With the acceleration of the process of agricultural modernization, many pesticides (insecticides, fungicides, and herbicides) are applied to the field and finally brought into the soils, causing serious damage to the environment. The problem of pesticide pollution has become increasingly prominent. This has highlighted the urgent need for effective and efficient remediation treatment technology for pesticide-contaminated soils. Biochar has a high specific surface area, high porosity, and strong adsorption capacity, making it a soil amendment agent and carbon fixation agent that can improve soil health and enhance adsorption capacity for pesticides to remediate contaminated soils. Recently, efforts have been made to enhance the physicochemical and adsorption properties of biochar by preparing modified biochar, and it has been developed to expand the application of biochar. Specifically, the following aspects were reviewed and discussed: (i) source and modification methods of biochar for pesticide remediation; (ii) the effect of biochar on the environmental fate of remediating pesticides; (iii) the effect of biochar on pesticide-contaminated soils; and (iv) potential problems for the large-scale promotion and application of biochar remediation of pesticides. In conclusion, this review may serve as a reference and guide for pesticide remediation, hence reducing the environmental concerns associated with pesticides in soil.

Pesticides usually occur as mixtures of multiple chemicals in the natural aquatic ecosystem, so research based on the toxicity data of a single compound on aquatic organisms is not enough to accurately assess the actual toxicity risk of pesticides. There is still a gap in the research on the reproductive toxicity of combined insecticides, herbicides and fungicides on zebrafish (Danio rerio). In this study, zebrafish were used to systematically investigate the separate and combined reproductive toxicity of imidacloprid (IMI), acetochlor (ACT) and tebuconazole (TBZ), which are commonly used in rice fields. Adult zebrafish were exposed to the three pesticides individually and in combination for 28 days, and the number, heartbeat, deformation rate, body length, and swim bladder development of F1 offspring embryos were observed and the reproductive hormones testosterone (T), estradiol (E2), and vitellogenin (VTG) contents and the expressions of nine reproductive genes (ar, esr2a, vtg1, gr, star, fshr, hmgcrb, 3βhsd and vasa) in the testes of the male and the ovaries of the female F0 zebrafish adults were measured to evaluate the individual and combined effects. The results showed that exposure to the mixtures of IMI, ACT and TBZ resulted in a decrease in heartbeat, body length and swim bladder development and an increase in the deformity rate of F1 offspring embryos compared to the individual exposure groups. In the combined exposure group, the content of T decreased significantly and the content of VTG increased significantly in the testes of the males; the content of T significantly increased, while the content of E2 and VTG significantly decreased in the ovaries of the females, indicating that combined exposure showed a more obvious endocrine-disrupting effect compared to the individual exposures. In addition, the expression of nine reproductive genes was significantly altered compared to the individual exposure groups. Therefore, our results indicated that the mixture of IMI, ACT and TBZ caused fewer number of F1 embryos, higher developmental defects of F1, greater disruption in the content of reproductive hormones and the expression of reproductive genes compared to the individual pesticides at the corresponding doses. Therefore, the presence of pesticides in mixtures in the real water environment is likely to increase the toxic reproductive effects on zebrafish and cause more serious impacts on aquatic ecosystems.

Although dicofol has been widely banned all over the world as a kind of organochlorine contaminant, it still exists in the environment. This study developed a high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS/MS) detection technique for dicofol, an environmental pollutant, for the first time using in-source fragmentation. The results confirmed that m/z 251 was the only precursor ion of dicofol after in-source fragmentation, and m/z 139 and m/z 111 were reasonable product ions. The main factors triggering the in-source fragmentation were the H⁺ content and solution conductivity when dicofol entered the mass spectrometer. Density functional theory can be used to analyze and interpret the mechanism of dicofol fragmentation reaction in ESI source. Dicofol reduced the molecular energy from 8.8 ± 0.05 kcal/mol to 1.0 ± 0.05 kcal/mol, indicating that the internal energy release from high to low was the key driving force of in-source fragmentation. A method based on HPLC-MS/MS was developed to analyze dicofol residues in environmental water. The LOQ was 0.1 μg/L, which was better than the previous GC or GC-MS methods. This study not only proposed an HPLC-MS/MS analysis method for dicofol for the first time but also explained the in-source fragmentation mechanism of compounds in ESI source, which has positive significance for the study of compounds with unconventional mass spectrometry behavior in the field of organic pollutant analysis and metabonomics.

Due to its high persistence in soil, oxyfluorfen has negative effects on environmental and human health. To reduce soil contamination and impacts on non-target organisms, biochar is introduced into soils to immobilize and sequestrate oxyfluorfen as a remediation practice. Three types of soils common in China were selected and biochar (rice hull, BCR) was added to investigate the desorption and bioavailability of oxyfluorfen after aging BCR for 0, 1, 3, and 6 months. Four chemical extraction methods were used to predict oxyfluorfen bioavailability. Results indicated that after addition of 0.5–2% unaged BCR, the desorption values of oxyfluorfen increased from 64–119 to 176–920 (μg/g)/(mg/L)ⁿ in the three soils compared with unamended soil. The bioaccumulation factor (BCF) values of oxyfluorfen in earthworms decreased from 0.80–1.7 to 0.10–1.56 after BCR addition. However, the desorption values decreased from 170–868 to 144–701 (μg/g)/(mg/L)ⁿ after aging. The bioavailability of oxyfluorfen in earthworms also increased after the aging treatments, while the BCF was still lower than with unaged BCR. The reduced BCF indicated lower exposure risk of oxyfluorfen to earthworms after amendment with biochar, even after aging 6 months. The bioavailability after extraction by Tenax showed a high linear correlation with uptake in earthworms, even after the 6-month aging treatment (R² > 0.80). Consequently, BCR could be a practical method to remediate contaminated soil and the 6h Tenax method could be a sensitive and feasible tool to assess the bioavailability of oxyfluorfen in soil.

In view of the defects in the previous detection of cuaminosulfate, which only focused on the analysis of copper ions, there is currently no analysis method available to determine the actual state of cuaminosulfate as chelated or bound. In order to investigate the dissipation and terminal residues in soil and watermelon of cuaminosulfate for food safety and environmental risk, a highly effective technique was developed to detect cuaminosulfate residues in watermelon and soil, and field experiments were conducted in China. After single-factor experiments, residual cuaminosulfate in samples was extracted by pure water, purified using a liquid–liquid approach combined with a dispersive solid-phase extraction, and detected by liquid chromatography tandem mass spectrometry (LC-MS/MS). The Box–Behnken design (BBD) study was used to find the optimal solutions for the time of liquid–liquid purification, the amount of extraction solvent, and the amounts of cleanup sorbents for the analytical method. The average recovery of the method was in the range of 80.0% to 101.1%, the average relative standard deviation (RSD) was 5.3–9.9%, and the detection limit was lower than 0.05 mg/kg. The BBD study not only improved the extraction rate of the method, but also saved time and was operated easily. The final residues of cuaminosulfate in watermelon at different sampling intervals were all lower than 0.05 mg/kg under field conditions. The cuaminosulfate in soils dissipated following exponential kinetics, with half-life values in the range of 9.39 to 12.58 days, which varied by different locations. Based on the validated method, food safety residues and soil residues can be determined rapidly and accurately.