Wenbing Tan

The impact of anaerobic oxidation of methane (AOM) coupled with denitrification on the emission of the denitrification intermediate N ₂ O remains poorly understood. Here, we investigated the influence of AOM coupled with nitrate and nitrite reduction on soil N ₂ O emissions and the associated microbial interactions. We show that AOM coupled with denitrification markedly reduces soil N ₂ O emissions, with the type I methanotroph Methylobacter species collaborating with the Methylophilaceae and Gemmatimonadaceae families to perform key roles. The suppression of N ₂ O emissions by AOM primarily stems from its role in supplying electrons and carbon sources, fueling complete denitrification by associated bacteria. In addition, we uncovered distinct microbial interaction strategies for AOM-coupled nitrate and nitrite reduction. While nitrite reduction necessitates both bacterial cooperation and extracellular electron transfer during its initial stages, nitrate reduction predominantly depends on methanotrophic bacteria alone at the outset. These findings advance our understanding of carbon-nitrogen cycle coupling and underscore AOM’s potential to simultaneously mitigate both CH ₄ and N ₂ O emissions.

Reactive oxygen species (ROS) serve as crucial signaling molecules in plants, enabling rapid responses to environmental stresses such as abiotic factors. ROS production primarily stems from the activation of enzymes such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidases and peroxidases, as well as disruptions in the respiratory and photosynthetic electron transport chains. This oxidative stress triggers signaling pathways that involve in calcium ion (Ca²⁺) influx across cell membranes, altering ionic conductance. ROS encompass hydroxyl radicals (OH•) and hydrogen peroxide (H₂O₂), which activate hyperpolarization‐activated Ca²⁺ channels and influence ion transport dynamics. Our review focuses on the mechanisms driving ROS generation and ion transport during plant responses to abiotic stress. We explore the regulation, characteristics, and potential structures of ROS‐activated ion channels in plants. Specifically, we examine the molecular responses and evolutionary adaptations of Shaker‐type K⁺ channels (AKT/KAT/GORK/SKOR) under stress conditions. Comparative genetic analyses highlight the conservation of these channels and other ROS‐regulated proteins (e.g., MDHAR, POX, and RBOH), suggesting their essential roles in plant to adapt to diverse stresses. This study underscores the significance of ROS‐regulated proteins in plant stress responses, advocating for further research to elucidate their fundamental roles.

Landfill leachate contains a range of organic and inorganic pollutants, including per-/polyfluoroalkyl substances (PFASs), which can infiltrate into surrounding soil and groundwater through leaching processes, and can pose a threat to human health via food chains and drinking water processes. Thus, the transport of PFASs in landfill leachate is a research hotspot in environmental science. This study investigates the complexation and adsorption mechanisms between humic substances and PFASs in landfill leachate at the molecular level. Experimental results demonstrate that the binding constant logK_sv of humic substances with PFASs correlates positively with specific ultraviolet absorbance (SUVA₂₅₄), absorbance ratio (A₂₅₀/A₃₆₅), humification index (HIX), and fluorescence index (FI), while it exhibits a negative correlation with the biological index (BIX). These findings indicate that high aromaticity is a prerequisite for molecular interactions between humic substances and PFASs, with polar functional groups further facilitating the interaction. Molecular-level analysis revealed that humic substances undergo complexation and adsorption with PFASs through hydrophobic interactions, van der Waals forces, hydrogen bonding, ionic bonding, and covalent bonding, by functional groups such as hydroxyl, aliphatic C-H bonds, aromatic C=C double bonds, amides, quinones, and ketones. Future efforts should focus on enhanced co-regulation and mitigation strategies addressing the combined pollution of PFASs and humic substances in landfill leachate.

Per- and polyfluoroalkyl substances (PFASs) presented in landfill leachate can be transported to groundwater and soil, posing risks to human health in food and water. However, the occurrence characteristics of PFASs in landfill leachate and the influence paths of abiotic and biotic factors have not been fully discussed. Our study found that the detection rate of PFASs in the leachate samples was 100%; ΣPFASs ranged from 1328 ng/L to 37,447 ng/L; and the average ΣPFASs was 9593 ng/L. Most of the physical and chemical indexes in the landfill leachate showed a significant positive correlation with PFASs concentration, with the main physical and chemical factors including TOC, sodium ion, chromium ion, and chloride ion. Moreover, dissolved organic matter had a very important influence on the environmental behavior of PFASs. The degree of dissolved organic matter (DOM) humification promoted the transportation of PFBA and PFBS from the landfill waste to leachate, while microbial DOM inhibited the transportation of ∑₁₃ PFCAs. The microorganisms in the leachate were mainly Firmicutes, Campylobacterota and Proteobacteria, among which there was a negative correlation between PFBS and Proteobacteria, indicating that PFBS was highly toxic to Proteobacteria and would inhibit the growth of Proteobacteria in leachate. Firmicutes and Campylobacterota had little influence on PFASs. However, Synergistota, and Halanaerobiaeota, which had a low abundance, both positively correlated with the various PFASs. This result may imply that these rare microphyla are the main microphyla driving the transformation of PFASs in leachate. Microorganisms in leachate indirectly affected the occurrence of PFASs, mainly by influencing the environmental factors in leachate. Therefore, abiotic factors are important factors affecting PFASs in the landfill leachate. In summary, PFASs pollution management in landfills should be enhanced by regulating abiotic factors to control PFASs in leachate.