Sources of airborne particulate matter-bound metals and spatial-seasonal variability of health risk potentials in four large cities, South Korea.

Fifteen airborne particulate matter-bound metals were analyzed at 14 sites in four large cities (Seoul, Incheon, Busan, Daegu) in South Korea, between August 2013 and June 2017. Among the seven sources resolved by positive matrix factorization, soil dust and marine aerosol accounted for the largest and second largest portions in the three cities; however, in Seoul, soil dust and traffic occupied the largest and the second largest, respectively. Non-carcinogenic risk assessed by inhalation of eight metals (Cd, Co, Ni, Pb, As, Al, Mn, and V) was greater than the hazard index (HI) of 1 at four sites located at or near the industrial complexes. Cumulative incremental lifetime cancer risk (ILCR) due to exposure to five metals (Cd, Co, Ni, Pb, and As) exceeded the 10-6 cancer benchmark at 14 sites and 10-5 at six sites, which includes four sites with HI greater than 1. The largest contributor to ILCR was coal combustion in Seoul, Incheon, and Daegu, and industry sources in Busan. Moreover, industry sources were the largest contributors to non-carcinogenic risk in Seoul, Busan, and Daegu, and soil dust was in Incheon. Incheon had the highest HI in spring because of the higher contribution of soil dust sources than in other seasons. The higher ILCR in Incheon in spring and winter and higher ILCR and HI in Daegu in autumn were mainly due to the influence of industry or coal combustion sources. Statistically significant differences in the ILCR and HI values among the sampling sites in Busan and Daegu resulted from the higher contribution of industry sources at a certain site in the respective city.

Emission of greenhouse gases from waste incineration in Korea.

Greenhouse gas (GHG) emission factors previously reported from various waste incineration plants have shown significant variations according to country-specific, plant-specific, and operational conditions. The purpose of this study is to estimate GHG emissions and emission factors at nine incineration facilities in Korea by measuring the GHG concentrations in the flue gas samples. The selected incineration plants had different operation systems (i.e., stoker, fluidized bed, moving grate, rotary kiln, and kiln & stoker), and different nitrogen oxide (NOx) removal systems (i.e., selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR)) to treat municipal solid waste (MSW), commercial solid waste (CSW), and specified waste (SW). The total mean emission factors for A and B facilities for MSW incineration were found to be 134 ± 17 kg CO2 ton-1, 88 ± 36 g CH4 ton-1, and 69 ± 16 g N2O ton-1, while those for CSW incineration were 22.56 g CH4 ton-1 and 259.76 g N2O ton-1, and for SW incineration emission factors were 2959 kg CO2 ton-1, 43.44 g CH4 ton-1 and 401.21 g N2O ton-1, respectively. Total emissions calculated using annual incineration for MSW were 3587 ton CO2-eq yr-1 for A facility and 11,082 ton CO2-eq yr-1 for B facility, while those of IPCC default values were 13,167 ton CO2-eq yr-1 for A facility and 32,916 ton CO2-eq yr-1, indicating that the emissions of IPCC default values were estimated higher than those of the plant-specific emission factors. The emission of CSW for C facility was 1403 ton CO2-eq yr-1, while those of SW for D to I facilities was 28,830 ton CO2-eq yr-1. The sensitivity analysis using a Monte Carlo simulation for GHG emission factors in MSW showed that the GHG concentrations have a greater impact than the incineration amount and flow rate of flue gas. For MSW incineration plants using the same stoker type in operation, the estimated emissions and emission factors of CH4 showed the opposite trend with those of NO2 when the NOx removal system was used, whereas there was no difference in CO2 emissions.

Source apportionment of PM2.5 at the coastal area in Korea.

In this study, we analyzed the chemical composition of fine particulate matter 2.5 µm or less (PM) collected at Incheon, the coastal area in Seoul, Korea every third day from June 2009 to May 2010. Based on the analyzed chemical species in the PM samples, the sources of PM were identified using a positive matrix factorization (PMF). Nine sources of PM were determined from PMF analysis. The major sources of PM were secondary nitrate (25.4%), secondary sulfate (19.0%), motor vehicle 1 (14.8%) with a lesser contribution from industry (8.5%), motor vehicle 2 (8.2%), biomass burning (6.1%), soil (6.1%), combustion and copper production emissions (6.1%), and sea salt (5.9%). From a paired t-test, it was found that yellow sand samples were characterized as having higher contribution from soil sources (p<0.05). Furthermore, the likely source areas of PM emissions were determined using the conditional probability function (CPF) and the potential source contribution function (PSCF). CPF analysis identified the likely local sources of PM as motor vehicles and sea salt. PSCF analysis indicated that the likely source areas for secondary particles (sulfate and nitrate) were the major industrial areas in China. Finally, using the source contribution of PM and associated organic composition data, principal component analysis (PCA) was conducted to evaluate the accuracy of the PM source apportionments by PMF. The PCA analysis confirmed eight of the nine PM sources. Our result implies that the chemical composition analysis of PM data and various modeling techniques can effectively identify the potential contributing sources.

Chemical characterization and source apportionment of fine and coarse particulate matter inside the refectory of Santa Maria Delle Grazie Church, home of Leonardo Da Vinci's "Last Supper".

The association between exposure to indoor particulate matter (PM) and damage to cultural assets has been of primary relevance to museum conservators. PM-induced damage to the "Last Supper" painting, one of Leonardo da Vinci's most famous artworks, has been a major concern, given the location of this masterpiece inside a refectory in the city center of Milan, one of Europe's most polluted cities. To assess this risk, a one-year sampling campaign was conducted at indoor and outdoor sites of the painting's location, where time-integrated fine and coarse PM (PM(2.5) and PM(2.5-10)) samples were simultaneously collected. Findings showed that PM(2.5) and PM(2.5-10) concentrations were reduced indoors by 88 and 94% on a yearly average basis, respectively. This large reduction is mainly attributed to the efficacy of the deployed ventilation system in removing particles. Furthermore, PM(2.5) dominated indoor particle levels, with organic matter as the most abundant species. Next, the chemical mass balance model was applied to apportion primary and secondary sources to monthly indoor fine organic carbon (OC) and PM mass. Results revealed that gasoline vehicles, urban soil, and wood-smoke only contributed to an annual average of 11.2 ± 3.7% of OC mass. Tracers for these major sources had minimal infiltration factors. On the other hand, fatty acids and squalane had high indoor-to-outdoor concentration ratios with fatty acids showing a good correlation with indoor OC, implying a common indoor source.

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.