Substantial role of check dams in sediment trapping and carbon sequestration on the Chinese Loess Plateau

Understanding the processes governing lateral terrestrial organic carbon transfer is confounded by the fact that organic carbon deposits on land have not yet been fully explored. Despite recent advances in understanding organic carbon deposition in aquatic ecosystems, the burial of organic carbon in dry depositional environments remains unclear. Here, combining large-scale field surveys and remote sensing techniques, we provide a robust estimate for sediment retention and organic carbon burial of check dams on the Chinese Loess Plateau. We find that the 50,226 active check dams have intercepted 10.2 +/- 0.6 Pg eroded sediment during 1970-2020, which equals to 46% of the sediment load of Yellow River. Based on 86 deep sediment cores, we estimate that 21.6 +/- 9.9 Tg of organic carbon was buried over the past 50 years by check dams with a burial rate of 468 +/- 204 g C m(-2) yr(-1), approximately one order of magnitude higher than that of global lakes/reservoirs. We also find that the organic carbon burial efficiency of check dams (similar to 80%) is significantly higher than in other depositional environments. We argue that organic carbon burial by check dams represents a significant terrestrial carbon sink and must be accounted for in global carbon budget.