• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.627-639
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• 2014

In respect of the nutrients cycling in coastal environment, regeneration in bottom layer is one of major source of nutrients. We analyzed the bottom water quality at the 14 stations during 9 years from 2004 to 2012 to investigate the characteristics of nutrients at bottom layer in Jinhae Bay. Concentrations of DIN, DIP and DSi showed the large seasonal variation and were higher in summer. Especially, average concentrations of these nutrients were two times higher in hypoxic season than in normoxic season. In summer, high concentrations of DIN, DIP and DSi caused by regeneration were common feature, but spatial distribution of DSi differ from that of DIN and DIP. DIN and DIP were higher in Masan Bay, while DSi was higher in Masan Bay as well as in center of Jinhae Bay. In comparison with DIN and DIP, DSi was significantly affected by nutrients regeneration at bottom layer in whole season. According to time series analysis, DIN concentration was decreased from approximately $14{\mu}M$ to $6{\mu}M$. This result induce that Si:N ratio at bottom layer in Jinhae Bay changed from approximately 1 to 3.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.3
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• pp.208-214
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• 1990

Phytoplankton samples for this study were collected by Van Dorn Sampler at 28 oceanographic stations in the southern waters of Korea in February, April and August, 1988 to characterize the distribution and species composition of phytoplankton and their relation to the movement of water masses. During the study periods, phytoplankton standing crops in the southern waters were maximum in April and minimum in February. When the geographical distribution and abundance of the phytoplankton were considered, the highest standing crops were found near the front zone formed between Cheju Island and Tsushima Island. Therefore, their abundance depends ell the location of the front zone. On the other hand, there were relatively low standing crops in the open sea off the coastal area from the front zone in February and August. The cause of the unusal low standing crops found in August at the station 205/01, the central part of the coastal area of the southern waters where the largest standing crops occurred in February and April, seems to be due to the intrusion of Tsushima warm waters. This is because the waters at the station have high temperature and salinity, poor dissolved oxygen and nutrient salts, which are identical to the characteristics of proper Tsushima warm waters. It seems that these warm waters may affect the poor productivity in this area. Seventy-two species in thirty-three genera of the phytoplankton were indentified from the samples. Among them, 61 species in 27 genera belong to diatoms and 12 species in 7 genera to dinoflagellates. The largest number of phytoplankton species occurred in August while the largest number of the tells in April. Predominant species were Eucampia zodiacus in February, Skeletonema costatum and Chaetoceros curvisetus in April and Chaetoceros affinis in August. Eucampia zodiacus which was dominant in February and April seems to be a indicator of the southern coastal waters of Korea and mixed waters west of Cheju Island.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.4
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• pp.259-268
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• 2003

The damage of water quality like red tide occurs every year inspite of the total load regulation of pollutant inflows from land such as COD, phosphorus and so on around Seto inland sea in Japan. It is attributed to the increase of primary production due to eutrophication. and the rising and settling from the sediment containing nutrient salt. Furthermore, the recent research shows that nutrient salt such as nitrogen and phosphorus, flows into Kii channel from land as well as the Pacific ocean. To investigate the distribution of water quality and flow and residual current in Kitan strait, the field observations were carried out. The field data were obtained a time each season from 1999 to 2002. The results of observations and data of other research institution are used to understand the mechanism of pollution in the strait.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.382-391
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• 2020

In this study, we used artificial intelligence algorithms for the prediction of dissolved oxygen in Jindong Bay. To determine missing values in the observational data, we used the Bidirectional Recurrent Imputation for Time Series (BRITS) deep learning algorithm, Auto-Regressive Integrated Moving Average (ARIMA), a widely used time series analysis method, and the Long Short-Term Memory (LSTM) deep learning method were used to predict the dissolved oxygen. We also compared accuracy of ARIMA and LSTM. The missing values were determined with high accuracy by BRITS in the surface layer; however, the accuracy was low in the lower layers. The accuracy of BRITS was unstable due to the experimental conditions in the middle layer. In the middle and bottom layers, the LSTM model showed higher accuracy than the ARIMA model, whereas the ARIMA model showed superior performance in the surface layer.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2007.05a
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• pp.282-284
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• 2007

연구 해역의 양식 굴 폐사는 여름철을 지나 수온이 하강하기 시작하는 9월 초순에서 중순경부터 시작되었으며, 강진만 중앙부분 양식장의 경우 조사당시에도 상당수 굴의 폐사가 진행되고 있었다. 병리학적 조사 결과, 각 조사정점별 채집한 굴에서 비브리오 속 세균들이 검출되었으나, 이들 세균은 해수 중에 상존하는 종류로 알려저 있으며, 기생충은 검출되지 않았다. 강진만과 인근한 남해와 산청기상관측소에서 측정된 기온(8${\sim}$9월)은 남해는 2005년에 전반적으로 낮았으며, 산청은 전년비 $2{\sim}5^{\circ}C$ 높은 상태를 유지하였으며, 강수량은 강진만에 유입되는 담수의 대부분을 차지하는 남강댐 수위에 영향을 미칠 것으로 예상되는 산청지방의 2005년 여름철(7${\sim}$9월) 일별 강수량은 집중호우의 특성을 보이지 않았으며, 굴 폐사가 발생한 9월의 강수량은 남해와 산청지방에서 전년과 평년비 $99.9{\sim}188.0mm$나 적은 양을 보였다. 해양환경측정망(St. 2, 강진만) 자료에 2005년 하계 수온이 2004년에 비해 $2^{\circ}C$, 2003년에 비해 $2.6^{\circ}C$ 높은 값을 보였으며, 양식 굴의 먹이생물과 직접적으로 연관이 있는 Ch1-a 농도는 2005년에는 대단히 낮은 값(2.15ug/L)을 보였으며, SS 농도도 낮은 값(4.6mg/L)을 보였다. 조사당시 수질환경은 양식 굴의 폐사에 직접적인 영향을 미칠만한 요인은 관찰되지 않았으나, 조사정점 1(지족)의 저층에서 2.87mg/L의 낮은 용존산소가 관찰되었으며, 2005년 8월 15일 관찰된 강진만의 남-북방향 수직분포도 저층을 따라서 3mg/L이하의 빈산소 수괴가 관찰되었다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.18 no.2
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• pp.101-114
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• 2012

The physico-chemical characteristics including water temperature, salinity, dissolved oxygen(DO), chemical oxygen demand (COD), chlorophyll-a(Chl. a), suspended particulate matter(SPM) and dissolved inorganic nutrients were investigated in the Garolim Bay, Yellow Sea, Korea in 2010 carried out six times per year at 11 fixed stations by Korea Fisheries Research & Development Institute. The water temperature, salinity, COD, dissolved inorganic nutrients, Chl. a and SPM showed significant difference between surface and bottom water but the other parameters didn't. There were not significant difference between stations. The water temperature showed typical change patterns of the temperate seawater. The annual average of salinity showed more than 31 so that there could not have occurred low saline water. The average of DO from June to August showed over than 3mg/L which showed higher than the below standard value of the hypoxic (oxygen-deficient) water. The average of Chl. a varied $1.68{\mu}g/L$ at surface, $2.38{\mu}g/L$ at bottom layer in June and $1.68{\mu}g/L$ at surface, $1.57{\mu}g/L$ at bottom layer at August. The dissolved inorganic nutrients showed high concentration in February and low concentration in August due to the limitation of the freshwater input in summer and phytoplankton used to the dissolved inorganic nutrients. The ratio of DIN/DIP showed 30.52 at surface and 37.89 at bottom layer in June which was higher than other month. The SPM was 44.15mg/L at bottom layer in February which was the highest value in this study due to the northwest monsoon. Because of the actively water change in the open sea without inflow of freshwater from land in Garolom Bay, there were not occurred low saline water and hypoxic water. thus, this Bay showed good water quality and required to be conserved continuously as important costal area for fisheries.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.2
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• pp.77-100
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• 2024

Circulation, tides, currents, harmful algal blooms, water quality, and hypoxic conditions in Jinhae-Masan Bay have been extensively studied. However, these previous studies primarily focused on short-term variations, and there was limited detailed investigation into the physical mechanisms responsible for ocean circulation in the bays. Oceanic processes in the bays, such as pollutant dispersal, changes on a seasonal time scale. Therefore, this study aimed to understand how the circulation in Jinhae-Masan Bay varies seasonally and to examine the effects of tides, winds, and river discharges on regional ocean circulation. To achieve this, a three-dimensional ocean circulation model was used to simulate circulation patterns from 2016 to 2018, and sensitivity experiments were conducted. This study reveals that convective estuarine circulation develops in Jinhae and Masan Bays, characterized by the inflow of deep oceanic water from the Korea Strait through Gadeoksudo, while surface water flows outward. This deep water intrusion divides into northward and westward branches. In this study, the volume transport was calculated along the direction of bottom channels in each region. The meridional water exchange in the eastern region of Jinhae Bay is 2.3 times greater in winter and 1.4 times greater in summer compared to that of zonal exchange in the western region. In the western region of Jinhae Bay, the circulation pattern varies significantly by season due to changes in the balance of forces. During winter, surface currents flow southward and bottom currents flow northward, strengthening the north-south convective circulation due to the combined effects of northwesterly winds and the slope of the sea surface. In contrast, during summer, southwesterly winds cause surface seawater to flow eastward, and the elevated sea surface in the southeastern part enhances northward barotropic pressure gradient intensifying the eastward surface flow. The density gradient and southward baroclinic pressure gradient increase in the lower layer, causing a strong westward inflow of seawater from Gadeoksudo, enhancing the zonal convective circulation by 26% compared to winter. The convective circulation in the western Jinhae Bay is significantly influenced by both tidal current and wind during both winter and summer. In the eastern Jinhae Bay and Masan Bay, surface water flows outward to the open sea in all seasons, while bottom water flows inward, demonstrating a typical convective estuarine circulation. In winter, the contributions of wind and freshwater influx are significant, while in summer, the influence of mixing by tidal currents plays a major role in the north-south convective circulation. In the eastern Jinhae Bay, tidally driven residual circulation patterns, influenced by the local topography, are distinct. The study results are expected to enhance our understanding of pollutant dispersion, summer hypoxic events, and the abundance of red tide organisms in these bays.

• Korean Journal of Ecology and Environment
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• v.35 no.1 s.97
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• pp.10-20
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• 2002

Changes of seasonal and vertical water quality was analyzed with physico-chemical data from Soyang and Paldang river-reservoir system in Korea during the 1996 to 1998. In Soyang river-reservoir system, the water column was well stratified, which narrow epilimnion layer of 5 to 10 m depth in spring to summer enlarged gradually about 40 m depth in fall as going to times. In contrast, metalimnion layer tended to be narrow during the same period. Water temperature of hypolimnion was maintained about $5^{\circ}C$ continuously throughout the year. DO of the epilimnion layer was supersaturated from spring to summer, however, it was decreased to 75% at the epilimnion layer and $45{\sim}50%$ at the hypolimnion layer at the late fall. The lowest conductivity of below $50\;{\mu}S/cm$ was observed at the metalimnion layer during thesummer to fall. In Paldang river-reservoir system, the water column wag well mixed layer throughout the year, although water temperature was changed seasonally from $5^{\circ}C$ in February to $28^{\circ}C$ in July. Water temperature between upper and lower layer was different about $5^{\circ}C$ from late spring (May) to early fall (September). DO was over and less saturated in upper and lower layer during the early summer to early fall, respectively. Conductivity was decreased to $90\;{\mu}S/cm$ in lower layer of below $4{\sim}5\;m$ depth during the late spring to early fall and that of upper layer of above 10 m depth decreased to about $100\;{\mu}S/cm$ during the late fall (November) and early spring (March). Retention time of Soyang river-reservoir system was much longer than that of Paldang river-reservoir system. Chlorophyll a, T-N and T-P concentration in Paldang river-reservoir system were higher than that of Soyang river-reservoir system by a factor of 2.7, 1.2 and 2.6, respectively. Algal blooming was deeply affected by the nutrients than the retention time.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.121-126
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• 1975

Chlorophyll a content in marine phytoplankton and nutrient in seawater were determined to study the influence of eutrophication of Jinhae Bay area on primary production. Sampels were taken in the surface layer and bottom of 21 stations in Jinhae Bay including Masan Bay and Hengam Bay, ana adjacent waters such as Geoje Bay and the estuary of Naktong River for refrence during summer Period in 1974. Chlorophyll a content was ranged from $0.52\;mg/m^3\;to\;25.16\;mg/m^3$ in whole area. Mean value of chlorophyll a was the highest in Masan Bay and the lowest in GeojeBay. It was noteworthy that chlorophyll a content of Hengam Bay was not much higher than that of neighboring ares and rather lower than that of the estuary of Naktong River in spite of high phosphate content. Linear relationship between increase of nutrients and chlorophyll a was found in Masan Bay and the estuary of Naktong River where N/P ratio of nutrients was over 12. This relationship however could not be found in most area of Jinhae Bay where N/P ratio of nutrients was lower than 2 which might due to the wastewater from the Chemical Fertilizer plant. Red tide and low dissolved oxygen waters due to eutrophication were observed during summer period in Masan Bay.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.4
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• pp.179-195
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• 2004

The trophic state of the coastal waters of the southern part of Korea was assessed using biogeochemical data obtained from the National Marine Environmental Monitoring Program conducted by the National Fisheries Research and Development Institute for six years. The trophic state of different areas, analyzed by non-metric multi-dimensional scaling (MDS) analysis, could divide the areas into three groups. Masan Bay, with suboxic water masses and/or the highest concentrations of dissolved inorganic nitrogen and phosphorus occurred, was assessed as being in a hypertrophic state. Ulsan Bay, Onsan Bay, Busan and Jinhae Bay, located near strong point sources, were in a eutrophic state. Other areas, including Tongyong, Yosu, Mokpo and Jeju island, were evaluated as being in a mesotrophic state. During 1997 to 2002, the average values of excess nitrogen, which is the difference between the measured dissolved inorganic nitrogen (DIN) and the corrected DIN using the Redfield ratio, were positive at Ulsan, Onsan, and Busan, where there were inflows from polluted rivers. In contrast, those were negative values in Haengam Bay, Gwangyang Bay and nearby Yosu. This suggests that the limiting element for phytoplankton growth differed among sites. The time series data of excess nitrogen showed gradual decrease over time in the hypertrophic waters, but the opposite trend in the mesotrophic waters. This indicated that the ratio of nitrogen to phosphate varied according to the trophic state of the coastal waters. The enrichment of organic matter in sediment in eutrophic waters would disturb the normal pattern of biogeochemical cycling of nitrogen and phosphate. In order to assess the condition of the coastal environment, the benthic boundary layer should be considered.