Linking source-to-sink processes, organic matter composition, and oxygen consumption on a shallow passive margin shelf sustained by small mountainous rivers
Journal
Geochimica et Cosmochimica Acta
Journal Volume
408
Start Page
40
End Page
55
ISSN
0016-7037
Date Issued
2025-11
Author(s)
Lin, Yu-Shih
Chang, Yuan-Pin
Wang, Jih-Terng
Chuang, Shu-Ying
Wang, Liang-Chi
Liu, James T.
Li, Hong-Chun
Hsu, Chieh-Wei
Abstract
Continental shelf sediments are a focal point for research on the transport, degradation, and burial of organic matter (OM), yet OM reactivity has rarely been examined within an integrated source-to-sink framework. This study investigates the relationships among source-to-sink processes, surface sediment OM composition, and oxygen consumption rates—used as a proxy for OM reactivity—of the northeastern Taiwan Strait, a passive margin shelf influenced by small mountainous rivers (SMRs). Distinct zonation of OM types was observed across the shelf. Petrogenic OM, the most abundant component, was concentrated in the depocenter, likely transported by hyperpycnal flows. Its association with low total oxygen uptake (TOU) underscores its refractory character. In contrast, fresh terrestrial OM, enriched in nearshore muds via hypopycnal flows or resuspension-advection processes, elevated TOU by nearly threefold compared to petrogenic OM-dominant sediments. As a minor component, marine OM exhibited a spatial distribution consistent with vertical delivery by the biological pump. High benthos-mediated oxygen consumption was found in silty and sandy sediments with the maximum marine OM proportion. Dissolved oxygen uptake showed a strong positive correlation with total hydrolyzable amino acids, derived from both marine and terrestrial sources. The observed connection between OM composition and oxygen consumption is attributed to the high-fidelity delivery of fresh and refractory OM from SMRs, followed by spatial partitioning driven by transport dynamics. The burial efficiency of terrestrial OM on this passive margin shelf was lower than on adjacent active margins, highlighting the critical role of shelf morphology in regulating carbon burial efficiency in SMR-sustained systems.
Subjects
Oxygen consumption rate
Passive margin shelf
Petrogenic organic matter
Small mountainous river
Total hydrolyzable amino acid
Publisher
Elsevier BV
Type
journal article