Enhanced phytoplankton and bacterioplankton production coupled to coastal upwelling and an anticyclonic eddy in the Ulleung basin, East Sea

Hyun, Jung‐Ho; Kim, Dongseon; Shin, Chang-Woong; Noh, Jae-Hoon; Yang, Eun Jin; Mok, Jin-Sook; Kim, Sung-Han; Kim, Hyuncheol; Yoo, Sinjae

doi:10.3354/ame01280

Cited by 78 publications

(61 citation statements)

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“…A similar high C org content as in the UB is rarely found in deep-sea sediment underlying oxic bottom water at depths exceeding 2000 m, except for a Chilean upwelling site (Lee et al, 2008). This high C org content in the UB is mainly associated with the combination of enhanced biological production resulting from the formation of coastal upwelling (Hyun et al, 2009a), enhanced new production in summer (Kwak et al, 2013), occurrence of an intrathermocline eddy resulting in the extraordinary subsurface chlorophyll a maximum (Kim et al, 2012), high C org accumulation rates exceeding 2 g C m −2 year −1 (Lee et al, 2008), and high export production . Consequently, high benthic mineralization resulting from the high C org in the sediment implied that the UB is a biogeochemical hotspot where significant turnover of organic matter and nutrient regeneration occur.…”

Section: The Ub As a Biogeochemical Hotspotmentioning

confidence: 75%

“…1). Compared to the other two basins, the surface waters of the Ulleung Basin (UB) are characterized by higher phytoplankton biomass and primary production (Yamada et al, 2005;Yoo and Park, 2009), which is associated with coastal upwelling (Hyun et al, 2009a). The enhanced biological production in the euphotic zone of the UB is responsible for the high C org content (> 2.5 % wt) in the sediment, and the highest rates of C org oxidation compared to other deep-sea sediments with similar depth range (Lee et al, 2008;Hyun et al, 2010).…”

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confidence: 99%

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Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

et al. 2017

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Abstract. Rates and pathways of benthic organic carbon (C org ) oxidation were investigated in surface sediments of the Ulleung Basin (UB) characterized by high C org contents (> 2.5 %, dry wt.) and very high contents of Mn oxides (> 200 µmol cm −3 ) and Fe oxides (up to 100 µmol cm −3 ). The combination of geochemical analyses and independently executed metabolic rate measurements revealed that Mn and Fe reduction were the dominant C org oxidation pathways in the center of the UB, comprising 45 and 20 % of total C org oxidation, respectively. By contrast, sulfate reduction was the dominant C org oxidation pathway, accounting for 50 % of total C org mineralization in sediments of the continental slope. The relative significance of each C org oxidation pathway matched the depth distribution of the respective electron acceptors. The relative importance of Mn reduction for C org oxidation displays saturation kinetics with respect to Mn oxide content with a low half-saturation value of 8.6 µmol cm −3 , which further implies that Mn reduction can be a dominant C org oxidation process even in sediments with lower MnO 2 content as known from several other locations. This is the first report of a high contribution of manganese reduction to C org oxidation in offshore sediments on the Asian margin. The high manganese oxide content in the surface sediment in the central UB was maintained by an extreme degree of recycling, with each Mn atom on average being reoxidized ∼ 3800 times before permanent burial. This is the highest degree of recycling so far reported for Mn-rich sediments, and it appears linked to the high benthic mineralization rates resulting from the high C org content that indicate the UB as a biogeochemical hotspot for turnover of organic matter and nutrient regeneration.

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Section: The Ub As a Biogeochemical Hotspotmentioning

confidence: 75%

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confidence: 99%

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

et al. 2017

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“…We speculate two potential scenarios: (1) An upward extension of denitrifying bacterial activity in the sediments to the bottom waters at 'micro-reducing environments̓ caused by high deposition rates of organic matter that might be accompanied with recent trends of warming and decrease in DO in the bottom layer, and (2) an 'aerobic denitrification,̓ which utilizes both DO and nitrate in the deep water column of the EJS, although this process has not yet been verified in an ocean system. The UB is the most productive region in the EJS due to a coupling of coastal upwelling and active eddy feature (Lee and Kim 2003;Hyun et al 2009). The region near the TtS is also a high primary production area due to the input of the Amur River (Tishchenko et al 2007).…”

Section: Extended Benthic Denitrification To Bottom Waters Vs 'Aerobmentioning

confidence: 99%

Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

Kim¹,

Min²,

Lee³

2012

Terr. Atmos. Ocean. Sci.

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We present evidence of denitrification on the continental slopes of the Ulleung Basin (UB) and the Eastern Japan Basin (EJB) near the Tatar Strait (TtS) in the East/Japan Sea (EJS), despite its high water column dissolved oxygen concentrations. Some nutrient concentration data deviate significantly from the fitted regression line of nitrate (N) vs. phosphate (P) in deep waters, indicating a loss of nitrate in the region. The EJS has a lower N/P ratio (ca. 12.4 below 300 dbar) than a traditional Redfield ratio (16). The N/P ratio and oxygen concentration are substantially lower at several locations whose depths are close to the sediment-water interface, near TtS (500 -1100 dbar) and in UB (1100 -2200 dbar). The decreased nitrate concentration is smaller than the expected nitrate level (a low N/P ratio of < 12.4), and a secondary nitrite peak near the bottom of these two regions: taken collectively, both indicate the presence of denitrification in the bottom layer. It is speculated that active re-mineralization and denitrification may occur simultaneously along the rich organic matter bottom layer on the slope environment. Denitrification rates are estimated at ~3 -33 μmol N m -2 d -1 . Current estimates do not support the previous idea of basin-wide denitrification in EJS, although the N/P ratio is low like in other hypoxic/anoxic seas. A better understanding of the denitrification process is necessary for predicting future changes of nitrogen cycle in the well-oxygenated EJS considering the decadal-scale physical and biogeochemical changes that have occurred.

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“…On a global scale, the value obtained for the southern EJS is generally at the higher level, comparing with other oceanic regions (Table 5). Taking into account that the southern EJS (especially the Ulleung Basin) is highly productive (Hyun et al, 2009), the estimate obtained in this study is rather remarkable. Such high estimates can be explained by the exceptionally high levels of atmospheric anthropogenic nitrogen deposition over the coastal seas downwind of East Asia (Krishnamurthy et al, 2007;Duce et al, 2008).…”

Section: Biogeochemical Implicationsmentioning

confidence: 78%

Sources and fluxes of organic nitrogen in precipitation over the southern East Sea/Sea of Japan

Yan

Kim

2015

Atmos. Chem. Phys.

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Abstract. We measured total dissolved reactive nitrogen in precipitation samples collected at Uljin, a Korean coastal site upwind of the southern East Sea/Sea of Japan (EJS), selected as a representative study site of atmospheric deposition over the northwestern Pacific margin. NO − 3 was found to be the most abundant nitrogen species, followed by NH + 4 and dissolved organic nitrogen (DON). Air-mass back-trajectory (AMBT) analysis revealed that a significant fraction of the inorganic nitrogen (NO − 3 and NH + 4 ) originated from mainland Asia, whereas the DON was primarily derived from Korea. Using varimax-rotated factor analysis in combination with major ions as tracers, agricultural activities in Korea were identified as the primary sources of DON in these samples. In addition, a positive correlation was found at Uljin between the size of organic fraction in total reactive nitrogen and nitrogen to carbon atomic ratio in organic matter. This correlation has also been observed at other locations worldwide, implying the utilization potential of atmospheric organic nitrogen might increase with its proportion in total nitrogen. Combining wet deposition measurements in this study with literature values for dry deposition observed at a remote island in the EJS, the total atmospheric depositional flux of reactive nitrogen was estimated to be 115 mmol N m −2 yr −1 over the southern EJS. Our study sheds new light on the potentially significant contribution to primary productivity of the northwestern Pacific Ocean by atmospheric deposition of nitrogen, especially the organic fraction.

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Enhanced phytoplankton and bacterioplankton production coupled to coastal upwelling and an anticyclonic eddy in the Ulleung basin, East Sea

Cited by 78 publications

References 38 publications

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Deep Nitrate Deficit Observed in the Highly Oxygenated East/Japan Sea and Its Possible Cause

Sources and fluxes of organic nitrogen in precipitation over the southern East Sea/Sea of Japan

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