• 수산해양기술연구
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• 제48권3호
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• pp.242-255
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• 2012

The Nemopilema nomurai a very large jellyfish that has been found in the East China Sea and is now are migrating to Korea and Japan. To investigate the occurrence of N. nomurai based on the changing marine environment of the East China Sea, we conducted field survey in the early summer from 2006-2008. We observed the marine environment using CTD and the occurrence of N. nomurai using FMT and bottom trawling. We caught the most N. nomurai in 2007 and the fewest in 2008 and environment factors influencing its are more sensitive temperature than salinity. Large quantities of N. nomurai with a small bell diameter were caught in 2007 and large individuals with a significant bell diameter were caught in 2008. This appeared which between the catch and bell diameter of N. nomurai had (-) correlation (R=-0.988, p=0.098). Meanwhile, the spatial distribution of N. nomurai concentrations in lower salinity mixed seawater inflow in Changjiang Diluted Water.

• 해양환경안전학회지
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• 제5권2호
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• pp.57-65
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• 1999

The in situ observations and the seawater analyses were conducted at all seasons from July 1996 to April 1999 for the purpose of describing the characteristics of seasonal variations of water quality in Mokpo harbour, Korea. Vertical stratification started to be formed in water column in spring, developed in summer and disappeared in fall. In summer, vertical density distribution of water column was found to be in stable structure with lower temperature and higher salinity of bottom water, and the vertical mixing of water between surface and bottom layers was restricted. In winter, however, surface water was found to be similar to bottom water in temperature and salinity, and water column was in unstable structure and in well-mixed condition between surface and bottom waters. The saturation percentage of dissolved oxygen(DO) in bottom water of inner part of Mokpo harbour at all seasons was shown to be decreased to the third grade or under the third grade of Korean standards of seawater quality. In particular, dissolved oxygen was oversaturated in surface water and undersaturated in bottom water in summer, due to stratification and organic pollution. The difference of DO concentration between surface and bottom waters was found to be greater in spring and summer than in fall and winter, due to stratification and photosynthesis of phytoplankton. The concentrations of chemical oxygen demand(COD) over the entire waters of Mokpo harbour were found to fluctuate from below the third grade to the first grade of Korean standards through all seasons and COD concentrations of same seasons were shown to be different year after year. In particular, in view of COD, the annual average seawater quality of Mokpo harbour was evaluated to be in third grade of Korean standards, due to organic pollution. The average COD of surface water was greater than that of bottom water in spring and summer, due to the autochthonous COD caused by production of phytoplankton in surface waters, while the average COD of surface water was similar to that of bottom water in fall and winter, due to the vertical mixing of water between surface and bottom layers.

• 한국수산과학회지
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• 제47권4호
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• pp.424-430
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• 2014

Two major temperature fronts, the Subpolar (Gosung, Gang-won-do; $38^{\circ}-41^{\circ}N$) and Thermal (Jukbyun, Gyeong-sang-buk-do; $36^{\circ}-37^{\circ}N$) fronts, are found in the East Sea along the east coast of Korea. These are located roughly where the Tsushima Warm Current and North Korea Cold Current intersect. To clarify the effect of the Thermal Front, we investigated seasonal variation in fish species composition using set nets in two areas located north (Jangho, Gang-won-do) and south (Hupo, Gyeong-sang-buk-do) of Jukbyun, Gyeong-sang-buk-do, and compared the sea water temperature and salinity. We collected a total of 38 fish species in Hupo and 25 in Jangho. Trachurus japonicus was the most common species at both sites, but the subdominant species differed. At Hupo, the subdominant species were Konosirus punctatus and Diodon holocanthus, whereas Clupea pallasii and Scomber japonicus were subdominant at Jangho. Based on Froese and Pauly (2014), subtropical fishes accounted for 55% of fish in Hupo but only for 33% in Jangho. The difference in fish species composition was most obvious in May and August. According to the Korea Hydrographic and Oceanographic Administration, sea surface temperature and salinity were slightly higher at Hupo than at Jangho. Our findings suggest that the oceanographic boundary resulting from the Thermal Front near Jukbyun, Gyeong-sang-bukdo may have a major effect on the distribution of migratory fish species.

• Ocean and Polar Research
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• 제30권3호
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• pp.335-345
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• 2008

In order to study spatial variabilities and major controlling factors, we measured fugacity of $CO_2(fCO_2)$, temperature, salinity and nutrients in surface waters of the North Pacific($7^{\circ}30'{\sim}33^{\circ}15'N$, $123^{\circ}56'E{\sim}164^{\circ}24'W$) between September$\sim$October 2007. The North Pacific and the marginal sea were distinguished by $fCO_2$ distribution as well as unique characteristics of temperature and salinity. There was a distinct diurnal SST variation in the tropical North Pacific area, and surface $fCO_2$ coincidently showed diurnal variation. In the North Pacific area, surface $fCO_2$ was mainly controlled by temperature, while in the marginal sea area it was primarily dependent on alkalinity and dissolved inorganic carbon concentrations. Air-sea $CO_2$ flux showed a large spatial variation, with a range of $-6.10{\sim}5.06\;mmol\;m^{-2}day^{-1}$. The center of subtropical gyre of North Pacific acted as a source of $CO_2(3.09{\pm}0.95\;mmol\;m^{-2}day^{-1})$. Tropical western North Pacific (i.e. the 'warm pool' area and the subtropical western North Pacific) acted as weak sources of $CO_2$($1.07{\pm}1.20\;mmol\;m^{-2}day^{-1}$ and $0.50{\pm}0.53\;mmol\;m^{-2}day^{-1}$, respectively). In the marginal sea, however, the flux was estimated to be $-0.68{\pm}1.17\;mmol\;m^{-2}day^{-1}$, indicating that this area acted as a sink for $CO_2$.

• 한국방재학회 논문집
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• 제5권1호
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• pp.13-21
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• 2005

부서지기 쉬운 큰 응집입자의 파괴 없이 미립자의 침강거동에 관한 실험을 정지수면 조건하에서 CCD(Charged Coupled Device) 카메라로 실시하였다. CCD 카메라를 통한 실험은 점착성 미립자의 연직분포의 농도와 농도의 연직분포에 대해 물리-화학적 인자(NaCl, 밀도, 온도 및 pH)의 영향을 조사하는 것이다. 부유된 미립자(alumina와 quartz) 농도의 연직분포는 $20,000\;mg/{\ell}$까지 CCD 카메라로 측정할 수 있었다. 점착성 퇴적물의 농도의 연직분포는 초기농도의 증가, 온도의 증가 및 염분의 증가로 커진다. 그리고 염분의 첨가로 미립자(alumina) 농도의 연직분포가 quartz보다도 더 빠르게 감소한다. 그와 더불어서 PH은 미립자(alumina) 침강거동에 영향을 끼친다. pH 4.2에서 미립자의 침강률은 낮고, pH 8.9에서 입자의 응집현상 때문에 미립자의 침강률은 크다. pH 9부터 침강 평균속도는 감소한다.

• 한국환경과학회지
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• 제10권3호
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• pp.179-185
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• 2001

To investigate daily variations of water mass distribution in the west and the east parts of Jeju Island, we implemented observations from June 20 to 22, 1997. (The results are as follows : Temperatures in the east and the west were similar in the surface, but $15.02^{\circ}C$ and $13.8^{\circ}C$ in the bottom, respectively.) In the east and west, the surface and the deep salinities are 33.81, 33.34 and 34.33, 34.11 respectively. The east shows higher temperature and salinity than the west. The distributions of nitrate in the east and the west were very similar in the surface regions.(In the deep regions, however, the east shows higher than the west.) The east shows higher phosphates than the west both in surface and deep regions. The silicate had similar distributions to nitrate. Chlorophyll-a of the west was twice higher than that of the east. The daily variations of temperature and salinity were largest at 30m depth, and pH was not much changed in the depth and the pH in day was higher than that at night. The variations of nutrients were much changed in the depth, and nitrate and phosphate at night were higher than those in day. Daily variations of silicate, however, was not much changed in the observation times. Ratio of N/P in the east and the west were 13 and 16, respectively, so that the west was higher than the east. However the ratios were two times higher both in the east and the west in day, when planktons are more active than at night. Si/P ratio showed little different between day and night and between surface and deep regions. The correlation of nitrogen and phosphorus was high (plus relation), and the correlation of AOU, nitrogen and phosphorus was high(plus relation) in the east, however, not high in the west.

• 콘크리트학회논문집
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• 제22권6호
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• pp.769-776
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• 2010

해수에 침적되어 있는 구조물은 일정한 외부 염화물 조건을 가지게 되지만 비래염분의 환경하에 있는 콘크리트 구조물은 지역, 해안으로부터 거리, 구조물의 방향, 풍향 등 주변환경에 따라서 다양한 조건의 외부 염화물 조건을 갖게 된다. 따라서, 해수와 직접 접하지 않더라도 지역적인 특성에 따라 비래염분에 의한 염해를 받을 수 있으며, 그러한 사례들이 보고되고 있다. 그러나, 이러한 비래염분 환경조건을 규명하기는 쉽지 않아 이제까지는 많은 연구가 행하여 지지 못하였다. 따라서, 이 연구에서는 우리나라의 해안가 27개 지역 72개 지점을 선정하여 3년간 대기중의 비래염분에 대한 측정을 실시하여 분석하였다. 그 결과, 비래염분은 지역적 특성이 강하게 나타났으며, 계절적인 영향 또한 크게 나타났다. 또한, 해안으로부터 거리에 따라서 $y=ax^{-b}$의 함수의 경향으로 감소하는 것으로 밝혀졌다. 이러한 비래염분 분포에 대한 분석결과는 향후 해안 인근 구조물의 내구성 설계나 유지관리에 큰 도움이 될 것으로 판단된다.

• 한국수산과학회지
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• 제15권4호
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• pp.255-262
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• 1982

1. 일반적으로 제주도 연안역에서의 영양염류 농도는 성분에 따라 차이가 있으나 표층보다 50 m이심에서의 농도가 $0.5\sim3$배 정도 높다. 2. 제주도 남동쪽 해역의 수온, 염분과 규산염, 질산염, 인산염, 용존산소의 농도 분포가 단조롭고 비교적 각 성분의 량도 적다. 3. 제주도 북쪽 해역은 한국남안연 안수의 영향을 받아 각 성분의 농도 분포가 복잡하고 그 변동 범위도 크다. 또 영양염류도 이 해역이 남동쪽 해역보다 풍부하다. 4. 제주도 남서쪽 해역은 황해저층냉수의 영향을 받아 영양염이 풍부하나 황해난류와 만나는 호경역이므로 그 분포상은 매우 복잡하다.

• Ocean and Polar Research
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• 제26권3호
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• pp.401-414
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• 2004

Temperature, salinity, alkalinity, pH, nutrient, chlorophyll, and iron were measured within the upper 250m water column around the Antarctic Polar Front in the Scotia Sea from late November to early December 2001. Temperature and salinity showed a rapid change across the Polar Front, and the temperature minimum layer existed only in the southern area of the Polar Front. Total $CO_2$ and nutrient concentrations were relatively high and increased rapidly with water depth in the southern area of the Polar Front, which was resulted from upwelling of the Antarctic deep water containing high concentrations of total $CO_2$ and nutrient. ${\Delta}C:{\Delta}N:{\Delat}P$ ratios measured in the norhem and southern areas of the Polar Front were 75:11.4:1 and 84:12.5:1, respectively, which were lower than the Redfield ratio. ${\Delta}Si:{\Delta}N$ ratio (3.65) measured in the southern area of the Polar Front was two times higher than that (1.95) in the northern area. These two ratios were higher than the ratio (1.0) measured in the temperate and tropical oceans. Chlorophyll concentrations were extremely high in the area of $59^{\circ}{\sim}60^{\circ}S$, which was attributed to favorable environmental conditions for phytoplankton growth in this area, such as sufficient iron, high water column stability, and high silicate concentration.

• 한국수산과학회지
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• 제40권6호
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• pp.394-410
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• 2007

Anchovy spawn from the end of May to mid-October, when the water temperature is $14.8-27.2\;^{\circ}C$ and the salinity is 26.0-33.6 psu. The main spawning season is between July to August, when the water temperature is $21.7-27.2\;^{\circ}C$ and the salinity is between 26.0-32.2 psu. The main spawning grounds of anchovy are coastal areas shallower than 50 m around the islands located in the Jeju Strait. Anchovy larvae are distributed near the fronts between Chuja-do, Jangsu-do, Yeoseo-do, and the open sea rather than in the spawning grounds. Anchovy eggs and larvae density increased in accordance with the high level of $Chlorophyll-{\alpha}$ during the summer season (July-August). In terms of the suspended sediment (SS) levels along the northern coast of the Jeju Strait, high densities of anchovy eggs (12.0-18.0 mg/L) were observed, mainly in the area affected by the coastal waters of the southern sea with high SS levels, while larvae (10.0-19.0 mg/L) tended to be distributed over a wide area with high SS levels, including the open sea. In terms of the dissolved oxygen (DO) content, eggs (5.4-6.8 mg/L) were observed in coastal areas with a high DO content, while larvae (4.2-6.4 mg/L) were distributed widely in areas with a relatively low DO content, from the southern coast to the open sea.