• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.553-568
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• 2018

Chromophoric Dissolved Organic Matter (CDOM) plays a dominant role in absorbing UV-VIS light and is also important in the biogeochemical carbon cycle due to the production of carbon dioxide from photo-oxidation at the sea surface in marine environments. Since absorption by CDOM was recently found to be responsible for increasing the energy absorbed in the mixed layer by 40 % over pure seawater, the importance of CDOM absorption in seawater for increasing sea surface temperature has come to be well recognized. We measured aCDOM and the absorption characteristics of CDOM during spring 2012 and 2014 in the southwestern East Sea. Distribution of CDOM in spring 2012 and 2014 was compared and S value was used to find the source of CDOM in the study area. As a result, the average $a_{CDOM}$ was $0.237m^{-1}$ ($0.009{\sim}0.988m^{-1}$) and the average S value was $16{\mu}m^{-1}$,which shows coastal properties. Also a positive correlation between Chl a and CDOM was observed ($r^2=0.34$), with an especially strong correlation near coastal stations. aCDOM in 2014 was about 40 % higher than aCDOM in 2012 during spring in the study area. This difference in aCDOM concentration resulted not only from annual variation but also from stratification and photobleaching in late spring 2012. This observation implies the possibility of flux of carbon dioxide into the atmosphere as a result of photo-oxidation in the East Sea.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.62-62
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• 2021

산업 고도화로 인하여 복잡하고 다양한 유기물의 사용량이 증가하였으며, 공공수역 내 새로운 오염물질이 유입됨에 따라 생화학적 산소요구량(BOD) 중심의 수질평가에 한계를 나타내었다. 이후 난분해성 물질을 고려한 유기물관리 정책과 총량관리의 필요성이 제기되었고 국내 하천과 호소에서는 총 유기탄소(TOC)를 유기물 관리지표로 설정하였다. 그러나 부영양 하천과 호소에서 TOC는 외부 부하뿐만아니라 식물플랑크톤의 과잉성장에 의해 증가할 수 있는 항목이므로 TOC 관리정책 추진을 위해서는 유기물의 기원에 대한 파악이 필요하다. 특히, 국내 하천에서 나타나고 있는 난분해성 유기물 오염도의 증가 추세에 대응한 실효성 있는 유기물 오염관리 정책을 수립하기 위해서는 다양한 유기물의 근원을 정확하게 파악하는 것이 매우 중요하다. 본 연구의 목적은 금강 수계 최대 상수원인 대청호를 대상으로 3차원 수리-수질 모델을 적용하여 유기탄소 성분 별 유입과 유출, 내부생성 및 소멸량을 평가하고 저수지시스템에서의 유기탄소 물질수지를 해석하는 데 있다. 유기탄소 물질수지 해석을 위해 AEM3D 모델을 사용하였으며 2017년을 대상으로 입력자료를 구축한 후 보정을 수행하였고 2018년을 대상으로 모델을 검정하였다. 모델은 유기탄소를 입자성, 용존성, 그리고 난분해성과 생분해성으로 구분하여 모의하며 유기물질 성상별 실험결과를 이용하여 입력자료를 구축하였다. 유기탄소 물질수지 해석을 위해 4가지의 탄소성분과 조류 세포 내 탄소의 질량 변화율을 계산하였다. 이를 위해 외부 유입·유출부하율, 수체 내 생성(일차생산, 재부상, 퇴적물과 수체 간 확산) 및 소멸률(POC 및 조류 침강, DOC 무기화, 탈질)을 고려하였다. 모델은 2017년과 2018년의 물수지를 적절히 재현하였으며 저수지의 성층구조를 잘 재현해내면서 전반적인 수온, 수질을 적절하게 모의하였다. 연간 TOC 부하량 중 내부기원 부하량은 2017년 68.4 %, 2018년은 높은 강우량의 영향으로 55.0%로 산정되었다. 내부 소멸 기작 중 침전으로 인한 손실이 가장 높은 것으로 나타났으며, 2017년과 2018년 각각 31.3%, 29.0%로 나타났다. TOC의 공간분포는 Chl-a 농도 분포와 유사하게 나타났으며, 댐 설치로 형성된 정체수역은 유역의 유기물 순환에 많은 영향을 미치는 것으로 평가되었다. TOC 관리 정책 기초자료 확보를 위해서는 향후 유역-저수지 시스템을 연계한 유기물 물질순환 심층 연구가 필요하다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.2
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• pp.51-61
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• 2010

Surface particulate organic carbon (POC) concentration was measured in the Northeastern Gulf of Mexico on 9 cruises from November 1997 to August 2000 to investigate the seasonal and spatial variability related to synchronous remote sensing data (Sea-viewing Wide Field-of-view Sensor (SeaWiFS), sea surface temperature (SST), sea surface height anomaly (SSHA), and sea surface wind (SSW)) and recorded river discharge data. Surface POC concentrations have higher values (>100 $mg/m^3$) on the inner shelf and near the Mississippi Delta, and decrease across the shelf and slope. The inter-annual variations of surface POC concentrations are relatively higher during 1997 and 1998 (El Nino) than during 1999 and 2000 (La Nina) in the study area. This phenomenon is directly related to the output of Mississippi River and other major rivers, which associated with global climate change such as ENSO events. Although highest river runoff into the northern Gulf of Mexico Coast occurs in early spring and lowest flow in late summer and fall, wide-range POC plumes are observed during the summer cruises and lower concentrations and narrow dispersion of POC during the spring and fall cruises. During the summer seasons, the river discharge remarkably decreases compared to the spring, but increasing temperature causes strong stratification of the water column and increasing buoyancy in near-surface waters. Low-density plumes containing higher POC concentrations extend out over the shelf and slope with spatial patterns and controlled by the Loop Current and eddies, which dominate offshore circulation. Although river discharge is normal or abnormal during the spring and fall seasons, increasing wind stress and decreasing temperature cause vertical mixing, with higher surface POC concentrations confined to the inner shelf.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.4
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• pp.292-301
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• 2012

The rise in sea surface temperature (SST) as a global warming enhance overall typhoon activity. We assumed that there exist thermodynamic limits to intensity that apply in the absence of significant interaction between storms and their environment. The limit calculations depend on SST and atmospheric profiles of temperature and moisture. This approach do appear to provide resonable upper bounds on the intensities of observed storms and may even be useful for predicting the change in intensity over a long period time. The maximum storm intensities was estimated through the global warming scenarios from IPCC-AR4 report over the North-East Asia. The result shows stronger intensities according to scenarios for increase of carbon dioxide levels. And storm surge simulations was performed with the typhoons which were combined route of the typhoon Maemi (2003) and intensity as climate change scenarios. The maximum increase of storm surge heights was shown about 29~110 cm (36~65%) regionally. Especially at Masan, the result of simulated maximum surge height exceed the 200 years return period surge.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.193-202
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• 1998

Water quality of Masan-Jinhae Bay was monitored from January 1996 to August 1997. The monitoring focused on the spatial and vertical gradients and seasonal changes of eutrophication parameters such as nutrients, DO and water transparency. Flagellate phytoplanktons persistently bloomed from April to October with monospecific or mixed algal blooms and dynamic algal successions were observed in this area. Algal blooms were highly correlated with salinity drops and made the water less transparent. Stratification of oxygen content was persistent through summer and oligo-oxygenation was developed in the bottom waters. Nutrient gradients were consistently maintained through the depth in summer and through spatial distribution from inner Masan Bay to outer Jinhae Bay in winter. Except the rainfall seasons, water quality was under the influence of the waste waters discharged from watershed around the Masan Bay. The waste waters would act as the primary factor for the water quality deterioration of the bay. Literature data for eutrophication were gathered and analyzed to review the water quality trends of the Masan and Jinhae bays since 1970. Annual mean COD and phosphate concentration consistently increased from 1975 to 1990 and decreased or dropped after 1991. The sediment of inner part of Masan Bay was dredged from 1991 to 1994 as a decontamination process and it is assumed that the dredging has weakened more or less the deterioration trend of the water quality of the bay.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1373-1377
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• 2007

준설은 수중굴착, 운반(배송), 매립 기술로 구분되는데, 국내에서는 아직까지 각 기술을 통합한 체계적인 연구가 수행되지 못하고 있다. 준설분야는 토질, 수리 등의 토목 분야 기술뿐만 아니라 기계, 제어, 환경 등 여러 분야의 기술들이 매우 복잡하게 연계되어 있으며, 제한된 소수의 기술자들과 특수 대형 장비-준설선에 의해 수행되기 때문이다. 최근에는 장비의 대형화, 첨단화가 진행되면서 선진국과의 기술격차로 인해 국제 경쟁력이 약화되어 심각한 위기에 처해있는 현장기술 분야이다. 유럽의 델프트 공대, IHC, 준설협회(CEDA)는 세계 기술 개발을 주도하고 있으며, 미국에서는 육군공병단의 수로국에서 준설을 담당하고 있으며 DOER(Dredging Operation & Environmental Research) 기술 개발을 주도하는 등 선진국에서는 이미 여러 연구가 진행되었으며 준설기술이 정착되어있다. 본 연구에서는 현재 현대건설에서 보유중인 아산3호를 모델로 축소모형을 제작하여 실험하였다. 본 연구에서는 선행실험으로 성층형성 및 석션펌프 작동시 물입자의 운동방향을 PIV로 촬영한 결과에 커터헤드를 추가 장착 시행하여 이를 바탕으로 수치해석시 발생할 수 있는 오류를 수정 보완 할 것이다. 차후 실험에서는 준설토의 조건과 기계적 조건 및 환경적인 영향력을 고려한 여러 가지 방법으로 진행할 계획이며, 실험 조건에서는 각 매개변수를 달리하여 이를 토대로 데이터를 구성하고, 측정을 통해서 얻어지는 결과 값을 기초로 하여 준설시에 환경과 매개변수의 조건에 따른 준설량의 특성을 파악하고 효율을 향상시킬 수 있는 방향을 제시할 것이며, 이를 통해서 기본적인 메뉴얼을 구성할 계획이다. 수리실험의 결과값을 바탕으로 이를 현실무 작업에 적용할 경우 효율적인 준설작업을 수행할 수 있을 것으로 판단된다. HDL-콜레스테롤 함량은 유의차가 없었다. 간조직 중 총지질, 총콜레스테롤 및 중성 지방 함량은 HC군이 NC군에 비하여 유의하게 증가되었다. HC-LREL 군과 HC-LREH군은 HC군에 비하여 간조직 중 총지질 함량만이 유의하게 저하되었다. 이상의 결과 연근 에탄올 추출물은 in vitro에서 HMG-CoA reductase 활성을 농도 의존적으로 저하시켰으며, in vivo 에서는 고콜레스테롤 식이급여로 증가되어진 LDL-콜레스테롤 및 중성지질 함량을 감소시키고, 감소되어진 인지질 함량을 증가시킴으로써 고콜레스테롤 혈증 및 지방간의 예방과 치료에 효과가 있을 것으로 사료되나 연근의 어떠한 성분의 작용 기전에 의한 것인지에 대해서는 더욱 체계적인 연구가 요구된다.}nlein$ nephritis가 3례로 가장 많았다. 미세변화 신증후군 71명 중 비재발군이 16명으로 22.5%, 비빈발 재발군 49.3%, 빈발 재발군 18.3%, 스테로이드 의존군 9.9%를 보였다. 결론 : 대전시에서의 신증후군 환아의 발생빈도는 15세이하 소아 10만명당 약 5명으로 추정되었으며 10여 년전과 비교하여 큰 변화를 보이지는 않았다. 또한 저자들의 임상병리학적 연구결과가 다른 문헌에서 보고된 소아 신증후군의 연구결과와 큰 차이를 보이지 않음을 알 수 있었다. 자극에 차이가 있지 않나 추측되며 이에 관한 추후 연구가 요망된다. 총대장통과시간의 단축은 결장 분절 모두에서 줄어들어 나타났으나 좌측결장 통과시간의 감소 및 이로 인한 이 부위의 통과시간 비율의 저하가 가장 주요하였다. 이러한 결과는 차가운 생수 섭취가 주로 결장 근위부를 자극하는 효과를 발휘하는 것이 아닌가 해석된다. 이와 같은 연구결과를 통해 생다시마를 주원료로 개발된 생다시마차와 생다시마 음료가 만성 기능성 변비 증세를 개선하는 효

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.712-720
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• 2022

In this study, we evaluated the production and photoreactivity of CDOM of two polar phytoplanktons - Phaeocystis antarctica and Phaeocystis pouchetii, in order to find out UV effects on phytoplanktons. In visible region, CDOM in media of both phytoplanktons under UV-R decreased during 48hrs incubation period. However, in UV region CDOM decreased 30 % in the media of P. antarctica, but increased 10% in media of P. pouchetii, compared to CDOM concentrations of control after 48 hr incubation. This result indicates that biota in polar environment would not well protected from UV-R harmful effect when P. antarctica is dominant because of loss of CDOM, but when P. pouchetii is dominant species, production of UV absorbing organic matter could play more efficiently for UV screening for marine biota. Also we confirmed that FDOM of humic substance (C-peak) produced by these phtoplanktons under UV-R stress were well matched with fluorescence characteristics of the UV-protecting compound, MAAs. This finding shows that Phaeocystis pouchetti with low photoreactivity would contribute to DOM pool of polar marine environment under stratification by global warming.

• The Korean Journal of Quaternary Research
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• v.32 no.1_2
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• pp.30-40
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• 2018

In response to the increase in anthropogenic greenhouse gases, the Arctic temperature is increasing rapidly by 2-3 times other regions. This larger Arctic warming than lower latitudes is called 'Arctic Amplification'(Overland et al., 2017; Goose et al., 2018). Associated with the Arctic Amplification, the Arctic sea ice is declining rapidly and Greenland ice sheet is melting rapidly, especially around the coastal margins (State of Climate, 2018). However, Antarctic climate change appears to be different from the Arctic. In the western part of Antarctica, surface temperature is rising rapidly with large sea and land ice melting, but in the eastern part, there is little temperature change with slight increase in sea ice extent. The contrasting east-west temperature response is illustrated by the deepening of the Amundsen Sea Low whose upstream brings warm maritime air to the Antarctic peninsula and Amundsen-Bellingshausen Seas, but downstream air provides cold air to the Ross Sea, increasing sea ice. Besides, the increase in Southern Annular Mode (SAM) phase due to stratospheric ozone reduction enhances westerly winds, pushing sea ice northward by Ekman divergence and cooling east Antarctica. In this study, we review the recent Antarctic climate change and its possible causes.

• Journal of Marine Life Science
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• v.2 no.2
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• pp.62-69
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• 2017

In order to assess the potential environmental factors in the vicinity of a fish cage farm, we investigated the biotic and abiotic factors during a short-term period in summer 2016 in two inner stations of Tongyeong Obi. High water temperature on August 10^th was apparent among the full depth of up to 29℃, which might have been related to the abnormally high temperatures of large amounts of the Changjiang River discharge along the Tongyeong coast. The concentration of nitrate+nitrite, ammonium, phosphate, and silicate ranged from 0.08 to 5.11 μM, 0.08 to 34.62 μM, 0.01 to 1.15 μM, and 1.46 to 31.79 μM, respectively. The nutrients were mainly supplied by precipitation and leaching from the bottom sediments in the fish culture farm area. It was not retained for a long duration because of the phytoplankton consumption and diffusion by water currents. The chlorophyll a concentration varied from 0.49 ㎍ l^-1 to 7.39 ㎍ l^-1. At that time, Chaetoceros debilis, C. pseudocurvisetus, and Pseudo-nitzschia delicatissima were rapidly proliferated and reached the level of 4.74 × 10⁹ cells l^-1. In particular, the lowest dissolved oxygen was recorded at 4.52 ㎍ l^-1 at the bottom layer after bloom. Therefore, even though phytoplankton blooms in summer have frequently occurred in a fish culture farm area, the oxygen-deficient environments were not found in neither the surface nor bottom layers, which implied that the water masses might be well exchanged from the mouth of the northwest and southeast between Obi and Mireuk Island in the study area.

• The Korean Journal of Quaternary Research
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• v.33 no.1_2
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• pp.1-23
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• 2021

In response to the increase in atmospheric carbon dioxide and greenhouse gases, the global mean temperature is rising rapidly. In particular, the warming of the Arctic is two to three times faster than the rest. Associated with the rapid Arctic warming, the sea ice shows decreasing trends in all seasons. The faster Arctic warming is due to ice-albedo feedback by the presence of snow and ice in polar regions, which have higher reflectivity than the ocean, the bare land, or vegetation, higher long-wave heat loss to space than lower latitudes by lower surface temperature in the Arctic than lower latitudes, different stability of atmosphere between the Arctic and lower latitudes, where low stability leads to larger heat losses to atmosphere from surface by larger latent heat fluxes than the Arctic, where high stability, especially in winter, prohibits losing heat to atmosphere, increase in clouds and water vapor in the Arctic atmosphere that subsequently act as green house gases, and finally due to the increase in sensible heat fluxes from low latitudes to the Arctic via lower troposphere. In contrast to the rapid Arctic warming, in midlatitudes, especially in eastern Asia and eastern North America, cold air outbreaks occur more frequently and last longer in recent decades. Two pathways have been suggested to link the Arctic warming to cold air outbreaks over midlatitudes. The first is through troposphere in synoptic-scales by enhancing the Siberian high via a development of Rossby wave trains initiated from the Arctic, especially the Barents-Kara Seas. The second is via stratosphere by activating planetary waves to stratosphere and beyond, that leads to warming in the Arctic stratosphere and increase in geopotential height that subsequently weakens the polar vortex and results in cold air outbreaks in midlatitudes for several months. There exists lags between the Arctic warming and cold events in midlatitudes. Thus, understanding chain reactions from the Arctic warming to midlatitude cooling could help improve a predictability of seasonal winter weather in midlatitudes. This study reviews the results on the Arctic warming and its connection to midlatitudes and examines the trends in surface temperature and the Arctic sea ice.