Herbicide thiencarbazone-methyl pedospheric disposition through sorption and degradation mechanisms in heterogenous soils

摘要

Thiencarbazone-methyl, a triazole herbicide was assessed for its environmental fate by carefully imitating and analyzing the natural pedosphere through diverse experiments involving adsorption, desorption, hydrolysis, photo-degradation and degradation in ten distinct soils. Sorption experiments were performed through batch equilibrium method. Soils' physicochemical properties highly influenced the sorption of the herbicide. Results were characteristic of an overall weaker physisorption and an exothermic response reflected by means of negative qualities for Gibbs free energy. Hydrolytic, photolytic and soil degradation experiments were performed for thiencarbazone-methyl for determination of the impact of biotic and abiotic parameters on its degradation. UV-Vis spectrophotometer and GC-MS was utilized for the investigation of thiencarbazone-methyl-treated soils after extraction at regular intervals. The adsorption co-efficient value ranged from 4.3 to 26.4 mu gml(-1). Minimum half-life in hydrolysis, photo-degradation and soil degradation experiments was 18, 18.7 and 16 days, respectively; while, the highest was 22, 22.6 and 23.9 days, respectively. Results depict moderate binding and low persistence of thiencarbazone-methyl to the selected soils whilst being highly susceptible to transformative pathways.