• 한국해양학회지
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• v.26 no.1
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• pp.77-82
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• 1991

Phytoplankton chlorophyll-a concentrations and primary productivities were measured and analyzed in the adjacent waters of Kori Nuclear Power Plant where thermal effluent is being discharged chlorophyll-a concentrations were ranged from 1.89 to 12.8 ug/l. Nanoplankton 9cell size; 3∼20 um) fractions of the total chlorophyll-a concentrations were ranged from 4.60 to 65.95% and picoplankton (cell size<3um) fractions contributed from 15.71 to 83.20%. Primary productivities measured by C 14 method were ranged from 165.17 to 645.79 mgC/m$^2$ /day and, nanoplankton and picoplankton contribution rate to the total primary productivity were ranged from 8.06 to 43.98% and from 19.64 to 81.45% respectively. these results imply that very tiny cell sized phytoplankton population are important in point of biomass and primary productivity of phytoplankton communities.

• 한국해양학회지
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• v.26 no.3
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• pp.255-261
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• 1991

Bacterial abundance and production in the water column over two seamounts (Horizon Guyot and magellan rise) in the central North Pacific were studied in March 1987. Bacterial abundance (0.9-2.3${\times}$10/SUP 8/ l/SUP -1/) in surface waters during the study period were in the lower limit of the values reported for oligotrophic areas. further, bacterial abundance in mesopelagic zone (mostly<5${\times}$ 10/SUP 7/ l/SUP -1/) was much lower than that reported from other tropical areas. Bacterial production 920-466 ng C l/SUP -1/ d/SUP -1/) in surface waters was also low compared to other oligotrophic oceanic environments. However, comparison of bacterial production with the earlier reported values of primary production from these regions suggested a significant role of bacteria in the utilization of organic matter in further studies on spatial distribution of bacterial production on both small and large scales in very oligotrophic aquatic environments are suggested to be necessary.

• Journal of Environmental Impact Assessment
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• v.11 no.4
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• pp.281-287
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• 2002

자연친화적 하천사업에 있어서 못은 하천환경을 구성하는데 기본단위이나 수환경상의 기능에 대한 평가는 이루어지지 않고 있는 실정이다. 못의 수환경을 평가하기 위하여 측정 자료를 토대로 한 일중 수질모형을 개발하여 적용하였다. 못의 하천환경에 대하여 물리적, 생태학적 관점에서 그 효과를 분석하였다. 못에 있어서 일중 수질은 혼합의 정도에 따라 영향을 크게 받으며 이러한 모의실험 결과는 향후 못의 조성에 따른 자료수집이나 일차 생산력을 이해하는데 유효하게 이용될 수 있을 것이다.

• Proceedings of the KSRS Conference
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• 2009.03a
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• pp.151-154
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• 2009

MODIS Aqua에 의한 한반도 주변 해역의 관측은 엽록소의 변동을 관측하여 해양환경변화를 관측하는데 주로 연구되었다. 그러나 황해는 Case II 해역으로 해양의 엽록소 관측에 오차가 크기 때문에 동해와 남해, 동중국해역을 관측한 연구가 발표되어 왔다. 특히 적조와 같은 이상변동을 관측하는데 해색자료의 활용은 매우 활발한 연구가 이루어졌다. 하지만 K490(Diffuse attenuation coefficient for downwelling irradiance at 490nm)은 OCTS, SeaWiFS, MODIS, MERIS 등의 해색자료에 의해 많은 자료가 생산되고 있으나 이를 이용한 한반도 주변 해역의 해양환경변동에 관한 연구는 부족한 실정이다. 본 연구에서는 2008년 한반도 주변해역에서 관측된 MODIS 자료를 처리하여 K490에 의한 시-공간적 변화를 분석하였다. 특히 K490에 의한 월 변화(monthly)와 통계처리 결과를 분석하여 기후변화의 주요 분석인자인 해양의 일차생산력을 판단하는데 중요한 영향을 미치는 K490의 공간 특성을 제시하였다. 한반도 주변 해역의 K490에 의한 시-공간적 특성은 육상의 주요 하천에서 기인하는 부유사와 서남해역의 재부유 물질에 의한 영향이 시-공간적으로 뚜렷하게 나타나는 것을 파악할 수 있었다.

• 한국해양학회지
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• v.24 no.3
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• pp.157-164
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• 1989

Quantitative species distribution and primary productivity of phytoplankton were studied monthly from August, 1987 to July, 1988 along with the quantitative distribution of total heterotrophic bacterioplankton and three groups of physiologically chracteristic bacterioplankton in the intertidal and subtidal waters off Kum River Estuary, Yellow Sea. A total of 121 phytoplankton taxa including 102 diatoms occurred, and cell concentration ranged from 15 to 5451 (cells/ml). The great spatio-temporal variations of the number of phytoplankton species and cell concentration well reflected the environmental differences between the intertidal and subtidal waters. Primary productivity (in Piopt, mgC/$m^3$/hr) ranged from 0.6 to 27.3. Just after the phytoplankton bloom (March) Piopt was very low in April at station 1, where amylolytic bacterioplankton also showed quite low population density. The peaks of primary productivity were not always coincided with those of phytoplankton standing crop. The ratio of Piopt's between samples well indicated the environmental differences between the intertidal and subtidal waters. Little characteristic trend was found in the scatter diagrams of phytoplankton standing crop along the population densities of total heterotrophic bacterioplankton and the three groups of physiologically characteristic bacterioplankton. In summer the phytoplankton standing crop was minimum in contrast with the high population density of bacterioplankton, which implies the influx of much allochthonous orgainc matter from Kum River. The scatter diagrams of Piopt along bacterioplankton population density revealed some phenomena there. Piopt had highly positive correlation with the population density of amylolytie bacterioplankton($R^2$=0.84) and that of lipolytic bacterioplankton($R^2$=0.70) while total heterotrophic bacterioplankton and proteolytic bacterioplankton had lesser correlations with Piopt. From the regression lines the increase of unit Piopt (mgC/$m^3$/hr) in the study area was calculated to mean the increase of $9.0{\times}10$ cells/ml and $8.0{\times}10$ cells/ml of amylolytic bacterioplankton and lipolytic bacterioplankton, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.1-9
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• 2009

Export fluxes of particulate organic carbon were estimated for the first time by using $^{234}Th/^{238}U$ disequilibrium in the southwestern East Sea during August 2007. They were calculated by multiplying POC/$^{234}Th_p$ ratios of sinking particles (larger than 0.7 ${\mu}m$) obtained from 150-200 m water depths to $^{234}Th$ fluxes that were estimated by integrating $^{234}Th/^{238}U$ disequilibrium from surface to 100 m water depth. Export fluxes ranged from 14 to 505 mg C $m^{-2}$ $day^{-1}$, with the highest value at station A2 and the lowest value at station D4. Primary production was well correlated with export flux, indicating that it was a major factor controlling export flux. Export flux in the East Sea was generally higher than those estimated in the open ocean and similar to or somewhat higher than those in the continental marginal seas. Export flux/primary production (EF/PP) ratios varied from 0.29 to 0.62, with an average of 0.43 and were somewhat higher in the basin area than in the coastal area. EF/PP ratio in the East Sea was rather similar to those estimated in the North Sea and Chukchi Sea, but much higher than those in the Labrador Sea, Barents Sea, and Gulf of Lions. Therefore, the East Sea is one of the major areas where a large amount of organic carbon produced in the euphotic zone sinks into the deep layer below 200 m water depth.

• Journal of the Korean association of regional geographers
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• v.9 no.2
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• pp.119-134
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• 2003

This paper analyzes Wu Ha-Youngs Cheonilrok in order to reconstruct the regional characteristics of farming in the late 18th-century Korean countryside. The projected objective is approached through the examination of various indices drawn from the volume such as environment, distribution of arable lands, major crops, agricultural techniques, and productivity. The main finding of this research is that unlike todays homogenous picture of agriculture, quite significant differences of agrarian practices existed across the country in the past. The regional differentiation was attributable foremost to natural environment. To elaborate, landform, climate and soil influenced the distribution and use of land plots, the kinds of main crops produced, and the agricultural productivity. The region-specific agricultural techniques result from the cumulative processes of trial and error against the given environment. Other social and economic conditions which include population, skill of the peasants, size of landownership, and irrigation facilities sustained the regional differentiation of agriculture.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.3
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• pp.200-209
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• 2008

Particle fluxes were measured with a time-series sediment trap from July 2003 to June 2005 at the St. KOMO(KOMO; Korea Deep-Sea Environmental Study Long-Term Monitoring Station, $10^{\circ}30'N,\;131^{\circ}20'W$) in the northeastern Pacific. Total mass fluxes at a depth of 4,960 m showed distinct seasonal variations with high values in the winter(December-February) and spring(March-May) and low values in the summer(June-August) and fall(September-November). Biogenic origin fluxes also displayed distinct seasonal variations similar to total mass fluxes. Particularly, calcium carbonate fluxes in winter and spring were more than two times greater than those in summer and fall. The prominent seasonal variations of total mass and biogenic fluxes were closely related with the seasonal changes of primary production in the surface waters; in winter and spring, primary production increased due to the enhanced supply of nutrients below the surface mixed layer by strong wind and less stratification, whereas it decreased as a result of the less supply of nutrient by reduced wind speed and strong stratification in summer and fall. The seasonal variations of total mass and biogenic fluxes in this study were higher than the differences of total mass and biogenic fluxes caused by the environmental changes such as El $Ni\tilde{n}o$ and La $Ni\tilde{n}a$ events in the previous studies. In order to understand the effects of El $Ni\tilde{n}o$ and La $Ni\tilde{n}a$ on the particle flux, therefore, the seasonal variation of particle flux in the northeastern equatorial Pacific needs to be well defined.

• 한국해양학회지
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• v.24 no.1
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• pp.52-61
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• 1989

The daily net primary production by phytoplankton and ammonium excretion by macrozooplankton (> $350{\mu}m$) were measured to understand the nitrogenous nutrient dynamics in the southern part of the East Sea of Korea. At most of the staions, water columns were well stratified and strongly developed pycnoclines and matching nutriclines could be found near the 20-60m. Total chlorophyll ranged between $1.22-3.24{\mu}g$ ChI/l and nano-fractions of chlorophyll ranged from 43.2 to 99.6% in the surface layer. The daily net primary production by phytoplankton ranged from 0.75 to 2.04 gC/$m^2$/d and averaged to be 1.5 gC/$m^2$/d. 1t is evidenced that the primary production and chlorophyll content are relatively high in frontal waters where the North Korean Cold Water meets with the East Korean Warm Water. The turnover time of nitrate in the euphotic zone ranged from 0.2 day to 1.6 day and averaged to be 0.8 day. The N:P ratio of the study area shows on the average 13.4 which indicates nitrogenous nutrient to be the limiting factor for phytoplankton growth. Ammonium excretion by macrowoplankton averaged out to 1.3mg at-N/$m^2$/d, and contributed 7.3% of daily total nitrogen requirement by phytoplankton in this area. Calculation of upward flux of nitrate to the surface mixed layer from the lower layer approximates 7% of nitrogen requirement by phytoplankton.

• 한국해양학회지
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• v.29 no.2
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• pp.145-151
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• 1994

Investigations on distributions of bacterial abundance and production in the mideast part of the Yellow Sea were made in August and October, 1991 as a part of study of "The Exploitation Research of Marine Resources on the Yellow Sea". Here, we report spatial and temporal characteristics of distributions of bacteria in the mideast part of the Yellow Sea including data reported by Son (1989) for the same area. During the whole study period, bacterial abundance ranged from 0.5${\times}$10/SUP 8/ 1/SUP -1/ to 19${\times}$10/SUP 8/ 1/SUP -1/. Seasonal changes and the difference between two studies in bacterial abundance were less than 3.5 fold ar each station in the study area, except October, 1991. An interesting result was that bacterial abundances except October, 1991 were generally lower than those expected from the established relationship between chlorophyll and bacterial abundance in the oceans. For the bacterial abundance observed in October 1991, controlling factor(s) of bacteria might be different from the rest of study period. Bacterial production (0.1∼2.9ug C 1/SUP -1/ d/SUP -1/) comprised a small fraction (18${\pm}$11%) of primary production. Though data are limited, low bacterial abundances compared to chlorophyll concentration and low values of bacterial production to primary production seemed to occur in the mideast part of the Yellow Sea. Unravelling the causes of these phenomena would be necessary to understand the ecology of bacteria in the region.