• Journal of Korean Society for Atmospheric Environment
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• 제32권3호
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• pp.289-304
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• 2016

The $PM_{10}$ and $PM_{2.5}$ aerosols were collected at the Gosan site of Jeju Island in 2013 and analyzed, in order to examine the variation characteristics of the chemical compositions in relation to the haze, Asian dust, and mixed haze-Asian dust episodes. Volume concentrations obtained from the Aerodynamic Particle Sizer (APS) were high in the range of $0.6{\sim}1.0{\mu}m$ particles for haze event, and in the range of $2.0{\sim}10.0{\mu}m$ particles for Asian dust event. For the haze event, nitrate concentrations increased highly as 8.8 and 25.1 times for $PM_{10}$ and $PM_{2.5}$, respectively, possibly caused by the inflow of air mass stagnated in eastern parts of China into Jeju area. For the Asian dust event, the concentrations of nss-$Ca^{2+}$, $NO_3{^-}$ and nss-$SO_4{^{2-}}$ increased 6.0, 1.5, 1.8 times for $PM_{10}$, and 2.3, 1.3, 1.6 times for $PM_{2.5}$, respectively. Meanwhile, for the mixed haze-Asian dust event, the concentrations of nss-$Ca^{2+}$ and $NO_3{^-}$ increased 13.4 and 3.2 times for $PM_{10}$, and 1.8 and 3.4 times for $PM_{2.5}$, respectively. The $NH_4NO_3$ content was higher than that of $(NH_4)_2SO_4$ during the haze event, however it was relatively low during the mixed haze-Asian dust event. The aerosols were acidified mostly by inorganic acids, and especially the nitric acid contributed highly to the acidification during both the haze and the mixed haze-Asian dust events. Meanwhile, the neutralization by ammonia was noticeably high during haze event when the stagnated air mass moved from China.

• Journal of Korean Society of Environmental Engineers
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• 제30권8호
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• pp.781-788
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• 2008

This study shows how to find out optimum co-substrate conditions and continuous operating parameters for maximum acidification of three different organic wastes - livestock wastewater, sewage sludge and food waste. Design of experiments and statistical analysis were revealed as appropriate optimization schemes in this study. Analyses of data obtained from batch tests demonstrated the optimum substrate mixing ratio, which was determined by maximum total volatile fatty acids(TVFA) increase and soluble chemical oxygen demand(SCOD) increase simultaneously. Suggested optimum mixing ratio of livestock wastewater, sewage sludge and food waste was 0.4 : 1.0 : 1.1 based on COD, respectively. Response surface methodology(RSM) contributed to find out optimum operating parameter - hydraulic retention time(HRT) and substrate concentration - for the semi-continuous acidogenic fermentation of mixed organic wastes. The optimum condition for maximum TVFA increase was 2 days of HRT and 29,237 mg COD/L. Empirical equations obtained through regression analysis could predict that TVFA increase would be 73%. To confirm the validity of the statistical experimental strategies, a confirmation experiment was conducted under the obtained optimum conditions, and relative error between theoretical and experimental results was within 4%. This result reflects that using statistical and RSM technique can be effectively used for the optimization of real waste treatment processes.

• Journal of Korean Society for Atmospheric Environment
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• 제17권6호
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• pp.475-485
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• 2001

The presence of airborne particles in the earth atmosphere expert important controls on the global climate because of their effects on the radiative balance. However, there are major uncertainties associated with the direct and indirect radiative effects of aerosols. In addition, their physicochemical properties cannot only the decline of air quality but also damage human health. Airborne particles were collected by two different commercial air samples, high volume sampler(for TSP) and low volume sampler(for P $M_{10}$ ) at the campus of Kunsan National University during February to September, 2000. In most cases, TSP and P $M_{10}$ were sampled once a week for the duration of 24 hours from 9:00 a.m. In addition samples were collected more intenisve, when the yellow dust was expected. Each sample was analyzed for pH and major ions concentration (C $l^{[-10]}$ , S $O_4$$^{2-}$, N $O_3$$^{[-10]}$ , N $a^{+}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$) by ion chromatography and atomic absorption spectrophotometry. Acidity (pH) of TSP and P $M_{10}$ ranged from 5.09 to 8.51 and from 6.22 to 7.54, respectively. The concentrations of airborne particles were found to satisfy both the short and long-term air quality standards during the sampling period. If the ratio of ionic concentrations originating from None sea salt(Nss) to sea salt(ss) in aerosol samples was concerned, it was found that the ionic concentrations from marine environment contributed dominantly in total mass concentration in the airborne particles. When seasonal trends were examined, the TSP concentrations in spring were higher than those of other seasons. It may result form frequent occurrences of yellow dust and during the spring season. The concentration ratio of P $M_{10}$ to TSP ranged from 0.78 to 1 during the sampling period. pH in the airborne particle was highest during spring, but the other seasons maintained almost same level. These results suggest that alkaline species in yellow dust can directly neutralize aerosol acidity. During spring season, yellow dust could be a positive factor that can defer the acidification of surface soil and water by neutralizing acidic aerosols in the atmosphere.osphere.

• Journal of Korean Society of Forest Science
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• 제86권1호
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• pp.98-104
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• 1997

Soil pollution intensity at Mt. Namsan in Seoul city which was expected to show significant soil contamination due to long-term air pollution was evaluated by comparing soil chemical properties at Mt. Kyebangsan in Hongcheon area as a control, and the bacteria participating in nitrogen or sulfur mineralization were assayed simultaneously in order to evaluate the validity of N and/or S mineralization bacteria as an index of soil contamination. The soil of Mt. Namsan showed 10 times higher concentration of hydrogen ion compared to that of Mt. Kyebangsan, which indicated that the soil had relatively been acidified seriously. Especially, large amount of canons were thought to be leached out from the soil, while the amount of extractable Al was getting larger and larger, which result in serious problems in soil ecosystem of the mountain. I could infer from soil chemical properties of the four study sites that the major reason of soil acidification was SOx deposition. However, the sulfur-reducing bacteria were not significantly different between the two regions, which indicated that the microbial dynamics of the soil ecosystem was not controlled by simple factor, but by multiple factors. By the way, the dynamics of bacteria participating in denitrification process was different between the two regions, which was more active at Mt. Kyebangsan than at Mt. Namsan. Thus, the microbial assay for nitrogen mineralization is desirable to be examined as a tool for evaluating soil health or microbial activity in soil ecosystem.

• Archives of Pharmacal Research
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• 제29권5호
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• pp.375-383
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• 2006

The anti platelet effects of a novel guanidine derivative, KR-32570 ([5-(2-methoxy-5-chlorophenyl) furan-2-ylcarbonyl]guanidine), were investigated with an emphasis on the mechanisms underlying its inhibition of collagen-induced platelet aggregation. KR-32570 significantly inhibited the aggregation of washed rabbit platelets induced by collagen $(10{\mu}g/mL)$, thrombin (0.05 U/mL), arachidonic acid $(100{\mu}M)$, a thromboxane (TX) $A_2$ mimetic agent U46619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin $F_2,\;1{\mu}M$) and a $Ca^{2+}$ ATPase inhibitor thapsigargin $(0.5{\mu}M)$ ($IC_{50}$ values: $13.8{\pm}1.8,\;26.3{\pm}1.2,\;8.5{\pm}0.9,\;4.3{\pm}1.7\;and\;49.8{\pm}1.4{\mu}M$, respectively). KR-32570 inhibited the collagen-induced liberation of $[^3H]$arachidonic acid from the platelets in a concentration dependent manner with complete inhibition being observed at $50{\mu}M$. The $TXA_2$ synthase assay showed that KR-32570 also inhibited the conversion of the substrate $PGH_2$ to $TXB_2$ at all concentrations. Furthermore, KR-32570 significantly inhibited the $[Ca^{2+}]_i$ mobilization induced by collagen at $50{\mu}M$, which is the concentration that completely inhibits platelet aggregation. KR-32570 also decreased the level of collagen $(10{\mu}g/mL)$induced secretion of serotonin from the dense-granule contents of platelets, and inhibited the NHE-1-mediated rabbit platelet swelling induced by intracellular acidification. These results suggest that the antiplatelet activity of KR-32570 against collagen-induced platelet aggregation is mediated mainly by inhibiting the release of arachidonic acid, $TXA_2$ synthase, the mobilization of cytosolic $Ca^{2+}$ and NHE-1.

• Bulletin of the Korean Chemical Society
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• 제15권1호
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• pp.37-45
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• 1994

$(NH_4)_{4.5}[H_{3.5}{\alpha}-PtMo_6O_{24}]{\cdot}1.5\;H_2O(A),\;(NH_4)_4[H_4{\beta}-PtMo_6O_{24}]{\cdot}1.5\;H_2O(B),\;and\;K_{3.5}[H_{4.5}{\alpha}-PtMo_6O_{24}]{\cdot}3\;H_2O(C)$ have been synthesized and their molecular structures have been also determined by single-crystal X-ray diffraction technique. The space groups, unit cell parameters, and R factors are as follows: Compound A, monoclinic, $A_{2/a}$, a= 19.074 (3), b=21.490 (3), c=15.183 (2) ${\AA};\;{\beta}$=109.67 (1) ${\AA}$; z=8; R=0.075($IF_0I>4{\sigma}(IF_0I);$ Compound B, triclinic, P$bar{1}$, a=10.776 (2), b=15.174 (4), c=10.697 (3) ${\AA};\;{\alpha}$ =126.29 (2), ${\beta}$=111.55 (2), ${\gamma}$=93.18 (2) ${\AA}$; Z=2; R=0.046($IF_0I>3{\sigma}(IF_0I);$): Compound C, triclinic, Pl, a=12.426 (2), b=13.884 (2), c=10.089 (1) ${\AA}$; ${\alpha}$=102.59 (2), ${\beta}$=110.73 (1), ${\gamma}$=53.93 (1) ${\AA}$; Z=2; R=0.074 ($IF_0I>3{\sigma}(IF_0I)$. Compounds A and C contain the well-known Anderson structure (planar structure) heteropoly oxometalate having approximate $bar{3}_m(D_{3d})$ symmetry, while compound B contains the bent structure heteropoly oxometalate having appproximate $2_{mm}(C2_v)$ symmetry. The bent structure and the planar one are geometrical isomers. These compounds are rot only novel heteroply molybdates containing platinate(IV) but also the first example of geometrical isomerism in the hexamolybdoheteropoly oxometalates. That isomerization surprisingly occurred because of the change of only 0.5 non-acidic hydrogen atom attached to the polyanion such as $[H_{3.5}{\alpha} -PtMo_6O_{24}]^{4.5-}{\to}[H_4{\beta}-PtMo_6O_{24}]^{4-}{\to}[H_{4.5}{\alpha} -PtMo_6O_{24}]^{3.5-}$. It seems that the gradual protonation of the polyanion plays an important role in that isomerism. These heteropolyanions form dimers by strong hydrogen bonds between two heteropolyanions in the respective crystal system.

• Korean Journal of Soil Science and Fertilizer
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• 제17권3호
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• pp.253-257
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• 1984

A field experiment was conducted in order to secure the basic information on the rational application of nitrogen and potassium for autumn growing Chinese cabbage (Brassica campastris ssp. pekinensis, var.; Miho 70 days). The results of the experiment are summarized as follows: 1. Potassium effect was observed where nitrogen applied either less than 15kg N/10a and heavy dose of 25kg N/10a. No potassium effect was observed where 20kg N/10a applied. In the case of 25kg N/10a, potassium effect was observed only in total weight but failed yield marketable product weighing over 1 kilogram per cabbage. 2. Nitrogen application, in general, tends to lower the soil pH and it is particularly true when heavy dose of over 20kg N/10a is applied. As a result, Chinese cabbage has increasingly removed soil born potassium and reduced exchangeable potassium content of the soil. 3. Oven dried cabbage which received 25kg N/10a plus potassium showed a low concentration of calcium and this phenomena seems to be attributable to the acidification of soils and it further caused failure in producing cabbages of marketing value.

• Korean Journal of Environmental Agriculture
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• 제15권2호
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• pp.188-197
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• 1996

This study was carried out to investigate yearly changes in the precipitation component and the source strength to acid precipitation in the rural area of Chinbuk province by analysis of the chemical components in the precipitation at National Honam Agricultural Experiment Station RDA in the suburbs of Iksan from 1991 to 1995. The average ratio of acid precipitation was 47.9% from 1991 to 1995. pH of the rain water in precipitation below 5mm was higher than that above 5mm and the concentration of the ions in the rain water was the highest in the first fraction$(0{\sim}5mm)$ of precipitation. The amount and ratio of the precipitation below pH 4.0 from 1991 to 1995 were 64mm and 1.4%, respectively. The order of the major ions concentration in the precipitation was $SO_4\;^{2-}$ > $NO_3\;^-$ > $Cl^-$ > $NH_4\;^+$ > $Ca^{2+}$ > $K^+$ ${\lrcorner}\;Mg^{2+}$. The relative contributions to the acidification of the rain in Iksan were 52% from $SO_4\;^{2-}$, 25% from $NO_3\;^-$ and 23% from $Cl^-$.

• Journal of Microbiology and Biotechnology
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• 제30권6호
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• pp.937-945
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• 2020

N-acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) plays a major role in development of biofilms, which contribute to rise in infections and biofouling in water-related industries. Interference in QS, called quorum quenching (QQ), has recieved a lot of attention in recent years. Rhodococcus spp. are known to have prominent quorum quenching activity and in previous reports it was suggested that this genus possesses multiple QQ enzymes, but only one gene, qsdA, which encodes an AHL-lactonase belonging to phosphotriesterase family, has been identified. Therefore, we conducted a whole genome sequencing and analysis of Rhodococcus sp. BH4 isolated from a wastewater treatment plant. The sequencing revealed another gene encoding a QQ enzyme (named jydB) that exhibited a high AHL degrading activity. This QQ enzyme had a 46% amino acid sequence similarity with the AHL-lactonase (AidH) of Ochrobactrum sp. T63. HPLC analysis and AHL restoration experiments by acidification revealed that the jydB gene encodes an AHL-lactonase which shares the known characteristics of the α/β hydrolase family. Purified recombinant JydB demonstrated a high hydrolytic activity against various AHLs. Kinetic analysis of JydB revealed a high catalytic efficiency (k_cat/K_M) against C4-HSL and 3-oxo-C6 HSL, ranging from 1.88 x 10⁶ to 1.45 x 10⁶ M^-1 s^-1, with distinctly low K_M values (0.16-0.24 mM). This study affirms that the AHL degrading activity and biofilm inhibition ability of Rhodococcus sp. BH4 may be due to the presence of multiple quorum quenching enzymes, including two types of AHL-lactonases, in addition to AHL-acylase and oxidoreductase, for which the genes have yet to be described.

• Korean Journal of Environmental Biology
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• 제36권1호
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• pp.50-61
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• 2018

The current study aimed to review the research trends on forest liming by age, country, and research topics, and seeks to summarize the effects of forest liming on soil, vegetation and water system in forest ecosystems. The recent goals of forest liming have been changed in response to changes in the acid deposition, and related studies have been mainly carried out in Europe and North America, where there is noted a massive forest decline, which was subsequently caused by acid rain. Most forest liming studies are noted to have focused on soil responses, however, the number of studies on the responses of vegetation and water system according to a literature review on the subject were relatively small. Meanwhile, forest liming influenced whole forest ecosystems through interaction between the soil, vegetation and water system as associated with the relevant regions. The changes in soil pH, base saturation, and cation exchange capacity by forest liming were noted as different depending on the soil layer and elapsed time after liming. The responses of vegetation to forest liming were shown in above- and below-ground plant growth and plant nutrient concentration, and also were noted to have varied depending on the available regional plant species and noted specific soil conditions. The chemical properties of the water system were changed similarly to those in the soil, leading to notable changes as seen in the planktons and available fish species in the region. Finally, these results could be used to plan further studies on forest liming, which would significantly benefit regional studies to promote the preservation of the species noted for protection in the region.