• Korean Journal of Ecology and Environment
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• v.39 no.1 s.115
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• pp.21-31
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• 2006

The objectives of this study were to analyze trends of temporal water quality and trophic state in Andong and Imha reservoirs using chemical dataset during 1993 ${\sim}$ 2004, obtained from the Ministry of Environment, Korea. According to long-term limnological analyses, Suspended solids (SS) in Imha Reservoir were 2 ${\sim}$ 8 fold2 greater, than those in SS of Andong Reservoir, and the high solids increased total phosphorus (TP) and biological oxygen demand ($BOD_5$) and decreased the transparency, measured as Secchi depth (SD). Chlorophyll-a (CHL-a) increased little or decreased slightly in the both reservoirs during the high solids, resulting in reduced yields of CHL-a : TP ratios. The deviation analysis of Trophic State Index (TSI) in Imha Reservoir showed that about 70% of TSI (CHL-a)-TSI (SD) and TSI (CHL-a)-TSI(TP) values were less than zero and the lowest values were-60, indicating that influence of inorganic solids (or non-volatile solids) on phytoplankton growth was evident in Imha Reservoir and the impact was greater than that of Andong Reservoir. Inorganic solids in Imha Reservoir resulted in light limitation on phytoplankton growth and thus contributed variations in the relations among three parameters of trophic state index. Especially, seasonal data analysis of nutrients in both reservoirs showed that during the postmonsoon, mean TP concentration was Imha Reservoir greater in than that in Andong Reservoir. The higher TP concentrantion was mainly attributed to increases of inorganic solids from soil erosions and nonpoint source inputs within the watershed. The high inorganic turbidity in Imha Reservoir should be reduced for the conservation of water quality for, especially a tap water supply.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.109-118
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• 2000

The dynamics of inorganic nutrients and phytoplankton population were examined at eight stations of Shihwa Reservoir, which situated near the cities newly constructed and the industrial complex of West-sea in Korea, from January to December 1999. Among environmental factors, average concentration of $NH_4$, SRP and SRSi were $522.7\;{\mu}g\;N/l$, $9.8\;{\mu}g\;N/l$ and $0.26\;{\mu}g\;Si/l$, respectively. Water quality was extremely deteriorated by a great amount of pollutants load into inner reservoir after the event of rainfall. Nutrients concentration was suddenly decreased toward the lower part. While $NO_3$ concentration did not much varied among stations, but it was relatively high in winter season. Chlorophyll-a concentration was high at the upper part of the reservoir, with average of $37.2\;{\mu}/l$, and closely related to the fluctuation of $NH_4$, SRP and SRSi concentrations. The phytoplankton development in the water column was dominated by diatom (autumn), prasinoid (winter) and dinoflagellate (summer). Dominant phytoplankton were composed to Skeletonema costatum of diatom, Prorocentrum minimum of dinoflagellate, Chroomonas spp. of cryptomonad, Eutreptiella gymnastica of euglenoid and Pyramimonas spp. of prasinoid. The large bloom of phytoplankton at the upper zone of the Shihwa Reservoir after inflow of a seawater were consistently observed. In consequence, water quality management of the inlet stream was assessed to be very important and urgent.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.174-187
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• 2008

In an effort to identify structure and function of microbial loop in Paldang reservoir, we monitored environmental and biological factors at Kyungan stream (station K), Paldang dam (station P) and the confluence of North and South Han River (station M) from March to December, 2005. DOC concentration was higher in March to May and November than the others. Nutrient concentration in station K detected relatively higher than that of two stations. Both of phosphate and silicate gradually increased at all stations until September, after then decreased. The highest Chl-$\alpha$ concentration was observed at all stations in April, and November. The carbon biomass of bacteria and HNF were relatively higher in March, May and August than the others, whereas that of the ciliate showed no significant difference in monthly fluctuation. Nevertheless, the significant relationships revealed between ciliate (P<0.001) and HNF (P<0.05) and bacterial density. Tintinnopsis cratera, Didinium sp., Vorticella sp., Paramecium sp. and Strombidium sp. were dominant species in ciliate community. The dominant species of phytoplankton were Stephanodiscus hantzschii and Cyclotella meneghiniana at almost stations in Spring, Summer and Autumn. However, Aulacoseira granulata accounted for >95% of phytoplankton biomass at station P and M in Autumn. The carbon biomass of zooplankton was highest at station P and M in June, and relatively higher biomass observed at all stations in August, October and November. Diaphanosoma brachyurum and Bosmina longirostris were dominant in stations P and M of June and in all stations of October and November, respectively. The maximum growth (A. granulata: $0.17\;d^{-1}$, S. hantzschii: $0.14\;d^{-1}$) and grazing rate (A. granulata: 1.93 preys $d^{-1}$, S. hantzschii: 1.63 preys $d^{-1}$) of Bosmina longirostris revealed in algal preys as Aulacoseira granulata and Stephanodiscus hantzschii. In conclusion, these results suggest that bacteria and phytoplankton can play the most crucial source as prey within microbial food chain in Spring and Summer and grazing food chain in Autumn, respectively.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.97-97
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• 1993

Primary tumor arises infrequently in the parotid gland and generally, only about 20 to 40 percent of which prove to be malignant. They are characterized by histopathologic diversity, slow tumor growth, significant proportion of patients who have received previous treatment elsewhere. We have reviewed retrospectively 101 cases of parotid gland tumors which were treated for the recent eight years (1985-1992), Non-neoplastic tumor-like lesions were all excluded.

• Journal of the Korean earth science society
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• v.39 no.5
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• pp.419-435
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• 2018

The purpose of this study is to understand meteorological and climatological factors that have influence on the garlic product in Seosan and Taean, and to analyze the economic value according to the use of climatical information data for garlic farmers. The climatological characteristics and trends in this area are analyzed using the meteorological data at the Seosan local meteorological agency from 1984 to 2013, the national statistical data for the product of garlic from 1989 to 2013, and the scenario data for climate change (RCP 4.5 and 8.5) for the period from 2001 to 2100. The results are as follows. First, the condition of lower temperature for garlic growth in winter season is satisfied with the mean air temperature. The wind speed are lower and stronger in Seosan and Taean than other garlic area. The suitable condition for the growth of northern type of garlic shows the decreasing trend in the accumulated precipitation in May. However, the area of growing the northern type garlic in the future is likely diminished because mean air temperature, accumulated precipitation, and mean wind speed are strong in the harvest time of garlic. Second, the seedtime of the northern and southern type of garlic using climate change scenarios (RCP 4.5, 8.5) in Seosan and Taean is getting late as time passes. and the harvest time gets faster, which indicates s that the period of garlic cultivation becomes shorter from 50 days to around 90 in the next 100 years. Third, the beginning days of white rot and delia platura of garlic are estimated by applying to the meteorological algorithm using mean air temperature and soil humidity. Especially, the beginning day of white rot garlic is shown to be faster according to the scenarios of RCP 4.5 and RCP 8.5. Fourth, the product of garlic (kg/10a) shows a high correlation with the minimum air temperature of a wintering time, the mean wind speed of a wintering time, the accumulated precipitation of a corpulent time, and the mean relative humidity of corpulent time of garlic. On the other hand, the analysis of garlic product when using the meteorological information data in cultivating garlic in Seosan and Taean reveals that the economic value increases up to 9% in total.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.492-500
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• 2017

The purpose of this study was to investigate the seasonal distribution of phytoplankton as prey for oysters and to characterize the environmental factors controlling their abundance from June 2016 to May 2017, in the northeast coast between Tongyeong and Saryang Island, particularly for the oyster farming area. During the survey period, water temperature changed from $7.54^{\circ}C$ in February to $29.5^{\circ}C$ in August. The abnormal high temperature persisted during one month in August. Salinity was low due to summer rainfall and typhoon. The lowest level was 30.68 psu in September, and it peaked at 34.24 psu in May. The dissolved oxygen (DO) concentration ranged from $6.0-9.45mg\;L^{-1}$, and the DO concentration in the surface layer was like that in the bottom layers. The seasonal trends of pH were also like those of DO. The pH ranged from 7.91 to 8.50. Nitrate with nitrite, phosphate, and silicate concentrations ranged from $0.14{\mu}M$ to $7.66{\mu}M$, from $0.01{\mu}M$ to $4.16{\mu}M$, and from $0.27{\mu}M$ to $20.33{\mu}M$, respectively. The concentration of chlorophyll a (Chl. a) ranged from $0.37{\mu}g\;L^{-1}$ to $2.44{\mu}g\;L^{-1}$ in the surface layer. The annual average concentration was $1.26{\mu}g\;L^{-1}$. The annual mean phytoplankton community comprised Bacillariophyta (69%), Dinophyta (17%), and Cryptophyta (10%), respectively. Dinoflagellate Prorocentrum donghaiense in June was the most dominant at 90%. In the summer, diatom Chaetoceros decipiens, Rhizosolenia setigera and Pseudo-nitzschia delicatissima were dominant. These species shifted to diatom Chaetoceros spp. and Crytophyta species in autumn. In the winter, high densities of Skeletonema spp. and Eucampia zodiacus were maintained. Therefore, the researchers thought that the annual mean Chl. a concentration was relatively lower to sustain oyster feeding, implying that the prey organism (i.e., phytoplankton) was greatly controlled by continuous filter feeding behavior of oyster in the vicinity area of the oyster culture farm.

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.71-80
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• 2019

Effects of environmental factors on phytoplankton succession and community structure were studied in Lake Chuncheon located in Bukhan River, South Korea. The data were sampled at three sites such as CC1 (lower side), CC2 (middle side), and CC3 (upper side of Lake Chuncheon) from 2014 to 2017. The annual average precipitation in Lake Chuncheon was 992 mm during the study period (2014~2017), and the annual precipitation was lower than 800 mm in 2014 and 2015. The annual average water temperature, total phosphorus (TP), and total nitrogen (TN) ranged from 17.0 to $21.1^{\circ}C$, 0.012 to $0.019mg\;L^{-1}$, and 1.272 to $1.922mg\;L^{-1}$, respectively. The TN concentration was relatively high in 2015 compared with the other study years, as a drought continued from 2014 to 2015. When comparing the correlation between precipitation and environmental factors, water temperature (p<0.01) and TP(p<0.05) showed positive correlations with rainfall. The average numbers of phytoplankton cells by branch were 2,094, 2,182, and $3,108cells\;mL^{-1}$ in CC1, CC2, and CC3, respectively. CC3 is considered advantageous for phytoplankton growth, even in small pollution sources due to low water depth. As a result of analyzing the relationship between precipitation and phytoplankton, the correlation between the two was shown to be high for 2016 (p<0.01) and 2017 (p<0.05), which is when precipitation was high. However, the correlation was not clear to 2014 and 2015. The relationship between water temperature and phytoplankton indicated a negative correlation with diatoms (p<0.01), yet positive correlations with green algae (p<0.01) and cyanobacteria (p<0.01). Diatoms increased in spring and autumn, which are characterized by low water temperature, and green algae and cyanobacteria increased in summer, when the water temperature is high. Our findings provide a scientific basis for characteristics of phytoplankton and water quality and management at the Lake Chuncheon.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.587-597
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• 2023

We evaluated the eutrophication of Saemangeum Lake, which causes abnormal growth of algae, using the Carlson index. Eutrophication characteristics of Saemangeum Lake were analyzed. For the study, water quality surveys were conducted at 7 stations in Saemangeum Lake every month in 2021. The concentration of Chl.a was slightly higher in the Mankyeong water system in winter, and slightly higher in the Dongjin water system in spring and summer, but overall, except for some periods, the concentration was similar to or lower than the lake water quality environmental standard of class 3. COD showed water quality similar to or above the lake quality environmental standard of grade 4 in both the Mankyeong and Dongjin water systems in the summer and Autumn. TOC concentrations were within lake water quality standard 3 at all sites. Total phosphorus concentrations exceeded the lake water quality standard of Class 4 and were higher in January and August after rainfall. In the correlation analysis between water quality factors, the correlation of organic matter, total phosphorus, and total nitrogen to salinity was relatively high. This reflected the water quality characteristics of freshwater, brackish water, and seawater areas due to seawater inflow through the drainage gate and freshwater inflow through upstream rivers. According to the characteristics of eutrophication fluctuations in Saemangeum Lake by trophic state index, the indices of Chl.a, SD, and TN showed water quality in the early stage of eutrophication, while the TP index showed a severe eutrophication state. The magnitude of the eutrophication index among water quality components was TSI(TP) > TSI(TN) > TSI(SD) > TSI(CHL) in all water systems. Quadrant analysis of the deviation of TSI(CHL) from TSI(TP) and TSI(SD) on a two-dimensional plane showed that there was no limiting effect of total phosphorus on algal growth in all water systems. In addition, the factors af ecting light attenuation appeared to be dominated by small particulate matter from outside sources.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.3
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• pp.147-158
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• 2007

To clarify the bloom pattern and species succession in phytoplankton community, the population dynamics with the determination of physico-chemical factors have been studies in Masan Bay, the south sea of Korea, for the periods November 2003-October 2004. Concentration of $NH_4-N$ was always higher than that of $NO_3-N$, which was similar level as compared to other costal areas. $PO_4-P$ concentration was lower than those in other coastal areas but similar to oligotrophic environments. Thus, phosphate seems the limiting nutrient rather than nitrogen. $SiO_2-Si$ concentration was also low as compared to other costal areas. Si:P ratio was low from autumn to winter, suggesting silicate and/or phosphate limitation during this period. The cell density of phytoplankton was high in winter 2003 and early autumn 2004. The carbon biomass was high in winter 2003 and summer 2004. And chlorophyll-a concentration was high in late autumn 2003 and summer 2004. Among 78 species of phytoplankton found in the bay during the investigated period, dominant species were two diatoms of Cylindrotheca closterium, Skeletonema costatum, and three dinoflagellates of Heterocapsa triquetra, Prorocentrum minimum, P. triestinum, and one raphidophyte of Heterosigma akashiwo. P. minimum dominated from late autumn to winter, but it was replaced by H. triquetra in late winter. P. triestinum dominated from late spring to early summer. Simultaneously, H. akashiwo cell density steadily increased, and it became dominant with C. closterium in late summer. With decreasing of H. akashiwo and C. closterium, S. costatum became the most dominant species in autumn. The canonical analyses showed that total phytoplankton cell density related to diatom cell density and it was affected by temperature, and concentrations of $NO_3-N\;and\;PO_4-P$. The carbon bio-mass and $chlorophyll-{\alpha}$ concentration related to diatom- and dinoflagellate cell densities and these were affected by flagellate cell density, salinity, and concentrations of $SiO_2-Si\;and\;PO_4-P$. Last six years monitoring data in Masan city obtained from Korean Meteorological Agency indicates gradual increase in air temperature. And the precipitation decreased especially in spring season. The winter bloom found in 2003 may be caused by the increase in the temperature and this bloom subsequently induced the nutrients depletion, which continued until next spring probably due to no precipitation. Therefore, the spring bloom, which had been usually observed in the bay, might disappear in 2004.

• Atmosphere
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• v.33 no.2
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• pp.275-295
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• 2023

In Korea, there are four institutions related to atmospheric science: the university's atmospheric science-related department, the Korea Meteorological Administration (KMA), the ROK Air Force Weather Group, and the Meteorological Industry Association. These four institutions have developed while maintaining a deep cooperative relationship with the Korea Meteorological Society (KMS) for the past 60 years. At the university, 6,986 bachelors, 1,595 masters, and 505 doctors, who are experts in meteorology and climate, have been accredited by 2022 at 7 universities related to atmospheric science. The KMA is carrying out national meteorological tasks to protect people's lives and property and foster the meteorological industry. The ROK Air Force Weather Group is in charge of military meteorological work, and is building an artificial intelligence and space weather support system through cooperation with universities, the KMA, and the KMS. Although the Meteorological Industry Association has a short history, its members, sales, and the number of employees are steadily increasing. The KMS greatly contributed to raising the national meteorological service to the level of advanced countries by supporting the development of universities, the KMA, the Air Force Meteorological Agency, and the Meteorological Industry Association.