Impact of microorganisms, humidity, and temperature on the enantioselective degradation of imazethapyr in two soils

Abstract

Imazethapyr (IM) is a chiral herbicide composed of an (-)-R-enantiomer and an (+)-S-enantiomer with differential herbicidal activity. In this study, the effects of microbial organisms, humidity, and temperature on the selective degradation of the (-)-R- and (+)-S-enantiomers of IM were determined in silty loam (SL) and clay loam (CL) soil with different pH values. The (-)-R-enantiomer of IM was preferentially degraded in two soils under different microorganism, humidity, and temperature conditions. The average half-lives of R-IM ranged from 43 to 66.1 days and were significantly shorter (P < 0.05) than those of S-IM, which ranged from 51.4 to 79.8 days. The enantiomer fraction (EF = (+)-S-enantiomer/((-)-R-enantiomer + (+)-S-enantiomer)) values were used to describe the enantioselectivity of degradation of IM were >0.5 (P < 0.05) in two unsterilized soils under different humidity and temperature conditions. The highest EF values were observed at unsterilized CL soil samples under 50% maximum water-holding capacity (MWHC) and 25 °C environmental conditions. The EF values of the IM enantiomers were significantly higher (P < 0.05) in CL soils (higher pH = 5.81) and were 0.581 (unsterilized) and 0.575 (50% MWHC; 25 °C) compared with those recorded in SL soil (lower pH = 4.85). In addition, this study revealed that microbial organisms preferentially utilized the more herbicidal active IM enantiomer.

Enantioselective environmental behavior of the chiral fungicide mandipropamid in four types of Chinese soil

“…The half-lives of the R-(−)-enantiomer and S-(+)-enantiomer were 35.9 and 39.8 d in Soil B with moisture contents of 24%, 25.1 and 26.5 d in Soil B with a moisture content of 32%, and 23.1 and 24.9 d in Soil B with a moisture content of 40%, respectively. The results showed that the degradation rates of mandipropamid enantiomers increased with increasing soil moisture content (Figure 3), which was similar to previous studies on the degradation of pesticides, such as allyl isothiocyanate, benzothiostrobin, alachlor, imazethapyr, S-metolachlor, and dufulin, in soil (Liu et al, 2019;Long et al, 2014;Walker et al, 1992;Wu et al, 2017;Yang, et al, 2016;K. K. Zhang et al, 2014).…”

“…For example, Wu et al. (2017) reported that enantioselective degradation of imazethapyr increased with increasing moisture content. K. K. Zhang et al.…”

“…The ES and EF values were calculated as .026−.052 (Table 3) and <0.5 (Supplemental Figure S9), respectively, which demonstrated that the R-(−)-enantiomer degraded more rapidly than its antipode in Soil B with different moisture contents, which was similar to previous studies. For example, Wu et al (2017) reported that enantioselective degradation of imazethapyr increased with increasing moisture content. K. K. Zhang et al (2014) revealed that the enantioselective degradation of dufulin was different with changes in moisture content, and the difference was soil dependent.…”

Chiral Analysis of Pesticides and Drugs of Environmental Concern: Biodegradation and Enantiomeric Fraction

“…Dissipation studies and field-only experiments with no incubation experiments considered were left out [72,149,[156][157][158][159][160][161][162][163][164][165][166][167]. beta-cypermethrin soil laboratory incubation experiments under sterile and non-sterile conditions HPLC-VWD enantioselective degradation of beta-cypermethrin observed; different degradation rates observed for the four beta-cypermethrin isomers; EF variation noticed during the degradation process [143] beta-cypermethrinsoil laboratory incubation experiments under sterile and non-sterile conditions with acidic and alkaline matrices, and with racemic mixture and individual enantiomers HPLC-UV enantioselective degradation of racemic-beta-cypermethrin observed only in non-sterile soils; different degradation rates and half-lives observed for the four beta-cypermethrin isomers; no enantiomeric enrichment observed during degradation of individual enantiomers [144] Regarding the analytical methods used to quantify pesticides' enantiomers during biodegradation, the trend is clear and high-performance liquid chromatography with a diode array detector (HPLC-DAD) [117,122,123,126,128,134,135,140,152] and an ultraviolet detector (UV) [120,129,132,136,138,141,144,146,150,151,155], as well as liquid chromatography tandem-mass spectrometry (LC-MS/MS) [21,...…”

Chiral NMR analysis reveals the environmental dependence of areolal scalemization in Piptothrix areolare

“…9 In this context, the impact of microorganisms, humidity, and temperature has been recently studied for the enantioselective degradation of the chiral herbicide imazethapyr. 10 Distribution and dispersion measurements were evaluated (Figure 3B,C) using the data set constructed with the optical purities of areolal and the environmental variables for the 427-day sampling period (Table 1). These variables belong to factors that directly influence on the physiology of a whole plant.…”