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The understanding on the chemistry of the East (Japan) Sea, a typical mid-latitude marginal sea, has been dramatically improved
through the CREAMS expeditions, an international cooperative study, carried out during 1990s. The CREAMS studies confirmed
that the East Sea has undergone dramatic changes during the last 50–60 years. One of the most promi...
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... Recent changes in dissolved O 2 and temperature in the East Sea's intermediate and deep waters indicate that the mode of deep-water formation has shifted from bottom to intermediate water formation, likely because of global warming and cli- mate change ( Kim et al. 1996;Gamo 1999;Kim et al. 2001;Kang et al. 2003;Chae et al. 2005). However, sudden bottom-water formation occurred in the Japan Basin in winter 2000-2001(Kim et al. 2002Talley et al. 2003). ...
The East Sea (Japan Sea) is experiencing changes in water temperature, oxygen content, and deep water circulation pattern. These changes, in turn, have affected and will continue to affect carbon cycling in the East Sea, directly and indirectly. As the physical dynamics of the East Sea resembles that of the open ocean, studying inorganic and organic carbon cycling in the East Sea may improve our understanding of global carbon cycling, and consequently enable us to predict more accurately the response of the carbon cycle to global climate change. In our review of inorganic carbon cycling, we focus on the uptake of anthropogenic carbon by the East Sea and the shoaling of the saturation depths of the aragonite and calcite caused by acidification. The saturation depths for aragonite and calcite in the East Sea have shoaled by about 80-220 and 500-700 m, respectively, compared to pre-industrial values. Anthropogenic CO2 in the bottom water of the Japan Basin ranged from 15 to 20 μmol kg-1. The largest water-column inventory of anthropogenic CO2, about 80 mol C m-2, was found in the Japan Basin. The uptake rate of anthropogenic CO2 decreased from 0.6 ± 0.4 mol C m-2 year-1 during the 1992-1999 period to 0.3 ± 0.2 mol C m-2 year-1 during the 1999-2007 period, potentially reflecting the slowing of deep water ventilation in the East Sea. In our review of organic carbon cycling, we focus on sinking particulate organic carbon (POC) and dissolved organic carbon (DOC). Sinking POC flux in the East Sea generally reflected conspicuous events in biological production at the surface. Sinking POC flux in the East Sea was higher than in the nearby Kuroshio region. DOC concentration in the Ulleung Basin of the East Sea was higher than in the open oceans. The high content of the lithogenic component and low radiocarbon content in sinking particles in deep waters suggests that the contribution of resuspended sediment, and potentially other allochthonous sources of organic carbon, is considerable in the East Sea. © Springer International Publishing Switzerland 2016. All rights reserved.
... Such understanding is critical for better assessment of ecosystem health in continental margins. Therefore, the existing time series programs in the marginal sea, namely, the EAST-I (East Asian Seas Timeseries) program for the JES (e.g., Kang et al., 2003) and the SEATS program for the SCS should be sustained and expanded in scope, especially in ecosystem observations. For the ECS, a program similar to the Cal-COFI (California Cooperative Oceanic Fisheries Investigations) program (http://www.calcofi.org/) ...
In this special issue we examine the biogeochemical conditions and marine
ecosystems in the major marginal seas of the western North Pacific Ocean,
namely, the East China Sea, the Japan/East Sea to its north and the South
China Sea to its south. They are all subject to strong climate forcing as
well as anthropogenic impacts. On the one hand, continental margins in this
region are bordered by the world's most densely populated coastal
communities and receive tremendous amount of land-derived materials. On the
other hand, the Kuroshio, the strong western boundary current of the North
Pacific Ocean, which is modulated by climate oscillation, exerts strong
influences over all three marginal seas. Because these continental margins
sustain arguably some of the most productive marine ecosystems in the world,
changes in these stressed ecosystems may threaten the livelihood of a large population of humans. This special issue reports the latest observations of the
biogeochemical conditions and ecosystem functions in the three marginal
seas. The studies exemplify the many faceted ecosystem functions and
biogeochemical expressions, but they reveal only a few long-term trends
mainly due to lack of sufficiently long records of well-designed
observations. It is critical to develop and sustain time series observations
in order to detect biogeochemical changes and ecosystem responses in
continental margins and to attribute the causes for better management of the
environment and resources in these marginal seas.
... What follows concentrates on the ecological response of the uptake of anthropogenic CO 2 (e.g., Gao et al., 2012). CREAMS began in 1993 as a Japan-Korea-Russia international research program to understand the water mass structure and circulation in the Japan/East Sea (e.g., Kang et al., 2003). As the countries involved in CREAMS research are all members of PICES, the necessity for strong ties between PICES and CREAMS was recognized. ...
... The international (Japan-Korea-Russia) cooperative program CREAMS (Circulation Research of the East Asian Marginal Seas), which started in 1993, have played important roles in advancing multi-disciplinary studies in the Japan Sea. The CREAMS confirmed significant changes in the ventilation system in the Japan Sea, a slowdown and complete stop of the bottom water formation for the past 50-60 years, which was quantitatively analyzed using a moving-boundary box model (e.g., Kang et al., 2003, and many references therein). US scientists joined the CREAMS II program in 1998, expanding the research areas (e.g., Talley et al., 2003;Min and Warner, 2005;Postlethwaite et al., 2005). ...
Chemical tracers in seawater, as well as physical parameters such as temperature and salinity, have been measured to better characterize the dynamics of water convection and its spatiotemporal changes in the Sea of Japan (also called the Japan Sea), a semi-closed, hyperoxic marginal sea (maximum depth: ̃3,800 m) in the northwestern corner of the Pacific Ocean. Repeated conductivity, temperature, and depth (CTD) observations and measurements of dissolved oxygen, for more than 30 years, have confirmed that the bottom layer of the Japan Sea, with a thickness of ̃1 km below the boundary at a depth of ̃2,500 m, is characterized by vertical homogeneity with fluctuations of potential temperature and dissolved oxygen of <0.001°C and <0.5 μmol kg-1, respectively. The timescale of the abyssal circulation in the Japan Sea has been estimated to be 100-300 years, using 14C and other chemical tracers. Stable isotope analyses for dissolved He, O2 and CH4 have given us information on their unique geochemical cycles in the Japan Sea. Profiles of the short-lived radioisotope 222Rn just above the sea bottom have brought new insights into the short-term lateral water movement with a timescale of several days in the Japan Sea bottom water. It is of special concern that the gradual deoxygenation and warming of the bottom water over the last 30 years have resulted in an ̃10% decrease in dissolved oxygen and ̃0.04°C increase in potential temperature, suggesting a change of the deep convection system in the Japan Sea. The temporal changes in the vertical profiles of tritium from 1984 to 1998 have suggested a shift of the abyssal circulation pattern from a ``total (overall) convection mode" to a ``shallow (partial) convection mode". It is likely that the global warming since the last century has hindered the formation of dense surface seawater and its ability to sink down to the bottom, isolating the bottom layer from the deep convection loop that is indispensable as the source of cold and oxygen-rich water. However, the decreasing trend of bottom dissolved oxygen between 1977 and 2010 was not monotonous; rather, it was interrupted by an occasional break in the winter of 2000-2001, when severely cold weather may have resulted in especially dense surface water to sink down to the bottom layer for its ventilation.
... Recent studies of the EJS have reported changes in DO in intermediate and deep waters, claiming that the mode of deep water formation has been shifting from bottom to intermediate water formation mode due to global warming (Kim and Kim, 1996; Kim et al., 2001; Kang et al., 2003; Chae et al., 2005). However, other studies reported sudden bottom-water formation in the northern EJS in winter 2000 –2001 (Kim et al., 2002; Senjyu et al., 2002; Talley et al., 2003; Tsunogai et al., 2003). ...
We present spatial distributions of the mixing ratio and properties of the East/Japan Sea Intermediate Water (ESIW) at its core density layer (σθ = 27.2-27.3) based on high-quality hydrographic data observed in the East/Japan Sea (EJS) during summer 1999. ESIW is defined as a source water type showing minimum salinity and maximum dissolved oxygen concentration. ESIW plays an important role in supplying dissolved oxygen and transporting anthropogenic carbon into the intermediate/deep layers in EJS. Studying the ESIW formation and distribution processes may provide insights on EJS's shallow- to mid-depth thermohaline circulation and recent ocean changes. Here, we combine the previously estimated mixing ratio of ESIW, based on Optimum Multi-Parameter (OMP) analysis, and its physicochemical properties, such as pressure, dissolved oxygen, and phosphate, interpolated onto several isopycnic surfaces (σθ = 27.20, 27.25, and 27.30). The physicochemical properties of ESIW show steep north-south gradients across the subpolar front at 40-41°N. Higher dissolved oxygen concentrations (≥335 μmol kg-1) of ESIW are found in the western Japan Basin particularly off the Primorye coast, indicating a potential source region. The spatial and depth distributions of apparent oxygen utilization (AOU) on the ESIW isopycnic surfaces indicate that the subduction of ESIW occurs at 131-133°E (Ulleung Basin) across the subpolar front to the south. The density layer of ESIW shoals near the Korean coast in the Ulleung Basin, implying a potential link to coastal upwelling. The relative age of ESIW at its core layer is estimated from the oxygen utilization rate and AOU. The correlation between the pCFC12 and relative ages, and AOU estimated at 90% surface water oxygen saturation condition suggests a decadal-scale ventilation of ESIW (≤24 years). Younger waters at the ESIW coexist with the high-salinity intermediate water at the same density layer in the eastern Japan Basin. Our analysis suggests that ESIW is sensitive to climate forcing and an important shallow- to mid-depth thermohaline circulation component of EJS.
... The East Sea may also be a regional reservoir of anthropogenic carbon through its active exchange with the atmosphere (Chen et al., 1995;Park et al., 2006). More detailed information of hydrographic properties distributions including that of the CFC tracer data of the East Sea observed from recent extensive hydrographic observations during the Circulation Research of East Asian Marginal Seas (CREAMS) program during the 1990s and the current expeditions in 1999 is described elsewhere (Kang et al., 2003;Kim et al., 2004;Talley et al., 2004;Talley et al., 2006; Talley web site, http://sam.ucsd.edu/onr_data/). ...
Dissolved carbon tetrachloride (CCl4) was measured for the first time in the East Sea (Sea of Japan) during the summer of 1999. Fairly high concentrations (> 0.5 pmol kg−1 at the minimum) of CCl4 were observed throughout the water column to the bottom (> 3500 m), with evidence of significant depletion of this compound in the well-oxygenated thermocline waters. CCl4 loss rates below 200 m depth were estimated to range from near zero to 0.05 yr−1 using a tracer-calibrated mixing model, and from 0.04 to 0.07 yr−1 using the CFC-12 partial pressure (pCFC-12) age technique. The results from the mixing model and pCFC-12 age technique are in fairly good agreement in the upper 1500 m of water column, but show systematic differences in the deep waters below 1500 m that are likely due to biases in the pCFC-12 age technique. Despite relatively rapid removal in the upper 500 m water column, the low removal rates for CCl4 in the cold, deep waters of the East Sea estimated using the mixing model (< 0.02 yr−1 for depths > 2000 m) indicate that this compound can be a potentially useful quantitative ocean tracer in certain regions.
... The carbon cycle studies in the EJS have been carried out as part of the CREAMS studies (Kang et al., 2003a). However, they focused on the solubility pump (Oh et al., 1999) among various pumping mechanisms in the ocean, such as the solubility pump at the air-sea interface, the biological pump in the surface waters, the carbonate pump associated with carbonate deposition at the sea floor, and the dynamic pump associated with ocean circulation. ...
Recent findings on water masses, biogeochemical tracers, deep currents and basin-scale circulation in the East/Japan Sea,
and numerical modeling of its circulation are reviewed. Warming continues up to 2007 despite an episode of bottom water formation
in the winter of 2000–2001. Water masses have definitely changed since the 1970s and further changes are expected due to the
continuation of warming. Accumulation of current data in deep waters of the East/Japan Sea reveals that the circulation in
the East/Japan Sea is primarily cyclonic with sub-basin scale cyclonic and anticyclonic cells in the Ulleung Basin (Tsushima
Basin). Our understanding of the circulation of intermediate water masses has been deepened through high-resolution numerical
studies, and the implementation of data assimilation has had initial success. However, the East/Japan Sea is unique in terms
of the fine vertical structures of physical and biogeochemical properties of cold water mass measured at the highest precision
and their rapid change with the global warming, so that full understanding of the structures and their change requires in-depth
process studies with continuous monitoring programs.
... It is extremely interesting to note that the shift in the conveyor-belt system in the East/Japan Sea has a remarkable resemblance to possible changes in the global oceanic conveyor-belt system in this century Gamo and Horibe (1983) for 1979, Chen et al. (1999 for 1992, Kang et al. (2003aKang et al. ( ) for 1996Kang et al. ( and 1999 associated with recent global warming: a weakening of Atlantic thermohaline circulation (Latif, Roeckner, Mikolajewicsz, & Ross, 2000;Manabe & Stouffer, 1993). A simple MBBM was successfully applied to quantify the processes involved in changes observed in the East/Japan Sea and used to predict the consequences of such changes in the future. ...
The East/Japan Sea is a mid-latitude marginal sea that has undergone dramatic changes during the last 50–60 years. One of the most prominent characteristics of these changes is a rapid decrease in the amount of dissolved oxygen in deep waters. As a consequence of these changes, some investigators have even argued that the East/Japan Sea might become an anoxic sea in the next 200 years. While the causes of these changes are still under investigation, it has been shown that they are mainly due to modifications in the mode of the deep water ventilation system in the East/Japan Sea: a slowdown and complete cessation of bottom water formation accompanied by an enhancement of upper water formation instead. A simple moving-boundary box model (MBBM) was developed in order to analyze and quantify the processes involved in such changes over the last 50–60 years. Using a MBBM, we estimated the levels of several conservative chemical tracers (CFCs, Tritium, SF6, 137Cs) and bioactive tracers (oxygen and phosphate) in the deep water masses of the East/Japan Sea, comparing these with the historical data available, and making predictions for the near future. The model predicts that the East/Japan Sea should remain well-oxygenated, despite recent rapid oxygen decreases in its deep waters, accompanied by such structural changes as a shrinking of its oxygen-depleted deeper waters and an expansion of its oxygen-rich upper waters over the next few decades.
The East Sea (also known as the Japan Sea) is connected to the Northwest Pacific via shallow straits and has independent deep water circulation, as a model miniature ocean. The radiocarbon age of dissolved organic carbon (DOC) in the East Sea ranged from 2,000 to 3,700 years, exceeding the water turnover time (∼100 years). The oldest DOC was found in the subsurface layer characterized by the Tsushima Warm Water. Comparison of the radiocarbon content and concentration of DOC in the East Sea to those in the ocean suggests that aged DOC was transported conservatively from the Northwest Pacific to the East Sea via the shallow Tsushima Warm Current. The fractions of DOC released by serial‐oxidation of the oldest DOC sample had identical radiocarbon ages, implying that refractory DOC was produced in situ and added to the DOC pool in the East Sea.
In this special issue we examine the biogeochemical conditions and marine ecosystems in the major marginal seas of the western North Pacific Ocean, namely, the East China Sea, the Japan/East Sea to its north and the South China Sea to its south. They are all subject to strong climate forcing as well as anthropogenic impacts. On the one hand, continental margins in this region are bordered by the world's most densely populated coastal communities and receive tremendous amounts of land derived materials. On the other hand, the Kuroshio, the strong western boundary current, which is modulated by climate oscillation, exerts strong influences over all three marginal seas. Because these continental margins sustain arguably the most productive marine ecosystems, changes in these stressed ecosystems may threaten the livelihood of a large human population. This special issue reports the latest observations of the biogeochemical conditions and ecosystem functions in the three marginal seas. The studies exemplify many faceted ecosystem functions and biogeochemical expressions, but they reveal only a few long term trends mainly due to lack of long term records. It is critical to develop and sustain time series observations in order to detect biogeochemical changes and ecosystem responses in continental margins and to attribute the causes for better management of the environment and resources in these marginal seas.
