Background Site In Korea Research Articles

Empirical estimation of size-resolved scavenging coefficients derived from in-situ measurements at background sites in Korea during 2013–2020

Owing to insufficient detailed in-field observations for explaining and quantifying the wet-scavenging coefficients, especially those below-cloud (Λbelow), prediction of accurate aerosol concentrations and/or behaviors in the atmosphere remains challenging. As a pioneering effort, this study focused on establishing an empirical equation for size-resolved Λbelow, which represent the characteristics in Korea, using long-term aerosol number size distribution and meteorological variable measurements at two background sites in Korea (Baengnyeong and Jeju). The median Λbelow values derived from the total number concentrations were 8.06 × 10−6 s−1 for Baengnyeong and 1.04 × 10−5 s−1 for Jeju, which are similar to or slightly lower than the Λbelow reported by previous in-situ studies. These may be caused by differences in the precipitation rates, precipitation drop sizes, aerosol chemical/hygroscopic properties, and aerosol size distributions at the measurement sites. Although the derived parameterization can cover a wide range (10 nm to 10 μm), the derived equation for the fourth-degree polynomial shows a high correlation coefficient of 0.81, indicating that the measured and fitted Λbelow converge within a narrow range. Moreover, the variation in Λbelow is relatively constant for aerosol diameters larger than ∼1 μm, similar to those derived from theoretical equations rather than empirical equations in previous studies. This study is thus expected to contribute to improving the below-cloud scavenging module implemented in a chemical transport model by covering a wide range of aerosol diameters to avoid overestimation by extrapolation of Λbelow.

Temporal Variations and Characteristics of the Carbonaceous Species in PM2.5 Measured at Anmyeon Island, a Background Site in Korea

Routine measurements of carbonaceous species in PM2.5 inculidng organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), and humic-like-substance carbon (HULIS-C) in PM2.5 were performed at Anmyeon Island (AI) to clarify the seasonal variation and carbonaceous aerosol concentrations at a background site in Korea between 2015 and 2016. The annual average OC and EC concentrations were 4.52±3.25 μg/m3 and 0.46±0.28 μg/m3, respectively, and there were no clear seasonal variations in OC and EC concentrations. The average concentrations of WSOC and water-insoluble organic carbon (WISOC) were 2.56±1.95 μg/m3 and 1.96±1.45 μg/m3, respectively, and their composition in OC showed high temporal variations. A low correlation between WISOC and EC was observed, while WSOC concentrations were highly correlated with secondary organic carbon concentrations, which were estimated using the EC tracer method. The results indicate that the formation of secondary organic aerosols is a major factor for the determination of WSOC concentrations in this region. HULIS-C was the major component of WSOC, accounting for 39–99% of WSOC and the average concentration was 1.88±1.52 μg/m3. Two distinct periods with high carbonaceous speciess in PM2.5 were observed and characterized by their OC/EC ratios. The high concentration of OC with high ratio of OC/EC was due to the influence of a mixture of emissions from biomass burning and secondary formation transported from outside AI. While, the high concentrations of OC and EC with low OC/EC ratio were related to local vehicular emissions.

Estimation of the Source Contributions for Carbonaceous Aerosols at a Background Site in Korea

To identify and quantify the contribution of the major sources for the ambient carbonaceous aerosols at a Global Atmosphere Watch (GAW) station in Korea, a receptor model, the Positive Matrix Factorization (PMF) model was applied for the one-year long measurement data. Particulate matter less than or equal to 2.5 μm in aerodynamic diameter(PM2.5) aerosols were sampled at Anmyeon Island GAW station from June 2015 to May 2016 and carbonaceous species including ~80 organic compounds were analyzed. According to the performance parameter evaluation, 5 or 7 factors were considered as optimal number of factors. It was found out that the results of 7 factors gave less contribution from the factor designated as mixed sources which we could not separate clearly. The major sources with 7 factors were identified with various analyses including chemical characteristics and air parcel movement analysis. The 7 factors with their relative contributions are; anthropogenic Secondary Organic Aerosols (SOA) (14%), biogenic SOA (15%), primary biogenic source (8%), local biomass burning (13%), transported biomass burning (16%), combustion related source (15%), and mixed sources (19%). The air parcel movement analysis results also support the identification of these factors. Thus, the Anmyeon Island GAW station has been affected by both regional and local sources for the carbonaceous aerosols.

Characteristics of formation and growth of atmospheric nanoparticles observed at four regional background sites in Korea

Measurements of the number concentration and size distribution of atmospheric nanoparticles were conducted at four sites on the west coast of the Korean Peninsula by using identical scanning mobility particle sizers (SMPSs) in October 2012. The new particle formation and subsequent growth (NPF) of atmospheric nanoparticles, which were identified by the cyclostationary empirical orthogonal function (CSEOF) analysis technique, was observed on 11 out of 21days at the Baengnyeong-do Comprehensive Monitoring Observatory (BCMO); and on 10 out of 21days at the Korea Global Atmosphere Watch Center (KGAWC) from October 9 to 29, 2012. We also observed NPF events for 9 out of 21days at both the Gosan Climate Observatory (GCO) and the Jeju Comprehensive Monitoring Observatory (JCMO). During the study period, NPF was simultaneously observed for five days at all four sites, which indicates that the NPF event had a spatial extent of at least 540km.A cold, dry and cloud-free continental air mass originated from northern China, formed favorable environmental conditions (e.g., increasing solar insolation at the surface) on simultaneous NPF at the four sites. These synoptic weather patterns were closely associated with an extraordinary typhoon passing over the south of Japan. The mean values of particle formation rates at BCMO (1.26cm−3s−1) and KGAWC (1.49cm−3s−1) were relatively higher than those at GCO (0.39cm−3s−1) and JCMO (0.74cm−3s−1), however, the growth rate showed a similar level among four sites. An increase in the spatial homogeneity and inter-site correlation of atmospheric particles among the four sites was apparent for small particles (diameter<30nm) on simultaneous NPF event days.

Observed Chemical Characteristics of Long-Range Transported Particles at a Marine Background Site in Korea

ABSTRACT Deokjeok Island is located off the west coast of the Korean Peninsula and is a suitable place to monitor the long-range transport of air pollutants from the Asian continent. In addition to pollutants, Asian dust particles are also transported to the island during long-range transport events. Episodic transport of dust and secondary particles was observed during intensive measurements in the spring (March 31–April 11) and fall (October 13–26) of 2009. In this study, the chemical characteristics of long-range-transported particles were investigated based on highly time-resolved ionic measurements with a particle-into-liquid system coupled with an online ion chromatograph (PILS-IC) that simultaneously measures concentrations of cations (Li+, Na+, NH4 +, K+, Ca2+, Mg2+) and anions (F−, Cl−, NO3 −, SO4 2−). The aerosol optical thickness (AOT) distribution retrieved by the modified Bremen Aerosol Retrieval (M-BAER) algorithm from moderate resolution imaging spectroradiometer (MODIS) satellite data confirmed the presence of a thick aerosol plume coming from the Asian continent towards the Korean peninsula. Seven distinctive events involving the long-range transport (LRT) of aerosols were identified and studied, the chemical components of which were strongly related to sector sources. Enrichment of acidic secondary aerosols on mineral dust particles, and even of sea-salt components, during transport was observed in this study. Backward trajectory, chemical analyses, and satellite aerosol retrievals identified two distinct events: a distinctively high [Ca2++Mg2+]/[Na+] ratio (>2.0), which was indicative of a preprocessed mineral dust transport event, and a low [Ca2++Mg2+]/[Na+] ratio (<2.0), which was indicative of severe aging of sea-salt components on the processed dust particles. Particulate Cl− was depleted by up to 85% in spring and 50% in the fall. A consistent fraction of carbonate replacement (FCR) averaged 0.53 in spring and 0.55 in the fall. Supporting evidences of Cl− enrichment on the marine boundary layer prior to a dust front were also found. Supplemental materials are available for this article. Go to the publisher's online edition of the Journal of the Air & Waste Management Association for sector and air mass classifications of clean and LRT cases. IMPLICATIONS The chemical characteristics of aerosol particles evolve as they undergo long-range transport (LRT) in the atmosphere from the source region. Aside from meteorological conditions, the signature of the source region influences the loading and chemical characteristics of LRT aerosols.

PM10, PM2.5미세먼지의 조성 및 오염 특성: 2008년 제주도 고산지역 측정 결과

The collection of atmospheric and particle samples was made at Gosan site of Jeju Island, which is one of the most representative background sites in Korea. Their chemical compositions have been analyzed to explore the pollution characteristics and emission sources. The mass concentrations of and particles were and , respectively, with the content of to as 61%. The ratios of nss-, , and were 0.94, 0.56, 1.02, respectively, indicating that these components were distributed mostly in the fine fractions. Based on the factor analysis, it was found that the compositions of fine particles were mainly influenced by anthropogenic sources, followed by soil or marine sources. The results of the backward trajectory analysis indicate that the concentrations of nss-, , , nss-, and Pb were high when the air parcels moved from the China continent, while relatively low with the air parcels coming from North Pacific Ocean and/or East Sea.

Characteristics of the ambient particulate PAHs at Seoul, a mega city of Northeast Asia in comparison with the characteristics of a background site

To identify the ambient characteristics of a mega city in Northeast Asia, the particulate PAHs in TSP were measured for 18 months at Seoul, the capital of Korea. The average concentration of the ambient particulate PAHs at Seoul for the sampling period was 26.6 ± 28.4 ng m − 3 with the range from 1.57 to 166 ng m − 3 . It showed winter maxima and summer minimum mainly due to the increased fuel consumption in winter both at Seoul and Northeast Asia. The ambient level of PAHs in Seoul was lower than the cities in China but higher than other urban areas. The stronger relationship between the ambient particulate PAHs concentrations and the inverse of the ambient temperature (1/T) at Seoul compared to Gosan, a background site in Korea and the difference of the distributions of BeP/BaP ratios at Seoul and Gosan might be due to the characteristics of Seoul which was governed by both transport from outside and local emissions. The relationship between the particulate PAHs concentration and (1/T) can be used as an indicator for those two factors for Seoul.

Apportioning and Locating Nonmethane Hydrocarbon Sources to a Background Site in Korea

Nonmethane hydrocarbons (NMHCs) measured between April 2004 and March 2005 at a background monitoring site on Sukmo Island, Korea were analyzed to identify and apportion NMHC sources. A total of 7694 samples and 35 NMHC species were analyzed. Positive matrix factorization (PMF), applied to identify and apportion the sources of NMHCs, resolved six sources: two fuel evaporative sources (36.3%), solvent sources (25.4%), mixed sources of vehicle exhaust and combustion (22.8%), petrochemical sources (9.6%), and biogenic sources (5.4%). During the summer, the largest contributors to ozone formation were biogenic sources (48.9% and 79.7% by maximum incremental reactivity and propene-equivalent concentration, respectively), which were situated locally, and secondary sources included solvent sources (22.2% and 7.4%) and fuel evaporative sources (15.6% and 8.2%). For evaporative-1 sources composed of long-lived alkanes, the potential source contribution function (PSCF) technique using 48 h back trajectories revealed oil and gas fields in China as potential source areas of fresh "regional" air masses. In addition, the PSCF results for evaporative-2 sources and a long-lived marker species of vehicle exhaust/combustion sources showed that the NMHC mixing ratio in Sukmo, South Korea was enhanced by long-range transport from the Shandong area in China.

Chemical characteristics of long-range transport aerosol at background sites in Korea

In this study, background concentration sites of Deokjeok and Gosan, which were deemed suitable for monitoring the impact of long-range transported air pollutants, were selected. An investigation of the source types of pollutants, their locations, and relative quantitative contributions to the particulate concentrations at both sites using appropriate methodologies to make initial estimations was conducted. Episodic measurements of PM 2.5, PM 10, and size distribution, along with its ion and carbon components were performed from 2005 to 2007, and a comprehensive analysis of the results was conducted utilizing back trajectory analysis. As for frequency of wind direction, it was quite apparent that the two sites are heavily influenced by air masses originating from the eastern and northern regions of China. For PM 2.5 and PM 10, the mass concentrations from north and east China were higher than other cases, originating from the ocean. In the northerly-wind case, meteorological properties for Deokjeok and Gosan and the influence of carbon emissions from northwest Korea resulted in a changing of air mass properties during transport. As was the case with mass concentration, the highest contribution for ionic and carbon components of PM 2.5 and PM 10 for both sites appeared for the westerly wind case. A specially high relative contribution, greater than 1.4 times, was apparent in the secondary aerosol case because of a large influence of long-range transported pollutants from east China. Carbon components exhibited different behaviors for the northerly and westerly wind cases compared with secondary aerosol. The major reason for this discrepancy appears to be the carbon emissions from northwest Korea.

Particulate PAHs levels at Mt. Halla site in Jeju Island, Korea: Regional background levels in northeast Asia

The levels of PM.25 PAHs at Mt. Halla site, Jeju Island, a background site in Korea were observed between March 1999 and March 2002. A seasonal variation was observed for the particulate PAHs concentrations with high levels during cold season similar to Gosan, a nearby coastal background site, due to the seasonal variations of fossil fuel usage in Asia. The total average concentration of ambient particulate PAHs was 404 ± 579 pg m − 3, about one order lower than the ambient level at Gosan. However, the ratios of the anthropogenic inorganic ion concentrations between Mt. Halla and Gosan were smaller, 1.5 for non sea-salt (nss) sulfate and 2.7 for nitrate. Two possible explanations for these characteristics are (1) two sites measured different air parcels and/or (2) the effect of local emissions were different at two sites. Based on the Bep/BaP ratio result, upper air wind direction data, backward trajectory analysis, and LIDAR measurement data at Gosan, it was found that the degree of the effects of local emissions to the sampling sites be the major reason for the different PAHs levels at two sites though, in some cases, the air parcels arriving at Mt. Halla were different from those arriving at Gosan. For secondary aerosol such as nss sulfate, the lower concentration difference indicates both site are affected by regional transport. It points that the measurement result for directly emitted species such as PAHs at Gosan might be significantly influenced by local emissions.

Identification of potential sources and source regions of fine ambient particles measured at Gosan background site in Korea using advanced hybrid receptor model combined with positive matrix factorization

The size‐ and time‐resolved measurement of particulate trace elements was made using an eight‐stage Davis Rotating Unit for Monitoring sampler and synchrotron X‐ray fluorescence system from 29 March to 29 May in 2002 at Gosan, Korea, which is one of the representative background sites in east Asia. As a result, continuous 3‐hour average concentrations were obtained for 19 elements including S, Si, Al, Fe, Ca, Cl, Cu, Zn, Ti, K, Mn, Pb, Ni, V, Se, As, Rb, Cr, and Br. Positive matrix factorization (PMF) method was applied to the size‐resolved aerosol data sets in order to identify the possible sources and to estimate their contribution to particulate matter mass in each size range. Twelve sources were then resolved in the fine size range (0.07 ∼ 1.15 μm), including continental aerosol, biomass burning, coal combustion, oil heating furnace, residual oil fired boiler, municipal incineration, nonferrous metal source, ferrous metal source, gasoline vehicle, diesel vehicle, copper smelter, and volcanic emission. A newly developed hybrid receptor model, concentration, retention time, and source emission weighted trajectory (CRSWT), was then applied to the source intensities derived from the PMF analysis by incorporating meteorological and source inventory information of the study region in order to suggest the regional information of long‐range transported fine aerosol sources. The CRSWT model was able to resolve highly potential source areas and pathways for the fine ambient aerosol at the Gosan background site.

Seasonal trend of particulate PAHs at Gosan, a background site in Korea between 2001 and 2002 and major factors affecting their levels

The concentrations of particulate Polycyclic aromatic hydrocarbons (PAHs) were measured at Gosan, a background site in Korea for 1 year between November 2001 and November 2002. The total concentrations of 14 PAH compounds at Gosan were between 0.52 and 14.76 ng m − 3 and about 3–15 times higher than those at other rural or remote sites in the world. Seasonal trend was observed for particulate PAHs concentrations at Gosan with higher levels during heating season due to increased fossil fuel usage and the movement of air parcels from Asian continent. Principal component factor analysis (PCF) for PAHs showed three factors; combination of coal combustion and vehicular emission, natural gas combustion, and unidentified one. However, PCF for the combined data of PAHs, inorganic ions, and elements revealed that the unidentified factor consists of crustal species, sea salts, and four PAH compounds. Thus, this factor is thought to be transport of crustal species with organics from combustion sources. The major variables which determine the sources of PAHs are the heating season and the movement of air parcels from Asian continent.

Temporal trend and long‐range transport of particulate polycyclic aromatic hydrocarbons at Gosan in northeast Asia between 2001 and 2004

The temporal trend of the particulate polycyclic aromatic hydrocarbon (PAH) level was observed at Gosan, a background site in Korea, for 4 years between November 2001 and January 2004. The total average concentration of ambient particulate PAH compounds was 3.65 ± 4.74 ng m−3, which was mainly affected by a rather small number of very high PAH level samples. The PAH level at Gosan was 1 or 2 orders higher than those at other remote sites and 1 or 2 orders lower than those in urban areas in northeast Asia. The particulate PAH concentrations were high during cold periods mainly because of the seasonal variation of fossil fuel usage amount in northeast Asia. When the PAH levels were high, the ratio of BeP‐to‐BaP was also high, which is an indicator of particle residence time in the air. On the basis of the backward trajectory and upper wind direction analyses, it was observed that when air parcels were from China, the PAH levels were high. Also, the compositions of PAH compound ratios were similar to those in Beijing in winter. These indicate influence of emissions from China, especially from coal combustion and long‐range transport. The relationship between the concentrations of PAHs and non‐sea‐salt‐(nss)‐SO42− was generally good when the PAH levels were high. However, the periods of peaks were different, implying different emission patterns.

Fine particle measurements at two background sites in Korea between 1996 and 1997

Five intensive field measurements were carried out at two background sites in Korea; Kosan and Kangwha during spring, fall, and winters of 1996 and 1997 to investigate the characteristics of long-range transport of air pollutants in northeastern Asia. Fine particles (PM 2.5) were collected by low-volume samplers and the concentrations of major ions, organic and elemental carbons, and nitric acid were quantified. The concentrations of anthropogenic species in PM 2.5 measured at both sites were generally higher than those at other background areas, Nagano, Japan and San Nicolas Is., USA due to continental outflow of air pollutants, but lower than those at an urban background site, Qingdao, China. The major components of PM 2.5 were sulfate, organic carbon (OC), and ammonium for Kosan and sulfate, OC, ammonium, and nitrate for Kangwha. The major fractions of sulfate at both sites are non-sea-salts (nss) sulfate. Based on the relationship among major anthropogenic species, analysis of the nss sulfate to total nitrate molar ratios, and backward air parcel trajectories, it was found that fine particles measured at both sites during the measurement periods are mainly coming from China. At Kosan, the concentrations of anthropogenic species were higher when air parcels were coming from southern China than when air parcels were from northern China. At Kangwha, however, the differences of the concentrations were not statistically significant since most air parcels were from northern China and local effects are prominent.

Relationship among inorganic ionic species in fine particles measured at two background sites in Korea

Relationship among inorganic ionic species in fine particles measured at two background sites in Korea

Carbonaceous species in fine particles at the background sites in Korea between 1994 and 1999

Organic carbon (OC) and elemental carbon (EC) in fine particles (PM 2.5) at two background sites, Kosan and Kangwha in Korea were measured during intensive field studies between 1994 and 1999. Fine particles were collected on pre-fired quartz filters in a low-volume sampler and analyzed using the selective thermal oxidation method with MnO 2 catalyst. The OC and EC concentrations at Kosan located at western tip of Cheju Island in southern Korea are lower than those at Kangwha located at western coastal area in mid-Korean peninsula. Still, the OC concentrations at Kosan are generally higher than those at other background areas in Japan and USA. The EC concentrations at Kosan are lower than or comparable to those at other background areas. The total carbon (TC, sum of OC and EC) to EC ratio values at both sites were higher than those at other background areas in Japan and USA. At Kosan, the OC and EC concentrations when air parcels were from southern China were higher than those when air parcels were coming from northern China. However, at Kangwha, the differences were statistically not clear since most air parcels were from northern China. Except when air parcels were from the North Pacific during summer, the OC and EC concentrations are well correlated indicating that both OC and EC share the same emission/transport characteristics. From the gaseous hydrocarbon data and the OC and EC relationship, it was found that during summer local biogenic emissions of OC might be significant at Kosan.