• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.457-467
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• 2019

To investigate the long-term variation characteristics of nutrients in the east coast of Korea, water temperature, salinity, dissolved oxygen, and nutrients were measured at three stations of Sokcho, Jukbyeon and Gampo coasts for five years from 2013 to 2017. For five years, the water temperature of the East Sea coast was in the range of $1.2{\sim}28.8^{\circ}C$, the salinity was in the range of 30.63~34.79 and the dissolved oxygen (DO) was in the range of 3.53~7.64 mL/L. Distribution and variation of the water environment factors in the study area were determined by the vertical stratification of water column and distribution of water temperature. The high DO concentration in Sokcho coast From 2015 to August 2016 is presumed to be the result of the southward inflow of North Korean Cold Water (NKCW). Concentrations of dissolved inorganic nitrogen (DIN, $NH_4-N+NO_2-N+NO_3-N$) ranged $0.11{\sim}24.19{\mu}M$, phosphate concentration ranged $0.01{\sim}1.75{\mu}M$, and silicate ranged $0.17{\sim}32.80{\mu}M$. The N:P ratio was in the range of 0.7~54.3 (mean 15.2) and the N:P slope was in the range of 11.67~13.75. The N:P ratios in this study were lower than the Redfield ratio (16), indicating that nitrate did act as a limiting factor in phytoplankton growth. The correlation ($R^2$) of total N:P ratio was as high as 0.95, indicating that the effect of the surrounding land or non-point sources was not significant. In conclusion, the spatial and temporal variation of nutrients in the east coast of Korea was determined by the vertical mixing of water mass with thermocline and mainly affected by physical factors such as influx of external water masses and coastal upwelling, and the influences from inflows from the land were minimal.

• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.119-130
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• 2006

As unialgal cultures to examine the growth kinetics of an algal species, Microcystis aeruginosa was grown in chemostats with nitrogen and phosphorus limitation. The nutrient concentrations of $NH_4\;^+\;and\;PO_4\;^{3-}$ to limit the growth of M, aeruginosa were approximately 200 ${\mu}M$ and 7 ${\mu}M$, respectively. Cell size of the algae decreased towards the $NH_4$-nitrogen limitation under a constant dilution rate, while it increased in the $PO_4$-limitaion. The cell quota of nitrogen under nitrogen-limited conditions was 6.1 ${\mu}mol$ mg $C^{-1}$ and, under nitrogen sufficient conditions, ranged from 9.5 ${\mu}mol$ mg $C^{-1}$ to 12.4 ${\mu}mol$ mg $C^{-1}$. In addition to the cell quota, the half-saturation constants for nitrogen uptake ($K_s$) and the growth rate (${\mu}_m$) was 36 ${\sim}$ 61 ${\mu}M$ and 0.28 ${\sim}$ 0.35 ${\mu}mol$ cell ${\cdot}$ $hr^{-1}$ to show high values in comparison with other algal species. As the limiting concentration, cell quota and uptake rate of M. aeruginosa were higher than those of any other species, the its nitrogen requirement would be great. In the other side, as the half saturation constant ($K_s$) for nitrogen uptake was higher, and the ratios ofmaximum uptake rate ($V_m$) and $K_s$ was relatively low, the species would have the low competitive ability in the low nitrogen concentration in the ambient water. However, the low concentration of nitrogen in the Nakdong River during the Microcystis outbreak would be the inevitable results of the algal blooms. In the lower Parts of the Nakdong River, the nutrient status was coupled with the growth kinetics of the blooming algae to have clear seasonal variations through a year.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.117-124
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• 1997

Vertical profiles of dissolved Cu and Ni at the upper 400 m water layer have been determined at two stations in the central East Sea in October 1995. This is the first report on the vertical distribution of trace metals in Korea. Copper concentrations are in the range of 2.1~5.8 nmol/kg and 1.6~2.4 nmol/kg for stations S and N, respectively. The vertical profile of Cu at S is found a scavenging type (i.e., drastic decrease with increasing depth). Concentrations of Ni range from 4.3 to 7.1 nmol/kg and from 3.4 to 5.4 nmol/kg for stations Sand N, respectively. At station S, Ni is best correlated with phosphate, but not at stations N. Such difference between two stations are probably due to their different vertical distribution of water masses. Station S has a strongly stratified water column with 6 distinct water masses, but station N with a well-mixed subsurface water layer extending from 50 to 300 m depth. Extremely low salinity (31.87~31.96 psu) found at the surface water of station S was interpreted as a result of the Yangtze River effluents which were probably fed into the East Sea through the Korea Strait during the late summer. Such seasonal appearance of low salinity in southern part of the East Sea was reported previously. The concentrations of Cu and Ni at two sites are comparable to those reported in the North Pacific. It was found that Ni mostly exist as dissolved phase.

• 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.

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.160-165
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• 1997

The actomyosin and myosin of the squid at 3$0^{\circ}C$ showed the highest Vmax and the actomyosin and myosin of the clam at 35$^{\circ}C$ and HMM at $25^{\circ}C$ showed the highest Vmax the thermostability of myofibrillar proteins is changed greatly according to the difference of KCI concentration. The myofibrillar proteins of the clam showed a higher thermostability than the myofibrillar proteins of the squid. When 3% ethanol solution was added and heated myofibrillar proteins, denaturation was accelerated and it was shown that there was a difference between animals in the denaturation velocity.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.383-392
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• 2013

The objective of this study was to determine the effects of N:P ratio on primary productivity measured as chlorophyll-a (CHL) using the approach of In Situ Nutrient Enrichment Bioassays (NEBs) in Daechung Reservoir. The effects of NEBs on the N:P mass ratios were compared with the field data obtained from monthly-chemical monitoring during 2009~2012. The short-term NEBs showed that the response of primary productivity in the phosphorus spiked treatments (5, 15, 20 and 30 N:P ratios) were greater than the responses in the control (C) and nitrogen spiked treatment (N:P ratio=150, $T_{VI}$). The response in the nitrogen treatment (N:P ratio=150, $T_{VI}$) was less compared to control and all five treatments ($T_I{\sim}T_{VI}$). The outcomes of the NEBs suggest that phosphorus limited the phytoplankton growth and nitrogen addition inhibited the algal growth. In the analysis of nutrients and CHL from the ambient epilimnetic water in Daechung Reservoir, minimum N:P ratios resulted in maximum concentrations of CHL. Overall, our results suggest that the N:P ratio was the key factor in regulating the phytoplankton growth in NEB experiments.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.117-117
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• 2003

다시마(Laminaria japonica) 생태육종 연구의 일환으로 완도산과 백령도산 품종의 재배시험을 전남 고흥군 명천어장과 계도어장에서 2001년부터 2002년까지 실시하였다. 시험기간 중 어장의 수온, 염분농도, 유속, 용존산소농도는 구간별로 유의차가 없었으며 수온은 1월부터 7월까지 점차 상승하였고, 염분농도는 5월까지 상승하다가 6월과 7월에 낮아졌다. 유속은 저층에서보다 표층에서 빨랐고, 용존산소농도는 1월부터 7월까지 점차적으로 낮아졌다. 어장의 영양염 변화는 구간별로 1월부터 7월까지 유의차가 없었으며 암모니아염이 5월에 다소 증가하였다. 일반적으로 전장과 엽폭은 4월까지 증가하다가 끝녹음으로 인하여 4월이후에는 다소 감소하였으나, 엽두께, 전중량, 비대도는 7월까지 계속적으로 증가하였다. 형질간의 상관관계는 모두 1%와 5% 수준에서 유의차가 있었다. 각형질에 있어서 품종과 환경간에 월별로 질적교호작용과 양적교호작용중 어느 한 쪽이 나타났다. 품종시험에 의한 유전력은 엽폭에서 가장 높았고, 엽두께에서 가장 낮았다. 표현형상관, 유전상관, 환경상관계수는 형질간에 대부분 높은 값을 보였으나 엽두께와 전중량간의 값이 일반적으로 낮았다. 부모와 자식간의 회귀에 의한 유전력은 계도어장의 엽두께에서 가장 높았으나 일반적으로 전중량에서 높았고, 육종가와 유전상관은 전중량에서 가장 높았다. 각 형질의 상대적 경제 가치를 고려한 선발 총점은 명천어장에서의 완도산 품종에서 가장 높았다.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.4
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• pp.235-243
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• 2007

In order to understand the water mass properties in the southern location of the East Sea in the Korean coasts, the vertical distributions (down to 2,000 m deep) of water temperature, salinity, and dissolved inorganic nutrients were determined in April of 2005. The water mass of the surveyed location showed distinct vertical layers; highly saline surface, surface mixing layer, and thermocline of low temperature and salinity. The water layer below 300 m was characterized by water temperature lower than $1^{\circ}C$ and salinity 34.06, showing a representative water mass of the East Sea. The inorganic nutrients rapidly increased from 200m in the northern and southern parts around Ulleung Basin. A marked environmental difference was found between two layers separated by thermocline. The upper layer of the thermocline was oligotrophic and the vertical distribution of nutrient was very stable. In the water layer between 100 and 200m the nutrients slightly increased but remained still stable. From southern coasts to northeastern Ulleung, the water mass properties were site specific; the thickness of the surface mixed layer and nutricline showed a trend diminishing toward the northern locations probably due to diminished influence of Tsushima water. Redfield ratio (N:P=16:1) based on the ratio of chemical composition in organism revealed that nitrogen value continuously decreased to less than 16 with the water depth down to loom from the thermocline. The value in the water layer deeper than 100 to 200 m, thereafter, showed an increasing trend (over 16). This result was further supported by the finding of lower chlrophyll a content in the layer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.6
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• pp.417-424
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• 1990

Effect of physical processes on the surface distributions of chlorophyll-a and nutrients was investigated in the southern sea of Korea during summer season. The northwestern area of Cheju Island had higher concentrations of the chlorophyll-a and nutrients than its southeastern area. A nutrient-rich patch was observed in the western area of Cheju Island and the northern area of $34^{\circ}N$ respectively. It seems that the patch in the western area of Cheju Island is formed by horizontal extension of the low-saline Coastal Water of China Contiental(CWCC), while the patch in the northern area of $34^{\circ}N$ by vertical mixing. Also, the high chlorophyll-a in the vicinity of Cheju Island appears to be ascribed to sufficient supply of nutrient from bottom water by coastal upwelling.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2004.11a
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• pp.93-93
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• 2004