Concentrations and ecological risk assessment of pesticide residues on soil biota in irrigated soil of Ziway, Ethiopia

Pesticide residues in soil samples were analyzed by a gas chromatograph-mass spectrometer. To evaluate the ecological risks posed to significant soil organisms, including earthworms (Eisenia fetida), springtails (Folsomia candida), and nitrogen-mineralizing microorganisms, we employed toxicity exposure ratios and risk quotients to assess potential impacts. The rank order of pesticides in soil based on their concentration was p,p'-DDE (dichlorodiphenyldichloroethylene) (M ± SD; 37.48 ± 16.76 μg kg-1) > propoxur (23.94 ± 10.71 μg kg-1) > propargite (22.09 ± 9.88 μg kg-1) > α-endosulfan (11.56 ± 5.17 μg kg-1) > malathion (10.22 ± 4.57 μg kg-1) > fenthion (7.78 ± 3.48 μg kg-1) > … > fenitrothion (0.11 ± 0.05 μg kg-1). Exposed soil organisms of F. candida and nitrogen mineralization are at risk due to chronic exposure to chlorpyrifos and fenthion, with TERmax toxicity exposure ratios of 0.86 and 1.20, respectively. The cumulative risk quotient of 5.3 indicates that the detected pesticide mixtures would pose significant ecological risks in traditional farming study areas. Therefore, to preserve soil quality and mitigate the risks associated with pesticide use, it is crucial to develop targeted integrated crop protection strategies.