Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

Meng, Qicheng; Zhang, Wenyan; Zhou, Feng; Liao, Yibo; Yu, Peisong; Tang, Yanbin; Ma, Xiao; Tian, Di; Ding, Ruibin; Ni, Xiaobo; Zeng, Dingyong; Schrum, Corinna

doi:10.1029/2021jg006705

Cited by 9 publications

(6 citation statements)

References 90 publications

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“…Dynamic changes in the Changjiang diluted water (CDW) (Zhang et al, 2018;Wei et al, 2021a), topography (Wang et al, 2012;Zhu et al, 2016), and variations of wind patterns (Ni et al, 2016) and ocean circulations (Zhou et al, 2017) appear to modulate the structure of the hypoxia jointly each year. The coupling between surface phytoplankton bloom and bottom hypoxia has been confirmed in several studies (Wang et al, 2017;Chen et al, 2021a;Meng et al, 2022). Furthermore, a temporal and spatial mismatch or decoupling of surface high-biomass regions and hypoxic zones was also observed.…”

Section: Introductionsupporting

confidence: 57%

Subsurface oxygen minima regulated by remineralization and bottom flushing along 123°E in the inner East China Sea

et al. 2023

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The summer hypoxia off the Changjiang Estuary is one of the largest coastal hypoxic systems in the world and has displayed spatial heterogeneity in recent years. Based on observation data in the summer of 2014, hypoxia was identified both in the bottom and mid-layers. Except for the typical bottom hypoxia in the submarine canyon, the subsurface oxygen minima (SOM) were captured in the mid-layer of 10~15 m, with lower dissolved oxygen in the mid-layer than at the bottom (30–50 m). This SOM phenomenon was located in the lower boundary of the pycnocline and above the Taiwan warm current (TWC) and Kuroshio subsurface water (KSSW). Due to the southern expansion of Changjiang diluted water (CDW), a high phytoplankton biomass (the maximum chlorophyll a of 25 μg L−1, pH of 8.6, and DO of 11 mg L−1) band occupied the surface area along 123°E. By analyzing the 24-h continuous observation and high-resolution profile data, we revealed that the subsurface oxygen minima were predominantly controlled by remineralization and bottom-flushing effects. Fast local consumption occurred near the pycnocline layer, while the lateral transport of oxygen-rich ambient water replenished the bottom oxygen deficit from south to north. We summarize and contextualize three hot spots of hypoxia into a conceptual diagram and emphasize the influences of advection, mixing, and respiration on their location and severity. Overall, compared with the discussion about the low DO background of TWC/KSSW, this research highlights the flushing effects of TWC/KSSW that will reshape the hypoxia structure and alleviate the hypoxia severity in the south hypoxia area off the Changjiang Estuary.

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Section: Introductionsupporting

confidence: 57%

Subsurface oxygen minima regulated by remineralization and bottom flushing along 123°E in the inner East China Sea

et al. 2023

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“…The model generally overestimated the DO concentration in bottom water when the observed DO concentration was <8 mg•L −1 (Figure 4D). This is probably because the sediment oxygen consumption was not taken into account by the model (Meng et al, 2022).…”

Section: Model Validation and Limitationsmentioning

confidence: 99%

Response Process of Coastal Hypoxia to a Passing Typhoon in the East China Sea

Meng

Zhou

et al. 2022

Front. Mar. Sci.

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Details of the development of coastal hypoxia in response to the passage of Typhoon Bavi (2020) in the East China Sea were reconstructed by numerical modeling using a three-dimensional coupled physical–biogeochemical model. The model was validated via repeated surveys along a transect across a submerged river valley off the Changjiang Estuary before and after the passage of Typhoon Bavi. Before Bavi’s arrival, survey data indicated that the coastal hypoxia had formed off the Changjiang Estuary. However, the hypoxia was not eliminated but instead migrated and aggravated along the observed transect after the typhoon passage. This phenomenon cannot be attributed to the typhoon-induced mixing. Simulation results reveal that the observed development and spatial migration of hypoxia was mainly controlled by typhoon-induced oceanic advection. Results show that Bavi stimulated a regional quasi-barotropic cyclonic loop circulation and coastal downwelling reversing general summer circulation patterns. The onshore transport of the warmer shelf water and subsequent downwelling resulted in a warming of coastal water. The southward coastal current and downwelling induced by the typhoon also led to a migration of the hypoxic zone. Meanwhile, a massive transport of resuspended planktonic detritus from the steep inner shelf and the shallow Changjiang bank toward the submerged river valley occurred. This study reveals that the typhoon-driven currents can play an important role in the development of hypoxia and redistribution of deposited organic matter in coastal shelf seas, which may have both short- and long-term effects on the regional marine biogeochemical environment.

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“…Coastal deoxygenation is driven by decaying organic matter, high water temperature, and water-column stratification (Breitburg et al, 2018). Elevated anthropogenic nutrient discharges enhance oxygen consumption by accelerating oxygen demand from mineralization and decomposition of organic material in the subsurface layer (Chen et al, 2022b;Meng et al, 2022;Oschlies et al, 2018;Reed and Harrison, 2016;Su et al, 2020). Global coastal waters have witnessed an exponential spread of low-oxygen regions in recent decades, partially associated with increased terrestrial N inputs (Conley et al, 2009;Reed and Harrison, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…The relative contributions of water-column oxygen consumption (WOC) and sediment oxygen demand (SOD) vary strongly due to differences in water depth and topography of the seabed (Bourgault et al, 2012;Jørgensen et al, 2022;Meng et al, 2022;Wang et al, 2018b). With drastic changes in nutrient loading and hydrodynamics in coastal waters, understanding the drivers and mechanisms of deoxygenation is crucial to establish comprehensive strategies to control and mitigate deoxygenation and forecast future DO trends.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen from agriculture and temperature as the major drivers of deoxygenation in the central Bohai Sea

Yang

Wang

Bouwman

et al. 2023

Science of The Total Environment

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Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

Cited by 9 publications

References 90 publications

Subsurface oxygen minima regulated by remineralization and bottom flushing along 123°E in the inner East China Sea

Subsurface oxygen minima regulated by remineralization and bottom flushing along 123°E in the inner East China Sea

Response Process of Coastal Hypoxia to a Passing Typhoon in the East China Sea

Nitrogen from agriculture and temperature as the major drivers of deoxygenation in the central Bohai Sea

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