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Ultrastructural Changes Induced by Telluric Acid in the Rat Liver (Telluric Acid가 흰쥐 간조직의 미세구조에 미치는 영향)

  • Son, Serk-Joo;Jeong, Young-Gil;Cho, Seung-Muk;Baik, Tai-Kyung;Choi, Chang-Do;Choi, Wol-Bong
    • Applied Microscopy
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    • v.25 no.4
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    • pp.83-103
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    • 1995
  • This experiment was carried out to investigate the effects of telluric acid on the histological and fine structural changes in the rat liver. Fischer 344 rats($150{\sim}200gm$) were used in this study as control and experimental groups. Telluric acid(5 mg/100 gm of body weight) suspensed in olive oil was given intraperitoneally to the animals of the experimental group and only olive oil to those of the control group. At the intervals of 3, 6 and 12 hours, 1, 2, 3, 5, 10, 20, 30 and 60 days after administration, the animals were sacrificed, and livers were obtained from the rats. For light microscopic examination of the liver, sections($5{\mu}m$) were stained with hematoxylineosin(H-E). For electron microscopic examination of the liver, sections were stained with uranyl acetate and lead citrate, finally examined with Zeiss EM 109 electron microscopes. The results obtained were as follows. 1. In the control group, round nucleus. well developed mitochondria, Golgi apparatus, rough endoplasmic reticulum(RER) and numerous glycogen particles were observed in the cytoplasm of the hepatocyte. In the cytoplasmic membranes of the hepatocyte, sinusoidal surface had numerous microvilli and cellular surface is combinated adjacent hepatocyte with desmosomes. The RER cisterns were dilated and zymogen granules were fewer than those of the dark cells. Kupffer cells with irregular nuclear membrane were observed. Fat storing cell and collagenous fiber bundle were observed in the Disse space. 2. Kupffer cell, inflammatory cells in the connective tissue of hepatic triad and lysosome were increased in the 3, 6, and 12 hour experimental group comparing with that of the control group. 3. In the 1 day experimental group, infiltration of inflammatory cells in interlobular connective tissue, dilatation of sinusoidal capillary and increasing of Kupffer cell were observed. Atropic change of hepatocyte and aggregation of glycogen particles in the cytoplasm of hepatocyte were observed. In this group, desmosome near bile canaliculi and collagenous fiber bundle in the Disse space were increased comparing with that of the 12 hours experimental group. In the 2 days experimental group, desmosome, lysosome, peroxisome and collagenous fiber bundle were increased comparing with that of the 1 day experimental group. Furthermore, lamellated bodies were also seen in the cytoplasm of the hepatocyte. 4. In 3 and 5 days experimental groups, transformations of hepatic cell cord and degeneration of the hepatocyte were markedly inclosed comparing with the all experimental groups. And damaged RER and mitochondria. collagenous fiber bundle were also inclosed comparing with that of the 2 days experimental group. Autophagosome and fat storing cells with large lipid droplets were also observed comparing with that of the 2 days experimental group. Tight junction and desmosome between the hepatocytes were separated. These degenerating changes were severe through the all experimental groups. 5. In the 10 and 20 days experimental groups, arrangement of hepatic cell cords and cell organelles of hepatocytes were similar to those of the control group. However, aggregation of glycogen particles, dilatation of sinusoidal capillary and infiltration of inflammatory cells remained. 6. In the 30 days experimental group, the tissue findings were similar to those of the control grout. But lamellated bodies in some hepatocytes and lysosome were remained in the cytoplasms of the Kupffer cells. In the 60 days experimental group, these all changes were recovered as the control group. In conclusion, telluric acid would directly induce the degenerative and necrotic changes on the hepatic tissue. However, these changes were perfectly recoverd in the 60 days experimental group as the control group.

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A Study on groundwater and pollutant recharge in urban area: use of hydrochemical data

  • Lee, Ju-Hee;Kwon, Jang-Soon;Yun, Seong-Taek;Chae, Gi-Tak;Park, Seong-Sook
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.09a
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    • pp.119-120
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    • 2004
  • Urban groundwater has a unique hydrologic system because of the complex surface and subsurface infrastructures such as deep foundation of many high buildings, subway systems, and sewers and public water supply systems. It generally has been considered that increased surface impermeability reduces the amount of groundwater recharge. On the other hand, leaks from sewers and public water supply systems may generate the large amounts of recharges. All of these urban facilities also may change the groundwater quality by the recharge of a myriad of contaminants. This study was performed to determine the factors controlling the recharge of deep groundwater in an urban area, based on the hydrogeochemical characteristics. The term ‘contamination’ in this study means any kind of inflow of shallow groundwater regardless of clean or contaminated. For this study, urban groundwater samples were collected from a total of 310 preexisting wells with the depth over 100 m. Random sampling method was used to select the wells for this study. Major cations together with Si, Al, Fe, Pb, Hg and Mn were analyzed by ICP-AES, and Cl, N $O_3$, N $H_4$, F, Br, S $O_4$and P $O_4$ were analyzed by IC. There are two groups of groundwater, based on hydrochemical characteristics. The first group is distributed broadly from Ca-HC $O_3$ type to Ca-C1+N $O_3$ type; the other group is the Na+K-HC $O_3$ type. The latter group is considered to represent the baseline quality of deep groundwater in the study area. Using the major ions data for the Na+K-HC $O_3$ type water, we evaluated the extent of groundwater contamination, assuming that if subtract the baseline composition from acquired data for a specific water, the remaining concentrations may indicate the degree of contamination. The remainder of each solute for each sample was simply averaged. The results showed that both Ca and HC $O_3$ represent the typical solutes which are quite enriched in urban groundwater. In particular, the P$CO_2$ values calculated using PHREEQC (version 2.8) showed a correlation with the concentrations of maior inorganic components (Na, Mg, Ca, N $O_3$, S $O_4$, etc.). The p$CO_2$ values for the first group waters widely ranged between about 10$^{-3.0}$ atm to 10$^{-1.0}$ atm and differed from those of the background water samples belonging to the Na+K-HC $O_3$ type (<10$^{-3.5}$ atm). Considering that the p$CO_2$ of soil water (near 10$^{-1.5}$ atm), this indicates that inflow of shallow water is very significant in deep groundwaters in the study area. Furthermore, the P$CO_2$ values can be used as an effective parameter to estimate the relative recharge of shallow water and thus the contamination susceptibility. The results of our present study suggest that down to considerable depth, urban groundwater in crystalline aquifer may be considerably affected by the recharge of shallow water (and pollutants) from an adjacent area. We also suggest that for such evaluation, careful examination of systematically collected hydrochemical data is requisite as an effective tool, in addition to hydrologic and hydrogeologic interpretation.ion.ion.

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Hydrogen Peroxide Modulates Phospholipase $A_2$ Aactivity and Endogenous Oxidative Stress in the Free Radical Induced Acute Lung Injury (과산화수소에 의한 급성폐손상시 염증성 지질분자의 생성기전에 관한 연구)

  • Bae, Chi-Hoon;Kang, Hyung-Seok;Lee, Sub;Jheon, Sang-Hoon;Ahn, Wook-Wu;Kwon, Oh-Choon
    • Journal of Chest Surgery
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    • v.35 no.5
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    • pp.343-349
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    • 2002
  • background: In an attempt to investigate the role of oxidants in the activation of phospholipase $A_2$(PLA$_2$) and endogenous oxidative stress in the lung. acute inflammatory lung injury was induced by the instillation of hydrogen peroxide into the trachea of Sprague-Dawley rats. Material and Method: To prove the hypothesis thats released oxidants from neutrophils activate the PLA$_2$ retrogradely, activities of PLA$_2$ and lysoplatelet activating factor acetyltransferase(lysoPAF AT) were assayed i hours after instillation of hydrogen peroxide. In addition, to confirm the impairing effects of the activation of PLA$_2$ associated with endogenous oxidative stress, lung weight/body weight ratio(L$\times$10$^{-3}$ B), protein contents(mg/two lungs) in bronchoalveolar lavage(BAL) were measured. As neutrophilic respiratory burst has been known to play a pivotal role in the genesis of endogenous oxidative stress associated with acute inflammatory lung injury, BAL neutrophils counts and level of lung myelperoxidase(MPO) were measured after hydorgen peroxide insult. Morphological and histochemical studies were also performed to identify the effect of the endogenous oxidative stress. Result: Five hours after hydrogen peroxide instillation, lungs showed marked infiltration of neutrophils and increased weight. Protein contents in BAL increased significantly compared to those of normal rats. PLA$_2$ activity was enhanced in the hydrogen peroxide instilled group. Interestingly, the accelerated production of platelet activating factor(PAF) was confirmed by the increased activity of lysoPAF AT in the $H_2O$$_2$ employed lung. Morphologically, light microscopic findings of lungs after instillation of hydrogen peroxide showed atelectasis and infiltration of inflammatory cells, which was thought to be caused by lipid mediators produced by PLA$_2$ activation. In cerium chloride cytochemical electron microscopy, dense deposits of cerrous perhydroxide were identified. In contrast, no deposit of cerrous perhydroxide was found in the normal lung.

Effects of Matrix Metalloproteinase Inhibitor on Ventilator-Induced Lung Injury in Rats (기계환기로 인한 백서의 급성 폐손상에서 Matrix Metalloproteinase Inhibitor의 효과)

  • Kim, Je-Hyeong;Park, Soo-Yeon;Hur, Gyu-Young;Lee, Seung-Heon;Lee, Sang-Yeub;Park, Sang-Myeon;Suh, In-Bum;Shin, Chol;Shim, Jae-Jeong;In, Kwang-Ho;Kang, Kyung-Ho;Yoo, Se-Hwa
    • Tuberculosis and Respiratory Diseases
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    • v.53 no.6
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    • pp.619-634
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    • 2002
  • Background : Many inflammatory mediators and collagenases are involved in the pathogenesis of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The increase of matrix metalloproteinase-9 (MMP-9, gelatinase-B) produced mainly by inflammatory cells was reported in many ALI models and connective tissue cells. In this study, the expression of MMP-9 in ventilator-induced lung injury (VILI) model and the effects of matrix metalloproteinase inhibitor (MMPI) on VILI were investigated. Methods : Eighteen Sprague-Dawley rats were divided into three groups: low tidal Volume (LVT, 7mL/Kg tidal volume, 3 $cmH_2O$ PEEP, 40/min), high tidal volume (HVT, 30mL/Kg tidal volume, no PEEP, 40/min) and high tidal volume with MMPI (HVT+MMPI) groups. Mechanical ventilation was performed in room air for 2 hours. The 20 mg/Kg of CMT-3 (chemically modified tetracycline-3, 6-demethyl 6-deoxy 4-dedimethylamino tetracycline) was gavaged as MMPI from three days before mechanical ventilation. The degree of lung injury was measured with wet-to-dry weight ratio and acute lung injury score. Expression of MMP-9 was studied by immunohistochemical stain with a mouse monoclonal anti-rat MMP-9 $IgG_1$. Results : In the LVT, HVT and HVT+MMPI groups, the wet-to-dry weight ratio was $4.70{\pm}0.14$, $6.82{\pm}1.28$ and $4.92{\pm}0.98$, respectively. In the HVT group, the ratio was significantly higher than other groups (p<0.05). Acute lung injury score measured by five-point scale was $3.25{\pm}1.17$, $12.83{\pm}1.17$ and $4.67{\pm}0.52$, respectively. The HVT group was significantly damaged by VILI and MMPI protects injuries by mechanical ventilation (p<0.05). Expression of MMP-9 measured by four-point scale was $3.33{\pm}2.07$, $12.17{\pm}2.79$ and $3.60{\pm}1.95$, respectively, which were significantly higher in the HVT group (p<0.05). Conclusion : VILI increases significantly the expression of MMP-9 and MMPI prevents lung injury induced by mechanical ventilation through the inhibition of MMP-9.

Fate of Heavy Metals in Activated Sludge: Sorption of Heavy Metal ions by Nocardia amarae

  • Kim, Dong-wook
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 1998.10a
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    • pp.2-4
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    • 1998
  • Proliferation of Nocardia amarae cells in activated sludge has often been associated with the generation of nuisance foams. Despite intense research activities in recent years to examine the causes and control of Nocardia foaming in activated sludge, the foaming continued to persist throughout the activated sludge treatment plants in United States. In addition to causing various operational problems to treatment processes, the presence of Nocardia may have secondary effects on the fate of heavy metals that are not well known. For example, for treatment plants facing more stringent metal removal requirements, potential metal removal by Nocardia cells in foaming activated sludge would be a welcome secondary effect. In contrast, with new viosolid disposal regulations in place (Code o( Federal Regulation No. 503), higher concentration of metals in biosolids from foaming activated sludge could create management problems. The goal of this research was to investigate the metal sorption property of Nocardia amarae cells grown in batch reactors and in chemostat reactors. Specific surface area and metal sorption characteristics of N. amarae cells harvested at various growth stages were compared. Three metals examined in this study were copper, cadmium and nickel. Nocardia amarae strain (SRWTP isolate) used in this study was obtained from the University of California at Berkeley. The pure culture was grown in 4L batch reactor containing mineral salt medium with sodium acetate as the sole carbon source. In order to quantify the sorption of heavy metal ions to N amarae cell surfaces, cells from the batch reactor were harvested, washed, and suspended in 30mL centrifuge tubes. Metal sorption studies were conducted at pH 7.0 and ionlc strength of 10-2M. The sorption Isotherm showed that the cells harvested from the stationary and endogenous growth phase exhibited significantly higher metal sorption capacity than the cells from the exponential phase. The sequence of preferential uptake of metals by N. amarae cells was Cu>Cd>Ni. The specific surFace area of Nocardia cells was determined by a dye adsorption method. N.amarae cells growing at ewponential phase had significantly less specific surface area than that of stationary phase, indicating that the lower metal sorption capacity of Nocardia cells growing at exponential phase may be due to the lower specific surface area. The growth conditions of Nocardia cells in continuous culture affect their cell surface properties, thereby governing the adsorption capacity of heavy metal. The comparison of dye sorption isotherms for Nocardia cells growing at various growth rates revealed that the cell surface area increased with increasing sludge age, indicating that the cell surface area is highly dependent on the steady-state growth rate. The highest specific surface area of 199m21g was obtained from N.amarae cell harvested at 0.33 day-1 of growth rate. This result suggests that growth condition not only alters the structure of Nocardia cell wall but also affects the surface area, thus yielding more binding sites of metal removal. After reaching the steady-state condition at dilution rate, metal adsorption isotherms were used to determine the equilibrium distributions of metals between aqueous and Nocardia cell surfaces. The metal sorption capacity of Nocardia biomass harvested from 0.33 day-1 of growth rate was significantly higher than that of cells harvested from 0.5- and 1-day-1 operation, indicatng that N.amarae cells with a lower growth rate have higher sorpion capacity. This result was in close agreement with the trend observed from the batch study. To evaluate the effect of Nocardia cells on the metal binding capacity of activated sludge, specific surface area and metal sorption capacity of the mixture of Nocardia pure cultures and activated sludge biomass were determined by a series of batch experiments. The higher levels of Nocardia cells in the Nocardia-activated sludge samples resulted in the higher specific surface area, explaining the higher metal sorption sites by the mixed luquor samples containing greater amounts on Nocardia cells. The effect of Nocardia cells on the metal sorption capacity of activated sludge was evaluated by spiking an activated sludge sample with various amounts of pre culture Nocardia cells. The results of the Langmuir isotherm model fitted to the metal sorption by various mixtures of Nocardia and activated sludge indicated that the mixture containing higher Nocardia levels had higher metal adsorption capacity than the mixture containing lower Nocardia levels. At Nocardia levels above 100mg/g VSS, the metal sorption capacity of activate sludge increased proportionally with the amount of Noeardia cells present in the mixed liquor, indicating that the presence of Nocardia may increase the viosorption capacity of activated sludge.

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Short-term Effects on Soil Property and Leaf Characteristics after Soil Amendment Treatments in Chestnut (Castanea crenata S. et Z.) Orchards (토양 개량제 처리가 밤나무 재배지의 토양 특성 및 잎 형질에 미치는 단기적 영향)

  • Kim, Choonsig;Kim, Weon-Seok;An, Hyun-Chul;Cho, Hyun-Seo;Choo, Gab-Chul;Lim, Jong-Taek
    • Journal of Korean Society of Forest Science
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    • v.101 no.3
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    • pp.405-411
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    • 2012
  • This study was conducted to evaluate short-term effects on soil properties and leaf characteristics after various treatments of soil amendments (organic fertilizer: 20 kg tree-1; compound fertilizer+wood-char: compound fertilizer 4 kg tree-1+wood-char 2 kg tree-1; lime fertilizer: 3 kg tree-1; mixed fertilizer: compound fertilizer 1 kg tree-1+organic fertilizer 10 kg tree-1+wood-char 1 kg tree-1; control) in chestnut (Castanea crenata S. et Z.) orchards of Jinju and Sancheong, Gyeongsangnam-do. Soil bulk density, soil pH, soil organic carbon, total nitrogen, exchangeable Ca2+ and Mg2+ in chestnut orchards were not significantly affected by soil amendment treatments. However, leaf weight was significantly higher in the lime fertilizer ($0.65\;g\;leaf^{-1}$) in Jinju and the organic fertilizer ($0.68\;g\;leaf^{-1}$) in Sancheong than in the control treatments (Jinju: $0.46\;g\;leaf^{-1}$; Sancheong: $0.53\;g\;leaf^{-1}$). Leaf area was also significantly higher in the lime fertilizer ($79.1\;cm^2\;leaf^{-1}$) in Jinju and the soil amendments ($70.4\;cm^2\;leaf^{-1}{\sim}78.2\;cm^2\;leaf^{-1}$) in Sancheong than in the control treatments (Jinju: $56.2\;cm^2\;leaf^{-1}$; Sancheong: $60.5\;cm^2\;leaf^{-1}$). Nitrogen concentration of leaf increased significantly in the mixed fertilizer (2.51%) and the compound fertilizer+wood-char (2.50%) compared with the control (1.98%) treatments. The results suggest that soil properties were not affected by soil amendment treatments during short-term period, but leaf characteristics and nitrogen concentration can be an indicator of soil nutrient improvements in chestnut orchards.

Effects of YK-209 Mulberry Leaves on Antioxidative Defense System of Liver in Streptozotocin-Induced Diabetic Rats (YK-209 뽕잎이 Streptozotocin 유발 당뇨쥐 간조직의 항산화계에 미치는 영향)

  • 유수경;이순재
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.31 no.6
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    • pp.1065-1070
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    • 2002
  • The purpose of this study was investigated the effects of YK-209 mulberry leaves on antioxidative defense system of liver in diabetic rats induced with streptozotocin (STZ). Male Sprague-Dawley rats weighing 100$\pm$10 g were randomly assigned to one normal and four STZ-induced diabetic groups; YK-209 mulberry leaves free diet (DM group),0.1% YK-209 mulberry leaves diet (DM-0.1Y group),0.2% YK-209 mulberry leaves diet (DM-0.2Y group) and 0.4% YK-209 mulberry leaves diet (DM-0.4Y group). Diabetes was induced by intravenous Injection of 55 mg/kg body weight of STZ in sodium citrate buffer (pH 4.3) via tail vein after 4 weeks feeding of experimental diets. Rats were sacrificed at the 9th day of diabetic states. Liver weight in all four diabetic groups were higher than normal group, but YK-209 mulberry supplementation groups were lower than DM group. Hepatic superoxide dismutase (SOD) activity was significantly decreased in all diabetic groups, compared with normal group. Hepatic glutathione peroxidase (GSHpx) activity was 7.3% decreased in DM group, compared with normal group, but those of DM-0.1Y and DM-0.2Y groups were maintained the normal level. The hepatic thiobarbituric acid reactive substances was markedly increased by 144% in DM group, compared with normal group, but those of DM-0. 1Y, DM-0.2Y groups were maintained the normal level. The contents of lipofuscin in liver were increased by 100% in DM group compared with normal group, but those of DM-0. 1Y, DM-0.2Y and DM-0.4Y groups were decreased to 42% 43% and 44%, respectively, compared with DM group. The hepatic superoxide radical (0$^2$-) contents in DM group were increased to 81%, compared with normal group, but those of DM-0.1Y and DM-0.4Y groups were similar to those of normal group. The present result indicate that YK-209 mulberry leaves regarded to suppress lipid peroxidation as an free radical scavenger system by the inhibition of oxidative stress.

Germination Dependency of Antioxidative Activities in Brown Rice (현미의 발아정도에 의한 항산화활성의 변화)

  • Kang, Bo-Ra;Park, Mi-Jung;Lee, Heum-Sook
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.35 no.4
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    • pp.389-394
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    • 2006
  • The change of antioxidative character by germination of brown rice was evaluated. From the total methanolic extract of brown rice, 2.5 mm-germinated brown rice, and 5 mm-germinated brown rice, SOD-like activity and nitrite scavenging ability were identified as antioxidative character. SOD-like activities and nitrite scavenging abilities of all samples were changed dose-dependently and germination-dependently. After successive partitioning with hexane, ethyl acetate (EtOAc) and water, each fraction was tested for these activities. SOD-like activities of all fractions were increased by germination, and especially hexane fraction and EtOAc fraction of 5 mm-germinated brown rice had more strong activities than 50 ppm vitamin C. The $EC_{50}$ values of SOD-like activity showed a gradual decrease by germination and that of EtOAc fraction of 5 mm-germinated brown rice was 17 ppm, which was lower concentration than that of 50 ppm vitamin C. The $IC_{50}$ values of nitrite scavenging ability at PH 1.5 also underwent a great decrease by germination and germinated brown rice had the nitrite scavenging ability at lower concentration than brown rice. The results suggest that SOD-like activity and nitrite scavenging ability are thought to be enhanced by the germination effect.

User's Impacts on Environmental Deteriorations of Trail in Tôkyusan National Park (덕유산(德裕山) 국립공원(國立公園) 등산로(登山路)의 환경훼손(環境毁損)에 대(對)한 이용영향(利用影響))

  • Seo, Byung Soo;Kim, Sei Cheon;Park, Chong Min;Lee, Chang Heon;Lee, Kyu Wan
    • Journal of Korean Society of Forest Science
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    • v.83 no.3
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    • pp.286-298
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    • 1994
  • The object of this study was to examine the user's impacts on the environmental deteriorations of trail at Ticket Office - Paekryunsa (Temple) Hyangch$\hat{o}$kpong - Dongyupryung - Chilyun Fall area in T$\hat{o}$kyusan National Park. Four trails were sampled in the study area according to the amount of users. Then the user's impacts on trail were measured at each trail. The Ticket Office-Paekryunsa trail was the most used district and followed at Paekryunsa-Hyangch$\hat{o}$kpong trail, Hyangch$\hat{o}$kpong-Dongyupryung trail in descending order. Dongyupryung-Chilyun Fall trail is not used by people because of rest rotation system. The entire width of trail was greater at the more heavily used trail. Maximum depth, cross-sectional area loss, and surface texture and roughness of trail were the highest at Paekryunsa-Hyangch$\hat{o}$kpong trail. Soil hardness, soil acidity, soil moisture content, organic matter content, and exchange canon were influenced by trampling. Soil hardness, soil acidity and exchange canon increased in tramples soil, but content of soil moisture and organic matter decreased therein. Environmental deteriorations of trail were significantly influenced by the amount of users and the slope of trail. Bared lands about $2.000m^2$ were appeared by trampling and camping around Hyangch$\hat{o}$kpong. Effects of carrying of rest rotation system for National Park were partly recognized at Dongyupryung-Chilyun Fall trail.

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Soil Chemical Characteristics and Comparison with Infested Status of Nematode(Meloidogyne spp.) in Plastic House Continuously Cultivated Oriental Melon in Songju (성주 지역 시설참외 연작지의 토양특성 및 토양선충 변화)

  • Jun, Han-Sik;Park, Woo-chul
    • Korean Journal of Environmental Agriculture
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    • v.20 no.2
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    • pp.127-132
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    • 2001
  • This study was conducted for ten years to evaluate the effective soil management for preventing the infection of root-knot nematode in the field of continuous cultivation with oriental melon under plastic house in Songju area of kyongbuk province. The content of available phosphate, total nitrogen, organic matter, CEC, and exchangeable base in the soil increased with the increase of continuous cultivation year. Especially salt content in the soil increased form 1.2 to 4.55 mS/cm and the yield of oriental melon dramatically decreased with the continuous cultivation year. The number of root-knot nematode was 91 per $300\;cm^3$ of soil in the field of continuous cultivation for 3 years and showed slight damage on the oriental melon, but it was 518 in the field of $4{\sim}6$ years continuous cultivation and showed that 50% of plants died in August, and the yield of late season was less than 50% compared to normal plant. For the seasonal changes in infection rate of root-knot nematode on oriental melon plant, 15% of the normal plant was infected by nematode in February and increased gradually by $10{\sim}20%$ per month, 60% of plants was infected in July. The density of root-knot nematode nymph was 167 in February and increased to 1,625 in August. The infection rate of nematode was 35%, and the number of nematode was about 54 in nursery soil originated from paddy soil, upland soil, and river sand. There were no relationship between the number of nematode and available phosphate or exchangeable base in the soil of plastichouse where oriental melon plants were grown.

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