Stereoselective bioaccumulation and dissipation of four stereoisomers of cyproconazole in earthworm-soil microcosm

Abstract

Cyproconazole is a representative and widely used triazole fungicide with four stereoisomers, which will bring some risks to non-target organisms. A fast analytical method on supercritical fluid chromatography-tandem mass spectrometry was established in 4 min, and the environmental hazards of chiral cyproconazole were studied in earthworm-soil microcosm, including stereoselective bioaccumulation and dissipation. In the process of bioaccumulation, the concentrations of cyproconazole stereoisomers in earthworms showed a trend of increasing first and then reaching a stable state at 6 mg/kg treatment, which was different from those at 0.6 mg/kg treatment (decease-increase-equilibrium). The concentration order was (2S,3R)- > (2S,3S)- > (2R,3R)- > (2R,3S)-cyproconazole and (2S,3S)- ≈ (2S,3R)- > (2R,3R)- > (2R,3S)-cyproconazole at 6 and 0.6 mg/kg treatments, respectively. The bioaccumulation factor (BAF) values were in the range of 0.018–0.55, showing weakly relative accumulation capacity. The dissipation of cyproconazole stereoisomers in artificial soil accorded with the first-order kinetics equation, and the half-lives were 20.1–23.6 and 7.66–8.28 days at 6 and 0.6 mg/kg treatments, respectively, without stereoselectivity and diastereoselectivity. In earthworms, the dissipation half-lives were 5.81–6.01 days with the preferential dissipation of (2R,3R)-cyproconazole. The study would help with the rational uses and risk assessments of cyproconazole.