The widespread use of antibiotics has led to the emergence of a large number of drug-resistant bacteria, accelerating the dissemination and spread of antibiotic resistance genes (ARGs) in the environment. Bacterial biofilms, serving as reservoirs of ARGs, pose potential risks to environmental health that should not be ignored. Studies on the presence and transfer of ARGs in biofilms have been conducted both domestically and internationally. This article summarises the research progress on ARGs in various environments and analyses the mechanisms and factors influencing the dissemination and transfer of ARGs in microplastics, activated sludge, and pipe wall biofilms, with a particular focus on phage-mediated ARG transfer. We also discuss current research gaps in this field to provide references for future biofilm management and health risk control of ARGs.

Biochar application is considered an effective method for reducing nitrous oxide (N₂O) emissions from soil. However, the mechanisms underlying the influence of various biochar dosages on soil N₂O emissions and the duration of one-time biochar application remain unclear. The effects of different biochar application rates and a one-time application on soil N₂O emissions in the Huanghuaihai Plain of China were investigated through a field experiment from 2020 to 2022. In the wheat and maize rotation system, six treatments were administered: no biochar (C0); 2 (C1), 4 (C2), 8 (C3), and 12 t/hm² biochar (C4) applied annually; and a one-time application of 12 t/hm² biochar (CS) in 2018. Our results indicate that, compared with C0, biochar significantly inhibited soil N₂O emissions, particularly in the C3 and C4 treatments, with reductions of 31.36–56.21% and 36.92–52.45%, respectively. However, CS did not significantly affect soil N₂O emissions during the study period. These findings suggest that the biochar’s inhibitory effect on soil N₂O emissions is contingent upon the dosage and frequency of application. A structural equation model revealed that biochar decreases soil N₂O emissions by enhancing the reduction in N₂O during denitrification. Under the conditions of this experiment, based on a logistic ecological model, a one-time application of 12 t/hm² biochar was projected to significantly reduce soil N₂O emissions for approximately 1.77 years. On the whole, biochar reduces soil N₂O emissions mainly by regulating N₂O production through denitrification, and the duration of this inhibition of N₂O emissions mainly depends on the application amount and frequency of biochar application.

Saline-alkali soil has poor fertility and low organic matter content, which are key factors that limit agricultural productivity. Intercropping systems can enhance biodiversity in farmlands, thereby increasing the organic matter content. During this process, soil microorganisms respond to environmental changes. Therefore, we conducted a three-year intercropping enhancement experiment using saline-alkali soil. To avoid nutrient and microbial differences caused by the varying nutrient demands of different crop types, we systematically sampled the tillage layer of the soil (0–20 cm) from the subsequent crop (wheat season) in the intercropping systems. We found that compared to the control group, the three intercropping systems significantly increased the nutrient content in saline-alkali soil, including total nitrogen, total phosphorus, total potassium, organic matter, available nitrogen, and available potassium. Notably, there were significant increases in total nitrogen, organic matter, and available potassium. The intercropping systems had varying effects on the alpha and beta diversities of soil bacteria and fungi. Specifically, the effect of intercropping on fungal alpha diversity was significantly greater than that on bacterial alpha diversity, whereas its effect on bacterial beta diversity was greater than that on fungal beta diversity. Additionally, intercropping influenced microbial community composition, increasing the abundance of Acidobacteria and Gemmatimonadetes and decreasing the abundance of Actinobacteria. It also increased the abundance of Ascomycota and Mortierella and decreased the abundance of Basidiomycota. Total nitrogen and soil organic matter were identified as the primary environmental factors that significantly affected bacterial community composition; however, they had no significant impact on fungal communities. Intercropping had different effects on the fungal and bacterial networks. It increased the stability and complexity of the bacterial network. However, although it improved the stability of the fungal network, intercropping reduced its complexity. In summary, intercropping with leguminous plants is an effective way to enhance soil nutrients, particularly organic matter, in saline-alkali soils. Simultaneously, intercropping affects the soil microbial community structure of subsequent crops; however, the responses of bacteria and fungi to intercropping are significantly different. The results of this study provide data support for improving saline-alkali land through planting systems.

Horizontal subsurface flow constructed wetlands (HFCWs) are capable of eliminating organic matter and nitrogen while emitting less methane (CH₄) and nitrous oxide (N₂O) than free water surface flow wetlands. However, the simultaneous removal of pollutants and reduction of greenhouse gases (GHG) emissions from high-strength wastewater containing high levels of organic matter and ammonium nitrogen (NH₄⁺-N) has not get been investigated. The influent COD concentration affected the efficiency of nitrogen removal, GHG emissions and the presence of iron from iron ore, but the COD and TP removal efficiencies remained unaffected. CO₂ and CH₄ fluxes were significantly influenced by influent COD concentrations, whereas less N₂O emissions were obtained during 7d. The highest CO₂ and CH₄ fluxes, along with the GHG emissions, were observed in HFCWs with COD concentrations of 375.6 mg/L and NH₄⁺-N concentrations of 159.0 mg/L at a COD/N ratio of 2.4. Conversely, the lowest CH₄ (-1.72 mg/m²/h) and N₂O fluxes (0.13 mg/m²/h) were recorded in HFCWs with COD concentrations of 375.6 mg/L and NH₄⁺-N concentrations of 162.4 mg/L at a COD/N of 4.5, although nitrogen removal was weak in these HFCWs. HFCWs at a COD/N ratio of 3.6 exhibited greater removal of nitrogen and other pollutants, along with a lower global warming potential (GWP). In conclusion, the concentrations of organic matter and NH₄⁺-N in wastewater affected both pollutant removal and GHG emissions. The simultaneous enhancement of pollutant removal and the reduction of GHG emissions can be achieved in HFCWs with a COD/N ratio of 3.6.

Agri-environmental subsidies had been implemented to promote sustainable agriculture in regions such as the EU and the U.S. prior to the year 2000. Contract-Based Agri-Environmental Schemes (AESs) are designed to promote green, sustainable agriculture by employing environmentally friendly farming practices (EFFPs) to reduce pollution and meet other environmental goals. A central challenge, however, is the limited inclusion of small farmers, who are key to agricultural sustainability and form the backbone of production, particularly in developing countries. This study aims to investigate the preferences and participation of small farmers in AESs to enable effective policy design. Using discrete choice experiments (DCEs) and a latent class model (LCM) on survey data collected in 2017 from three key rice-producing counties in China—Fangzheng (Heilongjiang), Qingtongxia (Ningxia), and Yixing (Jiangsu)—allowed us to identify two distinct preference classes: “experienced adopters” and “potential adopters”. The results confirmed (1) a high participation rate of small farmers in AESs. Compensation can further motivate them to sign a contract. (2) There is significant heterogeneity among small farmers’ preferences on various EFFPs, so flexible and modulated schemes are needed; (3) those with experience in EFFPs are more likely to participate in AESs; and (4) the modular AES contract with progressive subsidy ties makes payments directly based on EFFP adoption, addressing the shortcomings of China’s current area-based subsidy system. The results of this paper can help policymakers fine-tune farming policies that effectively engage smallholders, thereby alleviating tensions over production–pollution cycles and fostering a more targeted and sustainable agricultural policy system.