Adsorption-desorption behavior of benzobicyclon hydrolysate in different agricultural soils in China

Optimization and Application of the QuEChERS-UHPLC-QTOF-MS Method for the Determination of Broflanilide Residues in Agricultural Soils

In this study, the separation conditions of UHPLC-QTOF-MS and the extraction conditions of QuEChERS were optimized. The analytical process for determining Broflanilide residues in different soil types was successfully established and applied to its adsorption, desorption, and leaching in soil. Broflanilide was extracted from soil with acetonitrile and purified using PSA and MgSO4. The modified UHPLC-QTOF-MS method was used for quantification. The average recovery of Broflanilide was between 87.7% and 94.38%, with the RSD lower than 7.6%. In the analysis of adsorption, desorption, and leaching quantities in four soil types, the RSD was less than 9.2%, showing good stability of the method, which can be applied to determine the residue of Broflanilide in different soils.

Sorption and desorption of naphthenic acids on reclamation materials: Mechanisms and selectivity of naphthenic acids from oil sands process water

This study investigated the application of materials peat-mineral mix (PT) and Pleistocene fluvial sands from different location (PF-1 and PF-2) obtained from surface mining of oil sands as sorbents of naphthenic acids (NAs) from oil sands process water (OSPW). To understand the sorption properties and mechanisms of NAs in the materials, sorption and desorption studies were performed using decanoic acid (DA) and 5-phenylvaleric acid (PVA). Additionally, the removal efficiency was evaluated using real OSPW to understand the effect of NA structure on sorption. Equilibrium of DA and PVA was reached at 2 days for PT, and 3 and 6 days for PF materials, respectively. Langmuir isotherm best fitted the equilibrium data. Maximum sorption capacities for DA and PVA were, respectively, 16.8 × 10³ and 10⁴ mg/kg for PT, 142.9 and 81.3 mg/kg for PF-1, and 600 and 476.2 mg/kg for PF-2. Hydrophobic interactions, hydrogen bonding, and π-π interaction were the main sorption mechanisms. Desorption of model compounds from post-sorption materials was not observed for 14 days. The removal of NAs from real OSPW ranged from 20 to 54%. PT is the most promising sorbent of NAs from OSPW because it partially removed NAs with a wide range of molecular weights and structures at very low dosage. Sorption of NAs was affected by the total organic carbon of the materials, emphasizing the hydrophobic interaction as an important sorption mechanism. The results suggest that some mobility of NAs is expected to take place if the reclamation materials come in contact with OSPW, which might occur in an oil sands reclamation landscape.

Adsorption, mobility, and degradation of the pesticide propaquizafop in five agricultural soils in China

Propaquizafop is a fatty acid synthetic herbicide used to control annual and perennial grasses. To understand the potential environmental risks of propaquizafop to crops and food safety, the adsorption, mobility, and degradation of propaquizafop in five different soils were studied. At an initial concentration of 5 mg L^-1 propaquizafop, its adsorption equilibrium was reached within 24 h, and the adsorption rates were between 46.98 and 57.76%. The Elovich kinetic model provided the best fit for the kinetic model, with R² values between 0.9882 and 0.9940. For the isothermal adsorption tests, the Freundlich model was used to better fit the adsorption characteristics of propaquizafop in different soils, with R² values between 0.9748 and 0.9885. Increasing the concentration of Ca²⁺ was beneficial for propaquizafop adsorption. In the soil thin-layer chromatography tests, the R_f of propaquizafop in the five soil samples ranged from 0.076 to 0.123. The results of the soil column leaching tests showed that propaquizafop did not migrate in the five soil columns; it was not detected in the leachate of each soil column, and propaquizafop in the soil columns only existed in the 0-5 cm soil layer. The results of soil thin-layer chromatography and soil column leaching tests showed that propaquizafop is a pesticide with a weak migration ability. Under the same environmental conditions, the degradation rate of propaquizafop in different soils followed the order LF fluvo-aquic soil (T_1/2 = 1.41 d) > CS red loam (T_1/2 = 2.76 d) > SX paddy soil (T_1/2 = 3.52 d) > CC black soil (T_1/2 = 5.74 d) > BS ginseng soil (T_1/2 = 7.75 d). Considering the effects of soil moisture, incubation temperature, and microorganisms on propaquizafop degradation in the soil, temperature was found to have the greatest influence on its degradation rate.

Research status and development of microbial induced calcium carbonate mineralization technology

In nature, biomineralization is a common phenomenon, which can be further divided into authigenic and artificially induced mineralization. In recent years, artificially induced mineralization technology has been gradually extended to major engineering fields. Therefore, by elaborating the reaction mechanism and bacteria of mineralization process, and summarized various molecular dynamics equations involved in the mineralization process, including microbial and nutrient transport equations, microbial adsorption equations, growth equations, urea hydrolysis equations, and precipitation equations. Because of the environmental adaptation stage of microorganisms in sandy soil, their reaction rate in sandy soil environment is slower than that in solution environment, the influencing factors are more different, in general, including substrate concentration, temperature, pH, particle size and grouting method. Based on the characteristics of microbial mineralization such as strong cementation ability, fast, efficient, and easy to control, there are good prospects for application in sandy soil curing, building improvement, heavy metal fixation, oil reservoir dissection, and CO₂ capture. Finally, it is discussed and summarized the problems and future development directions on the road of commercialization of microbial induced calcium carbonate precipitation technology from laboratory to field application.

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.

Dissipation, adsorption-desorption, and potential transformation products of pinoxaden in soil

This study established and validated a simple and sensitive analytical approach for determining pinoxaden residues in soil. The dissipation and adsorption-desorption of pinoxaden in four kinds of Chinese soil were comprehensively investigated for the first time, and the possible metabolic products and pathways were identified. The developed method was successfully applied in dissipation and adsorption-desorption trials. Several influential factors, including temperature, organic matter, and moisture content, affected the dissipation rate of pinoxaden in soil. During the dissipation process, 1 hydrolytic intermediate and 13 possible transformation products were identified, and predicted metabolic pathways were composed of electron rearrangement, oxidation, cyclization, carboxylation, and so on. Both the adsorption and desorption isotherms of pinoxaden in four kinds of Chinese soil followed the Freundlich equation, and the Freundlich K_f values were positively correlated with the soil cation exchange capacity. According to the calculated Gibbs free energies, the adsorption of pinoxaden was an endothermic reaction and mainly a physical process. These results could provide some useful data for the determination of pinoxaden in other matrices and the evaluation of the environmental fate of pinoxaden in soil and other ecosystems.