• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.53-59
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• 2007

Optimal quenching curves have been studied for the accurate analysis of $^{14}C$ in groundwater polluted by reducing efficiency of volatile organic compounds (VOCs) in liquid scintillation counter (LSC). The quenching parameters (SQP(E)) were measured for ten VOCs such as benzene, toluene, ethylbenzene, o-(m-,p-)xylene, trichloroethylene (TCE), tetrachloroethylene(PCE), carbon tetrachloride and chloroform. The quenching curves were plotted using $^{14}C$ standard solution and chloroform as a quenching agent. Optimal plotting conditions were determined for standard solution, LSC measuring time and the concentration of chloroform. The quenching effects of chlorinated organic compounds such as TCE, PCE, carbon tetrachloride and chloroform were greater than those of BTEX (benzene, toluene, ethylbenzene and xylene). Optimum measuring time was 100 minutes far 7,000 dpm/mL standard solution. A few mL of chloroform should be added for good quenching curves. These quenching curves have good correlation coefficients (> 0.99) and the curves could be applied to accurate analysis of $^{14}C$ in groundwater and tap water.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.3
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• pp.305-317
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• 2010

In this research, a total of 11 newly designated offensive odorants in Korea in 2008 and 2010 (styrene (S), toluene (T), p-xylene (p-X), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), butyl acetate (BuAc), isobutyl alcohol (i-BuAl), propionic acid (PA), butyric acid (BA), isovaleric acid (IA), and valeric acid (VA)) were selected as target compounds and analyzed from two types of gutter system in the urban environment. Because of the environmental significance of these compounds as offensive odorants, the results are meaningful enough to explore their behavior and distribution in the urban environmental systems. In the course of this study, samples were collected three times a day from two different gutter systems representing the wet (W) and dry (D) conditions. A large fraction of volatile organic compounds (VOCs) data fell into method detection limit (MDL) range with exceptions of toluene, p-xylene, and methyl ethyl ketone. In contrast, the results of organic fatty acids were distinguished by the relative dominance of butyric acid and propionic acid over others. If the concentration data of all odorants were converted into odor intensity (OI), the results of aromatics, ketones, acetate, and alcohol groups approached zero level. However, odor intensity of organic fatty acids was noticeably higher with the value of 2.8 (on average) from both W and D system, suggesting their potent roles as odorants in gutter system.

• Journal of Life Science
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• v.26 no.5
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• pp.603-607
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• 2016

A crude extracellular lipase from solvent-tolerant bacterium Pseudomonas sp. BCNU 106 was highly stable in the broad pH range of 4-10 and at temperature of 37℃. Crude lipase of BCNU 106 exhibited enhanced stability in 25% organic solvents such as xylene (121.85%), hexane (120.35%), octane (120.41 %), toluene (118.14%), chloroform (103.66%) and dodecane (102.94%) and showed excellent stability comparable with the commercial immobilized enzyme. In addition, the stability of BCNU 106 lipase retained above 110% of its enzyme activity in the presence of Cu²⁺, Hg²⁺, Zn²⁺ and Mn²⁺, whereas Fe²⁺ strongly inhibited its stability. The detergents including tween 80, triton X-100 and SDS were positive signals for lipase stability. Because of its stability in multiple organic solvents, cations and surfactants, the Pseudomonas sp. BCNU 106 lipase could be considered as a potential biocatalyst in the industrial chemical processes without using immobilization.

• Journal of Environmental Science International
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• v.18 no.5
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• pp.517-525
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• 2009

We measured ambient concentrations of hazardous air pollutants such as volatile organic compounds (VOCs) and aldehydes in residential areas nearby small and medium scale shipbuilding companies. The VOC concentrations were higher during the normal operation periods than vacation at which almost all operations were shutdown. Concentrations of VOCs was higher, as the sampling site was nearer from shipbuilding companies. The major components of VOCs were m,p-xylene, ethylbenzene, o-xylene, toluene, and 1,3,5-trimethylbenzene which had been found as major VOC compounds emitted from painting processes of shipbuilding in the previous studies. The major components of aldehydes analyzed were benzaldehyde, acrolein, formaldehyde, and acetaldehyde. The concentration of aldehydes was highest at the furthest sampling point from shipbuilding companies because the formation of aldehyde compounds could be occurred by the secondary chemical reactions of VOCs. The results of this study shows a proper counterplan need to be established for the reduction of hazardous air pollutants emitted from small and medium scale shipping companies.

• Journal of Conservation Science
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• v.20
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• pp.81-88
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• 2007

For the conservation of wooden coffin from King Muryeong's Tomb we examined weight change, shrinkage rate, color changes, and permeation expansion according to the permeation pretreatment chemicals by producing experimental samples with similar physical properties. The result shows Dammar 2 %(in xylene) as the most excellent treatment for protecting deformation by contraction and strengthening materials which are also maintaining its original colors of wood. Therefore, we could get strengthening conservation treatments of dried wooden coffin materials by using Dammar.

• Environmental Engineering Research
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• v.12 no.2
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• pp.46-54
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• 2007

Concentrations of the principal volatile organic compounds, such as benzene, toluene, ethylbenzene, m,p,o-xylene, styrene, and chlorobenzene were measured at the solid waste treatment plants classified into four categories; municipal waste incinerator, municipal waste landfill site, industrial waste incinerator and industrial waste landfill site. The average concentration of VOCs in industrial waste treatment facilities was 33.43 ppb and was significantly higher than that measured at municipal waste treatment facilities (4.71 ppb). The average toluene concentrations measured at incinerators (13.05 ppb) were a little higher than those measured at landfill sites (11.54 ppb). The contribution of the waste treatment facilities to the concentration of benzene (0.35 ppb) and o-xylene (0.15 ppb) in the industrial area was relatively small. However, toluene measured in the industrial waste treatment facilities was the most abundant VOCs with the average concentration of 21.37 ppb. As a result of analyses of fingerprint, in cases of IISH and ILUS, a variety of compounds other than major VOCs were detected in high level. On the Pearson correlation analysis, the correlation was generally positive and some pairs of these VOCs were very strongly correlated (correlation coefficient > 0.75).

• Journal of Environmental Health Sciences
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• v.33 no.5
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• pp.359-364
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• 2007

The aim of this study were to assess the personal exposure to volatile organic compounds (VOCs) and to estimate the personal exposure using time-weighted average model. Three target VOCs (benzene, toluene, xylene) were analyzed in personal exposure samples and residential indoor, residential outdoor and workplace indoor microenvironments samples in the iron mill 30 workers during working 5 days. Personal exposure to VOCs significantly correlated with workplace concentration p<0.05), suggesting workplace had strong source and major contribution to personal exposure. Personal exposure could be estimated with time activity pattern and time weighted average (TWA) model of residential indoor and workplace concentrations measured. Time weighted mean microenvironments concentrations were close approximately of personal exposure concentrations. Total exposure for participants can be estimated by TWA with microenvironments measurements and time activity pattern.

• Advances in environmental research
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• v.2 no.2
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• pp.143-153
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• 2013

This study investigated the concentrations of odourous compounds in air, leachate, stream and well in and around Taju-Bello dumpsite. Meteorological parameters (temperature, relative humidity, wind velocity) and six odour families comprising sulphur ($H_2S$), ammonia ($NH_3$), aromatic (benzene, toluene, ethylbenzene, styrene, p-xylene, m-xylene), aliphatic (hexane), oxygenated (formaldehyde, acetaldehyde) and halogenated (tetrachloroethene, trichloroethene, carbontetrachloride) compounds were measured. Meteorological parameters suggested low dispersal of pollutants at L1 with possible perspiration and suffocation from exposure to high temperature, relative humidity and low wind velocity. The trend of abundance of odourous compounds at studied locations is of the order dumpsite (L1) > leachate (L4) > 100 m away from dumpsite (L2) > 200 m away from dumpsite (L3) > stream (L5) > well (L6). $H_2S$, Oxygenated and aromatic compounds were the major contributors to odour strength in these locations. Correlation, factor and cluster analyses of the data revealed similarities of sources as biogenics and xenobiotics inherent in the wastes as the main sources of these odourous compounds.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.388-391
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• 2004

A sol-gel fiber-optic biosensor with encapsulated pH-sensitive fluorophore and immobilized genetically modified toluene-o-xylene monooxygenase was developed to detect TCE and PCE, which are carcinogenic chlorinate organic compounds prevailing in ground water. The sensitivity was characterized for the composition of sol-gel, and manufacturing procedure. The intensity curve reveals a linear range of intensity for pollutant concentration range of 0.01ppm and 1ppm. The change in intensity was appeared to be larger at each of L for same condition, and, therefore, the wavelength of λ was chosen for the analytical measurement.

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.184.2-185
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• 2001