Dissipation and sorption-desorption of benzisothiazolinone in agricultural soils and identification of its metabolites

Abstract

Benzisothiazolinone has been widely used to control bacterial and fungal diseases in various agricultural crops by destroying the nuclear structure and interfering with the metabolism of microbial cells. In this study, the dissipation, transformation and sorption-desorption of benzisothiazolinone (BIT) in five soils were investigated to evaluate its environmental fate. Results showed that the degradation ofBITin all the tested soils fitted the first order kinetics and increased with soil organic matter (OM) content. Degradation differences between unsterilized natural and sterilized soils (t1/2= 0.09-26.66 and 6.80-86.64 d) suggested thatBITdegradation is primarily driven by biological processes and assisted by abiotic degradation. Additionally,BITdissipated fastest in flooded soils (t1/2= 0.20-4.53 d), indicating that anaerobic microorganisms are more likely to degradeBITcompared to aerobic microbes. Also, during the soil degradation process, two metabolites were monitored and identified for the first time.BITsorption was a spontaneous physical process with no desorption hysteresis effect, which fit the Freundlich model.BITcauses relatively strong sorption (log KOC= 3.76-4.19) and low persistence in soils, thus exhibiting a low potential risk for groundwater contamination.