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Agricultural mulch film pollution has become a prevailing concern. Studies have shown that the thickness of mulch film is a key factor affecting mulch film recycling, but research about farmers' choice on mulch film thickness is lacking. Based on survey data from 2025 households in five Chinese provinces in 2018, the Heckman two-stage model was used to analyze the influencing factors of farmers' choice on mulch film thicknesses. Mulch film had been used by 21.98% of the sample households, and 41.47% of the used mulch film did not meet the national thickness standard. The econometric results showed that farmers' product cognition and market factors were the two most important factors, and there was a significant negative correlation with the choice of film thickness. In addition, the choice of mulch film with different thicknesses was affected by household characteristics, subjective norms, and farmland property rights. Strengthening and stabilizing farmland property rights is a long-term mechanism to promote farmers to choose thicker mulch film. In addition to strengthening the production and sale of substandard film supervision, farmers' choice of film thickness should be included in village regulations and other rural grass-roots governance systems, especially in the mechanism design between agricultural farmland protective subsidies and the prevention of mulch film pollution, rather than just considering the recycling itself.

Soil fumigation using 1,3-dichloropropene (1,3-D) and chloropicrin (CP) is an important strategy for agriculture production; however, excessive emissions can cause air pollution and possible human exposure. In this study, solar light-driven CuInS2/ZnS:Al-TiO2 photocatalytic film was prepared through spin-coating on the flexible polyethylene terephthalate (PET) substrate of 0.1 mm. Using the photocatalytic film, degradation of 1,3-D was inhibited in the Pci-clor 60 formulation of 1,3-D and CP. However, the degradation of CP was accelerated in this formulation, and the half-life was shortened from 0.66 to 0.40 h. Emissions of 1,3-D from soil to the air were reduced by 97.30%, 97.17%, 47.10%, and 7.88%, for treatments of D + Film, D + C + Film, D + PET, and D, respectively. The efficiencies for reducing 1,3-D emission were significantly improved by about 1.1 and 11.3 times using the film, compared with using the PET alone and no film, respectively. Furthermore, fumigation effects on nematodes could still achieve higher than 90%. The findings provided a basis for the practical application of quantum dot films to reduce soil fumigants emissions by photocatalytic degradation.

Er2O3 nanorods were prepared by a hydrothermal method, and Sr-modified Er2O3 nanorods (Sr-Er2O3) were synthesized using an impregnation method. Their catalytic performance for oxidative coupling of methane was investigated. The catalysts were characterized by several techniques such as XRD, N2 adsorption, TEM, XPS, O2-TPD and CO2-TPD. Compared with Er2O3 and Sr-Er2O3 nanoparticles, Er2O3 and Sr-Er2O3 nanorods exhibit higher CH4 conversion and C2–C3 selectivity. This is caused by higher (O− + O2−)/O2− ratio, a higher number of chemisorbed oxygen species and moderate basic sites achieved on the nanorods catalysts. The Sr-Er2O3 nanorods afford a 23.2% conversion of CH4 with 50.3% selectivity to C2–C3 at 650 °C.

The development of biogas programs in rural China has led to great economic, social, ecological and environmental benefits. The focus of this study was the identification of the benefit relationship for various stakeholders via the evaluation of relevant policies, an analysis of the costs and benefits and an estimation of the environmental benefits of the livestock manure utilization in a biogas power generation company (BPGC) in Zhejiang province. The results demonstrated that the net present value (NPV) of the project was 8.85 million dollar, and the internal rate of return (IRR) was 36%. Compared to current projects, the BPGC had a higher investment potentiality. The annual environmental benefits of chemical oxygen demand and NH3–N reduction are 2.61 million dollar and 0.21 million dollar, respectively. The environmental benefits of the reduction of greenhouse gas emission is 1.54 million dollar/a. When the environmental benefits were considered in the cost–benefit analysis, the NPV of the project was 42.01 million dollar, and the IRR was 123.98%, and the BPGC exhibited significant social benefits. The government took advantage of a public–private partnership model to reach a common balance of benefits among government, enterprise, hog farms and the residents.

Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography-mass spectrometry. Among 12 solvents, acetone-cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box-Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g(-1) (acenaphthene) to 23.55 ng g(-1) (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g(-1) to 78.49 ng g(-1). The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8-109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer.

Biochar amendment has been extensively investigated as a method to remediate polluted soil. However, both increased and decreased pollutant biodegradation has been observed after biochar amendment is applied to soil. This study aims to demonstrate the effect of biochar amendment on 16 polycyclic aromatic hydrocarbon (PAH) dissipation and indigenous degradation bacteria in PAH-contaminated soil. Four biochars derived from dairy manure and rice hull (RH) produced at pyrolysis temperatures of 350 and 500 °C were used to investigate the effect of biochar amendment on PAH dissipation in sterile and non-sterile soil. Different biochars with a rate of 4.0 % dry weight were mixed with the soil and incubated for 90 days. Sixteen PAHs in the USEPA priority-controlled list were determined by gas chromatography–mass spectrometry. Terminal restriction fragment length polymorphism and quantitative polymerase chain reaction were employed to quantify the change in the number of gene copies of the bacterial community 16S rDNA, PAH-RHDα, and nitrogen cycle genes (nirS). The average removal efficiencies of all two-ring to four-ring PAHs in non-sterilized soil with biochar increased by 35 to 37 % compared with those in sterilized soil. Molecular biology analysis results demonstrated that biochar amendment can enhance the number of 16S rDNA, PAH-RHDα, and nirS gene copies in PAH-contaminated soil. Rice hull-derived biochar pyrolyzed at 350 °C most effectively stimulated dissipation of PAHs in contaminated soil. The removal efficiencies of two-ring to four-ring PAHs were higher than those of five- and six-ring PAHs in actual contaminated soil amended with biochar. Biochar amendment can stimulate PAH-metabolizing bacterial activity by enhancing the number of gene copies related to PAH degradation and by changing the structure of soil microbial community. Further studies should be conducted to evaluate the effect of biochar on PAH biodegradation in different soils at different rates of biochar application.