Dissolved Lead in the East China Sea With Implications for Impacts of Marginal Seas on the Open Ocean Through Cross‐Shelf Exchange

<p><span>As connected through relatively narrow and shallow straits, inflow and outflow volume transports of the northeast Asian marginal seas (NEAMS) are strongly forced to yield significant convergence or divergence and resulting rise or drop in spatially-averaged sea level. Here, we examined interannual variations of August NEAMS-mean sea level observed from satellite altimetry from 1993 to 2019. Typhoon activity was found to be a primary factor controlling the interannual variations of NEAMS-mean sea level in August. Relatively high August sea level over the NEAMS is derived in years when more typhoons pass through the East China Sea (Period H) due to typhoon-induced Ekman transports. The resultant NEAMS-mean sea level is a few cm higher than that during the years of less or no typhoon activity in the East China Sea (Period L). This study highlights the importance of typhoon (hurricane) activity on interannual variations of regional sea level in the mid-latitude and semi-enclosed marginal seas.</span></p>

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Quantifying the contributions of riverine vs. oceanic nitrogen to hypoxia in the East China Sea

Biogeosciences ◽

10.5194/bg-17-2701-2020 ◽

2020 ◽

Vol 17 (10) ◽

pp. 2701-2714 ◽

Cited By ~ 2

Author(s):

Fabian Große ◽

Katja Fennel ◽

Haiyan Zhang ◽

Arnaud Laurent

Keyword(s):

Oxygen Consumption ◽

East China Sea ◽

River Estuary ◽

Open Ocean ◽

East China ◽

Yangtze River Estuary ◽

Biogeochemical Model ◽

The East China Sea ◽

China Sea ◽

Nitrogen Loads

Abstract. In the East China Sea, hypoxia (oxygen ≤ 62.5 mmol m−3) is frequently observed off the Changjiang (or Yangtze River) estuary covering up to about 15 000 km2. The Changjiang is a major contributor to hypoxia formation because it discharges large amounts of freshwater and nutrients into the region. However, modeling and observational studies have suggested that intrusions of nutrient-rich oceanic water from the Kuroshio Current also contribute to hypoxia formation. The relative contributions of riverine vs. oceanic nutrient sources to hypoxia have not been estimated before. Here, we combine a three-dimensional physical-biogeochemical model with an element-tracing method to quantify the relative contributions of nitrogen from different riverine and oceanic sources to hypoxia formation during 2008–2013. Our results suggest that the hypoxic region north of 30∘ N is dominated by Changjiang inputs, with its nitrogen loads supporting 74 % of oxygen consumption. South of 30∘ N, oceanic nitrogen sources become more important, supporting 39 % of oxygen consumption during the hypoxic season, but the Changjiang remains the main control on hypoxia formation also in this region. Model scenarios with reduced Changjiang nitrogen loads and reduced open-ocean oxygen levels suggest that nitrogen load reductions can significantly reduce hypoxia in the East China Sea and counteract a potential future decline in oxygen supply from the open ocean into the region.

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Contrasting diversity pattern ofCytophaga–Flavobacteriain the estuarine and open ocean regions of the East China Sea

Marine Biology Research ◽

10.1080/17451000701696278 ◽

2007 ◽

Vol 3 (6) ◽

pp. 428-437

Author(s):

Yonghui Zeng ◽

Xihan Chen ◽

Nianzhi Jiao

Keyword(s):

East China Sea ◽

Open Ocean ◽

East China ◽

The East China Sea ◽

Diversity Pattern ◽

China Sea

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Biogeochemical characteristics of suspended particulates at deep chlorophyll maximum layers in the East China Sea

10.5194/bg-2017-290 ◽

2017 ◽

Cited By ~ 1

Author(s):

Qianqian Liu ◽

Selvaraj Kandasamy ◽

Baozhi Lin ◽

Huawei Wang ◽

Chen-Tung Arthur Chen

Keyword(s):

Organic Matter ◽

East China Sea ◽

East China ◽

Deep Chlorophyll Maximum ◽

The East China Sea ◽

Chl A ◽

Carbon And Nitrogen ◽

China Sea ◽

Marginal Seas ◽

Suspended Particulates

Abstract. Continental shelves and marginal seas are key sites of particulate organic matter (POM) production, remineralization and sequestration, playing an important role in the global carbon cycle. Elemental and stable isotopic compositions of organic carbon and nitrogen are frequently used for characterizing organic matter and distinguishing their sources in suspended particulates and surface sediments in the marginal seas. Here we investigate suspended particulate matters (SPM) collected from the deep chlorophyll maximum (DCM) layer in the continental shelf of the East China Sea for particulate organic carbon and nitrogen (POC and PN) contents and their isotopic compositions (δ13CPOC and δ15NPN) to understand biogeochemical characteristics of POM straddling at biotic-dominated DCM depths. When combined with hydrographic parameters, such as temperature, salinity and turbidity, and chlorophyll a (Chl a), these elemental and isotopic results revealed that POM in the DCM layers was largely from the newly-produced, in situ phytoplankton-dominated OM and have wider δ13CPOC and δ15NPN compositions than previously thought. As supported by the POC to Chl a ratio, a large variation of δ13CPOC was resulted from the changes in primary productivity and phytoplankton species, whereas the nutrient status and δ15N of dissolved nitrate were the main controlling factors of δ15NPN variability in the DCM layers. Consistently, the spatial distribution of δ15NPN showed a similarity with the current pattern in the East China Sea, with 15N-enriched freshwater in the coastal region and Kuroshio Water in the northeast of Taiwan Island, but nutrient-depleted Taiwan Warm Current Water in the mid-shelf; as the latter seems to have promoted the N2-fixation, resulting in the depleted δ15NPN in the mid-shelf. Furthermore, SPM investigated here seems not to be influenced by the terrestrial organic matter supplied by the Yangtze River (Changjiang) in summer 2013, a finding that is contrary to a number of previous studies' conclusion. Nonetheless, given the complications associated with stable isotopes of organic matter, additional parameters such as radiocarbon and biomarkers are crucial to revalidate whether or not SPM in the DCM depths is influenced by terrestrial organic compounds in the river-dominated East China Sea.

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Quantifying the contributions of riverine vs. oceanic nitrogen to hypoxia in the East China Sea

10.5194/bg-2019-342 ◽

2019 ◽

Cited By ~ 1

Author(s):

Fabian Große ◽

Katja Fennel ◽

Haiyan Zhang ◽

Arnaud Laurent

Keyword(s):

Oxygen Consumption ◽

East China Sea ◽

Open Ocean ◽

East China ◽

Yangtze River Estuary ◽

Changjiang River ◽

The East China Sea ◽

China Sea ◽

The Changjiang River ◽

Nitrogen Loads

Abstract. In the East China Sea, hypoxia (oxygen ≤ 62.5 mmol m−3) is frequently observed off the Changjiang (or Yangtze) River estuary covering up to about 15,000 km2. The Changjiang River is a major contributor to hypoxia formation because it discharges large amounts of freshwater and nutrients into the region. However, modelling and observational studies have suggested that intrusions of nutrient-rich oceanic water from the Kuroshio also contribute to hypoxia formation. The relative contributions of riverine versus oceanic nutrient sources to hypoxia have not been estimated before. Here, we combine a three-dimensional, physical-biogeochemical model with an element tracing method to quantify the relative contributions of nitrogen from different riverine and oceanic sources to hypoxia formation during 2008–2013. Our results suggest that the hypoxic region north of 30° N is dominated by Changjiang River inputs, with its nitrogen loads supporting 74 % of oxygen consumption. South of 30° N, oceanic nitrogen sources become more important supporting 39 % of oxygen consumption during the hypoxic season, but the Changjiang River remains the main control of hypoxia formation also in this region. Model scenarios with reduced Changjiang River nitrogen loads and reduced open-ocean oxygen levels suggest that nitrogen load reductions can significantly reduce hypoxia in the East China Sea and counteract a potential future decline in oxygen supply from the open ocean into the region.

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Mapping gaseous amines, ammonia, and their particulate counterparts in marine atmospheres of China's marginal seas: Part 2 – spatiotemporal heterogeneity, causes and hypothesis

10.5194/acp-2021-301 ◽

2021 ◽

Author(s):

Yating Gao ◽

Dihui Chen ◽

Yanjie Shen ◽

Yang Gao ◽

Huiwang Gao ◽

...

Keyword(s):

East China Sea ◽

Yellow Sea ◽

Bohai Sea ◽

Chemical Conversion ◽

The Yellow Sea ◽

East China ◽

Marine Atmosphere ◽

The East China Sea ◽

China Sea ◽

Marginal Seas

Abstract. In this study, spatiotemporal heterogeneities in the concentrations of alkaline gases and their particulate counterparts in the marine atmosphere over China's marginal seas were investigated in terms of causes and chemical conversion during two winter cruise campaigns, using semi-continuous measurements made by an onboard URG-9000D Ambient Ion Monitor-Ion chromatograph (AIM-IC, Thermofisher). During the cruise campaign over the East China Sea on December 27, 2019–January 6, 2020, the concentrations of atmospheric trimethylamine (TMAgas) varied by approximately one order of magnitude, with an average (±standard deviation) of 0.10 ± 0.04 µg m−3. Corresponding means were 0.037 ± 0.011 µg m−3 over the Yellow Sea on 7–16 January 2020 and 0.031 ± 0.009 μg m−3 over the Yellow Sea and the Bohai Sea on 9–22 December 2019. In contrast, the simultaneously observed concentrations of TMA in PM2.5, detected as TMAH+, over the East China Sea were 0.098 ± 0.068 µg m−3 and substantially smaller than 0.28 ± 0.18 μg m−3 over the Yellow Sea and the Bohai Sea on 9–22 December 2019. A significant correlation between TMAgas and particulate TMAH+ was obtained over the East China Sea, but no correlation existed over the Yellow Sea and Bohai Sea. The proportional or disproportional variations in concentrations of TMAgas with particulate TMAH+ over the sea zones were likely attributed to the difference in enrichment of TMAH+ in the sea surface microlayer. In addition, spatiotemporal heterogeneities in concentrations of atmospheric ammonia (NH3gas), atmospheric dimethylamine (DMAgas), and DMA in PM2.5, detected as DMAH+, were also investigated. Case analyses were performed to illustrate the formation and chemical conversion of particulate aminium ions in marine aerosols. Finally, we hypothesized a release of basic gases and particulate counterparts from the ocean to the atmosphere, together with secondary formation of DMAH+ and chemical conversion of TMAH+, in the marine atmosphere.

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