Behavior And Fate Of ～(14)C-labelled ZJ273 In Soils

ZJ273, Propyl 4-(2-(4, 6-dimethoxypyrimidin-2-yloxy)benzylamino) benzoate is a novel herbicide with the property of high activity, broad spectrum and low toxicity to animals. Its temporary register and production certificate were awarded by Department of Agriculture and National Development and Reform Commission of China, respectively. In order to achieve cosmically commercial application, the mechanism, mode of action, environmental behavior and fate of ZJ273 needed to be studied further.In this study, degradation of ZJ273 parent compound in water and soils, extractable residue (¹⁴C-ER), bound residue (¹⁴C-BR), mineralization, absorption, desorption, migration and leaching of ¹⁴C-labelled ZJ273 in soils were investigated under laboratory condition. The purpose of this study is to evaluate the environmental behavior and fate of ZJ273 in agroecosystem.The results were as follows:The decrease rate of ZJ273 in water with different pH followed the first order rate reaction, the half-life in water were 18.2⁴7.5 d and positively to water pH.After 60 days of incubation, the content of ¹⁴C-ER from ¹⁴C-labelled ZJ273 in five kinds of soil ranged from 6.2%⁵2.1% of applied amount, with the maximum level in alkaline soil (Paddy field on desalting muddy polder) while the minimal in acidic soil (Paddy soil on red sandstone soil). Total ¹⁴C-ER content in soils was positively related to soil pH. The half-life values of ZJ273 parent compound in the spiked soils ranged from 12.3 to 28.6d and positively to soil pH. Furthermore, during the whole course of incubation, ¹⁴C-ER content and half-life values of the parent compound in sterilized soils were higher thanthat in control. Bound 14C-labelled ZJ273 residue in five kinds of soil accounted for 45.7%⁷7.6% of applied amount. The pattern of the content of 14C-BR followed the law as acidic soil>neutral soil>alkaline soil. 14C-BR in soils was significantly negative to soil pH. Among the basic properties of soil, pH was found to be the dominant factor affecting BR formation of 14C-labelled ZJ273. 14C-BR content in sterilized soils was lower than that in control. After 60 days of incubation, the rate of 14C-labelled ZJ273 mineralized to 14C-CO2 through opening U-14C-benzoate ring in non-sterilized ranging from 0.2 19.9% of applied amount and that in sterilized soils was 0.2⁰.8%. It was found that microorganism play an important role in course of 14C-labelled ZJ273 mineralized to 14C-CO2 in soils.Adsorptions of 14C-labelled ZJ273 in soils followed Freundlich equation. The adsorption constant Kfwas about 285.6^614.1 and positively related to soil organic matter(OM). 14C-labelled ZJ273 could hardly be desorbed by water. The relation between the adsorption and desorption was negative. The Rf values in the tested soil by means of soil TLC were in range of 0.15 to 0.36 and were negatively related to soil organic matter. The herbicide was middle mobile in acidic soil, but was hardly mobile in the other kinds of soils. The content of 14C-labelled ZJ273 in 2cm-surface of soil-column was positively related to soil organic matter.