Ecological Risk Assessment for Six Pesticides in Farmland and Surface Water Ecosystems

Pesticides are extensively applied in agricultural production, thereby posing potential ecological risks to farmland and surface water ecosystems. This study utilized the toxicity data of terrestrial and aquatic organisms to construct Species Sensitivity Distribution (SSD) models and evaluated the ecological risks of six pesticides. In terrestrial ecosystems, the 5% hazard concentration (HC₅) values for avermectin, emamectin benzoate, bifenthrin, fipronil, and pymetrozine were 0.119, 0.387, 1.3 × 10^-3, 8.0 × 10^-3, and 0.243 mg L^-1, respectively. For acute toxicity to aquatic organisms, HC₅ values for avermectin, emamectin benzoate, bifenthrin, gamma-cyhalothrin, fipronil, and pymetrozine were 3.2 × 10^-3, 1.5 × 10^-3, 1.1 × 10^-5, 1.0 × 10^-6, 4.6 × 10^-3, and 29.883 mg L^-1, respectively. In addition, the ecological risk to terrestrial nontarget organisms was assessed using the Hazard Quotient (HQ). The results indicated that bifenthrin and pymetrozine posed significant potential risks to Trichogramma chilonis and Trichogramma brasiliensis, as their HQ values exceeded the trigger threshold of 5. These findings support pesticide risk assessment in farmland and surface water ecosystems and provide a scientific basis for their rational application.