Dissipation Dynamics and Persistence of Chlorpyrifos and Deltamethrin in Different Water Resources

Pesticide contamination in aquatic ecosystems presents significant environmental and public health risks, primarily due to the accumulation of toxic residues that threaten both aquatic ecosystems and human health. This study examined the persistence and degradation behaviour of chlorpyrifos and deltamethrin residues in various water sources, along with their degradation kinetics under controlled laboratory conditions. Validated and sensitive chromatographic method was employed to detect and quantify these tested pesticides, using gas chromatography with a micro-electron capture detector (GC-ECD). The limit of detection (LOD) and limit of quantification (LOQ) for the selected pesticides in different water samples were 0.01 and 0.03 µg ml–1, respectively. Additionally, recovery rates for the targeted pesticides in the tested water sources ranged from 89.0% to 100%. The data highlighted the impact of both the pesticide type and the water source on the degradation rate. Chlorpyrifos degraded more rapidly than deltamethrin across all water types. The pesticide half-lives (t₀.₅) were as follows: 3.07, 2.41, 13.45, and 9.96 days for chlorpyrifos, and 34.37, 16.03, 15.64, and 10.47 days for deltamethrin in deionized, hard, Nile River, and agricultural drainage water, respectively. Overall, no simple or consistent trend was observed in terms of pesticide-water interactions, degradation percentages, or changes in pH levels over extended periods.