• Journal of Korean Society for Atmospheric Environment
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• v.28 no.5
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• pp.485-494
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• 2012

The purpose of this study is to monitor the flux of $CO_2$ and BVOCs (biogenic volatile organic compounds) between the atmosphere and forest. The main research activities are conducted at Taehwa Research Forest (TRF), managed by the College of Agriculture and Life Sciences at Seoul National University. The TRF site is located 60 km north-east from the center of Seoul Metropolitan Area. The TRF flux tower is in the middle of a Korean Pine (Pinus Koraiensis) plantation ($400m{\times}400m$), surrounded by a mixed forest. Eddy covariance method was used for $CO_2$ flux above the forest and REA (Relaxed eddy accumulation) method applying eddy covariance was used for BVOCs flux. BVOCs flux that was measured in spring (from May 16 to 18) had distribution of 84 to $2917{\mu}g/m^2{\cdot}h$. Especially, it showed that d-limonene being strong reactivity composed the largest fraction of monoterpene. Ambient $CO_2$ concentration measured in Mt. Taehwa was 399 ppm and observed $CO_2$ fluxes between the atmosphere and forest suggested that during the day, $CO_2$ is absorbed by plants through photosynthesis and released during the night.

• Journal of Environmental Science International
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• v.24 no.2
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• pp.207-219
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• 2015

The purpose of this study is to show the geographical distribution and the temporal variation of the emission amount of biogenic volatile organic compounds(BVOCs) emanated from forests at Jeju Island. The total emission amount of BVOCs calculated by using the CORINAIR Methodology is $3612ton\;yr^{-1}$ at Jeju Island. More than half of BVOCs emissions is come from coniferous forest, and 45 per cent from broad leaved forest. The others is attributed to grassland. Of total emission of BVOCs, isoprene accounts for 28 per cent, monoterpene for 32 per cent, and other VOCs for about 40 percent, respectively. It can be shown that $3000{\sim}10000kg\;yr^{-1}$ of BVOCs is emitted at the zone with dense forest from an altitude of 500 m to the top of Mt. Halla, and less than $1500kg\;yr^{-1}$ at the zone an altitude of below 500 meters. The monoterpene emission is more than $1500kg\;yr^{-1}$ due to the existence of a colony of Abies koreana at the place with more than 1500 meters and a community of Pinus thunbergii and Cryptomeria japonica at the elevation of 500~700 m. In the case of isoprene emission, there is $1500{\sim}3000kg\;yr^{-1}$ at the zone of an elevation from 700 m to 1500 m due to dense broad leaved forest and very little of its emission at an elevation of more than 1500 meters because there is hardly broad leaved trees grown. In this study, emission of BVOCs according to the altitude above sea level is estimated under the situation of lack of the data for broad leaved tree. More detailed data and information for the distribution of broad leaved trees are needed in order to calculate more realistic BVOC emission.

• Analytical Science and Technology
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• v.28 no.3
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• pp.246-254
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• 2015

From 2013 to 2014, volatile organic compounds (VOCs) were analyzed to determine biogenic volatile organic compounds (BVOCs) and anthropogenic volatile organic compounds (AVOCs) at eight sites in Mt. Mudeung and one site in downtown, by using a GC/Mass-ATD (automatic thermal desorber). The concentration of terpene noted as biogenic volatile organic compounds at Pungamjeong (PA), in a forest of Chamaecyparis obtusa, was 821 pptv, which was the highest among the eight sites. This value was followed by Wonhyogyegok (WH: 785 pptv), Norritzae (NZ, coniferous forest: 679 pptv), Dongjeokgol (DJ, mixed species forest: 513 pptv), Jangbuljae (JB, Abies koreana: 476 pptv), and Seinbongsamgerri (SS, pine trees: 464 pptv). 11~15 species of terpene was detected in the forest depending on the site. At PA in May, α-pinene showed the highest value, occupied 20% of terpene followed by coumarin, sabinene, phellandrene, myrcene, borneol, eucalyptol, β-pinene, cymene, δ-limonene, γ-terpinene, camphor, camphene, and mentol in the order. The mean concentrations of AVOCs were 0.74~2.52 ppbv in the forests and 3.14 ppbv in the downtown area. From May to July, the AVOCs ratios of the downtown to each forest were 1.9~4.0. Among 10 species of AVOCs, the sum of toluene and benzene was 2.34 ppbv and occupied 75%. In June, the ratios of toluene were 44.1% at DJ site and 53.1% at JW site (downtown). The BVOCs showed a positive correlation with the AVOCs at the forest sites (r = 0.328), which was statistically insignificant (p = 0.184).

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.3
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• pp.457-468
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• 2018

To improve understanding of the physico-chemical characteristics of aerosols in the national park and comparing the air pollution between national park and the urban area nearby national park, the aerosol characterization study was conducted in Bukhansan National Park, Seoul, from July through September 2017. Semi-continuous measurements of $PM_{2.5}$ using PILS (Particle Into Liquid System) coupled with IC (Ion Chromatography) and TOC (Total Organic Carbon) analyzer allowed quantification of concentrations of major ionic species($Cl^-$, $SO_4{^{2-}}$, $NO_3{^-}$, $Na^+$, $NH_4{^+}$, $K^+$, $Mg{^{2+}}$ and $Ca{^{2+}}$) and water soluble organic carbon (WSOC) with 30-minute time resolution. The total mass concentration of $PM_{2.5}$ was measured by T640 (Teledyne) with 5-minute time resolution. The black carbon (BC) and ozone were measured with a minute time resolution. The timeline of aerosol chemical compositions reveals a strong influence from urban area (Seoul) at the site in Bukhansan National Park. Inorganic aerosol composition was observed to be dominated by ammoniated sulfate at most times with ranging from $0.1{\sim}32.6{\mu}g/m^3$ (6.5~76.1% of total mass of $PM_{2.5}$). The concentration of ammonium nitrate, a potential indicator of the presence of local source, ranged from below detection limits to $20{\mu}g/m^3$ and was observed to be highest during times of maximum local urban (Seoul) impact. The total mass of $PM_{2.5}$ in Bukhansan National Park was observed to be 10~23% lower than the total mass of $PM_{2.5}$ in urban area (Gireum-dong and Bulgwang-dong, Seoul). In general, ozone concentration in Bukhansan National Park was observed to be similar or higher than urban sites in Seoul, suggesting additional biogenic VOCs with $NO_x$ from vehicle emission were to be precursors for ozone formation in Bukhansan National Park.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.5
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• pp.536-546
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• 2016

The diurnal variations of $O_3$ and $NO_2$ in an urban park and the effects of air temperature and wind speed on the diurnal variations are investigated. $O_3$ and $NO_2$ concentrations were observed at a site in an urban park of Seoul from 27 July 2015 to 9 August 2015. The $O_3$ and $NO_2$ concentrations observed in the urban park are compared to those observed at the Gangnam air quality monitoring station (AQMS). The $O_3$ concentration is higher in the urban park than at the Gangnam AQMS in the daytime because the amount of $O_3$ dissociated by NO is smaller as well as partly because the amount of $O_3$ produced in the oxidation process of biogenic volatile organic compounds (VOCs) is larger in the urban park than at the Gangnam AQMS. The $NO_2$ concentration is lower in the urban park than at the Gangnam AQMS during day and night because the observation site in the urban park is relatively far from roads where $NO_x$ is freshly emitted from vehicles. The difference in $NO_2$ concentration is larger in the daytime than in the nighttime. To examine the effects of air temperature and wind speed on the diurnal variations of $O_3$ and $NO_2$, the observed $O_3$ and $NO_2$ concentrations are classified into high or low air temperature and high or low wind speed days. The high $O_3$ and $NO_2$ concentrations in the daytime appear for the high air temperature and low wind speed days. This is because the daytime photochemical processes are favorable when the air temperature is high and the wind speed is low. The scatter plots of the daytime maximum $O_3$ and minimum $NO_2$ concentrations versus the daytime averages of air temperature and wind speed show that the daytime maximum $O_3$ and minimum $NO_2$ concentrations tend to increase as the air temperature increases or the wind speed decreases. The daytime maximum $O_3$ concentration is more sensitive to the changes in air temperature and wind speed in the urban park than at the Gangnam AQMS.