Compositions and sources of sedimentary organic carbon on the tropical epicontinental sea

Lin, Baozhi; Liu, Zhifei; Zhao, Meixun; Sompongchaiyakul, Penjai; Zhang, Hailong; Blattmann, Thomas M.; Feng, Songlin; Wiesner, Martin G.; Le, Khanh Phon; Meas, Rithy; Sathiamurthy, Edlic

doi:10.1016/j.gca.2023.04.030

Cited by 10 publications

(11 citation statements)

References 80 publications

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“…The F m values of shelf sedimentary OC off South China (red triangles in Figure 4) are much lower than expected if it had originated from modern-day biological production in the overlying water column (0.56-0.84 vs. 0.93-1.17), despite some of them share similar δ 13 C values. Given the high sediment accumulation rates, smaller sampling Journal of Geophysical Research: Biogeosciences 10.1029/2023JG007909 intervals (0-2 cm) than the sediment mixed layer depth, and short transport distance of <200 km, the potential effects of bioturbation that mix particles with differing ages and 14 C decay due to lateral transport are unlikely to account for the low F m values observed in surface sedimentary OC on the shelf (Emerson et al, 1987;Lin et al, 2023). The low F m values of surface sedimentary OC on the shelf could be attributed by the laterally advected, pre-aged terrestrial organic materials.…”

Section: Shelf Sediments Off South Chinamentioning

confidence: 99%

Organic Carbon Sources in Surface Sediments on the Northern South China Sea

Lin,

Liu,

Eglinton

et al. 2024

JGR Biogeosciences

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The burial of organic carbon (OC) in marine sediments regulates CO2 content in the atmosphere. However, the OC sources and their effect on the OC preservation in sediments of the continental marginal sea remain elusive. Here, we survey the abundance, stable carbon and radiocarbon isotopes of OC, as well as mineral surface area and grain size in surface sediments from the shelf to the abyssal plain of the South China Sea. We found that the marine OC comprises the 63 ± 9% and 78 ± 14% of sedimentary OC off South China and Luzon, respectively. The petrogenic OC contributing to sedimentary OC in these sites is generally higher than that of soil OC (22 ± 10% vs. 12 ± 6%). The sedimentary OC off Taiwan is predominantly derived from petrogenic OC, accounting for 57 ± 10%, with remaining consisting of marine OC (36 ± 10%) and soil OC (6 ± 1%). High soil OC contents are found in fine sediments on the inner shelf off South China, and high petrogenic OC contents occur in fine sediments off Taiwan. Marine OC contents are high in fine sediments on the middle shelf and upper slope off South China, but low in coarse sediments on the outer shelf and upper slope, and fine sediments on the lower slope and abyssal plain. The OC sources, mineral surface area, and oxygen exposure time of OC together control the preservation of OC in sediments with their relative importance differing on varying depositional settings of this sea.

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Section: Shelf Sediments Off South Chinamentioning

confidence: 99%

Organic Carbon Sources in Surface Sediments on the Northern South China Sea

Lin,

Liu,

Eglinton

et al. 2024

JGR Biogeosciences

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“…However, repeated cycles of sediment resuspension further offshore result in intense OC degradation within this region (B. Lin et al, 2023).…”

Section: Spatial Variations In Organic Matter Quantity Source Age And...mentioning

confidence: 99%

“…In this regard, terrestrial OM is composed of a myriad of organic compounds with different chemical compositions, diverse mineral associations, and hence contrasting reactivities, all of which affect the sequestration potential of terrestrial OM in marine sediments (B. Lin et al, 2023;Wu et al, 2013;B. Zhao et al, 2021).…”

Section: Limitations and Future Directionsmentioning

confidence: 99%

“…Region VI consists of the Gulf of Thailand, a relatively shallow (70 m) semi-enclosed sea that receives sediment from the numerous rivers that discharge from Vietnam, Cambodia, Thailand, and Malaysia that engulf this region (B. Lin et al, 2023), and the Chao Phraya River in the northern Gulf of Thailand has the largest sediment discharge of these rivers (Z. Milliman & Farnsworth, 2011;B.…”

Section: Regionmentioning

confidence: 99%

“…However, monsoonal winds can reverse the flow to an anticyclonic circulation (J. T. Z. Liu et al, 2016), which contribute to the formation of mud deposits in the lower area of this region, downcurrent from the main rivers (Bai et al, 2021;B. Lin et al, 2023;B.…”

Section: Regionmentioning

confidence: 99%

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Unraveling Environmental Forces Shaping Surface Sediment Geochemical “Isodrapes” in the East Asian Marginal Seas

Paradis,

Diesing,

Gies

et al. 2024

Global Biogeochemical Cycles

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As major sites of carbon burial and remineralization, continental margins are key components of the global carbon cycle. However, heterogeneous sources of organic matter (OM) and depositional environments lead to complex spatial patterns in sedimentary organic carbon (OC) content and composition. To better constrain the processes that control OM cycling, we focus on the East Asian marginal seas as a model system, where we compiled extensive data on the OC content, bulk isotopic composition (δ13C and Δ14C), total nitrogen, and mineral surface area of surficial sediments from previous studies and new measurements. We developed a spatial machine learning modeling framework to predict the spatial distribution of these parameters and identify regions where sediments with similar geochemical signatures drape the seafloor (i.e., “isodrapes”). We demonstrate that both provenance (44%–77%) and hydrodynamic processes (22%–53%) govern the fate of OM in this margin. Hydrodynamic processes can either promote the degradation of OM in mobile mud‐belts or preserve it in stable mud‐deposits. The distinct isotopic composition of OC sources from marine productivity and individual rivers regulates the age and reactivity of OM deposited on the sea‐floor. The East Asian marginal seas can be separated into three main isodrapes: hydrodynamically energetic shelves with coarser‐grained sediment depleted in OC, OM‐enriched mud deposits, and a deep basin with fine‐grained sediments and aged OC affected by long oxygen exposure times and petrogenic input from rivers. This study confirms that both hydrodynamic processes and provenance should be accounted for to understand the fate of OC in continental margins.

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