Spatiotemporal patterns of pesticide residues in intensive agricultural soil and water bodies in Shaheed Benazirabad, Pakistan

Abstract

This study investigates the spatial and temporal distribution of 21 pesticides across soil and water in three major agricultural tehsils (Nawabshah, Sakrand, and Daur) of district Shaheed Benazirabad, Pakistan, spanning spring, summer, and autumn 2023. Method sensitivity and precision allowed for detection limits (LOD) ranging from 0.016–0.056 in water and 1.39–4.64 in soil with a limit of quantification (LOQ) ensuring high accuracy. Results showed peak pesticide concentrations during summer with detection rates of 74.15% in soil, and 61.2% in water followed by autumn (55.78% and 36%) and spring (30.91% and 24.4%) in soil and water respectively. Highest detection frequencies of chlorpyrifos (882 µg/kg), profenofos (663 µg/kg), malathion (645 µg/kg), and endosulfan (973 µg/kg) were found in soil. Significant concentrations of dimethoate (0.657 µg/L), DDT (0.675 µg/L), and bifenthrin (0.458 µg/L) were recorded in water samples. Sakrand soil exhibited the highest contamination during the summer season reaching the level of 5070 μg/kg soil, highlighting the impact of intensive agriculture practices. Significant correlations were found between pesticide retention and soil and water physiochemical properties. The highest positive correlation was found in pesticide retention with OM and soil pH with CaCO₃ and sulfate and nitrate in water. This study establishes a baseline for pesticide contamination in this agricultural region and analyzes the factors in soil and water that affect pesticide mobility. These findings suggested that environmental monitoring and strict pesticide regulation during peak agriculture season could minimize ecosystem contamination, protect human health, and encourage regulatory and conservation initiatives in high-intensity farming areas.