Chemical Composition and Light Absorption of PM2.5 Observed at Two Sites near a Busy Road during Summer and Winter
| Autor: | Sung Yong Cho, Seung-Shik Park, Hue Dinh Thi Hong, Min-Suk Bae |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
010504 meteorology & atmospheric sciences
Air pollution 010501 environmental sciences Aethalometer medicine.disease_cause 01 natural sciences lcsh:Technology lcsh:Chemistry medicine General Materials Science Organic matter Relative humidity Instrumentation Chemical composition lcsh:QH301-705.5 0105 earth and related environmental sciences biomass burning emissions Fluid Flow and Transfer Processes chemistry.chemical_classification Total organic carbon traffic emissions lcsh:T Process Chemistry and Technology General Engineering Particulates lcsh:QC1-999 roadway Computer Science Applications Aerosol traffic flow chemistry lcsh:Biology (General) lcsh:QD1-999 lcsh:TA1-2040 Environmental chemistry aerosol light absorption Environmental science lcsh:Engineering (General). Civil engineering (General) PM2.5 pollution episode lcsh:Physics |
| Zdroj: | Applied Sciences Volume 10 Issue 14 Applied Sciences, Vol 10, Iss 4858, p 4858 (2020) |
| ISSN: | 2076-3417 |
| DOI: | 10.3390/app10144858 |
| Popis: | To examine the difference in the major chemical composition of fine particulate matter (PM2.5) between two roadway sites, 24 h integrated PM2.5 samples were simultaneously collected both 15 m (Buk-Ku District Office (BKO) site) and 150 m (Chonnam National University campus (CNU) site) away from busy roads during the summer and winter periods these samples were taken to determine the concentrations of organic and elemental carbon (OC and EC), water-soluble organic carbon (WSOC), and water-soluble inorganic species. In addition, the real-time aerosol light absorption coefficients (Abs) were measured using a dual-spot seven-wavelength aethalometer at the CNU site to evaluate the influence of traffic and biomass burning (BB) emissions on the concentrations of organic aerosol particles. The hourly NO2 concentration was also observed at an air pollution monitoring network that is about 2 km away from the CNU site. During summer, 24 h PM2.5 concentrations (PM2.5 episode) which exceeded the Korean PM2.5 standard (35 &mu g/m3) were linked to increases in organic matter (OM) and SO42&minus concentrations that accounted for on average 35&ndash 41% and 26&ndash 30%, respectively, of the PM2.5 at the two sites. The increased SO42&minus concentration was most likely attributable to the inflow of long-range transported aerosols, rather than local production, as demonstrated by both the MODIS (Moderate Resolution Imaging Spectroradiometer) images and transport pathways of air masses reaching the sites. On the other hand, the OM, WSOC, and EC concentrations were directly attributable to traffic emissions at the sampling sites, as supported by the tight correlation between the OC and EC. A small difference between the absorption Å ngströ m exponent (AAE) values calculated at wavelengths of 370&ndash 950 nm (AAE370&ndash 950nm) and 370&ndash 520 nm (AAE370&ndash 520nm), and the poor correlation of absorption coefficient by brown carbon (BrC) at 370 nm (AbsBrC370nm) with K+ (R2 = 0.00) also suggest a significant contribution of traffic emissions to OM. However, the wintertime PM2.5 episode was strongly related to the enhanced OM and NO3&minus concentrations, which contributed 26&ndash 28% and 22&ndash 23% of the PM2.5 concentration, respectively. It is interesting to note that there were two distinct OC/EC ratios in winter: a lower OC/EC (~3.0), which indicates a significant contribution of traffic emissions to the OC and EC, and a higher OC/EC (~6.5), which suggests an additional influence of BB emissions as well as traffic emissions at the sites. Strong correlations between the OC and EC (R2 = 0.72&ndash 0.83) and the enhanced AAE370&ndash 520nm values compared to the AAE370&ndash 950nm support that BB emissions were also an important contributor to the wintertime OM concentrations as well as traffic emissions at the two sites. A good correlation between the gaseous NO2 and NO3&minus and meteorological conditions (e.g., low wind speed and high relative humidity) suggest that the heterogeneous oxidation of NO2 on moist particles could be an important contributor to wintertime particulate NO3&minus formation at the sites. The OC concentrations during summer and winter were higher at the BKO site, with a higher traffic flow and a shorter distance from the roadway than at the CNU site. However, there were slight differences in the concentrations of secondary inorganic species (NO3&minus SO42&minus and NH4+) between the sites during summer and winter. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|