Hydrolysis of propyrisulfuron in water: Kinetics, influence of 34 environmental factors, transformation products identification, mechanisms and toxicities.

Propyrisulfuron is a novel sulfonylurea herbicide used for controlling annual grass and broad-leaved weeds in fields, but its fates and behaviors in environment are still unknown, which are of utmost importance for environmental protection. To reduce its potential environmental risks in agricultural production, the hydrolysis kinetics, influence of 34 environmental factors including 12 microplastics (MPs), disposable face masks (DFMs) and its different parts, 6 fertilizers, 5 ions, 3 surfactants, a co-existed herbicide of florpyrauxifen-benzy, humic acid and biochar, and the effect of MPs and DFMs on its hydrolysis mechanisms were systematically investigated. The main hydrolysis products (HPs), possible mechanisms, toxicities and potential risks to aquatic organisms were studied. Propyrisulfuron hydrolysis was an acid catalytic pyrolysis, endothermic and spontaneous process driven by the reduction of activation enthalpy, and followed the first-order kinetics. All environmental factors can accelerate propyrisulfuron hydrolysis to varying degrees except humic acid, and different hydrolysis mechanisms occurred in the presence of MPs and DFMs. In addition, 10 possible HPs and 7 possible mechanisms were identified and proposed. ECOSAR prediction and ecotoxicity testing showed that acute toxicity of propyrisulfuron and its HPs for aquatic organisms were low, but may have high chronic toxicity and pose a potential threat to aquatic ecosystems. The investigations are significantly important for elucidating the environmental fates and behaviors of propyrisulfuron, assessing the risks in environmental protection, and further providing guidance for scientific application in agro-ecosystem.

Assessment of the Hydrolysis of Pydiflumetofen and Its Degradation Characteristics in Agricultural Soils.

Pydiflumetofen is a potent fungicide that effectively inhibits pathogenic fungal growth by regulating succinate dehydrogenase activity. It effectively prevents and treats various fungal diseases, including leaf spot, powdery mildew, grey mold, bakanae, scab, and sheath blight. Pydiflumetofen's hydrolytic and degradation properties were investigated indoors in four distinct soil types (phaeozems, lixisols, ferrosols, and plinthosols) to assess its risks in aquatic and soil environments. The effect of soil physicochemical properties and external environmental conditions on its degradation was also explored. Hydrolysis experiments found that pydiflumetofen's hydrolysis rate decreased with increasing concentration, regardless of the initial concentration. Furthermore, an increasing temperature significantly enhances the hydrolysis rate, with neutral conditions having higher degradation rates than acidic and alkaline conditions. Pydiflumetofen showed a degradation half-life of 10.79-24.82 days and a degradation rate of 0.0276-0.0642 in different soils. Phaeozems soils had the fastest degradation, while ferrosols soils had the slowest. Sterilization significantly reduced its soil degradation rate and extended its half-life, which confirmed that microorganisms were the primary cause. Therefore, when using pydiflumetofen in agricultural production activities, the characteristics of water bodies, soil, and environmental factors must be considered, while minimizing the emissions and environmental impact.

Adsorption-desorption and transport behavior of pydiflumetofen in eight different types of soil.

Pydiflumetofen, a fungicide of the class of succinate dehydrogenase inhibitors, can disrupt energy metabolism by inhibiting the synthesis of succinate dehydrogenase, thus effectively inhibiting pathogenic fungal growth and related yield losses.We studied the adsorption and desorption behaviors and interaction mechanisms of pydiflumetofen in eight different arable soils by the infrared spectroscopy and batch equilibrium method. Pydiflumetofen adsorption and desorption property of soils conformed with the Freundlich isotherm model and the values for the adsorption capacity KF-ads were in the range of 14.592-102.610. The adsorption constants (KF-ads) exhibited a significantly positive and linear correlation (p < 0.1) with soil organic matter and organic carbon content. Both high and low temperatures weakened the pydiflumetofen sorption capacity of the soil. In addition, the initial pH of the solution, its ionic strength, and the addition of exogenous biochar, humic acid, and different types of surfactants at different concentrations also affected the sorption property of the soil. Pydiflumetofen is weakly mobile and leachable in most soils, and, poses some threat to surface soil and water organisms, but does not contaminate groundwater.

Adsorption-Desorption and Migration Behaviors of Oxaziclomefone in Different Agricultural Soils in China.

Oxaziclomefone is an organic heterocyclic herbicide which has been widely used in rice fields. The aim of this paper is to investigate the adsorption-desorption and migration of oxaziclomefone in four Chinese agricultural soils. All the four soils show high adsorption capacity for oxaziclomefone, with similar adsorption rates at 84.48%-96.70%. Four adsorption kinetic models were used to fit the adsorption kinetic characteristics and the elovich model was the best, indicating that chemical processes were involved in adsorption. For the isothermal adsorption behavior of oxaziclomefone, the Freundlich model shows the best, indicating that the adsorption sites for oxaziclomefone in soil were heterogeneous. The retention factor in the soil thin-layer plates ranges from 0.083 to 0.250 and the retention factor 0-10 cm layer of the soil column was > 50, indicating that the herbicide was not easily migration from all four soils. Because oxaziclomefone has low mobility in different soils and is not easily leached, it poses a low potential threat of contaminating surface water and groundwater.