Fate characteristics of the chiral pesticide dufulin in flooded anaerobic soils and its interaction with soil microorganisms

Study on the Enantioselective Separation, Dissipation, and Residue of Chiral Fenpropathrin in Vegetables by Supercritical Fluid Chromatography-Tandem Mass Spectrometry (SFC-MS/MS)

Chiral fenpropathrin is a widely used pyrethroid insecticide. A fast supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) method was developed for the enantioselective study of fenpropathrin in five kinds of vegetables. The enantioseparation could be completed in 2 min, and the recoveries were 75.5-107.7% with RSDs of ≤15.2%. The dissipation half-lives of R-fenpropathrin and S-fenpropathrin were 2.32-3.62 days and 1.89-3.56 days, respectively. The dissipation of fenpropathrin was the fastest in cucumbers and the slowest in celery cabbage. R-Fenpropathrin was preferentially dissipated in celery and cucumber, which was opposite in lettuce and pakchoi. The final residues of rac-fenpropathrin in celery cabbage, pakchoi, and lettuce were a little above the European Union's maximum residue limits (MRLs) but less than the China's MRLs. The acute and chronic dietary intake risks of rac-fenpropathrin for all age groups were acceptable. The results would provide a basis for the rational application and risk assessment of fenpropathrin.

Effects of charged polystyrene microplastics on the bioavailability of dufulin in tomato plant

Microplastics (MPs) and pesticides commonly exist in the environment, yet the interactions between them and their subsequent impacts on plants remain poorly understood. Thus, this study aimed to investigate the impacts of differently charged polystyrene (PS) MPs, including PS-COO-, PS and PS-NH3+ MPs, on the fate of 14C-labelled new antiviral pesticide Dufulin (DFL) in a hydroponic tomato system. The results showed that MPs greatly reduced the growth of tomato plants, with suppression of 18.4-30.2%. Compared to the control group, PS-COO-, PS and PS-NH3+ MPs also reduced the bioaccumulation of DFL in whole tomato plants by 40.3%, 34.5%, and 26.1%, respectively. Furthermore, MPs influenced the translocation of DFL in plant tissues, and the values decreased at the rates of 38.7%, 26.5% and 15.7% for PS-COO-, PS and PS-NH3+, respectively. Interestingly, compared to the control group, PS-COO- exhibited a profound inhibitory effect on DFL concentrations in tomatoes, potentially resulting in a lower dietary risk in the hydroponic tomato system. This may be due to the strong adsorption between PS-COO- and DFL, and PS-COO- may also inhibit the growth of tomato plants. Overall, our study could provide valuable insights into the risk assessment of DFL in the presence of MPs in plant systems.

Long-term toxic effects of iron-based metal-organic framework nanopesticides on earthworm-soil microorganism interactions in the soil environment

With the widespread use of controlled-release nanopesticides in field conditions, the interactions between these nanopesticides and biological systems are complex and highly uncertain. The toxicity of iron-based metal organic frameworks (CF@MIL-101-SL) loaded with chlorfenapyr (CF) to terrestrial invertebrate earthworms in filter paper and soil environments and the potential mechanisms of interactions in the nanopesticide-earthworm-cornfield soil microorganism system were investigated for the first time. The results showed that CF@MIL-101-SL was more poisonous to earthworms in the contact filter paper test than suspension concentrate of CF (CF-SC), and conversely, CF@MIL-101-SL was less poisonous to earthworms in the soil test. In the soil environment, the CF@MIL-101-SL treatment reduced oxidative stress and the inhibition of detoxifying enzymes, and reduced tissue and cellular substructural damage in earthworms compared to the CF-SC treatment. Long-term treatment with CF@MIL-101-SL altered the composition and abundance of microbial communities with degradative functions in the earthworm intestine and soil and affected the soil nitrogen cycle by modulating the composition and abundance of nitrifying and denitrifying bacterial communities in the earthworm intestine and soil, confirming that soil microorganisms play an important role in reducing the toxicity of CF@MIL-101-SL to earthworms. In conclusion, this study provides new insights into the ecological risks of nanopesticides to soil organisms.

Stereoselective, Diastereoselective Dissipation and Risk Assessment of Chiral Metconazole in Soybean, Peanut, Cabbage, Celery, Tomato, and Soil

The stereoselective behaviors and dietary risks of metconazole (MZE) in soil and five vegetables were investigated. The results showed that there was species-specific stereoselective and diastereoselective dissipation, and the half-lives ranged from 0.69 to 8.17 days. cis-(+)-1S,5R-MZE was preferentially dissipated in soybean pods, cabbages, celeries, and tomatoes, which was contrary to soybean plants and soil. trans-(+)-1R,5R-MZE was preferentially dissipated in peanut plants, peanut shells, celeries, and tomatoes, while trans-(-)-1S,5S-MZE was preferentially dissipated in soybean plants. cis-MZE was preferentially dissipated in the test vegetables and soil, except celery. The stereoisomeric excess changes were higher than 10%, indicating that the stereoselectivity and diastereoselectivity should be considered in the risk assessment of MZE in soybean plants, pods, and peanut plants. The acute and chronic dietary intake risks of rac-MZE for different groups of people were acceptable. The preferentially dissipated and high activity cis-(+)-1S,5R-MZE with lower toxicity might be suitable for application as monocase.