Screening and Ecological Risk Assessment of Organochlorine and Synthetic Pyrethroid Pesticides in Kufa River using GC-MS

Abstract

The Kufa River (Shatt Al-Kufa) in Najaf Governorate, Iraq, faces escalating environmental degradation driven by agricultural runoff, untreated municipal wastewater, and industrial discharges. To evaluate the presence and ecotoxicological risks of persistent and current-use agrochemicals, surface water samples were collected across five representative sites (S1–S5) from August to December 2025 and analyzed for organochlorine pesticides (OCPs) and synthetic pyrethroids (SPs) using Gas Chromatography-Mass Spectrometry (GC-MS) following dichloromethane extraction. Quantitative screening revealed severe multi-pesticide contamination exceeding US EPA water quality criteria across all sampling stations. Extremely high concentrations of legacy contaminants were recorded at S1, notably Endrin (85.000ng/L) and P,P-DDT (67.000ng/L), while S5 exhibited severe pollution dominated by O,P-Methoxychlor (198.000ng/L), Dieldrin (0.970ng/L), and Aldrin (1.060ng/L). Furthermore, active agricultural applications were confirmed by the ubiquitous presence of the synthetic pyrethroid Lambda-cyhalothrin, which reached up to 4.001ng/L at S1. The co-occurrence of legacy organochlorines and active pyrethroids creates complex chemical mixtures in the aquatic environment, posing severe toxic hazards to aquatic biodiversity, threatening planktonic community stability, and impairing ecosystem self-purification capacity along the Euphrates River basin.