• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.176-186
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• 2000

The present study was carried out to clarify the structure and dynamics of copepod community and the relationship between this community and environmental factors during the period from February 1998 to July 1999. Copepods consists of 21 genera and 32 species, monthly variations of number of species were 15 species in May, 1998 and 2 species November, 1998. The number of species were 22 species in station 12 and station 1, 2, 3 occurred nauplii of copepoda only. Average abundance ranged from $8,330\;ind./m^3$ (in June, 1999) to $177\;ind./m^3$ (in November, 1998). Relationships between water temperature and number of species were as follows: 20 species occurred from 20.1 to $25.0^{\circ}C$ and nuplii of copepoda only occurred from 0.0 to $5.0^{\circ}C$. The number of species by salinity range were 19 species in $20.1{\sim}25.0%_o$ and 9 species in $0{\sim}0.5%_o$. The number of species by trophic state index (TSIm) of chlorophyll a were 25 species in oligotrophic state and 9 species in eutrophic state. Relationships between pH and number of species were as follows: 20 species occurred from 7.6 to 8.0 and from 9.1 to 9.5 was none. The number of species by DO range were 22 species in 6.5 to 7.5 mg/l and 1 species in 14.5 to 15.5 mg/l. The percentage calculated effect by stepwise multiple regression of the pearson correlation coefficient value of environmental factors and copepoda abundance (station 1-station 4) revealed that positive effect was 15.49% in COD, 25.86% in $Cl^-$, 19.75% in $NO_2-N$ and negative effect was 28.30% in $NO_3-N$. Also, Positive effect (station 5-station 12) revealed that 29.49% in water temperature, 28.27% in $NO_3-N$, 22.87% in $NO_2-N$ and negative effect was 30.18% in conductivity and 13.53% in DO.

• Korean Journal of Ecology and Environment
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• v.48 no.4
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• pp.253-262
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• 2015

The sustainability of Cypripedium japonicum, a rare plant designated by the Korea Forest Service, is threatened due to artificial factors such as habitat loss and climate change etc. and internal factors such as changes in biological properties of the habitat etc. but conservation research has not been performed in South Korea. The objective of this study is to establish the species conservation strategies by analyzing the characteristics of their habitats, including: 1) Population characteristics, and 2) habitat analysis of the vegetation and abiotic environments. From April to September, 2014, population characteristics [density (stems $m^{-2}$), flowering rate (%), and leaf area ($cm^2$)] in Cypripedium japonicum habitats such as Chuncheon (CC), Hwacheon (HC), Muju (MJ), and Gwangyang (GY) and vegetation characteristics (plant sociological research and ordination analysis), and abiotic environments [temperature ($^{\circ}C$), relative humidity (%), transmitted light ($mol{\cdot}m^{-2}{\cdot}d^{-1}$) and canopy openness (%)] were measured. Cypripedium japonicum was mainly distributed at elevation 450 to 990 m and 5 to $30^{\circ}$ slope. Slope direction was shown as 0 to $110^{\circ}$. Habitats temperature (mean $18.94^{\circ}C$) was well matched to seasonal changes. Differences among sites showed greater level according to latitude difference. It showed the highest in habitat, GY located in the South. On the other hand, relative humidity (77.38%) didn't show much difference among sites. The average degree of canopy openness was 18.17%. It showed the highest at HC (22.1%) and the lowest at MJ (16.1%). The average degree of transmitted light was $9.1mol{\cdot}m^{-2}{\cdot}d^{-1}$. It showed the highest at CC ($10.6mol{\cdot}m^{-2}{\cdot}d^{-1}$) and the lowest at GY ($6.87mol{\cdot}m^{-2}{\cdot}d^{-1}$). Chlorophyll content showed average 26.12 SPAD. It showed the highest at MJ (30.64 SPAD value) and the lowest at HC (23.69 SPAD value). Leaf area was average $253.35cm^2$. It showed the highest at CC ($281.51cm^2$) and the lowest at HC ($238.23cm^2$).

• Korean Journal of Ecology and Environment
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• v.42 no.3
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• pp.382-393
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• 2009

The objectives of this study were to characterize long-term annual and seasonal trophic state of Topjeong Reservoir using conventional variables of Trophic State Index (TSI) and to determine the empirical relations between the trophic parameters. For the analysis, we used water quality dataset of 1995$\sim$2007, which is obtained from the Ministry of Environment, Korea and the number of parameters was 9. Annual ambient mean values of TN and TP were 1.78 mg $L^{-1}$ and 0.03 mg $L^{-1}$, respectively and TN : TP ratios averaged 76, indicating that this system was nitrogen-rich hypertrophic, and was probably phosphorus-limitation for algal growth. Therefore, nitrogen varied little with seasons and years, and total phosphorus (TP) varied depending on season and year. Monsoon dilutions of TP occurred in August and monthly fluctuations of suspended solid (SS) was similar to those of chlorophyll-$\alpha$ (CHL). Annual mean values of BOD and $COD_{Mn}$ were 1.61 mg $L^{-1}$ and 4.23 mg $L^{-1}$, respectively and the interannual values were directly influenced by the intensity of annual rainfall. There were no significant differences in the trophic variables between the two sampling sites. Mean values of Trophic State Index (TSI, Carlson, 1977), based on TN, TP, CHL, and SD (Secchi depth), turned out as eutrophic state, except for the TN (hypertrophic). Regression analyses of log-transformed seasonal CHL against TP and TN showed that variation of the CHL was explained 37% by the variation of TP ($R^2$=0.37, p<0.001, r=0.616), but not by TN ($R^2$=0.03, p>0.05). Regression coefficient of $Log_{10}$CHL vs $Log_{10}SD$ was 0.330 (p<0.003, r=0.580), indicating that transparency is regulated by the organic matter in the system. Results, data suggest that one of the ways controlling the eutrophication would be a reduction of phosphorus from the watershed.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.105-123
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• 2018

Currently, satellite images act as essential and important data in water resources, environment, and ecology as well as information of geographic information system. In this paper, we will investigate basic characteristics of satellite images, especially application examples in water resources. In recent years, researches on spatial and temporal characteristics of large-scale regions utilizing the advantages of satellite imagery have been actively conducted for fundamental hydrological components such as evapotranspiration, soil moisture and natural disasters such as drought, flood, and heavy snow. Furthermore, it is possible to analyze temporal and spatial characteristics such as vegetation characteristics, plant production, net primary production, turbidity of water bodies, chlorophyll concentration, and water quality by using various image information utilizing various sensor information of satellites. Korea is planning to launch a satellite for water resources and environment in the near future, so various researches are expected to be activated on this field.

• Korean Journal of Weed Science
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• v.14 no.1
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• pp.62-70
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• 1994

This study was conducted to find out if there are some differences in germination, growth and morphological characteristics between rice(Oryza saliva) and barnyardgrass(Echinochloa crus-galli) under various cropping patterns and to abtain the fundamental information on weed control method in direct seeded rice. Rice was broadcast on soil-surface(Broadcast rice), drill seeded in soil(Drilled rice) and barnyardgrass was drill seeded in soil(Barnyardgrass) under dry(Dry condition) and water direct seeded condition(Water condition). Also rice was transplanted with 8-day seedlings(8 -day-old seedling) and 25-day seedlings(25-*day-old seedling) under transplanting condition(Transplanting condition) At 1, 2, 3, 5, 7, 10, 15 and 20 days after seeding or transplanting(DAS/T), plants were harvested to examine their germination, growth and morphology. The major results were as follows ; Until 5 DAS/T growth of rice and barnyardgrass were well established under dry condition but under water condition growth of shoots was mainly elongated. At 20 DAS/T barnyardgrass had greater plant height and shoot fresh weight than rice under direct seeded condition, while plant height and shoot fresh weight of rice was greater than those of barnyardgrass under transplanting condition. Root length of barnyardgrass was greater under the dry, drilled, direct seeded conditions than that of rice under the water, broadcast, transplanting condition, respectively. And root fresh weight of rice under direct seeded condition was similar to that of barnyardgrass but that of rice under transplanting condition was significantly greater than that of barnyardgrass. Barnyardgrass only formed mesocotyls and its length increased with increased depth of seeding. Leaf stage and leaf area of barnyardgrass was greater under the dry, drilled than those of rice under water, broadcast conditions, respectively, while those of rice was greater than those of barnyardgrass under transplanting condition. Chlorophyll contents were higher in barnyardgrass, dry direct seeded rice, transplanted rice, water direct seeded rice in descending order.

• Korean Journal of Weed Science
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• v.16 no.1
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• pp.14-20
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• 1996

Growth, nutrient uptake and photosynthesis as affected by submersion of shoot in pickerel weed (Monochoria vaginalis Presl.) were determined. The shoots of pickerel weeds in hydroponic culture were subjected to the submerged or emerged condition at 3- or 5-leaf stage for 8 or 10 days. Under submerged condition, growth in plant height was enhanced, but leaf number, leaf area, fresh and dry weight were reduced compared to those under the emerged condition. Similar responses in growth to submergence were obtained with the pickerel weeds rooted in the soil. Under submergence, chlorophyll content increased during the first 2 days, but thereafter remarkably decreased at 3-leaf stage and after the first 4 days at 5-leaf stage. Compared to the emerged condition, uptakes of $NH_4\;^+$-N, $NO_3\;^-$-N, $P_2O_5$ and $K^+$ were reduced, but uptakes of $Ca^{++}$ and $Mg^{++}$ increased under the submerged condition. Photosynthetic rate of shoot under water, measured by $CO_2$electrode, showed the maximum by 210 ${\mu}$moles $HCO_3\;^-$/g F.W. at the 8th day after submergence(DAS) at 3-leaf stage and 320 ${\mu}$moles $HCO_3\;^-$/g F. W. at 6 DAS at 5-leaf stage. These results indicate that pickerel weeds grow much better when the shoot is air-exposed and are less tolerable to submergence at 3 leaf-stage than at 5-leaf stage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.1
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• pp.71-79
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• 1999

As part of an on-going project investigating flux of materials in the Keum River Estuary, we have monitored seasonal variations of nutrients, suspended particulate matter (SPM), chlorophyll, and salinity since 1997. Meteorological data and freshwater discharge from the Keum River Dike were also used, Our goal was to answers for (1) what is the main factor for the seasonal fluctuation of nutrients in the Keum River Estuary? and (2) are there any differences in nutrient distributions before and after the Keum River Dike construction? Nitrate concentrations in the Keum River water were kept constant through the year. Whereas other nutrients varied with evident seasonality: high phosphate and ammonium concentrations during the dry season and enhanced silicate contents during the rainy season. SPM was found similar trend with silicate. During the rainy season, the freshwater discharged from the Keum River Dike seemed to dilute the phosphate and ammonium, but to elevate SPM concentration in the Keum Estuary. In addition, the corresponding variations of SPM contents in the estuarine water affected the seasonal fluctuations of nutrients in the Estuary. The most important source of the nutrients in the estuarine water is the fluvial water. Therefore, the distribution patterns of nutrients in the Estuary are conservative against salinity. Nitrate, nitrite and silicate are conservative through the year. The distribution of phosphate and ammonium on the other hand, display two distinct seasonal patterns: conservative behavior during the dry season and some additive processes during the rainy days. Mass destruction of freshwater phytoplankton in the riverine water is believed to be a major additive source of phosphate in the upper Estuary. Desorption processes of phosphate and ammonium from SPM and organic matter probably contribute extra source of addition. Benthic flux of phosphate and ammonium from the sediment into overlying estuarine water can not be excluded as another source. After the Keum River Dike construction, the concentrations of SPM decreased markedly and their role in controlling of nutrient concentrations in the Estuary has probably diminished. We found low salinity (5~15 psu) within 1 km away from the Dike during the dry season. Therefore we conclude that the only limited area of inner estuary function as a real estuary and the rest part rather be like a bay during the dry season. However, during the rainy season, the entire estuary as the mixing place of freshwater and seawater. Compared to the environmental conditions of the Estuary before the Dike construction, tidal current velocity and turbidity are decreased, but nutrient concentrations and chance of massive algal bloom such as red tide outbreak markedly increased.

• Journal of Wetlands Research
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• v.18 no.3
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• pp.301-312
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• 2016

This study has performed comparative analysis on characteristics of contaminated 35 tributaries on seasonal variation/point discharge load/pollutant distribution of water quality factors(8) in order to understand the effect of the watershed in Nakdong River Basin. As a results, the water quality of $BOD_5$(Biochemical Oxygen Demand), Chl-a(Chlorophyll a) and Fecal E. Coli shows II grade at tributaries of more than 50% without COD(Chemical Oxygen Demand), TP(Total Phosphate), TOC(Total Oxygen Carbon) and TN(Total Nitrogen) factors. The specific discharge(Q) were occupied about 54.4% (19 sites) as $0.05m^3/sec/km^2$ value. Among these results, the contaminant level of Dalseocheon, Hyeonjicheon, Seokkyocheon 1, Uriyeongcheon and Dasancheon was also high, which has to consider a discharged pollutant load(kg/day). The 35 major tributaries of Nakdong River were included in 7 mid-watershed, such as Nakdong Waegwan, Geumho River, Nakdong Goryung, Nakdong Changnyung, Nam River, Nakdong Milyang, Nakdong River Hagueon. Especially, the discharged pollutant load of Nam River and Geumho River also was high according to the amount of discharge such as Kachang dam, Gongsan dam and Nam river dam. Seasonal difference of the water quality factors such as $BOD_5$, TN, SS and Q was observed largely, on the other hand the TP and Chl-a was not. This is guessed due to the precipitation effect of site, biological and physicochemical degradation properties of pollutant and etc. The co-relationship between the seasonal difference and water quality factors was observed using a Pearson correlation coefficients. Besides, the Multiple Regression analysis using a Stepwise Regression method was conducted to understand the effect between seasonal difference and water quality factors/regression equations. As a result, the Multiple Regression analysis was adapted in the spring, summer and autumn without the winter, which was observed high at spring, summer and autumn in the order COD/TP, Chl-a/TOC, TOC/COD/$BOD_5$ water quality factors, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.3
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• pp.333-338
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• 2008

The tea has traditionally been used as a foodstuff by unique flavor, however recently not only the diversity of consumer demands but also the public interest in unique favorite and functional aspects have increased. It has been also reported that the main components contained in the leaves of tea (Camellia sinensis) include total nitrogen, free amino acids, polyphenols, and fiber, of which catechin has powerful bioactive effect such as anti-cancer, anti-aging, and anti-diabetic. (-)-Epigallocatechin gallate (EGCG) which is a major phenolic constituent of green tea extract has received considerable attention for a variety of important bioactivities. This study was carried out to obtain useful information for tea breeding programs, and to investigate the concentration of quality and functional related components in Korean indigenous tea germplasms. Korean indigenous tea lines were classified into three groups of sprout time, i.e, early, medium and late sprout time, and the ratio were 20%, 43% and 37%, respectively. There was a difference in characteristics among these Korean indigenous tea lines, leaf width of those ranged from 19.8 to 75 mm, leaf length was 35.5-160.0 mm, and leaf area was $660-8,400\;mm^2$. Experimental data on chlorophyll content (SPAD value) of Korean indigenous tea genetic resources ranged from 51.3 to 82.3. The concentrations of the total nitrogen, total free amino acids, and theanine were ranged 4.18-6.07%, 2.87-4.58%, and 1.64-2.66%, respectively. Also, catechin concentration showed from 11.54 to 15.07%, and concentration of caffeine was 2.82-4.23%. These results indicated indicated that it is possible to select elite lines with high concentration of quality related components and low concentration of caffeine from Korean domestic tea germplasms.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.328-335
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• 2010

This study was conducted to determine effects of soil pH and form of nitrogen fertilizers on tomato growth and chemical properties of greenhouse soil using ferigation system. Tomato (Lycopersicon esculentum Mill. cv. Superdoterang) were grown for three months in 18 L pots filled with two soil (pH 6.8 and pH 8.7). 4 different nitrogen fertilizers (urea, ammonium nitrate, ammonium sulfate, and potassium nitrate) were fertigated with different concentrations of 0, 10, 50, and 100 mg N/L during tomato cultivation. Soil pH 8.7 decreased yield and chlorophyll fluorescence compared with soil pH 6.8. Yield at soil pH 8.7 increased by ammonium nitrate and ammonium sulfate fertigation. Soil pH 6.8 induced increment of yield by nitrogen concentration than form of nitrogen fertilizers. Soil pH after cultivation of tomato decreased by application of ammonium nitrate and ammonium sulfate. Soil EC by 100 mg N/L application of ammonium sulfate was twice as much as other fertilizers. Form of nitrogen fertilizer had less effect on concentration of soil $NH_4^+$-N and $NO_3^-$-N in soil but the concentrations slightly reduced at pH 8.7. These results indicate that application of urea and ammonium nitrate for a nitrogen source of fertigation has little affects on soil chemical properties before and after tomato cultivation.