Microbiological research progress on greenhouse gas emissions in lakes of the Tibetan Plateau

Abstract

In recent years, under the influence of climate warming, lakes have rapidly expanded, becoming a hotspot environment for studying the biogeochemical cycles of elements such as carbon, nitrogen and sulfur. Microorganisms tightly couple the carbon, nitrogen, phosphorus and sulfur cycles, jointly regulating the source-sink patterns of greenhouse gases like CO₂, CH₄ and N₂O. However, how these processes interact and network in the complex natural environment, and how they jointly regulate the overall mechanism of greenhouse gas emissions, remain the forefront and key challenges of research. This review highlights the substantial spatiotemporal heterogeneity of lake greenhouse gas emissions, revealing profound influences from lake type, ice cover duration and seasonal pulse emissions on flux dynamics. At the molecular level, it elucidates the core driving role of microorganisms, including photosynthetic and chemotrophic autotrophic carbon fixation, heterotrophic decomposition of organic matter, methanogenesis/methanotrophy, and denitrification coupled with nitrogen-sulfur cycling, emphasizing the indicative significance of key functional genes. The review dissected how the availability of biogenic elements (carbon, nitrogen, phosphorus, sulfur) and their coupling relationships shape carbon cycling pathways by regulating microbial communities and activity. It assessed how climate change reconfigures lake carbon source-sink functions by altering physicochemical conditions and material inputs. Findings indicate that carbon cycling in Tibetan Plateau lakes constitutes a dynamically balanced process mediated by microorganisms and regulated by multi-element coupling. Thermophilic lakes serve as critical hotspots for activating ancient permafrost carbon and releasing substantial CH₄. Climate change may enhance primary production by extending growing seasons, yet simultaneously intensifies organic matter decomposition and greenhouse gas production through warming, increased external carbon inputs, and salinity changes. This dual effect risks transforming the system into a net carbon source, creating a positive feedback loop that exacerbates warming. We must develop integrated biogeochemical models that incorporate microbial mechanisms and multi-factor coupling. Based on these models, differentiated management strategies should be implemented to suppress emission hotspots, thereby providing critical scientific support and management solutions for regional green development and global carbon neutrality.