Organic carbon burial from multi-core records in Hulun Lake, the largest lake in northern China

Lakes are hotspots for carbon cycling and therefore important in the terrestrial carbon budgets. In this study, 15 sediment cores from Hulun Lake, the largest lake in northern China, were analyzed to determine the spatial and temporal trends of organic carbon (OC) burial during the past 150 years. The most plausible factors controlling OC burial are also discussed. The OC burial rates varied from 8.43 g m−2 yr−1 to 73.98 g m−2 yr−1 among the studied sediment cores and exhibited an overall northwest−southeast gradient, with the higher rates in the northwest part of the lake. The OC burial rate for the entire lake was 9.52 g m−2 yr−1 before 1900 and increased to 27.33 g m−2 yr−1 during the period 1900-1950 and then to 35.68 g m−2 yr−1 after 1950. The ratios of the post-1950 period to the pre-1900 and 1900-1950 periods were 3.53 and 1.68, respectively, which indicates an increasing trend of the OC burial rate over the past 150 years. The changes in the burial rates of OC were positively linked to climate warming rather than human activities in Hulun Lake, implying that Hulun Lake will be an increasingly important carbon pool in the future as global warming proceeds.