Sediment distribution and organic carbon burial in a subtropical hydroelectric reservoir
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Aquatic Sciences
RESEARCH ARTICLE
Sediment distribution and organic carbon burial in a subtropical hydroelectric reservoir Wai Wai Phyoe1 · Yong Qin1 · Ningxiao Yu1 · Fushun Wang1 Received: 23 September 2019 / Accepted: 1 July 2020 © Springer Nature Switzerland AG 2020
Abstract Reservoir sediment is a major player in the terrestrial carbon (C) budget, and the quantification of C burial in sediments is important in assessing the reservoir’s role in the global C budget. However, assessments of C burial in sediments of subtropical hydroelectric reservoirs and their potential as C sinks are thus far limited due to a lack of whole reservoir assessments of C burial. In this study, a combined seismic survey with sediment core analysis was conducted in the Xin’anjiang Reservoir, the first large hydroelectric reservoir in China. The total organic carbon (TOC), total nitrogen, isotopic C composition (δ13C), and sediment grain size were analyzed. 210Pb and 137Cs were used to obtain the sediment chronologies. The data suggest that bottom bathymetry of the pre-existing reservoir is an important factor on sediment accumulated within the reservoir. The sediment OC content and trophic state became controlling factors and accelerated the OC burial in the sediment. Based on the interpolated sediment thickness data and total reservoir area, the average TOC burial rate was estimated at 34.0 g C m−2 year−1 (ranging 0–676.7 g C m −2 year−1). This rate is within that estimated by sediment coring (mean 40.4 g C m −2 year−1, −2 −1 ranging 15.8–110.1 g C m year ) as a result of high heterogeneity of sediment distribution and irregular sedimentation. However, the result was close to the estimates of previous studies, demonstrating that the combined method here can also be an effective way to conduct future estimation of C burial in freshwater reservoirs. Keywords Sediment distribution · Total organic carbon burial · Sedimentation rate · Burial rate · Subtropical reservoir
Introduction Inland waters are crucial sites for organic carbon (OC) storage and conduits for transporting materials to the ocean. Based on new data on the area and distribution of the inland waters, the terrestrial carbon (C) exports to inland waters were 5.1 Pg C y ear−1 (Drake et al. 2017) and the global riverine C transported to oceans totalled 0.9 Pg C year−1 (Cole et al. 2007), indicating that the C loss from inland waters * Fushun Wang [email protected] Wai Wai Phyoe [email protected] Yong Qin [email protected] 1
Ningxiao Yu [email protected]; [email protected]
School of Environmental and Chemical Engineering, Shanghai University, P.O. Box 144, No. 99, Shangda Road, Baoshan District, Shanghai 200444, China
through a combination of respiration and sedimentation was approximately 4.2 Pg C year−1 (Drake et al. 2017). Moreover, the contribution of inland waters to the global C cycle has been significantly altered by human activity, including reservoir construction, which results in both C burial in sediments and C emissions to the atmosphe
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