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.

This study presents an integrated approach for the remediation of zinc- and ammonium-contaminated water using duckweed, followed by the valorization of the harvested biomass through anaerobic digestion for biogas production. Duckweed was cultured with various initial concentrations of zinc (Zn, 0 mg/L, 2.5 mg/L, and 5 mg/L) and ammonium (NH₄⁺-N, 0 mg/L, 20 mg/L, and 40 mg/L). Subsequently, duckweed was subjected to chemical pretreatment with sulfuric acid and the obtained residual solid and liquid fractions were evaluated as substrates for methane production. The liquid fraction consistently yielded higher methane production compared to the solid fraction. However, when duckweed was grown in zinc- and ammonium-rich conditions (2.5 or 5.0 mg/L Zn and 20 mg/L NH₄⁺-N), methane production from the liquid hydrolysate was significantly reduced (120.90 ± 12.03 mL/g COD and 129.82 ± 10.65 mL/g COD, respectively) compared to the control duckweed (201.67 ± 5.72 mL/g COD). The lowest methane yields were observed for duckweed grown solely in zinc (111.32 ± 5.72 and 99.88 ± 10.49 mL/g COD for 2.5 and 5.0 mg/L Zn, respectively), attributed to the inhibitory effect of high dissolved zinc concentrations in the liquid fraction. The applicability of this integrated system is particularly relevant for the agricultural and industrial sectors, where wastewater streams are often co-contaminated with nutrients and trace metals. By demonstrating that acid-pretreated, zinc-rich duckweed biomass can be used for biogas production—provided that process conditions are optimized to mitigate metal inhibition and acidification—this study provides actionable strategies for developing circular, sustainable wastewater treatment systems. The approach not only maximizes pollutant removal and resource recovery, but also addresses environmental safety concerns associated with residual metals in the digestate.