2025年12月2日

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Nilesh Kumar Meshram,
Rhitwik Chatterjee,
Sameer Shafi Ganaie,
Kalyan Adhikari

摘要

Abstract

Pesticides render adverse effects on human health and ecosystems. Metalaxyl (phenylamine fungicide) is both carcinogenic and mutagenic to mammals and aquatic creatures. Considering its half-life, persistence, solubility, mobility, and widespread use in cultivation, Metalaxyl has been chosen for the subsurface transport study of pesticides. Groundwater from the Bhagirathi–Churni–Jalangi interfluvial region of the western Bengal basin, belonging to the Ca–Mg–Cl facies, has been found to be contaminated (97% of the samples exceeding 0.1 μg/L) with Metalaxyl (median concentration 2.385 μg/L). The alluvial sandy soils (average permeability 4.5 cm/h, feebly acidic pH, and low soil organic carbon) overlying the aquifers of the region were found to be free from Metalaxyl contamination, indicating a poor adsorptive capacity (K_D = 0.42) of the native soil. An experimental tank was filled with such native alluvial soil and divided into parts simulating an agricultural field and a residential area. In the agricultural field, the application of 600 mg/L of Metalaxyl solution, followed by simulated rainfall, carried the pesticide to the subsurface soil–water system. Vertical migration is faster than lateral migration, as indicated by decreasing concentrations of Metalaxyl away from the agricultural field. The deeper parts of the aquifer system were found to be more vulnerable than shallower ones to the accumulation of the harmful fungicide.

Graphical abstract

Research Highlights

Pesticides render adverse effects on human health and ecosystems. Metalaxyl (phenylamine fungicide) is both carcinogenic and mutagenic to mammals and aquatic creatures.

Groundwater from the Bhagirathi-Churni-Jalangi interfluvial region of Western Bengal basin, belonging to the Ca-Mg-Cl facies, has been found to be contaminated (97% of the samples exceeding 0.1 μg/L) with Metalaxyl (median concentration 2.385 μg/L).

In the agricultural field, application of Metalaxyl solution followed by rainfall carry the pesticide to the subsurface soil-water system. Vertical migration is faster than lateral migration.

The alluvial sandy soils (average permeability 4.5 cm/hr, feebly acidic pH, and low soil organic carbon) overlying the aquifers of the region were found free from Metalaxyl contamination, hinting towards the poor adsorptive capacities (KD=0.42) of the native soil.

The deeper parts of the aquifer system were found more vulnerable than shallower ones to the accumulation of the harmful fungicide.