Young Sunwoo

Seasonal variations of monoterpene emissions from Pinus densiflora in East Asia.

The emission rates and compositions of monoterpene from Pinus densiflora were investigated in the Gumsung (GM) and Worak (WM) mountains. The standard emission rates (ERs: ERs is the monoterpene emission rate at standard temperature, 30 degrees C) from P. densiflora ranged from 0.817 to 1.704 (microgC/gdw-h). The ERs and beta-values of total monoterpene were measured at the two study sites (GM and WM). In the spring and summer, the ERs were the highest, while relatively low values (<0.058microgC/gdw-h) were measured in the autumn and winter. In GM and WM sites the beta-value obtained for the different seasons ranged from 0.047 to 0.179, with an average of 0.09. The major monoterpene compounds from P. densiflora were alpha-pinene, myrcene, beta-phellandrene, d-limonene and alpha-terpinene. The fractional compositions of individual monoterpene compounds were significantly different between the two test sites in the summer and winter. The ERs of the older group (31-40 years) were higher than those in the younger group (21-30 years). However, the monoterpene compositions were similar between the two age groups.

Iron Speciation of Airborne Subway Particles by the Combined Use of Energy Dispersive Electron Probe X-ray Microanalysis and Raman Microspectrometry

Quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), known as low-Z particle EPMA, and Raman microspectrometry (RMS) were applied in combination for an analysis of the iron species in airborne PM10 particles collected in underground subway tunnels. Iron species have been reported to be a major chemical species in underground subway particles generated mainly from mechanical wear and friction processes. In particular, iron-containing particles in subway tunnels are expected to be generated with minimal outdoor influence on the particle composition. Because iron-containing particles have different toxicity and magnetic properties depending on their oxidation states, it is important to determine the iron species of underground subway particles in the context of both indoor public health and control measures. A recently developed analytical methodology, i.e., the combined use of low-Z particle EPMA and RMS, was used to identify the chemical species of the same individual subway particles on a single particle basis, and the bulk iron compositions of airborne subway particles were also analyzed by X-ray diffraction. The majority of airborne subway particles collected in the underground tunnels were found to be magnetite, hematite, and iron metal. All the particles collected in the tunnels of underground subway stations were attracted to permanent magnets due mainly to the almost ubiquitous ferrimagnetic magnetite, indicating that airborne subway particles can be removed using magnets as a control measure.

Hydrogen peroxide concentrations in the ambient air of Seoul, Korea

Abstract Gas-phase hydrogen peroxide (H 2 O 2 ) was measured to investigate its distribution in the ambient air of downtown Seoul. These measurements were made during all four seasons, from 12 February, 1998 to 16 September, 1999, using the cold trap method and HPLC with fluorescence detector. Simultaneous measurements were also made of other photochemical oxidants and trace gases (O 3 , NO 2 , CO and SO 2 ) and meteorological parameters (relative humidity, temperature, solar radiation and wind speed). The mean of all observations for hydrogen peroxide was 0.081 ppbv and the measured range was below the level of detection ( ppbv ) to 0.380 ppbv . The highest mean (± standard deviation) concentrations appeared during the summer ( 0.104±0.068 ppbv , detection limit ∼0.380 ppbv ) and the lowest concentrations were seen during the winter ( 0.042±0.021 ppbv , detection limit ∼0.098 ppbv ). Gas-phase hydrogen peroxide showed a diurnal variation with maximum concentrations in the afternoon. From correlation analysis results, the relationship between gaseous H 2 O 2 and some parameters [ O 3 (r=0.37) , temperature ( r =0.42), aldehydes ( r =0.41)] showed positive correlations. Negative correlations between H 2 O 2 and others [ NO 2 (r=−0.34) , CO (r=−0.41) , and SO 2 (r=−0.30) ] were seen. Thus, as expected, photochemical activity, competing reactions and primary pollutant concentrations appeared to be the most significant factors in controlling the gas-phase H 2 O 2 concentration in Seoul during the measurement period.

Novel hybrid technology for VOC control using an electron beam and catalyst

Noble (Pt, Pd) and transition metals (Mn, Cu) were employed as coupling catalysts to evaluate the toluene (1500 ppm C of initial concentration) removal efficiencies in the electron beam (EB)-catalyst coupling system. The toluene removal efficiency was 60.1% in the EB-only system at a dose of 8.7 kGy. In the presence of the metal catalysts (Pt, Pd, Cu and Mn), the removal efficiency was enhanced by 37, 33, 6 and 22%, respectively, compared to that of EB-only treatment. It was found that the selectivity to CO2 with Pt and Pd coupling were relatively higher than those of Cu and Mn. Especially the CO2 selectivity of EB-Pt coupling was significantly high at a relatively low absorbed dose. The removal efficiencies were compared for loading of catalyst and there was no significant difference among 0.1, 0.5 and 1.0 wt%.

Atmospheric Concentrations of PM2.5 Trace Elements in the Seoul Urban Area of South Korea

Abstract Fine particles (PM2.5) were collected during all four seasons, from April 2001 to February 2002, in Seoul, South Korea, using an annular denuder system. Elemental compositions of ambient PM2.5 were analyzed using the proton-induced X-ray emission method. The greatest contributors (≥2%) to the PM2.5 mass were sulfur (S), silicon (Si), chlorine (Cl), aluminum (Al), and iron (Fe) in the spring; S in the summer; and S and Cl in the fall. S, Cl, and Si were the major elements in the winter. S was the most abundant species among the elements, ranging from 5.3 to 7.9%, followed by Si and Cl. From analysis of variance, PM2.5 mass, Al, Si, potassium, calcium, and Fe showed significant seasonal differences during the four seasons (p < 0.001). Enrichment factor (EF) analysis was carried out to identify the sources affecting the aerosol in the Seoul area. On the basis of the mean EF values, elemental S, copper, zinc, and lead may be emitted from anthropogenic sources (EF > 50). Elemental Al, Si, titanium, and Fe may be emitted from crustal sources (EF < 3). Additionally, a correlation analysis was carried out for source identification. The results of the correlation analysis were confirmed by the results of the EF analysis.

DIAGNOSTIC ANALYSIS OF OFFENSIVE ODORANTS IN A LARGE MUNICIPAL WASTE TREATMENT PLANT IN AN URBAN AREA

A diagnostic study was conducted to examine the effectiveness of malodor removal from a large-scale municipal waste treatment plant in an urban area. To this end, the odor pollution status was investigated from a total of 16 spots in the treatment facility to cover the dual treatment lines consisting of regenerative thermal oxidation (first stage) and a wet chemical scrubber (second stage). As a simple means to learn more about the odorant removal efficiency of different treatment units, samples collected from ambient spots as well as before and after each treatment unit were analyzed for 22 key offensive odorants (i.e., reduced sulfur compounds, carbonyl compounds, nitrogenous compounds, volatile organic compounds, and fatty acids) along with dilution-to-threshold ratios based on the air dilution sensory test. The removal patterns differed greatly between different odorant groups across different processing units. The effectiveness of this dual treatment system was optimized for such odorants as hydrogen sulfide and ammonia, while it was not the case for others (e.g., some aldehydes and organic acids). The results thus suggest the need for the validation of the efficiency in many types of odor processing units and for establishing new control techniques to cover a list of odorants un-subordinate to preexisting methods.

A Study on the Isoprene Emissioin Rates from Deciduous Tree(Quercus Mongolica Fischer)

The standard emission rate(ERs) of isoprene was quantitatively measured in situ from Quercus mongolica Fischer that dominates more than about 85% of domestic oak trees. The ERs values in spring and summer were similar to 64.4 and 58.1 (), respectively. The ERs in autumn, 7.06(), was about times lower than those in spring and summer. The coefficient of determination () between ERs and ranged from 0.593 to 0.836. The correlation coefficients between the ERs and PAR. the ER and temperature suggested that ERs have strong correlation with PAR(photosynthetically active radiation) and temperature. In addition, the high values of PAR, temperature, and ERs were found in the time zone of (spring), (summer), and (autumn).

Study on Natural VOC Emission Rates and Characteristics Emitted from Larix Leptoleis (Sieb. et Zucc.) Gordon

In order to investigate the compositions and the emission rates of monoterpenes emitted from coniferous trees, those from Larix leptoleis (Sieb, et Zucc.) Gordon were measured. In spring and summer, the major monoterpenes were , myrcene; however, were most abundant in fall. The total mean monoterpene emission rates were during the whole period. The higher monoterpene emission rates were found in fall compared to those in spring and summer. In addition, the slopes () between emission rate and temperature were two times lower in fall than those in spring and summer. It was also found that Larix leptoleis (Sieb. et Zucc.) Cordon had lower monoterpene emission rates than P. densiflora and P. rigida.

Integrated nitrogen removal biofilter system with ceramic membrane for advanced post-treatment of municipal wastewater

ABSTRACT The pre-denitrification biofilm process for nitrogen removal was combined with ceramic membrane with pore sizes of 0.05–0.1 µm as a system for advanced post-treatment of municipal wastewater. The system was operated under an empty bed hydraulic retention time of 7.8 h, recirculation ratio of 3, and transmembrane pressure of 0.47 bar. The system showed average removals of organics, total nitrogen, and solids as high as 93%, 80%, and 100%, respectively. Rapid nitrification could be achieved and denitrification was performed in the anoxic filter without external carbon supplements. The residual particulate organics and nitrogen in effluent from biofilm process could be also removed successfully through membrane filtration and the removal of total coliform was noticeably improved after membrane filtration. Thus, a system composed of the pre-denitrification biofilm process with ceramic membrane would be a compact and flexible option for advanced post-treatment of municipal wastewater.

Testbed for Micro-scale Urban Air Quality Monitoring System

In recent years, the environmental problems have become considerably big issues throughout the world. For knowing the environmental problems we have to measure the environment quality and get the data by monitoring the environment. Currently there are many researches are going on in this area. Those researches are using big and expensive environmental measurement equipment. In this reason, they cannot install enough equipment to measure micro-scale area. This lead us to work on a micro-scale air quality monitoring system named AirScope. In AirScope we are using small and cheep sensors for monitoring the urban air quality. In this paper we present AirScope testbed to reduce the problems when we deploy to the micro scale.