Millennial reconstruction of organic carbon burial and n-alkane-based source identification in Sayram Lake, Xinjiang, China

Organic carbon burial in lake sediments plays a crucial role in understanding the terrestrial carbon cycle. Sayram Lake (Xinjiang, China), located in the Tianshan Mountains of arid Central Asia, provides a unique opportunity to investigate the mechanisms governing organic carbon burial in deep lakes over the past millennia. With the source apportionment based on n-alkanes, the carbon burial pattern in the Tianshan Mountains over the past millennium was reconstructed using an integrated framework of Bayesian change-point detection and wavelet analysis. The organic carbon burial rate (OCBR) in Sayram Lake was characterized by the coexistence of periodicity and stages, with a significant power peak within the 40-90-year period range and the strongest signal occurring at approximately the 60-year period. Sediment grain size played a relatively minor role in the carbon burial process in Sayram Lake. The OCBR has been at a low level and has shown a decreasing trend since the Little Ice Age, which differs significantly from the trends observed in lakes within global inland basins. The influence of lake environmental system evolution and climate change on organic carbon burial was assessed using regional climate change datasets, which provided new data and insights into the mechanisms governing carbon burial in deep-water lakes within arid mountain ecosystems.

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