• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.221-231
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• 2009

This study was carried out to comparatively identify characteristics of turbid water influence in Imha Reservoir, Soyang Reservoir, and Daecheong Reservoir in Korea. We used 3 years dataset from 2002 to 2004 and analyzed seasonal water quality characteristics, particular parameters in association with turbidity, and light transparency to figure out the trends. All parameters to be used in the study were total phosphate (TP), total nitrogen (TN), chlorophyll-${\alpha}$ (Chl), suspended solids (SS), Secchi depth (SD), conductivity, and verticallight extinction coefficienct($K_d$), euphotic zone ($Z_{eu}$), and critical depth ($Z_p$). All parameters depend on season and watershed. Suspended solids from Soyang Reservoir were usually caused by TP, mainly related to living wastes and agricultures in upper stream. Daecheong Reservoir was influenced by organic matters related to large phytoplankton biomass in summer and inorganic suspended solids by nutrients in the winter. However, in case of Imha Reservoir, turbid water, consisted in silt and clay through heavy precipitation remained in the waterbody to decrease water transparency along with TP and caused the light limitation in winter. Overall results suggest that it was necessary to establish various management programs because the reasons occurring turbidity were varied according to the reservoir circumstances.

• Korean Journal of Remote Sensing
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• v.36 no.2_2
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• pp.237-247
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• 2020

Here, we generated maps of primary production in the coastal waters of the East Sea using sea surface chlorophyll-a concentrations (CHL), photosynthetically available radiation (PAR), euphotic depth induced by GOCI along with sea surface temperature (SST) from satellites of foreign countries as input parameters, and carried out a sensitivity analysis for each parameters. On 25th of July in 2013 when a wide cold waters appeared and on 13th of August in 2013 when a big harmful algal bloom existed in the study area, it shows high productivities with averages 1,012 and 1,945 mg C m^-2 d^-1, respectively. On August 25, 2013, when the cold waters and red tide retreated, it showed an average of 778 m^-2 d^-1, similar to the results of the previous analysis. As a result of the sensitivity analysis, PAR did not significantly affect the results of the primary production, but the euphotic depth and CHL showed aboveaverage sensitivity. In particular, SST had a large influence to the results, thus we could imply that an error in SST could lead to a large error in the primary production. This study showed that GOCI data was available for primary production study, and the accuracy of input parameters might be improved by applying GOCI, which can acquire images 8 times a day, making it more accurate than foreign polar orbit satellites and consequently, it is possible to estimate highly accurately primary production.

• Journal of the korean society of oceanography
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• v.31 no.4
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• pp.196-206
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• 1996

Vertical profiles of the chlorophyll ${\alpha}$, phytoplankton abundance, nutrients and sigma-t were compared with the vertical distribution of phytoplankton species in conjunction with $^{14}$C primary production in the Southern Waters of the East Sea, Korea. In the upper mixed layer the water column was only weakly stratified and ambient nitrogenic nutrient concentrations were markedly depleted. Dissolved silicate seemed to be another limiting nutrient in the surface layer. The occupation of different water depths by several dominant diatom species was well explained by the degree of silicification of each cell and the silicate concentration of ambient seawater. Subsurface chlorophyll maxima were continuously observed in the lower parts of the euphotic layer and the depth coincided with nutricline, supporting our view that chlorophyll maximum was sustained partially by enhancement of in situ growth of phytoplankton and partially by increase of cellular chlorophyll content. The persistence of chlorophyll maximum layer was attributed to the physiological adaptation of the phytoplankters to low light intensities and to the utilization of regenerated nutrients. Integrated water column production of organic matter by photosynthesis appeared to be better related to phytoplankton cell division than to the cell growth in terms of biosynthesis of pigments and other intracellular components.

• Ocean and Polar Research
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• v.32 no.3
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• pp.291-297
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• 2010

In the summer of 2008 (August 4-14), vertical and horizontal distributions of inorganic nutrients and dissolved organic carbon (DOC) were measured in the southwestern East Sea. Concentrations of DOC were determined for the first time in the southwestern East Sea using the high-temperature combustion oxidation (HTCO) method, and results were compared with those measured by another laboratory. Concentrations of DOC ranged from 58 to 104 ${\mu}M$ in the upper 200 m, showing a typical decreasing pattern with depth. Generally, concentrations of DOC were relatively lower, with higher nutrient concentrations, in the upper layer of the coastal upwelling zone. Concentrations of DOC ranged from 54 to 64 ${\mu}M$ in the deep Ulleung Basin (200-1500 m), and were higher than those in the Pacific and Atlantic oceans. In association with rapid vertical ventilation of the euphotic, this difference indicates a larger accumulation of semi-labile DOC in the deep East Sea than in the major oceans. A correlation between apparent oxygen utilization (AOU) and DOC in the deep ocean of the East Sea revealed that only a small portion (<10%) of the sinking DOC, relative to the sinking particulate organic carbon (POC), contributes to microbial degradation. Our results present an important data set of DOC in the East Sea, which plays a critical role in carbon cycle modeling and sequestration.

• Ocean and Polar Research
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• v.27 no.1
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• pp.1-13
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• 2005

The samples for organic carbon analysis were collected between $5^{\circ}\;and\;17^{\circ}N$ along $131.5^{\circ}W$ in the northeast Pacific KODOS (Korea Deep Ocean Study) area. The mean concentration of total organic carbon (TOC) in the surface mixed layer $({\sim}50 m)$ was $100.13{\pm}2.05{\mu}M-C$, while the mean concentration of TOC in the lower 500m of the water column was $50.19{\pm}4.23{\mu}M-C$. A strong linear regression between TOC and temperature $(r^2=0.70)$ showed that TOC distribution was controlled by physical process. Results from the linear regression between chlorophyll-a and TOC, and between chlorophyll-a and particulate organic carbon (POC), decreasing of dissolved organic carbon (DOC) in the surface layer caused by non-biological photo-oxidation process. Below the surface layer, biological production and consumption occurred. DOC accumulation dominated in the depth range of $30{\sim}50m$ and DOC consumption occurred in the depth range of $50{\sim}200m$. TOC was inversely correlated with apparent oxygen utilization (AOU) and TOC/AOU molar ratios ranged from -0.077 to -0.21. These ratios indicated that TOC oxidation was responsible fur $10.9{\sim}30.1%$ (mean 20.2%) of oxygen consumption in the NE Pacific KODOS area. In the euphotic zone, distributions of dissolved and particulate organic matter were controlled by photo-chemical, chemical, biological and physical processes.

• 한국해양학회지
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• v.27 no.2
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• pp.91-100
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• 1992

For the study on the structure and characteristics of the primary production system in the southern waters of the East Sea, chlorophyll, phytoplankton standing stocks. nutrients and hydrographic properties were investigated and analyzed in conjunction with measurement of C-14 based primary productivity. The primary productivity was relatively high in comparison with the previous studies, ranging from 284 to 4,574 mgC$.$m/SUP -2/$.$day /SUP -1/ and averaged to be 2,000 mgC$.$m/SUP 02/$.$day/SUP -1/. The standing stocks within the euphotic zone were fairly high, but ambient inorganic nitrogenous nutrient concentrations were too low to support the high production. This implied that there might be active recycling of nitrogenous nutrients by heterotrophic processes and the upward flux of nutrients by vertical mixing. Subsurface chlorophyll maxima were continuously observed in the lower parts of the euphotic layer and the depth coincided with the nutricline rather than isopycnal surfaces, supporting the view that chlorophyll distributions and primary production were primarily influenced by nutrient supply. Despite low nutrient concentrations, phytoplankton standing stocks and production were fairly high and the fraction of autotrophic nano- and picoplankton production was significant.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.280-286
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• 2007

In order to find out the effects of the anticyclonic eddy on the distribution of nutrients and chlorophyll concentrations in the Ulleung Basin during spring and summer, we measured temperature, salinity, nutrients, and chlorophyll from the surface to 200 m water depth at five stations in July 2005 and April 2006. In spring, surface mixed layer was very deep inside the eddy, about 200 m, but it was relatively shallow outside the eddy, about $20{\sim}60$ m. Inside of the eddy, nutrients in the surface waters were sufficient by supply from the deep layer, whereas outside of the eddy, they were fairly depleted due to the stratification in the surface layer. In spring, chlorophyll concentrations were relatively low inside of the eddy due to the deeper surface mixed layer compared with the euphotic depth, and the depth-integrated chlorophyll concentrations outside of the eddy were twice as much as those inside of the eddy. In summer, nutrients in the surface waters were completely depleted at all stations due to the well stratification in the surface layer. The typical distribution pattern of subsurface chlorophyll maximum was observed at all stations, and the depth-integrated chlorophyll concentrations inside of the eddy were almost twice as much as those outside of the eddy. The anticyclonic eddy appearing in the Ulleung Basin every year significantly affects the phytoplankton biomass, with the opposing effects in spring and summer; in spring, the anticyclonic eddy suppresses phytoplankton growth, but in summer, it enhances the phytoplankton biomass.

• 한국해양학회지
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• v.27 no.2
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• pp.154-163
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• 1992

Bacterial abundance, production, and environmental parameters were investigated three times to study distribution of bacterial variables and to examine how estuarine mixing would influence the distribution of bacterial variables in the euphotic zone of the estuarine system of the Mankyung river and Dongjin river during a period of October, 1990-August, 1991. Although a limited number of investigations were made, bacterial abundance and production showed large variations from 0.4 to 5.8${\times}$10/SUP 9/ 1/SUP -1/ and from 0.1 to 22.2 ug C 1/SUP -1/ d/SUP -1/, respectively. The wide ranges of bacterial variables indicated very dynamic changes in conditions of bacterial growth in the estuary. Interestingly, bacterial abundance substantially increased with depth in most stations f shallow depth. but bacterial production remarkably decreased with depth. We propose that the observed distribution of bacterial abundance and production would be explained by estuarine mixing in the estuary. Analyses of mixing diagrams showed that estuarine mixing would mix conservatively bacteria and bacterial production. Further, estuarine mixing often seemed to cause an increase in bacterial abundance and reduction of bacterial production presumably due to resuspension of sediment. This suggests that roles of estuarine mixing would be significant in the distribution of bacterial abundance and production, and thus in biogeochemical cycles in the estuary.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.57-63
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• 2004

Primary productivity of phytoplankton was measured by $^{14}C$ method from January to October of 1996 in Seonakdong River. This river was a highly productive freshwater showing the euphotic depth of 1.4 m in August and 2.1 m in the remaining season. Chlorophyll-a concentrations of phytoplankton ranged from 67 ${\mu}g\;L^{-1}$ to 894 ${\mu}g\;L^{-1}$ and showed the great increase in August. Maximum specific productivity was 2.1 ${\sim}$4.3 mg C mg $chl-a{-1}\;hr^{-1}$ and occurred above 0.4m depth. In photosynthesis-irradiance relation, photoinhibition or photosynthetic suppression of phytoplankton occurred clearly in the cold seasons, while phytoplankton (mainly Microcystis aeruginosa and its relatives) in August did not show any symptom of the photosynthetic inhibition against the high irradiance. The specific productivity of phytoplankton was eventually dependant upon incident irradiance to show the linear correlation with received irradiance infield, and the areal productivity of phytoplankton upon chlorophyll-a standing crops. In the downstream of the Nakdong River, phytoplankton productions have linearly increased since the estuarine barrage construction to reflect the gradual eutrophication in the estuarine area. Average chlorophyll-a increase of 10 ${\mu}g\;chl-a\;L{-1}$ absolutely corresponded to the primary production acceleration of 30 mg C $m^{-2}\;day^{-1}$ on the annual basis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.45-55
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• 1998

Phytoplankton community and primary productivity have been investigated in a fall season in the southern coastal waters of the last Sea, Korea. A strong thermocline formed at the 20\~60\;m$ layer and a cold water mass also existed in the bottom around Yong-il Bay. The offshore of the surveyed area was likely to be influenced by relatively warmer water, whereas the inshore represented Higher primary productivity with lower water temperature and lower salinity. A total of 133 species of phytoplankton occurred, representing 107 spp. of diatom, 23 spp. of dinoflagellate 3 spp. of silicoflagellate. Skeletonema costatum and Asterionellepsis glacialis were most predominant with more than $30\%$ dominance ratio, while Leptocylindrus danicus was also dominant at all transect lines. Standing crops of phytoplankton ranged from $2.7{\times}10^3\;to\;141.6{\times}10^3\;cell^{\ell-1}$. Chlorophyll a concentration varied with stations and layers, but the $30\~50$ m layer showed maximun with about $1.18{\mu}g{\ell}^{-1}$ rather than at the surface layer. It is believed that the maximun in standing crops and chlorophyll of phytoplankton formed at the $20\~50$ m layer above the thermocline during the survey. Phytoplankton primary productivity ranged from 0.32 to 3.04 mgC $m^{-3}\;hr^{-1}$, showing higher at the inshore than at the offshore. The range of integrated primary productivity was $263.3\~1085.5 mgC\;m^{-2}\;day^{-1}$ for the euphotic layer. Photosysthesis rates varied with the range from 0.76 to 8.04 mgC mgChl $\alpha^{-1}\;hr^{-1}$. Phytoplankton photosynthesis at the inshore was saturated at lower irradiance ($15\~35\%$ of surface) and showed higher efficiency, Thus, it revealed that the phytoplankton community probably adapted to the middle of euphotic layer because the depth of mixing layer became thinner due to the formation of thermocline.