TY - JOUR T1 - Terrestrial organic carbon age and reactivity in the Yellow River fueling efficient preservation in marine sediments JF - Earth and Planetary Science Letters Y1 - 2022 A1 - Zhang, Yushuang A1 - Galy, Valier A1 - Yu, Meng A1 - Zhang, Hailong A1 - Zhao, Meixun AB - The Yellow River is one of the largest suppliers of sediments and organic carbon (OC) to the ocean. Previous studies have revealed that OC transported by the Yellow River largely derives from the erosion of the Chinese Loess Plateau, which is dominated by pre-aged soil carbon and could be efficiently preserved in marine sediments. Here, we used ramped oxidation radiocarbon analysis (RPO-14C) to characterize the age and reactivity distribution of OC in two Yellow River suspended sediment samples and six Bohai Sea and Yellow Sea (BS–YS) surface sediments from a transect along the sediment transport pathway. RPO-14C independently characterizes the full spectrum of OC thermal stability and isotope compositions to reveal the source, age and reactivity structure of OC transported by the Yellow River and preserved in Chinese marginal sea sediments. We calculated the activation energy (E) distribution—a proxy for bonding environment and by extension reactivity—which, combined with 14C and stable carbon isotope (δ 13C) compositions, reveals OC origin and stability. Our data suggest that 96% of OC in Yellow River suspended sediments is biospheric and weathered petrogenic, while unweathered petrogenic OC only accounts for 4% which is almost an order of magnitude lower than the fossil OC estimates (32%) based on compound specific 14C analysis. RPO data reveal the prevalence of aged biospheric loess OC in the Yellow River. We use δ 13C, 14C and RPO-derived activation energy data to quantify the contribution of terrestrial OC to surface sediments in the BS–YS. The resulting estimates of terrestrial OC proto-burial efficiencies yield an average value of 89 ± 30%, revealing overall very high terrestrial OC preservation in the BS–YS. Additionally, and somewhat counter intuitively, we find that the preservation of terrestrial OC decreases with increasing E. This pattern may arise from an enhanced preservation of a pre-aged C4 plants derived fraction of the loess-derived OC associated with secondary clays characterized by smaller grain size and higher surface area. Alternatively, the high E component of the Yellow River OC might comprise partially weathered petrogenic carbon, undergoing further mineralization during transport from rivers to marginal sea sediments via marine organic matter priming. VL - 585 UR - https://linkinghub.elsevier.com/retrieve/pii/S0012821X22001510 ER - TY - JOUR T1 - Sources and radiocarbon ages of aerosol organic carbon along the east coast of China and implications for atmospheric fossil carbon contributions to China marginal seas JF - Science of The Total Environment Y1 - 2018 A1 - Yu, Meng A1 - Guo, Zhigang A1 - Wang, Xuchen A1 - Eglinton, Timothy Ian A1 - Yuan, Zineng A1 - Xing, Lei A1 - Zhang, Hailong A1 - Zhao, Meixun KW - AEROSOLS KW - China marginal seas KW - Fossil carbon KW - Radiocarbon (14C) tracer KW - Total organic carbon AB - Aerosol deposition is an important mechanism for the delivery of terrestrial organic carbon (OC) to marginal seas, but OC age characteristics of aerosols are not well constrained and their contributions to sediment OC burial have not been quantified. Total suspended particle samples were collected along the east coast of China at Changdao (CD), Qingdao (QD) and Huaniao Island (HNI), and were analyzed for total organic carbon (TOC) isotopes (13C and 14C) in order to bridge this information gap. TOC δ13C and Δ14C values ranged from − 23.6 to − 30.5‰, and − 153 to − 687‰, respectively, with the latter corresponding to 14C ages ranging from 1280 to 9260 yr. Estimated contributions of fossil carbon to TOC based on 14C mass balance approach ranged from 26 to 73%, with strong seasonal variations in fossil carbon observed at CD. Fossil carbon at CD showed the highest proportion (73%) in winter, reflecting anthropogenic emissions and the lowest proportion (26%) in summer, caused by biomass contribution (annual ave., 52% ± 17%). In contrast, the fossil carbon at both QD (57–64%) and HNI (57–67%) dominated throughout the year, reflecting local anthropogenic influences and long-range transport. Mass balance estimates indicate that atmospheric deposition and riverine export accounted for 31% and 69% of fossil carbon inputs to the China marginal seas (CMS) respectively, with fossil carbon burial efficiencies approaching 100% in the CMS. On a global scale, an atmospheric fossil carbon deposition flux of 17.2 Tg C yr− 1 was estimated, equivalent to 40% of the estimated fluvial flux to the ocean, and potentially accounting for 24–41% of fossil OC burial in marine sediments. Therefore, the atmospheric deposition constitutes an important source of fossil carbon to marine sediments, and could play a key role in regional and global scale OC budgets and biogeochemical cycles. VL - 619-620 UR - https://linkinghub.elsevier.com/retrieve/pii/S004896971733259X ER -