• Journal of the Korean Society of Marine Environment & Safety
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• v.9 no.2
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• pp.53-57
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• 2003

Low salinity water appears by outflow of fresh water from the Yangtze River in southwestern sea of the Korean peninsula. The water volume discharged form the Yangtze River is not constant with year, according to the time series data recorded in the past, the maximum value of the discharged volume is two times as high asr minimum value. Therefore, the distribution of low salinity water over study area with different discharged fresh water volume is studied using numerical model, Princeton Ocean Model (POM). POM is three dimensional circulation model selecting a $\sigma$­coordinate. According to the result of numerical simulation by the Model, current velocity on the continental slope is faster than those in other regions, current which flows toward the central part of the Yellow Sea through western part of Jeju exists, and also, southward flow along the coastal region exists. the greater discharged volume from the Yangrze River is. the lower salinity water appears closer to Jeju.

• Ocean and Polar Research
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• v.26 no.1
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• pp.65-75
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• 2004

In order to understand the water masses and their distribution in the eastern Yellow Sea from winter to spring, a cluster analysis was applied to the temperature and salinity data of Korea Oceanographic Data Center from 1970 to 1990. From December to April, Yellow Sea Cold Water (YSCW) dominates the eastern Yellow Sea, whereas Eastern Yellow Sea Mixed Water (MW) and Yellow Sea Warm Water (YSWW) are found in the southern part of the eastern Yellow Sea. MW appears at the frontal region around $34^{\circ}N$ between YSCW in the north and YSWW in the south. On the other hand, Tshushima Warm Water (TWW) is found around Jeju Island and the South Sea of Korea. These water masses are relatively well-mixed throughout the water column due to the winter monsoon. However, the water column begins to be stratified in spring due to increased solar heating, the diminishing winds and fresh water discharge, and the water masses in June may be separated into surface, intermediate and bottom layers of the water column. YSWW advances northwestward from December to February and retreats southeastward from February to April. This suggests a periodic movement of water masses in the southern part of the eastern Yellow Sea from winter to spring. YSWW may continue to move eastward with the prevailing eastward current to the South Sea from April to June. Also, the front relaxes in June, but the mixed water advances to the north, increasing salinity. The salinity is also higher in the nearshore region than offshore. This indicates an influx of oceanic water to the north in the nearshore region of the eastern Yellow Sea in spring in the form of mixed water.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.207-207
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• 2021

The Vietnamese Mekong Delta(VMD) covers an area of 62,250 km² in the lowest basin of the Mekong Delta where more than half of the country's total rice production takes place. In 2016, an estimated 1.29 million tonnes of Vietnam's rice were lost to the country's biggest drought in 90 year and particularly in VMD, at least 221,000 hectares of rice paddies were hit by the drought and related saltwater intrusion from the South China Sea. In this study, 3D numerical simulations using Delft3D hydrodynamic models with calibration and validation process were performed to examine flow characteristics, climate change scenarios, water level changes, and salinity concentrations in the nine major estuaries and coastal zones of VMD during the 21^st century. The river flows and their interactions with ocean currents were modeled by Delft3D and since the water levels and saltwater intrusion in the area are sensitive to the climate conditions and upstream dam operations, the hydrodynamic models considered discharges from the dams and climate data provided by the Coupled Model Intercomparison Project Phase 6(CMIP6). The models were calibrated and verified using observational water levels, salinity distribution, and climate change data and scenarios. The results agreed well with the observed data during calibration and validation periods. The calibrated models will be used to make predictions about the future salinity intrusion events, focusing on the impacts of sea level rise due to global warming and weather elements.

• Ocean and Polar Research
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• v.43 no.3
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• pp.127-140
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• 2021

At the estuaries of Bonggang and Miryong streams in the Korean southern coast, the spatiotemporal distribution and habitat environment of a nerite snail, Clithon retropictum (Gastropoda: Neritidae), which has been assigned as a legally protected species of Korea, were explored. Physicochemical environmental factors such as water temperature, salinity, tidal level distribution as well as biotic environments (chlorophyll-a concentration and epilithic microalgae composition) were monitored every month. The relationships between the environmental factors and spatiotemporal distribution of the nerite snail population were analyzed. Water temperature, salinity, and water level varied by season and lunar tidal rhythm. The spatiotemporal distribution of the nerite snail was mostly related to water salinity. Among epilithic algae which were the priority prey of snails, blue-green algae and green algae dominated in summer and autumn, while diatoms predominated during winter and spring. Chlorophyll-a concentration was highly and positively correlated with the population density of the nerite snail. The correlation coefficients were different depending on the taxon (Family) of epilithic algae. The mean population density was 302.2 inds m^-2 and 271.8 inds m^-2 in Bonggang Stream and Miryong Stream, respectively. The egg capsules of the nerite snail in the two habitats were observed from March (in Bonggang Stream) or April (in Miryong Stream) to August, and newly hatched juveniles recruited in the habitats from August were assessed with regard to frequency distributions of shell width. The occurrence of large-sized snails in upper stream reaches of both Bonggang and Miryong indicated the movement of spats from the mouth to the upper reaches during the whole life cycle.

• ALGAE
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• v.34 no.2
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• pp.111-126
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• 2019

The phototrophic dinoflagellate Biecheleriopsis adriatica is a small suessioid species characterized by a fragile thin wall. Although the morphology of this dinoflagellate is well established, there is currently little information available on its distribution and the environmental factors that influence this distribution. Thus, to investigate the spatial and seasonal distributions of the vegetative cells of B. adriatica in Korean waters, surface water samples were collected on a seasonal basis from 28 stations in the East, West, and South Sea of Korea and Jeju Island from April 2015 to October 2018, and abundances of the vegetative cells of B. adriatica were quantified using quantitative real-time polymerase chain reactions, for which we developed the species-specific primer and probe set. Simultaneously, major environmental parameters, including temperature, salinity, nutrient concentrations, and dissolved oxygen concentrations were measured. The vegetative cells of B. adriatica were detected at 20 of the 28 sampling stations: 19 stations in summer and 6 in autumn, although from no stations in either spring or winter. The ranges of water temperature and salinity at sites where this species was detected were $17.7-26.4^{\circ}C$ and 9.9-34.3, respectively, whereas those of nitrate and phosphate concentrations were not detectable-96.2 and $0.18-2.66{\mu}M$, respectively. Thus, the sites at which this species is found are characterized by a narrow range of temperature, but wide ranges of salinity and concentrations of nitrate and phosphate. The highest abundance of the vegetative cells of B. adriatica was $41.7cells\;mL^{-1}$, which was recorded in Jinhae Bay in July 2018. In Jinhae Bay, the abundance of vegetative cells was significantly positively correlated with the concentration of nitrate, but was negatively correlated with salinity. On the basis of these findings, it appears that the abundance of B. adriatica vegetative cells shows strong seasonality, and in Jinhae Bay, could be affected by the concentrations of nitrate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.11 no.3
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• pp.123-127
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• 1978

Distributions of microplankton in two different regions of the East China Sea were studied based on the plankton samples collected by R. V. Umitaka Maru of Fisheries University of Tokyo, Japan in September, 1975. The abundance distribution and species composition of the two areas were interpreted with their temperature-salinity properties. The two areas aye characterized by differences in the depth of thermocline, the nature of surface and bottom waters, and the abundance and species composition of microplankton.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.162-175
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• 2000

The present study was carried out to clarify the distribution of rotifera with salinity variation during the period from February 1998 to July 1999. Rotifera consists of 27 genera and 88 species, from the maximum occurrence of 39 species in November, 1998 to the minimum of 21 species March, 1998. With 32 dominant species, Keratella cochlearis cochlearis, K. cochlearis f. tecta, Ascomorpha saltans saltans and Asplanchna (s. str.) priodonta priodonta occurred predominantly. Distribution of Rotifera related to salinity showed that 36 species occurred in the freshwater zone, 3 species in the mixo-oligohaline zone ($0.5{\sim}5.0%_o$) and mixo-mesohaline zone ($5.1{\sim}28.0%_o$) respectively, on the other hand 2 species (Asplanhna (s. str.) priodonta priodonta, Synchaeta oblonga) in all zones. Average abundance by salinity ranged from $1,273\;ind./m^3$ ($25.0{\sim}28.0%_o$ to $16,259\;ind./m^3$ ($15.1{\sim}20.0%_o$. The percentage composition calculated effect by stepwise multiple regression of the pearson correlation coefficient value of environmental factors and Rotifera abundance (station $1{\sim}4$) revealed that it was 74.32% in BOD, 72.15% in COD, 69.77% in conductivity, 65.87% in $Cl^-$ and 58.27% in chlorophyll a. Also, (Station $5{\sim}12$) revealed 9.11% in $Cl^-$, 7.67% in TP and 6.20% in chlorophyll a.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.27 no.1
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• pp.17-32
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• 2022

The buffer capacity of southern Korean waters in summer was quantified using data set of temperature, salinity, dissolved inorganic carbon, total alkalinity obtained from August 2020 cruise. The geographical distribution and variability of six buffer factors, which amended the existing Revelle factor, are discussed their relationship with the hydrological parameters of temperature and salinity. The calculated results of six buffer factors showed the spatial variations according to the distributions of various water masses. The buffer capacity was low in the East Sea Surface Mixed Water (ESMW) and South Sea Surface Mixed Water (SSMW) where upwelling occurred, and showed an intermediate value in the Yellow Sea Surface Water (YSSW). In addition, the buffer capacity increased in the order of high temperature Tsushima Warm Current (TWC) and Changjiang Diluted Water (CDW). This means that the Changjiang discharge water in summer strengthens the buffer capacity of the study area. The highest buffer capacity of CDW is due to its relatively higher temperature and biological productivity, and a summer stratification. Temperature showed a good positive correlation (R²=0.79) with buffer capacity in all water masses, whereas salinity exhibited a poor negative correlation (R²=0.30). High temperature strengthens buffer capacity through thermodynamic processes such as gas exchange and distribution of carbonate system species. In the case of salinity, the relationship with buffer capacity is reversed because salinity of the study area is not controlled by precipitation or evaporation but by a local freshwater input and mixing with upwelled water.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.178-179
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• 2005

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.212-213
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• 2005