Molecular and radiocarbon constraints on the fate of sedimentary organic carbon in a human-impacted river-dominated ocean margin

Organic carbon (OC) burial in river-dominated ocean margins plays a pivotal role in the global carbon cycle, impacting atmospheric CO2 levels over the long term. Despite its significance, uncertainties persist regarding the influence of external environmental factors and intrinsic properties on sedi...

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Bibliographic Details
Published in:Marine Geology
Main Authors: Wang, Chenglong, Zhang, Chuchu, Zhang, Zhuoyue, Liao, Qihang, Zhang, Yang, Wang, Ning, Wang, Yaping, Zou, Xinqing
Format: Report
Language:English
Published: ELSEVIER 2024
Subjects:
Geology
Oceanography
River -dominated Ocean margins
Hydrodynamic sorting
Human perturbations
Mineral protection
Molecular biomarkers
Dual carbon isotope
Geosciences
Multidisciplinary
EAST CHINA SEAS
CHANGJIANG ESTUARY
SUBAQUEOUS DELTA
LAPTEV SEA
MATTER
COASTAL
PRESERVATION
VARIABILITY
DISPERSAL
GRAPHITE
laptev
Laptev Sea
Online Access:http://ir.gig.ac.cn/handle/344008/72022
https://doi.org/10.1016/j.margeo.2024.107322
Description
Summary:Organic carbon (OC) burial in river-dominated ocean margins plays a pivotal role in the global carbon cycle, impacting atmospheric CO2 levels over the long term. Despite its significance, uncertainties persist regarding the influence of external environmental factors and intrinsic properties on sedimentary OC. In this study, we conducted a comprehensive analysis of surface sediments from the East China Sea, examining geochemical properties (including total OC content [TOC], Delta C-14, delta C-13, and C/N ratio), terrestrial biomarkers (n-alkanes), and mineral properties (such as specific surface area, Al/Si ratio, and mineral composition). Our aim was to shed light on the fate of sedimentary OC. The surface sediment's Delta C-14 values displayed significant spatial heterogeneity, delineating four distinct sub-regions. Strong positive correlations (all p < 0.01) were found between the triangle C-14 values and fine-grained sediments, specific surface area, and clay minerals, suggesting the potentially pivotal role of mineral protection in shaping the fate of sedimentary OC. The proportion of terrestrial OC gradually decreased towards the south, while marine OC proportion increased, corresponding to the enrichment of Delta C-14. The co-variation of Delta C-14 values, mineral properties, and OC source proportions suggests that terrestrial OC may undergo progressive replacement by marine OC during southward transport. Temporal variations in triangle C-14 values indicated that seabed erosion led to a significant increase in triangle C-14 values (p < 0.01) in the coastal mud belt, a phenomenon likely common in river-dominated ocean margins globally due to the new sediment cycle during the Anthropocene.

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