Pymetrozine is a selective insecticide with a unique chemical structure and mode to control hemipteran and homopteran. While pymetrozine has brought great benefits to crop production by killing insects, its residues i...Pymetrozine is a selective insecticide with a unique chemical structure and mode to control hemipteran and homopteran. While pymetrozine has brought great benefits to crop production by killing insects, its residues in soil may have a detrimental effect on environment. Therefore, it is of great importance to investigate its behaviors in soil. In this study, the sorption and desorption of pymetrozine on six Chinese soils were investigated using a batch equilibrium approach to understand its mobile behavior in the soils. Both sorption and desorption isotherms ofpymetrozine were in good agreement with the Freundlich model. The sorption coefficient KF varied between 3.37 and 58.32 mL. g-1 and the sorption isotherms were nonlinear, with 1/n ranging from 0.57 to 0.91. A regression equation was proposed to predict the solption of pymetrozine on six different soil samples： log KF = 4.3708 - 4.5709 × log （pH in 0.01mol·L-1 CaC12） ＋ 0.4700 × log OC% ＋ 0.0057 × sand （%） ＋ 0.0022 × CEC（clay）, with R2 = 0.9982. The organic carbon content of soil positively affected the sorption ofpymetrozine, but soil pH had a negative effect on the sorption. Additionally, effects of CaC12 concentration, soil to solution ratio and pesticide form were investigated. The sorption was promoted with an increase in soil to solution ratio and a decrease in CaC12 concentration. The possible variation of the five formulated products of pymetrozine was also investigated.展开更多
文摘Pymetrozine is a selective insecticide with a unique chemical structure and mode to control hemipteran and homopteran. While pymetrozine has brought great benefits to crop production by killing insects, its residues in soil may have a detrimental effect on environment. Therefore, it is of great importance to investigate its behaviors in soil. In this study, the sorption and desorption of pymetrozine on six Chinese soils were investigated using a batch equilibrium approach to understand its mobile behavior in the soils. Both sorption and desorption isotherms ofpymetrozine were in good agreement with the Freundlich model. The sorption coefficient KF varied between 3.37 and 58.32 mL. g-1 and the sorption isotherms were nonlinear, with 1/n ranging from 0.57 to 0.91. A regression equation was proposed to predict the solption of pymetrozine on six different soil samples： log KF = 4.3708 - 4.5709 × log （pH in 0.01mol·L-1 CaC12） ＋ 0.4700 × log OC% ＋ 0.0057 × sand （%） ＋ 0.0022 × CEC（clay）, with R2 = 0.9982. The organic carbon content of soil positively affected the sorption ofpymetrozine, but soil pH had a negative effect on the sorption. Additionally, effects of CaC12 concentration, soil to solution ratio and pesticide form were investigated. The sorption was promoted with an increase in soil to solution ratio and a decrease in CaC12 concentration. The possible variation of the five formulated products of pymetrozine was also investigated.
