Assessing the influence of chlorantraniliprole on agricultural soils: dissipation kinetics, degradation, microbial activity and functional biodiversity

Abstract

A comprehensive evaluation of the use of plant protection products (PPP) of the pesticide chlorantraniliprole (CAP) in soils has been done considering chemical and microbiological aspects. The study has been focused on the two most representative soil textures in greenhouse in the Southeast of Spain, clay (CS) and sandy clay loam soil (SCLS). The research has been divided into two phases, including laboratory (for 7 months) and field (for 2 months) studies to expand information on the behavior of the target pesticide in soils and their microorganisms. A combination of ultrasound-assisted QuEChERS extraction and ultra-high performance liquid chromatography with Q-Exactive-Orbitrap mass spectrometry (UHPLC-Q-Exactive-Orbitrap) was validated to determine the fate of the parent pesticide and its metabolites and has shown the great persistence characteristic of CAP in soil, with half-lives of 210 days under laboratory conditions and 86 days in the field study, fitting to first and biphasic kinetic models of dissipation, respectively. The suspect screening has allowed the additional detection of 6 metabolites in the laboratory and 2 metabolites in the field studies. The 5-bromo-N-methyl-1H-pyrazole-3-carboxamide metabolite has been detected in both laboratory and field studies, but also a previously undescribed metabolite N-methylprop-1-en-2-amine. Finally, a study of the impact of this PPP on the soil microbiota, a clear indicator of the state of an ecosystem or crop, revealed that after three months of exposure to CAP under laboratory conditions, soil microbial activities were affected, but this effect depended on soil.