The remineralization of sedimentary organic carbon in different sedimentary regimes of the Yellow and East China Seas

Zhao, Bin; Yao, Peng; Bianchi, Thomas S.; Arellano, A. R.; Wang, Xuchen; Yang, Jinlong; Su, Rongguo; Wang, Jinpeng; Xu, Yahong; Huang, Xin; Chen, Lin; Ye, Jun; Yu, Zhigang

doi:10.1016/j.chemgeo.2018.08.012

Cited by 65 publications

(61 citation statements)

References 91 publications

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“…Statistical analyses show that the annual average DO concentration decreased as the nitrate concentration increased, whereas the AOU increased as the nitrate concentration increased (Figure 8), further reflecting the role of enhanced nutrient availability in the decreases in bottom DO concentration in the NYS. Furthermore, as reported by previous studies (Hu, 1984;Zhao, 1996), the NYSCWM is characterized by a cyclonic eddy in summer. Due to the convergence of the cold cyclonic eddy, the terrigenous and marinederived particulate organic matter can gradually aggregate and settle down, forming the central mud deposits (Figure 1b) within the NYSCWM (Cheng et al, 2004;Hu, 1984;Hu et al, 2011Hu et al, , 2013.…”

Section: Journal Of Geophysical Research: Oceanssupporting

confidence: 78%

“…This mud area also corresponds to the bottom high‐AOU and low‐DO saturation zone in the NYSCWM, suggesting that the accumulation of organic matter and remineralization in this region can be conducive to the drawdown of DO concentration in summer. Actually, the terrestrially derived particulate organic carbon (POC) accounts for a small fraction (~3%) of the sedimentary organic carbon in the YS muddy areas (Tao et al, ; Zhao et al, ). Moreover, these inputs of POC, mainly from the Yellow River, were pre‐aged and thus contributed a more decay‐resistant component to the POC in the YS (Bao et al, ; Tao et al, , ; Wang et al, ; Xue et al, ; Zhao et al, ); over the past decades, due to the decrease in the total suspended solids load, POC flux form of the Yellow River has also decreased by 90% (Ran et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…By contrast, the labile marine‐sourced organic carbon from primary production is the major component (~97%) of POC in the YS (Tao et al, ; Zhao et al, ), and the enhanced nutrient availability may lead to increased inputs of fresh marine POC (Zhu et al, ). As a result, the terrestrially derived POC can be efficiently buried in sediments (Tao et al, ), while the decomposition of marine‐sourced POC dominates the mineralization process in the YS (Song, Liu, Zhu, et al, ; Zhao et al, ). More importantly, due to the existence of a cyclonic eddy in the central YS, the transport path of marine POC from upper layer to sediments is prolonged and thus the decomposition of POC is largely promoted in water column below the pycnocline (Zhao et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Actually, the terrestrially derived particulate organic carbon (POC) accounts for a small fraction (~3%) of the sedimentary organic carbon in the YS muddy areas (Tao et al, 2016;Zhao et al, 2018). Moreover, these inputs of POC, mainly from the Yellow River, were pre-aged and thus contributed a more decay-resistant component to the POC in the YS (Bao et al, 2016;Tao et al, 2015Tao et al, , 2016Wang et al, 2012;Xue et al, 2017;Zhao et al, 2018); over the past decades, due to the decrease in the total suspended solids load, POC flux form of the Yellow River has also decreased by 90% (Ran et al, 2013). By contrast, the labile marine-sourced organic carbon from primary production is the major component (~97%) of POC in the YS (Tao et al, 2016;Zhao et al, 2018), and the enhanced nutrient availability may lead to increased inputs of fresh marine POC (Zhu et al, 2014).…”

Section: Journal Of Geophysical Research: Oceansmentioning

confidence: 99%

“…Moreover, these inputs of POC, mainly from the Yellow River, were pre-aged and thus contributed a more decay-resistant component to the POC in the YS (Bao et al, 2016;Tao et al, 2015Tao et al, , 2016Wang et al, 2012;Xue et al, 2017;Zhao et al, 2018); over the past decades, due to the decrease in the total suspended solids load, POC flux form of the Yellow River has also decreased by 90% (Ran et al, 2013). By contrast, the labile marine-sourced organic carbon from primary production is the major component (~97%) of POC in the YS (Tao et al, 2016;Zhao et al, 2018), and the enhanced nutrient availability may lead to increased inputs of fresh marine POC (Zhu et al, 2014). As a result, the terrestrially derived POC can be efficiently buried in sediments (Tao et al, 2016), while the decomposition of marine-sourced POC dominates the mineralization process in the YS (Song, Liu, Zhu, et al, 2016;Zhao et al, 2018).…”

Section: Journal Of Geophysical Research: Oceansmentioning

confidence: 99%

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Deoxygenation and Its Controls in a Semienclosed Shelf Ecosystem, Northern Yellow Sea

et al. 2019

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Deoxygenation is a global problem in open oceans and coastal regions and has led to the expansion of oxygen minimum zones and coastal hypoxia. Here, using time series observations in the northern Yellow Sea, we illustrate the seasonality of deoxygenation and associated mechanisms in this semienclosed shelf ecosystem and explore the linkage of dissolved oxygen (DO) declines with seawater warming and anthropogenic eutrophication. Our results show that the DO concentration displayed a decreasing trend in winter, with rates of~0.76 and~0.78 μmol kg −1 yr −1 in the surface and bottom waters, respectively. The rapid decline in DO was also observed in the bottom water in summer, with a decreasing rate of~1.43 μmol kg −1 yr −1 . In winter, when the water column is vertically homogeneous, the near saturation of DO indicates that physical mixing overwhelmed biological activities, and the estimated results and a linear correlation between DO concentration and temperature suggest that ocean warming is the most plausible driver of deoxygenation in this region in winter. In the stratified water column during summer, increased nutrient availability at the surface and consequently enhanced productivity are responsible for the drawdown of DO in the bottom layer, and the stoichiometric pattern between DO and nitrate also suggests a cascading linkage between the exacerbation of eutrophic conditions and bottom deoxygenation. Our results provide strong evidence that a rapid, semienclosed shelf-scale decline in DO is underway and highlight the necessity of nutrient reduction strategies in the future. Plain Language Summary Studying the deoxygenation and its drivers is important tounderstand the changing marine ecosystem. As an important semienclosed marginal shelf sea in the Northwest Pacific, the Yellow Sea (YS) is one of the world's 64 Large Marine Ecosystems. Due to the natural and anthropogenic stressors, the YS ecosystem has undergone drastic changes over the past decades. In this study, using the long-term monitoring data set in the northern YS (NYS), the deoxygenation and associated mechanisms in this semienclosed shelf ecosystem are examined in seasonality, and the linkage of dissolved oxygen declines with seawater warming and anthropogenic eutrophication is explored. The results imply that a rapid, semienclosed shelf-scale declining of dissolved oxygen is ongoing in the continental margin area, reflecting an alarming symptom of coastal environment degradation in the NYS. This work also offers a viewpoint of deoxygenation mechanisms in terms of seasonality in the multiple pressures-influenced margins, improving our understanding of the marine environmental responses to anthropogenic and natural perturbations.

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Section: Journal Of Geophysical Research: Oceanssupporting

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Journal Of Geophysical Research: Oceansmentioning

confidence: 99%

Section: Journal Of Geophysical Research: Oceansmentioning

confidence: 99%

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Deoxygenation and Its Controls in a Semienclosed Shelf Ecosystem, Northern Yellow Sea

et al. 2019

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Carbon isotopic constraints on the degradation and sequestration of organic matter in river‐influenced marginal sea sediments

Druffel

et al. 2022

Limnology & Oceanography

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Organic matter degradation and sequestration in marine sediments are important processes involved in carbon cycling in the ocean. Here, we present the results of carbon isotope ( 14 C and 13 C) and concentration measurements of sedimentary organic carbon (SOC), pore-water dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) in sediments collected from the East China Sea, Yellow/Bohai Sea, and South China Sea. Our results indicated that selective degradation and preservation of organic matter occurred in these sediments, and marine-derived young organic carbon degraded preferentially and rapidly, resulting in high concentrations of pore-water DOC and DIC with distinct carbon isotopic signatures. The average 14 C age of pore-water DOC was thousands of years younger than that of SOC in the sediment, suggesting that DOC was newly produced and cycled much faster than SOC. Aged SOC was refractory and preserved in sediments. Using a dual-isotope three-end-member model, the contributions of potential sources to SOC, DOC, and DIC were estimated. Marine-derived biomass organic carbon contributed the most to DOC, and dissolution of biogenic carbonate contributed the most to DIC. Riverine inputs of pre-aged soil and fossil organic carbon dominated the SOC pool. Our study demonstrated that marginal sea sediments are important sites of young DOC and DIC fluxes into the water column, thus acting as a major pathway for carbon and nutrient cycling in the ocean.

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Methane in the Yellow Sea and East China Sea: dynamics, distribution, and production

Zhang

et al. 2021

J. Ocean. Limnol.

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The remineralization of sedimentary organic carbon in different sedimentary regimes of the Yellow and East China Seas

Cited by 65 publications

References 91 publications

Deoxygenation and Its Controls in a Semienclosed Shelf Ecosystem, Northern Yellow Sea

Deoxygenation and Its Controls in a Semienclosed Shelf Ecosystem, Northern Yellow Sea

Carbon isotopic constraints on the degradation and sequestration of organic matter in river‐influenced marginal sea sediments

Methane in the Yellow Sea and East China Sea: dynamics, distribution, and production

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