Insight into abiotic and biotic transformations of fenaminstrobin in water and soil: Kinetics, transformation mechanism and ecotoxicity

Abstract

In 2009, fenaminstrobin was officially registered in China as a strobilurin pesticide, particularly developed for effectively controlling fungal diseases. Despite its widespread use, limited information is available regarding its environmental persistence and eco-toxicological profile. Herein, we comprehensively assess the abiotic and biotic transformations of fenaminstrobin, along with the associated ecological risks. Findings indicate that fenaminstrobin exhibits stability in water and soil under dark conditions; however, it undergoes substantial degradation when exposed to simulated sunlight, primarily due to the formation of photo-isomers. Furthermore, various factors within the water matrix that influence photo-degradation rates are revealed. Ten transformation products (TPs) are identified via high-resolution mass spectrometry in conjunction with suspect and non-target screening methodologies. Subsequently, a plausible transformation pathway is proposed based on the analysis of molecular functional groups and density functional theory (DFT) calculations. The pathway involves processes such as hydration, hydrolysis of chlorobenzene and oxime-ether, as well as redox reactions. Eco-toxicity assessments, integrating the predicted toxicity based on the Ecological Structure–Activity Relationship (ECOSAR) program with experimental data, reveal that certain TPs associated with fenaminstrobin remain highly toxic to aquatic organisms, albeit their ecological risk decreases over the course of its transformation. This study elucidates the transformation mechanisms and ecological risks of fenaminstrobin, providing critical insights for its effective and safe utilization.