The fate of carbon in check dam sediments

• Published in: Earth-science reviews 2022-01, Vol.224, p.103889, Article 103889
• Main Authors: Yao, Yufei, Song, Jinxi, Wei, Xiaorong
• Format: Article
• Language: English
• Subjects: Carbon cycle; Carbon redistribution; Soil deposition; Soil erosion; Stabilization mechanism
• ISSN: 0012-8252; 1872-6828
• DOI: 10.1016/j.earscirev.2021.103889

Check dams are small engineering structures. They are used worldwide for soil and water conservation, gully rehabilitation, hydrological regulation, and food supply. Eroded materials trapped and buried in check dams constitute an important carbon (C) sink. However, as a typical deposition site, systematic information about C cycling processes in check dams is relatively unknown, despite its crucial role in estimating the fate of buried C and elucidating the ongoing C sink/source debate on soil erosion. This study reviewed the stock, source, enrichment, distribution, stability, and underlying mechanisms of sediment C in check dams. Current studies have found a large amount of C stored in check dams (approximately 1–30 Mg C km−2 yr−1), and have demonstrated that C retention ability relied more on factors governing sediment production and trapping at larger scales than on check dam trapping efficiency at smaller scales. Stable isotopes, radiocarbon, geochemical properties, biomarkers, and spectroscopy methods have proven to be practical in identifying the sources of sediment C but can only be used in certain situations because of their intrinsic limitations. Both enrichment and impoverishment of sediment C compared with source soils have been reported, and have depended on soil erosion type, land-use type, sediment connectivity, and the loss of C during transportation. Sediment C generally increases from the back of the check dam to the front along the flow pathway and fluctuates vertically, depending on the clay and sand layers of the deposition couplets. Information about C mineralization and sequestration is relatively limited, and the existing studies have shown reduced C mineralization and promoted C-fixing potential in check dam sediments. Given the specific benefits of deposition couplets in reflecting information about burial period, erosion intensity, and historical land use, further studies should integrate C stability with soil erosion and deposition information for the deposit profiles. The responses of C cycling to climate change and human disturbances, such as warming, dam-break, tillage, and fertilization for check dam sediments require further research. •Check dams store significant C depending on sediment input and trapping efficiency.•Both enrichment and impoverishment of sediment C occur compared with source soils.•Sediment C raises with flow path horizontally and fluctuates with couplets vertically.•Stable C fractions dominated in the sedi