Circulations associated with cold pools in the Bohai Sea on the Chinese continental shelf

Zhou, Feng; Huang, Daji; Xue, Huijie; Xuan, Jiliang; Yan, Tao; Ni, Xiaobo; Zeng, Dingyong; Li, Jia

doi:10.1016/j.csr.2017.02.005

Cited by 70 publications

(34 citation statements)

References 47 publications

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“…Among these factors, the topographic features are most static and stay the same for years or longer. The strong vertical mixing of the water column displayed in Figures 2a-2c is not very different from the previously reported winter pattern Zhou et al, 2017). The spring-neap tidal variation is normally a factor that affects the current intensity, but this variation is too weak in the Bohai Sea to change the seasonal water circulation (Wang et al, 2010), let alone the entirely different winter pattern in this study (Figure 4a).…”

Section: Influencing Factors On the Atypical Residual Currents Duringcontrasting

confidence: 65%

“…While highly turbid waters induced by strong resuspension escape the Bohai Sea via the southern Bohai Strait by strong NSCC in winter . This character of sediment budget in the Bohai Sea has been verified by many observations and model studies (e.g., Bi et al, 2011;Bian et al, 2013;Lu et al, 2011;Zhou et al, 2017) and becomes a consensus: "storage in summer but transport out of the Bohai Sea in winter" . The high SSC observed in this study (Figures 2c and 2f) confirms that the winter season is indeed the time when major sediment transport events take place.…”

Section: Implications For Estimating Long-term Sediment Flux Through supporting

confidence: 57%

“…During winter season, strong northerly winds prevail with the longest fetch from the head of the Liaodong Bay to the Laizhou Bay, generating strong waves in the southern and southwestern Bohai Sea that favors strong vertical mixing and more resuspension in the coastal area (Bi et al, ; Wang, Wang, et al, ). From May to September when weak southeastern winds prevail, significant stratification of water column exists (Wang et al, ; Zhou et al, ). This seasonal pattern is clearly seen in Figure where wide ranges of temperature (6.52–16.17 °C; Figure d) and salinity (31.86–32.19 PSU; Figure e) exhibit with strong vertical gradient.…”

Section: Discussionmentioning

confidence: 99%

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Novel, Repeated Surveys Reveal New Insights on Sediment Flux Through a Narrow Strait, Bohai, China

Wang

et al. 2019

JGR Oceans

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Straits are both a choke point and passage through which material and energy are exchanged between two adjoining water bodies. Understanding the mechanisms that drive these exchanges therefore is vital to quantifying the water and sediment budgets in regional and global oceans. Here we present a study in which a novel, phase‐averaging method was employed to better estimate the net‐suspended sediment fluxes through the entire Bohai Strait, the only passage for the massive Yellow River‐delivered sediment to leave the enclosed Bohai Sea for the open Yellow Sea. In winter, the transport through the strait was nearly barotropic in waters well mixed by the energetic winter monsoons. The transport became primarily baroclinic (opposite directions between upper and lower layers) in spring due to stratification, especially in the southern part of the strait. Intermittent but frequent southerly winds in northerly dominated winters were responsible for a net westward sediment transport into the Bohai Sea, a finding contrary to a status quo view. Hence, previous studies in which these intermittent southerly wind busts were not included are believed to have overestimated the sediments export from the Bohai Sea.

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Section: Influencing Factors On the Atypical Residual Currents Duringcontrasting

confidence: 65%

Section: Implications For Estimating Long-term Sediment Flux Through supporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

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Novel, Repeated Surveys Reveal New Insights on Sediment Flux Through a Narrow Strait, Bohai, China

Wang

et al. 2019

JGR Oceans

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“…DO, pH, and DIC were investigated during the summers of 2017 and 2018 along an inshore-offshore transect across the known oxygen depletion area with four cruises being conducted each year (Figure 1 and Table 1). The transect, located off Qinhuangdao City, crossed the southwest of the bowl-shaped depression extending from northeast to southwest (Figure 1; Zhou et al, 2017). In summer, cyclonic circulation is dominant in this area, and horizontal transport in bottom water is weak, with the current velocity <30 cm s −1 (Zhou et al, 2017).…”

Section: Sample Collection and Analysismentioning

confidence: 97%

Summertime Oxygen Depletion and Acidification in Bohai Sea, China

et al. 2020

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Increasing attention has recently been drawn to oxygen depletion and ocean acidification in coastal seas and their impacts on the marine ecosystem. Intensive organic matter degradation combined with weak water exchange is considered to be mainly responsible for bottom water oxygen depletion and acidification. Hypoxia and acidification in the bottom water of Bohai Sea have been frequently observed in summer seasons over the past decade. In this study, monthly surveys were conducted along an inshore-offshore transect in the north Bohai Sea from May to August in 2017 and 2018. The physical structure of the water column in the study area was characterized by a well-mixed surface layer and an essentially homogeneous deep layer that were separated by a strong pycnocline over the period from mid-Jun to late August in both years. Dissolved oxygen (DO), pH, and dissolved inorganic carbon (DIC) in the water column were also split into two layers by the pycnocline and varied little in each layer. No significant interannual variations were observed for the temporal progressions of DO, pH and DIC in the bottom water. Average DO concentration and pH in the bottom water linearly decreased with time from May to August while DIC presented an opposite trend. DO became increasingly unsaturated from mid-June to late August when DO decreased to 96 µmol L −1 and pH to 7.74. The molar ratio of net oxygen consumption to DIC production was 1.42, similar to the Redfield ratio (1.30). Pelagic respiration (>60%) linked to degradation of fresh organic matter prevailed over sediment respiration (<40%) in contributing to the oxygen depletion and acidification observed in this shallow water body. The duration and intensity of oxygen depletion and acidification in the study area were strongly affected by stormy weather events such as typhoons.

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“…The Bohai Sea is a semi-enclosed shallow-water marginal sea of the northwest Pacific Ocean with seasonal stratification (Huang et al, 1999;Zhao et al, 2017;Zhou et al, 2017) and a summertime dissolved oxygen (DO) deficit in its bottom waters (Zhai et al, 2012(Zhai et al, , 2019Zhao et al, 2017;Wei et al, 2019). Spatiotemporal variations in [CH 4 ] and thereby sea-to-air CH 4 fluxes have been previously investigated by Li et al (2010), Zhang et al (2014), and Zang (2018), showing that the Bohai Sea is usually supersaturated with CH 4 , with moderate sea-to-air CH 4 fluxes from 0.8 to 53.9 µmol m −2 d −1 .…”

Section: Introductionmentioning

confidence: 99%

Exploring Sources and Biogeochemical Dynamics of Dissolved Methane in the Central Bohai Sea in Summer

2020

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To clarify the sources and biogeochemical dynamics of dissolved methane (CH 4 ) in shallow-water coastal oceans, we investigated the concentrations, sea-to-air fluxes, and net cycling rate of CH 4 in the central Bohai Sea in summer 2018. During the survey, both summertime stratification and dissolved oxygen (DO) deficit were observed. In the surface layer, CH 4 concentration ([CH 4 ]) ranged from 3.08 to 10.27 nmol kg −1 . The average sea-to-air flux was estimated at 6.46 ± 3.32 µmol m −2 d −1 , indicating that the Bohai Sea serves as a source of atmospheric CH 4 . In the bottom layer, [CH 4 ] ranged from 4.29 to 31.04 nmol kg −1 . The downward increase in [CH 4 ] within the water column indicated substantial sources of CH 4 in the seafloor. Based on the complex relationship between the saturation ratio of CH 4 and DO, three types of CH 4 release from the seafloor were identified, including diagenesis of buried organic matter, natural leakage from geological settings, and anthropogenic release from offshore oil/gas development. The saturation ratios of CH 4 in bottom waters were positively correlated with the degree of stratification of the water column. Using a two-layer box model, sedimentary CH 4 release rates at two oxygen-deficient stations were estimated to be 56.0-60.8 µmol m −2 d −1 , which was much higher than the sea-to-air fluxes. The modeling results also indicated that the majority of seafloor released CH 4 (>90%) was consumed in the water column of this shallow-water coastal sea. This is the first comprehensive study on CH 4 cycling in the Bohai Sea. This work shows the indicative role of DO in identifying multiple CH 4 sources and highlights the dominance of water stratification and microbial consumption in local CH 4 dynamics. KEY POINTS -Dissolved CH 4 exhibited complex relations with oxygen in the Bohai Sea. -Three types of CH 4 sources from seafloor were identified. -Stratification hampered the upward transport of dissolved CH 4 . -Strengths of CH 4 cycling terms are quantified.

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Circulations associated with cold pools in the Bohai Sea on the Chinese continental shelf

Cited by 70 publications

References 47 publications

Novel, Repeated Surveys Reveal New Insights on Sediment Flux Through a Narrow Strait, Bohai, China

Novel, Repeated Surveys Reveal New Insights on Sediment Flux Through a Narrow Strait, Bohai, China

Summertime Oxygen Depletion and Acidification in Bohai Sea, China

Exploring Sources and Biogeochemical Dynamics of Dissolved Methane in the Central Bohai Sea in Summer

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