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The impact of land cover change in the intertidal zone (8.2% of the total surface area) on meteorology was evaluated using the Weather Research and Forecasting (WRF) model during summer (19 - 21 August 2016) and winter (9 - 11 February 2016). The heat flux change in the intertidal zone due to the tidal effects was greater in summer than in winter. During high tide in summer, the heat flux increased before sunrise and after sunset and decreased after sunrise and before sunset. During low tide, the overall heat flux decreased. In winter, a notable feature was the positive sensible heat flux before sunrise and after sunset during high tide due to a high sea surface temperature. The horizontal and vertical impacts of the tidal phenomena on the coastal meteorology were more pronounced during high tide than during low tide. The temperature decreased in inland areas and intertidal zone in summer afternoons, and increased at sea in winter mornings. The water vapor mixing ratio during the summer period increased in inland from the coastline. The wind speed during high tide at sea increased overall in summer and winter due to the decreased roughness length. During the summer period, the westerly wind speed significantly increased in the lower atmosphere (within 0.4 km) over coastal areas, and the easterly wind speed increased at the heights (approximately 1 km) of the return current of the sea breeze. These horizontal and vertical variations in sea breeze circulation induced horizontal meteorological differences in the Seoul metropolitan areas (approximately 30 km away from the coastline) and vertical differences within the planetary boundary layer (approximately 1.5 km altitude).

The impacts of natural dimethyl sulfide (DMS) and ship emissions on marine environments and particulate matter (PM) over the western and southern sea areas around South Korea were studied based on field campaigns from August–September 2017 and May–June 2018 using the Community Multi-scale Air Quality v5.3.2 modeling system. DMS oxidation enhanced the concentrations of both sulfur dioxide (SO2) and sulfate (SO42−) in PM2.5 by 6.2–6.4% and 2.9–3.6%, respectively, in the marine atmosphere during the study period, whereas it slightly decreased nitrate (NO3−) concentrations (by −1.3%), compared to the simulation without DMS oxidation chemistry. Furthermore, ship emissions increased the concentrations of SO42−, NO3−, and NH4+ by 4.5%, 23%, and 7.3%, respectively. Methane sulfonic acid concentration was 0.17 μg m−3, suggesting the importance of the addition channel in the DMS oxidation pathway. The model simulation indicated that ship emissions in the target area contributed dominantly to non-sea-salt SO42−, and the marine DMS emission source was non-negligible. The geographical distribution of PM toxicity (aerosol oxidative potential) was assessed in the marine atmosphere during the study period.

A water cyclone, developed to collect and preserve biological aerosols in a small liquid flow, was interfaced with a total organic carbon analyzer to measure the aerosol organic and inorganic carbon fractions. The total carbon was compared against parallel measurements of elemental carbon (EC) and organic carbon (OC) using a Sunset Real Time ECOC Analyzer between 12–29 January 2009. A National Institute for Occupational Safety and Health (NIOSH) like protocol for the measurements included four temperature steps ending at 840 °C for OC under a helium atmosphere followed by two temperature steps ramped to 850 °C for EC in a helium–oxygen atmosphere. Carbon data comparison between the water cyclone-TOC and the TOC measured by the analyzer indicated good agreement (r2 = 0.82, linear regression slope = 0.98, p

The global trends in sea spray aerosol (SSA) emissions, dimethyl sulfide (DMS) flux from sea to air, and aerosol optical depth (AOD) during 2000-2015 were analyzed using the satellite-based, ECMWF reanalysis, and model-predicted data. The SSA emissions were estimated using a widely used whitecap method with a sea surface temperature (SST) dependence. The sea-to-air DMS fluxes were estimated by a thin film model based on the DMS concentration in seawater and its gas transfer velocity. The yearly global mean anomaly in DMS fluxes showed a significant downward trend during the study period, whereas the SSA emissions showed an upward trend. In terms of regional trends, the increases in SSA emissions during 2000-2015 occurred over the tropical southeastern Pacific Ocean and Southern Ocean, whereas any downward trends in SSA emissions were localized. The DMS fluxes during the study period showed a clear downward trend over most oceans, except for the strong upward trend at low latitudes. In general, the AOD from the MODerate resolution Imaging SpectroRadiometer (MODIS) showed upward trends across the entire Southern Hemisphere (SH), whereas there were downward trends in most areas of the Northern Hemisphere (NH). Therefore, the upward trend of AOD in the SH were derived mainly from the SSA emission trend, due to smaller contribution of anthropogenic sources in the SH.

Measurements for size-resolved chemical composition were made at the Anmyeon Island station on the western coast of the Republic of Korea between May 28 and June 20, 2016. This study determined the main chemical compositions of size-resolved particulate matter (i.e., organic carbon, elemental carbon, water-soluble organic carbon, water-soluble ions, and benzene carboxylic acids) from a total of eight chemically size-resolved sets using micro-orifice uniform deposit impactors. The sum of the species presents a prominent accumulation mode peak at a diameter of 0.56 μm without the coarse mode peak. In the accumulation mode, SO42− (49.3%) was the dominant particle component in the size range of 0.1–1.8 μm. Organic carbon and elemental carbon accounted for 13.5% and 0.4%, respectively. Benzene carboxylic acids indicate the accumulation mode peak at the diameter of 0.56 μm. The size-resolved equivalent ion concentration ratios between all measured cations and anions and the ion neutralization model, which uses four major ions, were compared. As a result, the concentration of Na+ is of importance in the accumulation mode for the equivalent ion concentration.

A long-lasting severe haze event was observed over the Seoul metropolitan region (SMR: Seoul, Incheon, and Gyeonggi-do), South Korea, in the winter of 2013 (January 12–16). We comprehensively investigated the atmospheric processes affecting particulate matter (PM) distributions during the haze event, as well as its impact on human health in the study area. These analyses were performed based on meteorological and PM observations and numerical modeling, which included the WRF-CMAQ modeling system and the Environmental Benefits Mapping and Analysis Program-Community Edition (BenMAP-CE). High PM10 concentrations during the haze event were mostly observed in the western and southern parts of the SMR. Significant differences (60–70 μg m−3) in the mean PM2.5 concentrations for haze and non-haze days were predicted mainly in the west-northwest areas of SMR. This might be primarily due to the pollutant transport (horizontal and vertical) from large emission sources (e.g., Chinese emissions) and, in part, their local accumulation (by local emissions) under high-pressure conditions and slow-moving air flows (i.e., blocking effect) around SMR. In addition, the enhanced PM2.5 concentrations in the study area during the haze event led to an increase in the number of premature deaths.

In order to determine the quantitative contributions of PM2.5 on the South-west shoreline of Korea, filter based samplings were conducted in the summertime of 2017 and 2018 (total 32 days) via shipborne measurements using both a high volume and middle volume air sampler. Water-soluble organic carbon, water-soluble ions, organic carbon and elemental carbon, elemental species, and organic molecular markers by Liquid Chromatography–tandem Mass Spectrometry were utilized to characterize the collected substrates. The current study investigates the (1) chemical characteristics of PM2.5, (2) source apportionment using positive matrix factorization (PMF), and (3) relationship between sources and the dithiothreitol (DTT) assay during the two sampling periods. A mean PM2.5 concentration of 19.3 μg/m3 was observed along the entire sampling route. The ratio of water-soluble to organic carbon implies that secondary aerosol formation is dominant. The result of methanesulfonic acid (MSA) suggests the contribution of a marine-oriented biogenic source of PM2.5. The PMF source apportionment model showed six source categories with reasonably stable profiles: 1) sulfate-rich, 2) MSA-rich, 3) nitrate-rich, 4) secondary organic, 5) continental, and 6) biomass burning sources. The PMF showed three strong events (i.e., long-range transport, mixed (ocean and long-range stay), and domestic origin events) in the contributions of sources, as well as a dependence on wind transport. Higher associations with DTT oxidative potential normalized to PM2.5 mass concentration (DTT–OPm) related to long-range transport, hence, confirming the impacts of the highest intrinsic oxidative potential.

The temporal variations (diurnal and seasonal) of the optical properties and direct aerosol radiative forcing (DARF) of different aerosol components (water-soluble, insoluble, black carbon (BC), and sea-salt) were analyzed using the hourly resolution data (PM2.5) measured at an urban site in Seoul, Korea during 2010, based on a modeling approach. In general, the water-soluble component was predominant over all other components (with a higher concentration) in terms of its impact on the optical properties (except for absorbing BC) and DARF. The annual mean aerosol optical depth (AOD, τ) at 500nm for the water-soluble component was 0.38±0.07 (0.06±0.01 for BC). The forcing at the surface (DARFSFC) and top of the atmosphere (DARFTOA), and in the atmosphere (DARFATM) for most aerosol components (except for BC) during the daytime were highest in spring and lowest in late fall or early winter. The maximum DARFSFC occurred in the morning during most seasons (except for the water-soluble components showing peaks in the afternoon or noon in summer, fall, or winter), while the maximum DARFTOA occurred in the morning during spring and/or winter and in the afternoon during summer and/or fall. The estimated DARFSFC and DARFATM of the water-soluble component were in the range of -49 to -84Wm-2 and +10 to +22Wm-2, respectively. The DARFSFC and DARFATM of BC were -26 to -39Wm-2 and +32 to +51Wm-2, respectively, showing highest in summer and lowest in spring, with morning peaks regardless of the season. This positive DARFATM of BC in this study area accounted for approximately 64% of the total atmospheric aerosol forcing due to strong radiative absorption, thus increasing atmospheric heating by 2.9±1.2Kday-1 (heating rate efficiency of 39K day-1τ-1) and then causing further atmospheric warming.

In this study, the long-term trend in atmospheric carbon monoxide (CO) concentration was analyzed using the CO levels measured (intermittently) at an air quality monitoring (AQM) station in Seoul, Korea, between the years 1987 and 2013. Temporal trends in CO were analyzed on an annual and seasonal basis in reference to other important air pollutants such as methane (CH4), particulate matter (PM10), sulfur dioxide (SO2), nitrogen monoxide (NO), nitrogen dioxide (NO2), mercury (Hg), and ozone (O3). The annual mean of CO for the entire period was 0.93 ± 0.22 ppm. CO levels were reduced by 83% from 3.25 ± 0.78 ppm (1987) to 0.51 ± 0.31 ppm (2013). Its relative reduction was compared over three periods chosen arbitrarily as period 1 (fast reduction, 1987–1988), period 2 (intermediate reduction, 1999–2000), and period 3 (slow reduction, 2004–2013). The concentrations of CO were strongly correlated with others (e.g., SO2, NO, NO2, O3, and Hg), suggesting the effects of similar source processes (e.g., fuel combustion). The reduction in its level was marginally consistent with the decreasing trend in the total CO column concentration in Seoul by the Measurements of Pollution in the Troposphere (MOPITT) satellite between 2000 and 2013, indicating decreasing anthropogenic CO emissions (despite increasing anthropogenic CO2 emissions). The rapid relative reduction of CO in period 1 and the subsequent slower but moderate reduction thereafter appear to reflect the effects of both enforcement of administrative regulations and advances in emissions control technologies.

The contributions of various PM2.5 emission sources to ambient PM2.5 levels during 2013 in the main hub port city (Busan, South Korea) of East Asia was quantified using several receptor modeling techniques. Three receptor models of principal component analysis/absolute principal component score (PCA/APCS), positive matrix factorization (PMF), and chemical mass balance (CMB) were used to apportion the source of PM2.5 obtained from the target city. The results of the receptor models indicated that the secondary formation of PM2.5 was the dominant (45–60%) contributor to PM2.5 levels in the port city of Busan. The PMF and PCA/APCS suggested that ship emission was a non-negligible contributor of PM2.5 (up to about 10%) in the study area, whereas it was a negligible contributor based on CMB. The magnitude of source contribution estimates to PM2.5 levels differed significantly among these three models due to their limitations (e.g., PM2.5 emission source profiles and restrictions of the models). Potential source contribution function and concentration-weighted trajectory analyses indicated that long-range transport from sources in the eastern China and Yellow Sea contributed significantly to the level of PM2.5 in Busan.

A strategy is proposed for the design of wall envelopes to improve unsteady thermal performance in non-air-conditioned buildings and to reduce energy costs in air-conditioned buildings. The thermophysical properties of building materials (e.g., burnt bricks, mud bricks, laterite stone, cinder concrete, and expanded polystyrene) were measured experimentally using a thermal analyzer. A total of 28 combinations for composite walls were designed with expanded polystyrene as an insulation material based on seven criteria and were subjected to 8 different external surface heat transfer coefficients, which were tested for unsteady thermal performance parameters and air-conditioning cost-saving potential. In this paper, unsteady thermal transmittance obtained from admittance method has been employed to compute cost saving potential of air-conditioning for the various wall envelopes. The use of C–H5 design at a 2 m/s wind speed was found to increase the decrement lag of burnt brick, mud brick, laterite stone, and cinder concrete composite wall envelopes by 48.1%, 49.0%, 59.5%, and 47.0%, respectively, relative to the common wall design (C–H1) in non-air-conditioned buildings. The laterite with a C–H5 design offers the highest annual energy cost savings (1.71 $/m2 at 2 m/s), the highest life cycle cost savings (18.32 $/m2 at 2 m/s), and the lowest payback period (4.03 yrs at 2 m/s) in all tested building materials for air-conditioned buildings. The overall results of this study are expected to open new paths to deliver simple design strategies for energy-efficient buildings.

The Greenland Ice Sheet (GrIS) has been a topic of extensive scientific research over the past several decades due to the exponential increase in its melting. The relationship between air pollution and GrIS melting was reviewed based on local emission of air pollutants, atmospheric circulation, natural and anthropogenic forcing, and ground/satellite-based measurements. Among multiple factors responsible for accelerated ice melting, greenhouse gases have long been thought to be the main reason. However, it is suggested that air pollution is another piece of the puzzle for this phenomenon. In particular, black carbon (BC) and other aerosols emitted anthropogenically interact with clouds and ice in the Arctic hemisphere to shorten the cloud lifespan and to change the surface albedo through alteration of the radiative balance. The presence of pollution plumes lowers the extent of super cooling required for cloud freezing by about 4◦C, while shortening the lifespan of clouds (e.g., by altering their free-energy barrier to prompt precipitation). Since the low-level clouds in the Arctic are 2–8 times more sensitive to air pollution (in terms of the radiative/microphysical properties) than other regions in the world, the melting of the GrIS can be stimulated by the reduction in cloud stability induced by air pollution. In this study, we reviewed the possible impact of air pollution on the melting of the GrIS in relation to meteorological processes and emission of light-absorbing impurities. Long-term variation of ground-based AERONET aerosol optical depth in Greenland supports the potential significance of local emission and long-range transport of air pollutants from Arctic circle and continents in the northern hemisphere in rapid GrIS melting trend.

The source apportionment of volatile organic compounds (VOCs) was examined using receptor models (positive matrix factorization and chemical mass balance) and a chemical transport model (CTM). The receptor model-based analysis was performed using the datasets collected from four different sites from the megacity of Seoul during the years 2013-2015. The contributions of VOC emission sources to ozone (O3) and PM2.5 concentrations and the subsequent health effects in the study area were also assessed during a photochemically active period (June 2015) using a three-dimensional CTM, Community Multi-scale Air Quality (CMAQ), and the Environmental Benefits Mapping and Analysis Program (BenMAP). The solvent use and the on-road mobile emission sources were found to exert dominant controls on the VOC levels observed in the target city. VOCs transported from regions outside of Seoul accounted for a significant proportion (up to approximately 35%) of ambient VOC levels during the study period. The solvent use accounted for 3.4% of the ambient O3 concentrations during the day (daily mean of 2.6%) and made insignificant contributions to PM2.5 (

Long-term trends in global sea spray aerosol (SSA) emissions and dimethyl sulfide (DMS) fluxes from sea to air during the recent global warming hiatus (2000–2015) were analyzed using satellite observations and modelling data. The SSA emissions were estimated using a widely used whitecap method with sea surface temperature (SST) dependence. In addition, sea-to-air DMS fluxes were also used to quantify the secondary contributions of DMS through its sequential oxidation and gas-to-particle conversion. Aerosol optical depth (AOD) was estimated by an aerosol optical model using the number concentration of SSA and non-sea-salt sulfate from DMS. The estimated AOD, which was derived from the SSA and DMS emitted from the sea surface, was compared with satellite-derived AOD to quantify its (primary and secondary) contribution to atmospheric aerosol loading (i.e., observed AOD). Yearly global mean anomalies in DMS fluxes and AOD derived from SSA showed statistically significant downward trends during the recent global warming hiatus, whereas SSA emissions and AOD derived from DMS oxidation did not. In terms of regional trends, the decreases in SSA emissions during 2000–2015 occurred over the central Pacific Ocean, the Indian Ocean, and the Caribbean Sea, whereas upward trends in SSA emissions occurred over the tropical southeastern Pacific Ocean, the Southern Ocean, and the North Atlantic Ocean. DMS fluxes during the study period showed a clear downward trend over most regions of the global ocean. The estimates of the contributions of SSA (primary) and DMS (secondary) to atmospheric aerosol loading were 23–62% and 26–38%, respectively, with the largest primary contribution (~90%) over the Southern Ocean.

In this study, the air pollutants emitted from aircraft within the boundary layer (BL) were investigated for their impacts on the ozone (O3) concentration at and around three international airports (Incheon, RKSI; Gimpo, RKSS; and Jeju, RKPC) using the WRF-CMAQ modeling system during the summer of 2010. The analysis was performed using two sets of simulation scenarios: (1) with (i.e., TOTAL case) and (2) without aircraft emissions (i.e., BASE case). The model study suggested that aircraft emissions within the BL over the three airports can have a significant impact on the O3 (and NOx) concentrations in the source regions (the airports) and their surrounding/downwind areas. A significant negative impact of aircraft emissions on the O3 concentrations in the late afternoon (19:00 LST) was predicted near the three airports with their largest impact of −20 ppb near the RKSI at 19:00 LST. This was attributed mainly to the high NOx conditions in the VOC-limited areas and possibly in part to the rapid titration of O3 by NO around these airports. The rate of photochemical O3 destruction due to the aircraft emissions near the three airports was the most dominant contributor to the O3 levels compared to the other physical processes.

PM2.5 emissions from open biomass burning (BB) in Northeast Asia (NEA: China, Mongolia, Korea, and Japan) during 2000–2013 were estimated using satellite-derived data (GFASv1.0 and GFED3). The annual mean BB PM2.5 emission in NEA during the study period was 660 Gg yr−1, in which considerable inter-annual variability was observed. In general, PM2.5 emissions in NEA were the highest in spring (Mar.–May), likely due to the burning of crop residues and forest fire. The contribution of PM2.5 from open BB in Northeast Asia was less than 10% of the anthropogenic PM2.5 emission, except in Mongolia, wherein BB emission was the predominant source of PM2.5. Although the emissions calculated by GFASv1.0 were significantly higher than GFED3 by a factor of 2.66 (Mongolia) to 10.9 (South Korea) due to difficulty in small fire detection by GFED3, they generally showed consistent temporal variation on average. In general, statistically significant long-term trends of open BB PM2.5 emissions were not observed in NEA, except in South Korea.

The emissions of ozone precursors, NOx and VOCs from a biogenic source and port-related sources (ship, shipping container truck, and cargo handling equipment) were estimated in Busan during 2013. Total biogenic isoprene emission in Busan during 2013 was estimated to be 4,434 ton yr -1 with the highest emission (e.g., 28 ton day -1 ) in summer using a BEIS method. Seasonal ozone production rates by isoprene ranged from 0.15 (winter) to 2.08 (summer) ppb hr -1 , contributing the predominant portion to ambient ozone levels. Total emissions of NOx and VOCs from ship traversing Busan ports were estimated to be 29,537 and 814 ton yr -1 , respectively, showing the significant contribution to total NOx emission in Busan. The emissions of ozone precursors were significantly different depending on ship tonnage and port location. Compared to the ship emission, the emissions of NOx and VOCs from the shipping container trucks in Busan were insignificant (2.9% for NOx and 3.9% for VOCs). Total NOx and VOCs emissions from the cargo handling equipment were estimated to be 1,440 and 133 ton yr -1 , respectively with the predominance of yard tractors.

In this study, the pollution status of particulate matter (PM) in ambient air was investigated based on the concentration data of three important PM fractions (PM2.5, PM10, and TSP) measured from a central area in Seoul, Korea during the period from 2004 to 2013. The mean concentrations of each fraction measured for the entire study period were found to be 26.6 ± 2.59, 54.0 ± 15.0, and 75.3 ± 16.6 μg m−3, respectively. The seasonal mean of PM2.5 varied in the range of 22.9 ± 7.10 (fall) to 30.2 ± 7.58 μg m−3 (winter). In contrast, PM10 and TSP showed a summer minimum (40.1 ± 12.6 and 55.6 ± 17.8 μg m−3, respectively) and a spring maximum (67.1 ± 16.7 and 93.7 ± 21.1 μg m−3, respectively). The contribution of regional or long-range transport to the observed PM levels in the study area, if estimated by comparison to the data of the regional background area, was found to explain up to 72% of its input. The long-term trend of PM indicated a gradual decreasing pattern over a 10 year period, although that of PM2.5 was rather complicated to interpret in the recent years. The overall results of our study nonetheless confirm the potent role of legislation efforts put consistently to improve the air quality through the years.

In this study, spatial and temporal variations of radiative forcing(RF) and mean temperature changes due to green-house gases(CO 2 , CH 4 , and N 2 O) emitted from commercial aircraft were examined based on the simplified expres-sion at the airports in Korea during 2009~2010. The radiative transfer model (SBDART) was used to comparewith the RF and mean temperature changes calculated from the simplified expressions for greenhouse gas CO 2 . TheRF simulated by the SBDART was about 67% higher than that of the simplified expression, on average. Thehighest mean RF(up to 9.0 mW/m 2 for CO 2 ) and mean temperature changes(up to 9.7×10 -5 �K/day for CO 2 ) for allGHGs occurred at Ulsan airport during the study period, whereas the lowest RF and temperature changes atYangyang (for CO 2 ) and Sacheon airports (for CH 4 and N 2 O). In the case of CH 4 and N 2 O, their effects to the RFand mean temperature change were negligible compared to CO 2 . Key words : Greenhouse gas emissions, Radiative forcing, Mean temperature change, Airport, Aircraft, Simplifiedexpression, Radiative transfer model, SBDART

The environmental behavior and pollution status of nickel (Ni) were investigated in seven major cities in Korea over a 13-year time span (1998–2010). The mean concentrations of Ni measured during the whole study period fell within the range of 3.71 (Gwangju: GJ) to 12.6 ng m −3 (Incheon: IC). Although Ni values showed a good comparability in a relatively large spatial scale, its values in most cities (6 out of 7) were subject to moderate reductions over the study period. To assess the effect of major sources on the long-term distribution of Ni, the relationship between their concentrations and the potent source processes like non-road transportation sources (e.g., ship and aircraft emissions) were examined from some cities with port and airport facilities. The potential impact of long-range transport of Asian dust particles in controlling Ni levels was also evaluated. The overall results suggest that the Ni levels were subject to gradual reductions over the study period irrespective of changes in such localized non-road source activities. The pollution of Ni at all the study sites was maintained well below the international threshold (Directive 2004/107/EC) value of 20 ng m −3 .

Monthly variations of radiative forcing (RF) and mean temperature changes by greenhouse gases emitted from commercial aircraft were estimated based on the simplified expression at four international airports (Incheon, Gimpo, Jeju, and Gimhae Airports) during the years of 2009~2010. The highest RF and mean temperature change in the study area occurred at Incheon Airport, whereas the lowest RF and mean temperature change at Gimhae Airport. During 2009~2010, the mean RF and mean temperature change estimated from aircraft emissions at Incheon Airport were approximately 30.0 and , respectively. The mean RF and mean temperature changes caused by other greenhouse gas was significantly small ( and ). Meanwhile, emissions caused negative mean RF ( at Incheon Airport) and the decrease of mean temperature () due to consumption of atmospheric in the aircraft engine.

Concentrations of ozone were continuously measured at four urban monitoring sites (Gu Ro (G); No Won (N); Song Pa (S); and Yong San (Y)) in Seoul, Korea from 2009 to 2011. The annual mean concentrations of ozone (in ppb) at these sites were found on the order of N (21.8 ± 19.3) > S (21.4 ± 20.14) > G (20.9 ± 18.0) > Y (18.8 ± 17.4). During peak hours (12–6 pm), the ozone concentrations were significantly higher (75, 69, 67, and 64% at site S, Y, N, and G, respectively) than overall 24 hour mean values. Seasonal variations of ozone have quite similar patterns at every site with systematic increases during spring (March–May) and summer (June–August) with the summer daytime mean (12–6 pm) values of 40.7 (site Y)–49.3 ppb (site S). The concentrations of ozone exhibited strong inverse correlations with other criteria pollutants (e.g., oxides of nitrogen and carbon monoxide), while a significant positive correlation was observed with some meteorological parameters (e.g., ultraviolet ray and solar radiation). Evidence collected in this study confirm that the spatio-temporal distribution of ozone in the study areas should be affected by the anthropogenic sources (e.g., vehicles, residential, and industrial sources) in concert with such well-known variables as the NO x –VOC chemistry and a number of natural parameters (e.g., wind speed, geographic position, and solar radiation).

Particulate matter (PM) generally comprises such chemical components as inorganic ions, organic carbon (OC), elemental carbon (EC), and metals. In terms of environmental studies, these major chemical components of particulate matter (MCP) are important in understanding PM distribution, behaviors and source apportionment. In this study, the MCP fractions of total suspended particles (TSP) were measured at an urban residential area in Seoul, Korea from February to December in 2009. The behavior of each individual MCP was studied in order to explain their relationship to environmental conditions and sources. The MCP measured during this study period was able to account between 54% (spring) to 67% (fall) of total TSP composition. During the study period, it was found that the TSP sampled comprised mostly: anions, OC, cations, EC, and metals in decreasing order of abundance. Although such relative ordering seems to remain fairly constant over time, the relative balance of this relationship may be altered by variations in environmental conditions.

In this work, 17-polychlorinated dibenzo-p-dioxin/furan (PCDD/Fs) isomers were measured in ambient air at four urban sites in Seoul, Korea (from February to June 2009). The concentrations of their summed values (ΣPCDD/Fs) across all four sites ranged from 1,947 (271 WHO05 TEQ) (Jong Ro) to 2,600 (349 WHO05 TEQ) fg/m3 (Yang Jae) with a mean of 2,125 (± 317) fg/m3 (292 WHO05 TEQ fg/m3). The sum values for the two isomer groups of ΣPCDD and ΣPCDF were 527 (30 WHO05 TEQ) and 1,598 (263 WHO05 TEQ) fg/m3, respectively. The concentration profile of individual species was dominated by the 2,3,4,7,8-PeCDF isomer, which contributed approximately 36 % of the ΣPCDD/Fs value. The observed temporal trends in PCDD/F concentrations were characterized by relative enhancement in the winter and spring. The relative contribution of different sources, when assessed by principal component analysis, is explained by the dominance of vehicular emissions along with coal (or gas) burning as the key source of ambient PCDD/Fs in the residential areas studied.

A detailed description of an interactive relationship is made between water-soluble ionic components in PM 2.5 and their precursor gases using the hourly resolution data measured at an urban monitoring site in Seoul during the year of 2010. Their diurnal variability was found to be correlated with their precursor gases (HNO 3 and NH 3 ). In the case of NO 3 − and NH 4 + , a close similarity was seen in their diurnal trends, especially during spring. There were no noticeable differences in the formation pathway of NO 3 − , SO 4 2− , and NH 4 + aerosols between day and night. For NO 3 − formation, heterogeneous hydrolysis of N 2 O 5 might play a significant role in the nighttime enhancement of the oxidation rate. In addition, the concentrations of major anions (e.g. NO 3 − , SO 4 2− , and Cl − ) exhibited highly diverse seasonal patterns with their maximum values occurring in spring, summer, and winter, respectively. The overall results of this study suggest that the formation pathway of NO 3 − and SO 4 2− aerosols should be regulated by a competing relationship between the NH 3 -lean (spring and winter) and NH 3 -rich conditions (summer and fall).

Using a cation exchange resin of polystyrene-DVB copolymer as a carbon source for the production of activated carbon, the effects of operating parameters on the physical properties of activated carbon such as specific surface area and specific pore volume were experimentally studied. In carbonization process specific surface area and specific pore volume of carbonized pro- duct decreased with the increase of carbonization temperature and time. They were proportional to activation temperature and time up to the specific temperature and time in activation process. In carbonization process the increase of heating rate gave negative effect to the properties. The properties of activated product, on the contrary, increased with the heating rate in carbonization process. The properties of activated carbon manufactured with the resin exchanged with divalent cations were lower than those with raw resin.

Emissions of air pollutants and greenhouse gases (GHGs) from aircraft activities at 11 small-scale airports were investigated using the emissions and dispersion modeling system (EDMS) version 5.1.3 during the two year period of 2009~2010. The number of landing and take-off (LTO) at these airports was dominant for the aircraft type B737, accounting for more than 60% of the total LTOs. Out of the 11 small-scale airports, Gwangju (GJ, RKJJ) airport was the largest emitter of air pollutants and GHGs, whereas Yangyang (YY, RKNY) airport was the smallest emitter. The emissions of NO x and VOCs in 2010 at the 11 airports ranged from 1.9 to 83 ton/y and 0.1 to 17 ton/y, respectively. In 2010, the emissions of CO 2 ranged from 394 to 21,217 ton/y. The emissions of most air pollutants (except for NO x and PM 10 ) and GHGs were estimated to be the highest in taxi-out mode. The highest emissions of NO x and PM 10 were emitted from climb-out and approach modes, respectively. In addition, the total LTOs at the 11 small-scale airports accounted for the range of 9.3~9.9% of those at four major international airports in Korea. The total emissions of air pollutants and GHGs at the 11 airports ranged from 4.8 to 12% of those at the four major airports. Key words: Aircraft. EDMS, Air pollutants, Greenhouse gas, Emission, Airport

The impact of pollutant emissions by the significant amount of road traffic around beaches on the ozone (O 3 ) concentrations in the surrounding regions were evaluated using a numerical modeling approach during 6 days (29 July through 3 August) of the beach opening period (BOP) in 2010. On-road mobile emissions at several roads close to beaches in Busan, Korea during the study period were estimated from the emission factors, vehicle kilometers traveled, and deterioration factors. The emission data was then applied to the 3-D chemical transport model. A process analysis (PA) was also used to assess the contributions of the individual physical and chemical processes to the production or loss of O 3 in the study area. The model study suggested the possibility that road traffic emissions near the beach area can have a significant impact on the O 3 concentrations in the source regions as well as their surrounding/downwind regions. The maximum negative impact of mobile emissions on the O 3 concentrations was predicted near the beach areas: by −9 ppb during the day due to both the high NO x emissions with the high NO x /VOC ratio and meteorological conditions and −9 ppb at night due to the fast titration of O 3 by NO. The PA showed that the contribution of chemical process to the decrease in O 3 concentrations (up to −5.5 ppb h −1 ) due to mobile emissions near the beach areas was the most dominant compared to the other physical processes.

Long-term monitoring of ammonia concentration and other trace gases was made at hourly intervals along with meteorological parameters in Seoul, Korea for a one-year period (1 September 2010–23 August 2011). The mean ammonia concentrations measured at two sites (Gwang-Jin (GJ) and Gang-Seo (GS) districts) were 10.9 ± 4.25 and 12.3 ± 4.23 ppb, respectively. A comparison of the seasonal data shows its relative dominance at both GJ and GS sites during the warm period (summer and spring) over the cool period (winter and fall). Likewise, over the diurnal scale, relative dominance during daytime was also apparent (p

Removal characteristics of lead-contaminated soil at the military shooting range located in the Changwon city were studied experimentally using soil washing process. As a washing solution, hydrogen chloride (HCl) concentrations of 0.001, 0.01, 0.1 and 0.2 N were used, and soil : solution ratios were 1 : 2, 1 : 3, 1 : 4, and 1 : 5. Particle diameter of contaminated soil of 4- 0.075 mm, and washing period of 5, 10, 15, 20, 30, 60, and 120 min were used as operating parameters. The optimum concentration

The emissions of greenhouse gases (GHGs) and air pollutants from aircraft in the boundary layer at four major international airports in Korea over a two-year period (2009–2010) were estimated using the Emissions and Dispersion Modeling System (EDMS) (i.e. activity-based (Landing/Take-Off (LTO) cycle) methodology). Both domestic and international LTOs and ground support equipment at the airports were considered. The average annual emissions of GHGs (CO 2 , N 2 O, CH 4 and H 2 O) at all four airports during the study period were 1.11 × 10 3 , 1.76 × 10 −2 , −1.85 × 10 −3 and 3.84 × 10 8 kt yr −1 , respectively. The emissions of air pollutants (NO x , CO, VOCs and particulate matter) were 5.20, 4.12, 7.46 × 10 −1 and 3.37 × 10 −2 kt yr −1 , respectively. The negative CH 4 emission indicates the consumption of atmospheric CH 4 in the engine. The monthly and daily emissions of GHGs and air pollutants showed no significant variations at all airports examined. The emissions of GHGs and air pollutants for each aircraft operational mode differed considerably, with the largest emission observed in taxi-out mode.

In this study, fine-particle (PM2.5) ionic composition in the city of Seoul was investigated using short-term measurement data (1 h interval) collected during the year 2010. The partitioning of semi-volatile inorganic species and phase state of aerosols were studied using ISORROPIA II thermodynamic equilibrium model. The analysis of ionic composition identified the relative dominance of NO 3 − , SO 4 2 − , and NH 4 + in the fine particles. The presence of strong correlation between these components indicates similarity of their formation pathways. Seasonal patterns of these ionic components and their gas-phase precursors were somewhat different from each other. The observed SO 4 2 − / SO 2 mass ratio indicated a significant role of the gas-phase oxidation of SO2 (to H2SO4) in the SO 4 2 − formation. Moreover, both SO42− and NO3− were almost completely neutralized by NH4+ to form (NH4)2SO4 and NH4NO3. The formation of NO3− aerosol would be ammonia-sensitive (i.e., deficit ammonia), as evidenced by smaller total ammonia concentration than the sum of total sulfate and nitrate concentrations. The uptake of SO2 on dust particles during Asian dust event is also likely to exert controls on SO42− concentrations.

The impact of a considerable increase in traffic volume on the emission and concentrations of air pollutants was investigated at three beaches (Haeundae (HB), Gwanganri (GB), and Songjeong (SB)) in Busan during beach opening period (BOP) in 2011. During the BOP, passenger car was the major vehicle type, followed by taxi, and van. CO was the major contributor of total air pollutant emissions followed by NOx, VOC, and PM 10 . For the temporal variation of the emission of air pollutants during the BOP, it was generally the highest in the afternoon followed by the evening and morning, except for SB. For the spatial variation of their emission, it was the highest at GB followed by SB and HB. The emissions of air pollutants during the BOP were generally higher than those during the Non-BOP, except for HB. In contrast, the significant impact of the traffic volume increase on the concentrations of air pollutants at monitoring sites near the three beaches during the BOP were not found compared to the Non-BOP due to the significant distances between monitoring sites of air pollutants and monitoring sites of traffic volume at the beaches.

Emissions of air pollutants and greenhouse gases (GHGs) by aircraft at the Gimhae International Airport (GIA) were investigated using the Emissions and Dispersion Modeling System (EDMS) version 5.1.3. The number of Landing and Take-Off (LTO) at the GIA for aircraft B737 was dominant, accounting for more than 60% of the total LTOs. For air pollutant emissions, CO was the most dominant pollutant by aircraft, followed by , VOCs, , etc. The emissions of CO, , and VOCs in 2009 (and 2010) at the GIA were 974 (968), 447 (433), 118 (122) ton/yr, respectively. The emissions of GHGs such as , , and in 2009 (and 2010) were 110,795 (111,114), -0.157 (-0.151), and 1,989 (1,998) ton/yr, respectively. The negative number in emission represents the consumption of atmospheric in the engine. In addition, the emissions of most air pollutants (except for ) and GHGs were estimated to be high in Taxi-Out and Climb-Out modes.

The quantitative composition of total suspended particulates (TSP) in the atmosphere is identified to consist mainly of ions, organic carbon (OC), element carbon (EC), and metals. In terms of environmental analysis, the rest of the TSP composition may be defined as unknown fraction () which is yet difficult to analyze both quantitatively and qualitatively. In this study, the major components of TSP were measured at an urban residential area (Gang Seo) in Seoul, Korea from February to December 2009. These TSP data were analyzed in various respects to explain the relationship between known and unknown constituents. During this study period, TSP was comprised mainly of unknown compounds (48.6%) followed by ions, OC, EC, and metals. The results of this study indicate that the distribution of exhibits a strong similarity with , as they both increase with increasing TSP levels. However, if the concentrations of and are normalized against TSP, they exhibit a strong inverse correlation with each other due probably to larges differences in solubility. To establish a better strategy for air quality control in urban atmosphere, more efforts are needed to characterize unidentified proportion of particulate matters.

The environmental behavior of particle-bound secondary organic carbon (SOC) was investigated with respect to its fractionation at four urban sites in Seoul, a megacity in Korea from Feb to Dec 2009. Empirical estimates of SOC formation were comparatively evaluated using the multiple linear regression and constrained mass balance (i.e., CO and EC tracers) methods. The SOC fraction estimates were significantly different depending on the applied methods. The multiple linear regression method used for the estimation of SOC fraction was more reliable than the constrained mass balance approach due to the limited number of available daily PM measurement during each season. Seasonal and spatial patterns in the SOC fractions were examined at the four urban sites. Seasonally averaged SOC fractions ranged from 15 to 65% of the total organic carbon concentration. According to this study, the SOC fractions were significantly high in the spring and summer relative to other seasons.

The ionic composition of PM2.5 samples was investigated by their datasets of cationic (Na?, NH₄?, K?, Mg 2+ , and Ca 2+ ) and anionic components (Cl?, NO₃?, and SO₄ 2- ) along with relevant environmental parameters collected from an urban monitoring site in Korea at hourly intervals in 2010. The mean (and SD) annual concentration of PM 2.5 was computed as 25.3 ㎍ m -3 with the wintertime maximum. In addition, sum concentrations (neq m -3 ) of five cationic species (291) were slightly lower than 3 anionic species (308). Most cations exhibited the highest seasonal values in spring, while anions showed more diversified seasonal patterns. According to PCA, five major source categories were apparent with the relative dominance of secondary inorganic aerosols (SIA). The results of our study suggest consistently that the distribution of ionic constituents in an urban area is affected by the combined effects of both natural and anthropogenic processes.

The photochemical characteristics of ozone (O3) and its main precursors (e.g. NOx and VOCs) were investigated in relation to the photochemical O3 budget and O3eNOxeVOC sensitivity, based on a modeling approach using data sets observed during intensive field campaigns conducted under various environmental conditions (i.e. urban (Seoul), rural (Yang Pyeong), landfill (Dae Gu), coastal (Gwang Yang), and remote sites (Jeju Island). The production of O3 under most environmental conditions (especially, spring season at the urban site) was found to be more strongly sensitive to VOCs than NOx .A t the landfill site and during summer at the rural and coastal sites, the production of O3 was partially sensitive to NOx. On the other hand, despite the remote air on Jeju Island, the production of O3 was mainly VOC-sensitive (high NOx levels), but in part NOx-sensitive (low NOx levels), due to the transport processes from different environmental regions (e.g. heavily and less polluted locations).

In this study, a series of experiments were carried out to measure temporal stability of reduced sulfur compounds (RSCs) in Tedlar bag samples as a function of elapsed storage time. To this end, temporal variability of 4 RSC standard gases (, , DMS, DMDS) was measured up to 29 days. For the purpose of comparison, RSC samples were stored in both individual and mixed state. In the case of mixed standard, samples were also examined to allow comparison between light and dark condition. Then results of data were the most stable with the least change in its concentrations through the end of exps (29 days). When compared with previous studies, the extent of stability appeared to be influenced by the initial concentration levels of samples. When the patterns were compared between individual and mixture samples, differences were not significant in the case of and DMS. The effects of light conditions on temporal stability were seen to be fairly sensitive on most RSC other than . The results of our study confirm that the stability of RSC storage is affected by their involvement in photochemical reactions.

Long-term trend in emission ratio of NO2 to NOx was analyzed in relation to traffic activities using ambient monitoring data (such as NO, NO2, NOx, and O3) collected from 7 urban roadside (U-RS) and 7 urban background (U-BG) locations in Seoul, Korea over a 14-year period (1996–2009). In general, the temporal trend of NO2 concentrations is less distinctive than that of NOx, whether being downward or upward. However, if their differences are checked statistically, only a few cases were significant. The mean emission ratio of NO2 to NOx values varied slightly across the 7 U-RS sites during the study period, ranging from 0.11 to 0.19. In general, there was no significant annual trend in the relative fraction of NO2 in NOx emission (f(NO2)) at U-RS, with an exceptional downward trend at one site (slope of −0.008 y−1). On the other hand, diurnal variations of f(NO2) were likely affected by driving conditions and fuel type of vehicles. The overall results of this study suggest that NOx emission control strategies such as diesel particulate filter (DPF) or diesel oxidation catalyst (DOC) should have direct influences on f(NO2) values at U-RS sites.

In an effort to assess long-term variations of urban air quality over a broad spatial scale, the concentrations of PM10 (particulate matters with aerodynamic size below 10 μm) measured from a total of 16 urban roadside (U-RS) stations in Korea over a decadal period (1998 and 2008) were analyzed in a number of respects. As a major criterion for evaluation, these PM data were examined with respect to landmarking active clean-up activities (e.g., Natural Gas Vehicle Supply (NGVS) program enforced since 2000 and upgrading of fuel quality since 2004) and emission control retrofits since 2003 throughout major urban areas in Korea. The mean concentrations of PM10 from all 16 U-RS stations varied from 51.3 ± 10.3 (before 2000) to 70.3 ± 19.4 μg m−3 (after 2001). The results derived from 4 regional background stations were also analyzed as a reference to the urban data sets. The analysis of our PM data between before and after such clean-up activity for air quality indicates the existence of highly diversified temporal patterns. The measured PM values from only a few U-RS stations exhibited statistically significant declining trends over a decadal period. It is thus concluded that the effect of clean-up activity like NGVS and emission control retrofits, although claimed to make zero-emissions of fine particles, did not result in an overall reduction in PM10 levels.

Emission of air pollutants such as nitrogen oxides (NO x ), hydrocarbons (HC), SO 2 , and particulate matter (PM) and CO 2 from ship during 2009 in Busan port was estimated based on activity-based method. The significant fraction (> 50%) of ship emission resulted from container and general cargo ships. Emission at port operation mode was the most dominant compared to at sea and maneuvering modes. Emission at North port was the largest source of air pollutants among ports. The magnitudes of air pollutants NO x , SO 2 , HC, CO 2, and PM in Busan port were 8.7 × 10 3 , 8.23 × 10 3 , 0.35 × 10 3 , 4.86×10 6 , and 0.67 × 10 3 ton/yr, respectively. The ratio of NO x to VOC is about 25. Our ship emission estimate is 2 times higher than that in CAPSS emission inventory. Key Words :NO x , Vessel category, Engine power, Actual speed, Emission factor 1) 1. 서 론 세계화의 가속화로 늘어가는 인적, 물적 교통량은 선박의 물동량을 증가 시키고 이로 인한 선박의 엔진배출로부터 발생하는 대기오염은 심각한 수준으로 인식되고 있다. 선박배출은 특히 선박 입 ․ 출항이 빈번한 주요 무역항 인접지역의 대기질(NO