• ALGAE
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• 제19권2호
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• pp.145-148
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• 2004

As a result of the 2-year monthly monitoring of the phytoplankton community at 3 stations in Mankyeong Estuary, Korea, we learned that cyan bacterial species of the genus Anabaena occurred at most sampling points with huge salinity differences (0.1-32.5 psu). We isolated several clones of Anabaena spp. from the monitoring stations, and screen out two euryhaline and nitrogen-fixing Anabaena clones, CB-MAL21 and CB-MAL22. The two clones were grown under various environmental gradients such as temperature (20, 30, 35 and 40$^{\circ}C$), salinity (0, 2, 5, 15 and 30psu), and $PO_4^{3-}$-P concentration (0, 1.6, 8.0, 40 and 200 ${\mu}M$M). Growth of CB-MAL21 and CB-MAL22 was measured by daily monitoring of chlorophyll fluorescence from each experimental culture for more than three serial transfers. Both the two experimental clones did not grow at 0psu. Maximal growth rates of the two clones were markedly reduced at lower $PO_4^{3-}$-P concentrations showing negligible growth at 0 and 1.6 ${\mu}M$M. However, growth of CB-MAL21 was not affected by low $NO_3^--$ concentration in culture media, showing the nitrogen-fixing ability. Maximum biomass yields of the two clones decreased dramatically at 35 and 40$^{\circ}C$. Optimal growth conditions for the two experimental clones were determined to be 20-30$^{\circ}C$, 40 ${\mu}M$M $PO_4^{3-}$-P, and wide salinity range from 5.0 to over 30psu. Best growth of CB-MAL21 was shown at (20$^{\circ}C$-15psu), which is less saline and cooler condition than those (i.e., 30$^{\circ}C$-30psu) for the best growth of CB-MAL22. The euryhaline and nitrogen-fixing CB-MAL21 strain thus can be a candidate laboratory culture for the future cyan bacterial marine biotechnology in temperate coastal waters.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 1997년도 가을 학술발표회 프로그램
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• pp.1.1-32
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• 1997

Atmospheric monitoring capabilities were established in 1988 by the University of Florida at Duke forest, near Durham. NC: Cary forest, near Gainesville, FL: and Austin forest, near Nacogdoches, TX. Continuous (hourly averaged) measurements of air quality (ozone, nitrogen oxides and sulfur dioxide) and meteorological variables were made at these three low elevation (< 200 meters), rural locations in the southeastern U.S. for more than three years. During the same period at these sites wet and dry acid deposition samples were collected and analyzed on an event and weekly basis, respectively The monitoring locations were selected to determine actual atmospheric exposure indices for southern pine species in support of on-site surrogate exposure chamber studies conducted by Southern Commercial Forest Research Cooperative (SCFRC) investigators. Daily and quarterly averaged ozone maxima were higher (55 ppb) at the northernmost site in the network (Duke forest) in the second and third quarters (spring and summer seasons) and lower (35 ppb) in the first and fourth quarters (winter and fall seasons), when compared to ozone levels at the two southernmost sites (Cary and Austin forests). Seasonal ozone levels at the latter two sites were similar Nitrogen oxieds and sulfur dioxide levels were insignificant (< 5 ppb) most of the time at all sites, although soil emissions of NO at two sites were found to influence nighttime ozone concentrations. Typical maximum quarterly and annual aggregate ozone exposure indices were significantly higher at Duke forest (92.5/259 ppm-hr) than those values observed at the two southern sites (65.6/210 ppm-hr). Acid deposition (wet and dry) components concentrations and deposition fluxes observed at the Duke forest, NC piedmont site, were generally greater, dependent on site and season, than corresponding variables measured at either of the two southern coastal plain sites (Cary and Austin forests). Acid deposition variables observed at the latter two sites were remarkably similar, both qualitatively and quantitatively, although the sites were located 1300 km apart. A comparison of deposition fluxes of elemental nitrogen (NO3, NH4') and sulfur (5042-, SO3) components in wet and dry forms indicated that wet deposition accounts for approximately 70% of the total nitrogen and 73% of the total sulfur input on an annual equivalent basis at all sites.

• 한국환경복원기술학회지
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• 제13권6호
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• pp.75-86
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• 2010

This study used a phytosociolocal approach in classifying the vegetation communities of evergreen broad-leaved forest in Gageodo island of Korea, and the results are as follows: Quercus acuta community was classified into Dendropanax morbifer subcommunity, Daphniphyllum macropodum subcommunity, and Quercus acuta typical subcommunity. In the study sites, soil organic matter, total nitrogen, available phosphorous, exchangeable K, exchangeable Ca, exchangeable Mg, cation exchange capacity, and soil pH were ranged from 15.23~18.89%, 0.73~0.99%, 4.31~15.06 (mg/kg), 1.09~1.13 ($cmol^+$/kg), 21~7.15 ($cmol^+$/kg), 1.33~2.10 ($cmol^+$/kg), 33.04~38.28 ($cmol^+$/kg) and 4.47~4.83 respectively. The Dendropanax morbifer subcommunity were found in sites with high percentage of organic matter, total nitrogen, and low percentage of exchangeable Mg and Ca while the Daphniphyllum macropodum subcommunity were found in sites with low percentage of organic matter, total nitrogen, exchangeable Mg and Ca. The Quercus acuta typical subcommunity were found in sites with high percentage of organic matter, total nitrogen, exchangeable Mg and Ca. It is urgently needed to work for the preparation of an island management plan to the levels of species through habitat conservation.

• 한국환경과학회지
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• 제30권3호
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• pp.195-206
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• 2021

Contaminated marine sediment is a secondary pollution source in the coastal areas, which can result in increased nutrients concentrations in the overlying water. We analyzed the nutrients release characteristics into overlying water from sediments and the interaction among benthic circulation of nitrogen, phosphorus, iron, and sulfur were investigated in a preset sediment/water column. Profiles of pH, ORP, sulfur, iron, nitrogen, phosphorus pools were determined in the sediment and three different layers of overlying water. Variety types of sulfur in the sediments plays a significant role on nutrients transfer into overlying water. Dissimilatory nitrate reduction and various sulfur species interaction are predominantly embodied by the enhancing effects of sulfide on nitrogen reduction. Contaminant sediment take on high organic matter, which is decomposed by bacteria, as a result promote bacterial sulfate reduction and generate sulfide in the sediment. The sulfur and iron interactions had also influence on phosphorus cycling and released from sediment into overlying water may ensue over the dissolution of ferric iron intercede by iron-reducing bacteria. The nutrients release rate was calculated followed by release rate equation. The results showed that the sediments released large-scale quantity of ammonium nitrogen and phosphate, which are main inner source of overlying water pollution. A mechanical migration of key nutrients such as ammonia and inorganic phosphate was depicted numerically with Fick's diffusion law, which showed a fair agreement to most of the experimental data.

• 한국균학회지
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• 제23권3호통권74호
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• pp.275-283
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• 1995

The nutritional requirements of mycelial growth for Pleurotus spp. were studied. As the carbon sources, soluble starch and dextrin, nitrogen sources, arginine and ammonium tartrate, and calcium sources, $CaCO_3$ enhanced mycelial growth. Optimum C/N ratio was 100 : 1. On the base of results from the experiment on nutritional requirements, the following receipe is suggested for growth of Pleurotus spp.; starch 15 g, arginine 3.484 g, ammonium tartrate 3.06 g, $CaCO_3$ 0.314 g, $KH_2PO_4$ 8.138 g, $K_2HPO_4$ 1.584 g, $MgSO_4{\cdot}7H_2O$ 1.5 g for P. sajor-caju and 2.5 g for P. ostreatus. $FeSO_4{\cdot}7H_2O$ 0.02 g, $ZnSO_4{\cdot}7H_2O$ 0.03 g, $MnSO_4{\cdot}7H_2O$ 0.02 g, optimum pH 6.0. This new synthetic medium is tentatively designated as Park's medium.

• 한국환경과학회지
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• 제9권4호
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• pp.275-284
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• 2000

The studyies on physico-chemical factors and phytoplankton at the 3 rivers in the Taejon city were conducted from November 1997 to May 1998. The Results were as floows; In the water quality, the down streams were generally worse than the upper streams. Water temperature was varied from 2.4$^{\circ}C$ to 23.$0^{\circ}C$; DO from 1.80mg/$\ell$ to 17.6mg/$\ell$ ; pH from 4.7 to 10.4 ; BOD from 0.78mg/$\ell$ to 8.80mg/$\ell$ ; COD from 0.32mg/$\ell$ to 8.26mg/$\ell$ ; SS from 2.0mg/$\ell$ to 43.0mg/$\ell$ ; total phosphate was from 0.001mg/$\ell$ to 0.709mg/$\ell$ ; total nitrogen 0.01mg/$\ell$ to 11.69mg/$\ell$. In phytoplankton species, they were identified as total 191 taxa composed of 8 classes, 18 orders, 35 families, 74 genera, 152 species, 35 varieties and 4 forms. The dominant species were Synedra ulna in Taejon-chon, Diatomavulgare in Yudong-chon, Oscillatioria princeps, Scenedesmus qadricauda, Synedra ulna, and Diatom vulgare in Gap-chon. Standing crops of phytoplankton were from 2,076 cells/$m\ell$ to 97,356 cells/$m\ell$

• 한국자기공명학회논문지
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• 제1권2호
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• pp.126-140
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• 1997

Mesoporous MCM-41 gallosilicate material was synthesized through shifting through shifting gallosilicate polymer equilibrium towards a MCM-41 phase by addition of acid. The location of Cu(II) exchanged into MCM-41 and its interaction with various adsorbate molecules were investigated by electron spin responance and electron spin echo modulation spectroscopies. It was found that in the fresh hydrated material, Cu(II) is octahedrally coordinated to six water molecules. This species is located in a cylindrical channel and rotates rapidly at room temperature. Evacuation at room temperature removes three of these water molecules, leaving the Cu (II) coordinated to three water molecules and anchored to oxygens in the channel wall. Dehydration at 45$0^{\circ}C$ produces one Cu (II) species located in the inner surface of a channel as evidenced by broadening of its ESR lines by oxygen. Adsorption of polar molecules such as water, methanol and ammonia on dehydrated CuNa-MCM-41 gallosilicate material causes changes in the ESR spectrum of Cu (II), indicating the complex formation with these adsorbates. Cu (II) forms a complex with six molecules of methanol as evidenced by an isotropic room temperature ESR signal and ESEM data like upon water adsorption. Cu(II) also forms a complex containing four molecules of ammonia based on resolved nitrogen superhyperfine interaction.

• The Korean Journal of Ecology
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• 제20권6호
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• pp.451-459
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• 1997

Seasonal and spatial distribution of vascular plants were examined and related to soil texture, pH, moisture and nutrient contents in the riparian zone of the Balan Stream. In spring the area was dominated by Alopecurus aequalis var. amurensis, was displaced by Persicaria thunbergii and Humulus japonicus in summer. From the stream channel to bank, soil texture and pH were not significantly differentiated, moisture decreased, organic matter and K increased, and TKN and available P increased in June and decreased in August. DCA ordination analysis by species distribution showed spatially and seasonally distinct patterns seasonal difference was evident on axis 1, and spatial difference according to the distance from stream channel was clear, too. Both axis 1 and axis 2 scores were significantly correlated with biomass, pH, and phosphate. Species richness increased were significantly correlated with biomass, pH, and phosphate. Species richness increaed with increasing organic matter and phosphate, and decreased with increasing soil moisture and K. Biomass increased with increasing organic matter, but was negatively related to pH, moisture, TKN, available P and K. Available P was significantly correlated with biomass, pH, and total soil nitrogen. In conclusion, the distribution of riparian vegetation was governed by soil physico-chemical properties, which are primarily determined by how far it is from the stream channel.

• 환경생물
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• 제31권2호
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• pp.61-68
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• 2013

Microalgae can grow autotrophically with the supply of light, carbon dioxide and inorganic nutrients in water through photosynthesis. Generally, microalgal growth is limited by the concentrations and relative ratio of nitrogen (N) and phosphorus (P) among the nutrients in the aquatic environment. Each microalga has its specific optimum N : P ratio resulting in dominance in a particular water having similar nutrient composition. Algal bloom is an immense growth of certain microalga commonly cyanobacterium and can be sequestrated by reducing the limiting nutrient, generally P in the freshwater. Moreover, dominance of a less toxic blooming strain can be established by manipulating N : P ratio in the water. On the other hand, microalgal biomass of a certain species can be enhanced by increasing limiting nutrient and adjusting the N : P ratio to the target species. The above-mentioned eco-physiological features of microalgae can be more completely interpreted in connection with their genomic informations. Consequently, microalgal growth regulation which can be achieved on the basis of its eco-physiological and further genomic insights would be helpful not only in the control of algal bloom, but also for an increased yield of algal biomass.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
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• pp.117-128
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• 1999

The removal of nitrogen oxides(NOx) from $N_{2}/O_{2}$ gas using a pulsed corona discharge was investigated as a function of the reduced electric field(E/N) and the energy density(J/L). A kinetic model was developed to characterize the chemical reactions taking place in a pulsed corona discharge reactor. The model calculates the fractional concentrations of radical species at each pulse-on period and utilizes the radicals to remove NOx for the subsequent pulse-off period. Electron collision reaction data are calculated using ELENDIF program to solve Boltzmann equation for electron energy distribution function, and the subsequent chemical reactions are calculated using CHEMKIN-II program to solve stiff ODE(ordinary differential equation) problems for species concentrations. The corona discharge energy per pulse and the time-space averaged E/N were obtained by fitting the model to experimental data. The model calculation shows good agreement with the experimental data, and predicts the formation of other species such as $NO_{2}$, $O_{3}$ and $N_{2}O$.