Saline lakes play a crucial role in the global carbon cycle. However, the impacts of climate change and human activities on organic carbon mineralization in saline lake sediments are not well understood. This study aims to elucidate the microbial mechanisms of organic carbon mineralization in saline lake sediments and their responses to environmental changes such as salinity and nitrogen input. We conducted a series of experiments on saline lake sediments with different salinities. We investigated the effects of different types of organic matter inputs (e.g., algal and grass organic matter), bacterial biomass-derived organic matter, and varying salinity and nitrogen levels on organic carbon mineralization and priming effects (PE). Geochemical analyses and microbial community analyses were performed to identify the key factors driving organic carbon mineralization. Our results show that different types of organic matter inputs induce positive PE in saline lake sediments, with grass organic matter inducing stronger PE than algal organic matter. Bacterial biomass-derived organic matter significantly increases N₂O production by stimulating methanogenesis and nirK-regulated denitrification pathways. Salinity has a greater impact on microbial abundance, diversity, community structure, and organic carbon mineralization than nitrogen input. Under anaerobic conditions, organic carbon mineralization in saline lake sediments is stronger than under aerobic conditions, and CO₂ production rates show a hump-shaped pattern with increasing salinity. These results provides new insights into the microbial mechanisms of organic carbon mineralization in saline lake sediments and their responses to environmental changes. The findings highlight the importance of considering the interactions between salinity, nitrogen input, and microbial communities in understanding the carbon cycle of saline lakes. These results have significant implications for predicting the impacts of global climate change on carbon emissions from saline lake ecosystems.
 

Saline lake sediments,Organic carbon mineralization,Microbial mechanisms,Salinity,Nitrogen input