Degradation of cyflumetofen and formation of its main metabolites in soils and water/sediment systems.

Abstract

Cyflumetofen is a novel benzoyl acetonitrile acaricide without cross-resistance to existing acaricides. In the present study, for the first time, the environmental behaviors of cyflumetofen and the formation of its main metabolites, 2-(trifluoromethyl) benzoic acid (B-1) and 2-(trifluoromethyl) benzamide (B-3), in the four types of soil (black soil, sierozem, krasnozem, and fluvo-aquic soil) and three types of water/sediment systems (Northeast Lake, Hunan paddy field, and Beijng Shangzhuang reservoir) under aerobic and anaerobic conditions were investigated. The degradation dynamics of cyflumetofen followed first-order kinetics. Under aerobic environment, the half-lives of cyflumetofen in black soil, sierozem, krasnozem and fluvo-aquic soil were 11.2, 10.3, 12.4, and 11.4days. Under water anaerobic conditions, the half-lives were 13.1, 10.8, 13.9, and 12.8days. The effects of different conditions and soil types on the half-lives of cyflumetofen were studied using a one-way ANOVA test with post hoc comparison (Tukey's test). It was shown that the differences in black soil, krasnozem, and fluvo-aquic soil were extremely significant difference (p<0.05) under aerobic and water anaerobic conditions. And there is a strong correlation between half-life and pH. Under aerobic environment, the half-lives of cyflumetofen in Northeast Lake, Hunan paddy field, and Beijng Shangzhuang reservoir were 15.4, 16.9, and 15.1days. Under anaerobic conditions, they were 16.5, 17.3, and 16.1days. Analyzing the differences of the half-lives under aerobic and anaerobic conditions, the difference only in Shangzhuang reservoir was extremely significant difference (p<0.05). In soils, cyflumetofen degraded metabolites B-1 and B-3, from the first day 0.24% B-1 was generated, while, only very low levels of B-3 generated at the same time. As time increased, B-3 gradually increased, cyflumetofen reduced gradually. Until 100days, there were about 3.5% B-1 and B-3 in the soils. In the water/sediment systems, from the first day, it degraded into B-1 in the sediment, and in the water mainly degraded into B-3.