Long-term patterns and drivers of carbon burial variations in alpine lakes of Northwest Yunnan, China under regional warming.

Lakes are crucial terrestrial carbon sinks for the Earth's surface systems, where the burial and transformation of total organic carbon (OC) and inorganic carbon (IC) are strongly influenced by watershed surface processes. In alpine regions with limited direct human impact, long-term warming trends can enhance key proce-sses, such as algal growth and the mineralization of organic matter, thereby altering OC and IC accumulation and burial dynamics. We examined spatial patterns, synergistic relationships and controlling factors of carbon burial under regional warming across six alpine lakes in northwestern Yunnan (deep lakes: Dinggongniang Co, Gaigong Co Na, Wodi Co; shallow lakes: Dinggong Co, Bigu Tianchi, Shudu Lake), by employing multiple proxies including total nitrogen, chlorophyll, OC and IC contents, combined with climate reconstruction data. Results showed that 1.14 ℃ increase in temperature over the past 150 years had significantly reshaped carbon sequestration across lakes. The response magnitude of primary productivity to temperature increases in shallow lakes (Bigu Tianchi: 39%; Shudu Lake: 58%; Dinggong Co: 30%) was significantly greater than in deep lakes (Dinggongniang Co: 14%; Gaigong Co Na: 7%; Wodi Co: 20%). Distinct carbon cycling processes were observed between lake types. In deep lakes, algal contributions to OC were negligible while enhancing synchronous OC-IC deposition, indicating stratification simultaneously inhibited autochthonous carbon burial while promoting organic matter preservation. Conversely, there were strong chlorophyll-OC correlations with weakened OC-IC coupling in shallow lakes, revealing algal-dominated organic carbon production coupled with enhanced mineralization processes. Furthermore, atmospheric deposition altered inorganic carbon burial regimes through nitrogen enrichment in alkaline waters (Dinggongniang Co, Gaigong Co Na, Wodi Co, Shudu Lake, Bigu Tianchi). Elevated pH promoted carbonate precipitation and IC accumulation, while acidic inputs suppressed IC burial in acidic lake (Dinggong Co) and modified OC-IC burial relationship. Overall, the carbon burial processes in alpine lakes exhibited different responses to regional environmental changes, which were strongly related to lake depth, pH, and other limnological characteristics.