• CHIN Ech
• PHOEURNG Tork
• Keo Sombath
• Earng Khy Eam
• Paul Baudron

Pesticide contamination poses a significant risk to the critical Tonle Sap–Mekong River (TS-MR) system, which sustains aquatic ecosystems and human livelihoods in Cambodia. This study investigated the spatial and seasonal hydraulic propagation of pesticides across the Tonle Sap River (TSR), Mekong River (MKR), and Bassac River (BSR) during the dry (March 2025) and rainy (June 2025) seasons. Water samples from sixteen sites were analyzed using Solid Phase Extraction (SPE) followed by Gas Chromatography-Mass Spectrometry (GC-MS) screening for 451 pesticide compounds. The analysis revealed a stark seasonal contrast: no pesticides were detected during the rainy season. Conversely, the highly restricted pyrethroid insecticide, Cypermethrin, was the only pesticide quantified during the dry season, exhibiting extreme localized concentrations up to 26.21 μg/L at a site along the MKR (S10-MK). Seasonal electrical conductivity (EC) data further confirmed significant water quality differences between the TSR and the MKR/BSR, with higher values suggesting localized pollutant inputs in the BSR during the dry period. The calculated maximum Risk Quotient (RQ) for Cypermethrin was approximately 0.01, indicating a low overall ecological risk to the aquatic environment. However, the extreme localized concentration highlights the presence of distinct point source pollution, likely from unchecked agricultural runoff or direct discharge. This research underscores the critical role of river hydrodynamics in pollutant distribution and provides essential data for targeted water management strategies, emphasizing the need for stricter control over restricted pesticide use in high-risk zones.

"Hydraulic Propagation and Ecological Risk of Cypermethrin in the Lower Mekong River System, Cambodia", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.12, Issue 10, page no.a738-a743, October-2025, Available :http://www.jetir.org/papers/JETIR2510092.pdf

"Hydraulic Propagation and Ecological Risk of Cypermethrin in the Lower Mekong River System, Cambodia", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.12, Issue 10, page no. ppa738-a743, October-2025, Available at : http://www.jetir.org/papers/JETIR2510092.pdf