Groundwater Vulnerability to Pesticide Pollution in a Semi-Arid Agricultural Basin and Electrocoagulation-Based Mitigation

Groundwater resources in arid and semi-arid regions are increasingly threatened by overextraction, climate variability, and contamination from agricultural practices. In areas where groundwater is the primary or sole source of freshwater, pesticide infiltration from intensive crop production poses a critical environmental and public health concern. This study investigates the occurrence and electrochemical removal of four widely used pesticides—lufenuron, ethoprophos, dichlobenil, and picloram—from groundwater in a semi-arid agricultural basin located in Southeastern Türkiye. Groundwater samples were collected from two distinct locations within a 1,500 km² area and analysed using gas chromatography techniques. Detected concentrations at the first sampling site were 0.54 µg/L (lufenuron), 0.14 µg/L (ethoprophos), 0.38 µg/L (dichlobenil), and 0.61 µg/L (picloram), while values at the second site were 0.48 µg/L, 0.42 µg/L, 0.26 µg/L, and 0.17 µg/L, respectively. To mitigate pesticide contamination, an electrocoagulation (EC) process using aluminium (Al) electrodes was applied. The effect of critical operational parameters—namely initial pH (6–7), current density (2.5 mA/cm²), and electrolysis duration (30 minutes)—was systematically evaluated to optimize removal performance. The EC treatment achieved outstanding removal efficiencies ranging from 98% to 99% for all pesticides tested. Post-treatment concentrations were brought well below international drinking water standards, confirming the process's effectiveness. In addition to its technical efficacy, electrocoagulation offers a low-cost and environmentally sustainable solution that can be scaled for broader application in water-stressed agricultural regions. The findings highlight the urgent need for integrated groundwater protection strategies and demonstrate the potential of electrochemical technologies in addressing pesticide pollution in vulnerable aquifer systems.