• 약학회지
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• 제29권4호
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• pp.176-182
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• 1985

As a part of the studies on adsorptive properties of Korean halloysite clays, Hadong white clays of premium grade were examined for geometric pore structured by mercury porosimetry and for specific surface areas by nitrogen adsorption according to the BET procedure. Three size fractions of the native clay sample were derived from passage BS #100, #200 and #325 meshes, respectively. Several parameters lhus observed in relation to the pore structures are shown below: 1. The size fraction of BS #100, #200 and #325 show internal pore volumes of 25.3, 30.2 and $35.0m^2g^{-1}$, respectively. 2. In the distribution curves of the cumulative pore volume against pore diameter, it has been shown that the larticle sizes, the steeper the distribution over the larger ranges of pore diameters. The converse is true the smaller particles. 3. Internal pore areas increase with decrease in pore sizes. It follows that the pores having diameters of $\leq$0.1$\mu\textrm{m}$ are responsible for more than 90% of the total pore area. 4. The behaviour of nitrogen adsorption can be best described by BET type IV isotherm. Further, the hysteresis loops of the adsorptiondesorption curves become narrower with decresing particle sizes. 5. The specific surface areas observed for the fractions of BS #100, BS #200 and BS #325 are 34.6, 35.4 and 43.2m $^2g^{-1}$, respectively. and the calcined clay of BS #325 has a specific surface area near $30.4m^2g^{-1}$.

• 아시안잔디학회지
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• 제10권3호
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• pp.195-211
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• 1996

Dictyostelids cellular slime molds were isolated from the soils of Gokneung and Anyang streamside in Korea. The fifteen species including two undescrihed species were identified. These were as follows ; Dictyostelium macrocephalurn D. sphaerocephalum, D. aureum var. aureum, D.mucoroides, D. minutum, Polyspondyium pallidum. D. giganteum, P. violaceum. D. purpureum. D.brefeldianum, D. flavidum, D. mucoroides var. storoniferum, D. septentrionalis, D. aureum var. luteolum,D. aureo-stipes var. aureo-stipes. D. macrocephalum was the dominant species. and D. sphaerocephalum. D. aureum var. avreum were relatively common. D. mucoroides var. storoniferum, D. septentrionalis were the undescrihed species in Korea. In the soils of streamside, dominant species was shifted by D. macrosephalum, D. sphaerocephalum. which were rare in the forest soils. The total clones per gram of streamside soils were greater than that of forest soils, whereas the number of species in streamside was smaller than the in forest soils. As a result, the ratio of the number of clones to species was very high in the soils of streamside, Environmental factors of soil pH, water content, organic content, total nitrogen and total phosphorus made a effect differently on the cellular slime molds community. Key words: Cellular slime molds, D. macrocephalum, D. sphaerocephalum, Shift of dominant species, Environmental factors.

• 한국환경과학회지
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• 제27권11호
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• pp.1117-1127
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• 2018

This study was carried out to gather basic data for the purpose of proposing a plan to improve the water quality and conserve the aquatic ecosystem of the Singu Agricultural Reservoir in Korea. The water quality, sediment composition, benthic macroinvertebrate distribution, and fish distribution in the Singu Reservoir were analyzed; the reservoir is located close to farmlands, forests, villages, and livestock breeding areas. The results of the water quality analysis are as follows: 5.8~7.8 mg/L for dissolved oxygen, 13.1~20.7 mg/L for chemical oxygen demand, 14.4~18.8 mg/L for suspended solid, 0.96~1.70 mg/L for total nitrogen, 0.07~0.11 mg/L for total phosphorous, and $41.9{\sim}49.8{\mu}g/L$ for $chlorophyll-{\alpha}$. In total, 75 benthic macroinvertebrate specimens belonging to 4 classes, 7 orders, 14 families, and 17 species were recorded. The ecological scores of the benthic macroinvertebrate communities ranged from 11 to 23. Fish specimens recorded belonged to two families and four species. The dominant fish species were Carassius auratus and Pseudorasbora parva, both of which are water-pollutant tolerant species.

• 한국초지조사료학회지
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• 제11권1호
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• pp.53-59
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• 1991

This experiment was conducted to investigate the effects of propionic acid and wilting on fermentation quality of Italian ryegrass silage. Grass material was wilted for a day before ensiling and propionic acid(0. 0, 0. 2. 0. 5 and 0.8 7~ of fresh matter) was applicated at ensiling time. Chemical composition, fermentation acids, pH, microbial population and distribution of the nitrogen contents were evaluated. The results obtained are summarized as follows: 1. The contents of dry matter and water soluble carbohydrate in the silage were increased by wilting, and crude fibre, NDF and ADF were decreased with increasing propionic acid levels. 2. The pH values of the silage increased by increasing DM content, but decreased with increasing propionic acid levels. Lactic acid content lowed in wilted silage, and acetic acid and butyric acid formation were decreased with increasing propionic acid levels. 3. Total nitrogen content in the silage was i n ~ r e a s e d ( ~ < . 05) by addition of propionic acid and wilting, and was the highest in the prewilting-0.8 Q propionic acid applicated silage. The production of NHBN was decreased with propionic acid and was the lowest in the 0.8 % treated silage. 4. The number of total bacteria and yeasts were estimated $10^6~10^7$, $10^2~10^3$ respectively. Moulds number were decreased with increasing propionic acid levels.

• Geomechanics and Engineering
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• 제17권2호
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• pp.157-164
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• 2019

The effect of electrochemical modification of the physical and mechanical properties of sandstone from Paleozoic coal measure strata was investigated by means of liquid nitrogen physical adsorption, X-ray diffraction and uniaxial compressive strength (UCS) tests using purified water, 1 mol/L NaCl, 1 mol/L $CaCl_2$ and 1 mol/L $AlCl_3$ aqueous solution as electrolytes. Electrochemical corrosion of electrodes and wire leads occurred mainly in the anodic zone. After electrochemical modification, pore morphology showed little change in distribution, decrease in total pore specific surface area and volume, and increased average pore diameter. The total pore specific surface area in the anodic zone was greater than in the cathodic zone, but total pore volume was less. Mineralogical composition was unchanged by the modification. Changes in UCS were caused by a number of factors, including corrosion, weakening by aqueous solutions, and electrochemical cementation, and electrochemical cementation stronger than corrosion and weakening by aqueous solutions.

• 생태와환경
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• 제53권4호
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• pp.355-364
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• 2020

본 연구에서는 낙동강 수계 8개의 보 구간에서 퇴적물의 변화에 대하여 알아보았다. 보 구간의 퇴적물을 채취하여 유기물, 영양염류, 금속류 항목을 분석하였으며, 시간의 흐름에 따른 변화를 알아보았다. 보를 기준으로 상류부에는 퇴적물이 세립해지거나 세립한 퇴적물이 증가와 감소를 반복하는 것으로 나타났으며, 하류부에서 조립한 퇴적물을 유지하는 것으로 나타났다. 퇴적물의 유기물 및 영양염류는 입도와 강한 상관성을 보이고 있으며, 조립한 상태를 유지하는 지점보다 퇴적물이 세립해지는 지점에서 증가하였다. 유기물과 영양염류의 농도가 증가하는 지점이 있었으나 하천·호소 퇴적물 오염평가 기준의 기준치를 넘는 지점이 없어 유기물, 영양염류에 대하여 오염 정도가 미약한 상태로 보인다. 금속류의 경우 전반적으로 농도가 증가하는 것으로 나타났으며, 입도 및 유기물, 영양염류와 상관성이 미약하였다. 일부 금속이 독성이 나타날 가능성이 있는 II등급에 속하는 지점이 있으나 I등급과 농도 차이가 많지 않으며 대부분의 금속이 I등급을 유지하여 금속류에 대한 오염정도는 미약한 것으로 판단된다. 본 연구결과가 낙동강 수계의 퇴적물 변화를 모두 대표할 수는 없지만 보 구간의 퇴적물 변화 특성을 이해하는 자료로 활용이 가능할 것으로 생각되며, 향후 독성평가를 진행하거나 보 구간에서 입도와 금속류의 분포 및 상관관계에 대한 지속적인 연구가 진행되어야 할 것으로 보인다.

• Journal of Ecology and Environment
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• 제42권1호
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• pp.12-19
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• 2018

Background: The objective of this study was to determine the relationship between soil environmental factors and halophyte distribution in the west coast of South Korea. Soils of our study sites were categorized into two groups: salt marsh and estuary marsh. Results: Salinity was higher in the salt marsh group than that in the estuary marsh group. However, total nitrogen, silt, and clay contents were higher in the estuary marsh group than those in the salt marsh group. Although altitude had a wider range in the salt marsh group, the mean altitude was higher in the estuary marsh group than that in the salt marsh group. Annual halophytes of seed propagation species were distributed parallel to the coast line on salt marsh. Higher coverage of vegetation was found in the area closer to the coast line. Plant density was higher near dead parental plants in estuary marsh, showing less difference in area that was more distant from the coast line. Conclusions: Results of canonical correspondence analysis (CCA) for vegetation distribution and sediment environmental factors and germination analysis in the coast line showed significant relationship with halophyte distribution. Therefore, they can be used as an indicator of coastal plant movement due to sea level rise.

• 한국수산과학회지
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• 제26권6호
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• pp.557-566
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• 1993

한국연안해역 표층퇴적물중의 유기물함량 분포특성을 밝히기 위하여 1993년 2월에 총117개 정점에서 중력식 corer로 채취한 표층퇴적물 시료에 대해서 유기탄소와 질소함량, 강열감량, 화학적산소요구량, phaeopigment 및 총황화물량을 측정하였다. 표층퇴적물중 유기 탄소 및 질소함량은 각각 $0.03{\sim}5.41\%$(평균 $1.08\%$), $0.01{\sim}0.44\%$(평균 $0.18\%$) 범위였는데 진주만에서 부산항사이의 남해동부연안역에서 각각 평균 $2.18\%$와 $0.23\%$로서 한반도 주변해역중 가장 높았고 금강에서 동진강에 이르는 군산연안 해역이 각각 평균 $0.17\%$와 $0.03\%$로 가장 낮은 분포였다. 주요인 분석의 결과는 조사해역의 표층퇴적물중 유기물함량 분포특징을 잘 나타냈는데 유기물 함량 즉 부영양화의 정도에 따라 서해와 남해동부해역이 뚜렷이 구분되며 부산항과 마산만 입구에서의 높은 C/N비는 이 수역이 인근 도시의 생활하수나 산업폐수의 영향을 크게 받고 있음을 보여준다. 또한 마산만내의 표층퇴적물은 높은 황화물량을 보여 다른 해역과 뚜렷이 구분된다.

• Ocean and Polar Research
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• 제45권3호
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• pp.103-111
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• 2023

To evaluate the impact of effluents from land-based fish farms on the coastal ocean of Wando, Korea, we analyzed inorganic nutrients, particulate organic carbon (POC), dissolved organic carbon (DOC), and colored dissolved organic matter (CDOM) in the effluent and influent of land-based fish farms during the summer (July) of 2021. The average concentrations of nutrients (Dissolved inorganic nitrogen, phosphorus, and silicate; DIN, DIP, and DSi, respectively) in the effluents of this study area were 17±3.7 μM, 1.4±0.7 μM, and 14±1.6 μM, respectively. The average concentrations of POC and DOC were 37±22 μM and 81±13 μM, respectively, with POC accounting for about 30% for total organic carbon in effluents. The Reduced Dissolved Inorganic Nitrogen/Total Dissolved Inorganic Nitrogen ratio (0.7), potential short-period index, indicates that the discharge of nutrients excreted by the fish and unconsumed feed into coastal water results in such nutrients being deposited and accumulated in the sediment. Subsequently, this continuous accumulation triggers the release of ammonium ions during organic matter decomposition, and the ammonium-enriched waters that encroach on fish farms as influent seem to be due to the diffusion of high concentrations of ammonium from bottom sediment. Furthermore, we used fluorescence indices to examine the characteristics of organic matter sources, obtaining mean values of 1.54±0.19, 1.06±0.06, and 1.56±0.06 for the humification index, biological index, and fluorescence index, respectively, in the effluent. These results indicate that the organic matters had an autochthonous origin that resulted from microbial decomposition, and such organic matters were rapidly generated and removed by biological activity, likely supplied from the sediment. Our results suggest that the effluent from land-based fish farms could be a potential source of deoxygenation occurrence in coastal areas.

• 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.