• Journal of Environmental Science International
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• v.31 no.9
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• pp.767-779
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• 2022

In this study, sediment cores were sampled from tidal flats (six sites) in the west and south coastal wetlands, the blue carbon stock in the tidal flat sediments was calculated, and the blue carbon stock characteristics and influencing factors were analyzed. The sediment particle size of the west coastal tidal flats was larger than that of the south coastal tidal flats, and the organic carbon content in the south coastal tidal flats was more than twice that of the west coastal tidal flats. Blue carbon stock per unit area was 28.4~36.8 Mg/ha on the west coastal tidal flats and 69.8~89.8 Mg/ha on the south coastal tidal flats, which was more than twice higher in the south coastal tidal flats than in the west coastal tidal flats. The total amount of blue carbon stock in the tidal flats was the highest in Suncheon Bay tidal flats at 153,626 Mg, and followed by Gomso Bay tidal flats at 141,750 Mg, Hampyeong Bay tidal flats at 58,420 Mg, Dongdae Bay tidal flats at 44,900 Mg, Cheonsu Bay tidal flats at 36,880 Mg, and Jinhae Bay tidal flats at 26,205 Mg. Blue carbon stock per unit area was higher in the south coastal tidal flats, but the total amount of blue carbon stock in the tidal flats was higher in the west coast. The slope of the regression function of blue carbon stock with respect to the organic carbon content in the tidal flat sediments was estimated to be about 0.05 to 0.07, and the slope of the regression function was higher in the west coastal tidal flats than in the south coastal tidal flats.

• Korean Journal of Environmental Biology
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• v.31 no.1
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• pp.19-36
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• 2013

Physiochemical characters of sea waters during summer flood- and winter dry-seasons and their spatial variations were investigated along the coastal area off the eastern South Sea, Korea. Using the hierarchical clustering method, in this study, we present comprehensive analyses of coastal waters masses and their seasonal variations. The results revealed that the coastal water of the study area was classified into six water masses (A to F). During summer season, the surface water was mainly occupied by the coastal pseudo-estuarine water (water mass B) with low salinity and high nutrients and the river-dominated coastal water (water mass C) with low nutrients, respectively. The bottom water was dominated by cold water (water mass D) with very low temperature, high salinity and high nutrients, compared to masses of surface water. Notably, the water mass B, with high concentrations of nutrients (silicate and nitrogen) and low salinity, which is strongly controlled by the water quality of river freshwater, seems to play an important role in controlling the water quality and further regulating physical processes on ecosystem in the eastern coastal area of South Sea. The water mass D (bottom cold water) coupled with a strong thermocline, which exists in near-bottom layer along the western margin of Korea Strait, has a low temperature, pH and DO, but abundant nutrients. This water mass disappears in winter owing to strong vertical mixing, and subsequently may act as a pool for nutrients during winter dry-season. On the other hand, vertically well-mixed water column during the winter season was typically occupied by the Tsushima (water mass E) and the coastal water (water mass F) with a development of coastal front formed in a transition zone between them. These winter water masses were characterized by low nutrient concentration and balance in N/P ratio, compared with summer season with high nutrient concentrations and strong N-limitation. Accordingly, the analysis of water masses will help one to better chemical and biological processes in coastal area. In most of the study area, characteristically, the growth of phytoplankton community is limited by nitrogen, which is clearly different with coastal environment of West Sea of Korea, with a relative lack of phosphorus. It showed the western and the southern coasts in Korea are substantially different from each other in environmental and ecological characteristics.

• Journal of the korean society of oceanography
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• v.37 no.4
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• pp.212-223
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• 2002

Cochlodinium polykrikoides bloom in 1995 was studied with a focus on an unusual coastal environment in the South Sea of Korea. Data on temperature, salinity, and zooplankton biomass during 1965-1998 and nutrients during 1990-1998 and chlorophyll-a during 1995-1998 were used in this study. These data were obtained from the serial oceanographic observations in Korean waters carried out by the National Fisheries Research and Development Institute. In 1995 the C. polykrikoides bloom began in the coastal area around Narodo Island in August and consequently occurred to the whole coastal area of the South and East Seas of Korea. During June-October 1995, the coastal environment was unusual compared with the long-term means during 1965-1998. In June 1995, sea surface temperature was 1-2$^{\circ}C$ warmer than in other years in all coastal areas, while salinity was high only to the east of Jeju Island. In August 1995, a strong coastal front appeared inshore of a line between Jeju and Tsushima Islands. In particular, a strong coastal front which showed the characteristics of upwelling front occurred in the coastal area around Narodo and Sorido Islands, not only because of a strong intrusion of the Tsushima Warm Current but also because of the upwelling of cold bottom water. Salinity was low in the neighboring waters of western side of Jeju Island. Nutrients and chlorophyll-a were high in the inshore area between Narodo and Sorido Islands in 1995 in contrast with the other years and areas. Zooplankton showed an unusually high abundance in the coastal area in October 1995. We conclude that the Tsushima Warm Current strongly influenced the South Sea of Korea in 1995 and created strong upwelling front bordering cold upwelled water in the coastal area around Narodo and Sorido Islands. It leads us that these physical structures introduce the favorable environment for the development of C. polykrikoides blooms. We suggest that C. polykrikoides has a bio-physical tolerance of high shear and stress and prefers frontal and upwelling relaxed areas as its habitat. We also find that nutrients were not supplied to the coastal area from the offshore where a low salinity water mass with high nutrients appeared around Jeju Island. Because the strong upwelling front protect the reach of offshore low saline water mass. The main source of nutrients was the upwelled water mass in the coastal area of Wando-Narodo-Sorido.

• Korean Journal of Environmental Biology
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• v.30 no.4
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• pp.328-338
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• 2012

We investigated seasonal changes in the marine environments and phytoplankton communities in the western part of south coastal waters of Korea during May 2009 and February 2010. In multidimensional scaling analysis of in situ data obtained by shipboard observations, the coastal waters comprised four different water masses: Yellow Sea water mass (YW) of low temperature and salinity, and high suspended solids and nutrient concentrations; south-western coastal water mass (SW) of high salinity and nutrient concentrations; Tsushima Current water mass (TW) of low nutrient concentrations, and high temperature and salinity; and closed bay water mass (CW). The spatial extent of these water masses varied according to seasonal environmental characteristics. In particular, at most study sites, TW expanded during autumn toward coastal waters. Phytoplankton abundances peaked during autumn in CW and spring in YW, which coincided with periods of high nutrient concentrations. In particular, diatoms predominated, and attained an abundance of more than 90% in most water masses. However, dinoflagellates in TW comprised a proportion of approximately 20% abundance.

• Ocean and Polar Research
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• v.30 no.4
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• pp.379-399
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• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.

• Ocean and Polar Research
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• v.34 no.1
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• pp.37-51
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• 2012

We investigated the distribution and species composition of zooplankton in relation to hydrographical characteristics in the Korea Strait during the winter (February) and summer (July) of 2009. Satellite images of sea surface temperatures and in situ CTD data showed that the southeastern water zone (St3-5) off Jeju Island was strongly influenced by the Tsushima Current during both the winter and summer, whereas the Changjiang Diluted Water, characterized as water with relatively low salinity, was evident in the coastal waters of Jeju Island during the summer. During winter, zooplankton abundance was significantly higher than in the summer, with dominance by copepods, ostracods, siphonophorans, appendicularians, and nauplii. In both seasons, copepods represented >70% of the total zooplankton population. Calanus sinicus, a large calanoid copepod, was dominant in near the coast, and that may be associated with the intrusion of low salinity water (i.e., the Changjiang Diluted Water) along the coast. The abundance of P. parvus s.l. and A. omorii, known as neritic copepods, was mainly associated with the Korea Southern Coastal Water. Foraminiferans, Ostracods, O. plumifera, and P. aculeatus were concentrated in the southeastern water off Jeju Island during both seasons; showing their association with the Tsushima Current, which is characterized warm, high salinity water. Our results suggest that the distribution, abundance, and species composition of zooplankton are highly influenced by different water masses in the Korea Strait.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.401-409
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• 1983

The distribution of anchovy eggs and larvae was studied using the ichthyoplankton samples and oceanographic data collected in the western and southern waters of Korea over the period of April through June in 1981 and 1982. Three water masses, the Tsushima Warm Current, the South Korean Coatal Water and the Yellow Sea Bottom Cold Water, are found to exert extensive influences of the distribution of anchovy eggs and larvae. The Tsushima Warm Current contacts with the South Korean Coastal Water to produce a coastal front between Cheju Island and Tsushima Island in the southern waters of Korea. Off the west coast of Korea, a coastal front is also formed running parallel with the western coast-line of Korea in the area between the Yellow Sea Bottom Cold Water and the extended part of the South Korean Coastal Water. In the southern waters of Korea anchovy eggs were found chiefly in the coastal waters inside the front, and larvae appeared to both sides on the front. The distribution of anchovy eggs and larvae off the west coast of Korea, however, was limited largely to the coastal waters of more than $12^{\circ}C$ in temperature. In the southern waters of Korea prelarvae appeared in the coastal area, and postlarvae in the offshore area. While in the western waters of Korea prelarvae were found in the southern part of the waters, and postlarvae in the northern part. Anchovy eggs and larvae were distributed in the considerably limited area of the coastal waters off the south coast of Korea in 1981 when the temperature gradient of the coastal front was sharper than in 1982.

• 한국해양학회지
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• v.11 no.2
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• pp.77-88
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• 1976

The water movements in the south sea of Korea are deduced from the distributions of water properties. In summer the flow path of the Tsushima Current is deflected off from the Korean coast; between the coast and the current there exist eddies. Cyclonic eddies are particularly dominant in the southeastern area of Sorido Is. In winter, the sunken coastal water flows out along the bottom toward the southeast, and compensation is made at the surface by the coastward intrusion of off-shore waters. The so-called coastal counter- current of the area seems to be a cyclonic eddy which prevails in summer and autumn.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.30-31
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• 2005

• 한국해양학회지
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• v.13 no.2
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• pp.5-10
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• 1978

The coastal cold water near Ulsan, Korea, almost always appears in summer. From the results of some data analysis, it is found that this cold water has an important relation to the anticlockwise circulation appearing near the coast where the anticlockwise circulation turns its current direction from south to east.