Human-caused increases in organic carbon burial in plateau lakes: The response to warming effect.

The patterns of organic carbon sequestration in lakes, along with their temporal dynamics, have profound implications for assessing the strength of terrestrial carbon sinks and the global carbon budget. The complexity of fluctuations in organic carbon burial in freshwater lake basins, along with the intricate interactions among various controlling factors over time, remains challenging to comprehend. By utilizing data on the organic carbon burial of sedimentary cores from twelve plateau lakes in a gradient of urbanization, this study employed a rigorous methodology to quantify the factors and origins that contribute to lacustrine carbon sequestration. The findings indicate that the rate of Total Organic Carbon (TOC) accumulation in lakes in highly urbanized areas has significantly surpassed that in areas with minimal urbanization since 1985. This trend of divergence has persisted for more than four decades. During the period from 1958 to 2008, soil nutrient characteristics (29.576 %) and human impact (16.684 %) were the major factors regulating the organic carbon burial in plateau lakes. Human pressures indirectly impact carbon sequestration through earth-surface processes in the lake basin, causing carbon burial to lag behind environmental indicators (e.g., δC and C/N) by approximately 5 years. Meanwhile, the carbon sequestration efficiency of plateau lakes shows a positive feedback to climatic warming with intensified urbanization, primarily regulated through the impacts on lake basin environments. The results will further enhance our understanding of the response of the lake ecosystem carbon cycle to anthropogenic influences.