Characterization of carbonaceous species of ambient PM2.5 in Beijing, China
- Tsinghua University, Beijing (China). Department of Environmental Science and Engineering
One-week integrated fine particulate matter (i.e., particles {lt}2.5 {mu}m in diameter; PM2.5) samples were collected continuously with a low-flow rate sampler at a downtown site (Chegongzhuang) and a residential site (Tsinghua University) in Beijing between July 1999 and June 2000. The annual average concentrations of organic carbon (OC) and elemental carbon (EC) at the urban site were 23.9 and 8.8 {mu}g m{sup -3}, much higher than those in some cities with serious air pollution. Similar weekly variations of OC and EC concentrations were found for the two sampling sites with higher concentrations in the winter and autumn. The highest weekly variations of OC and EC occurred in the winter, suggesting that combustion sources for space heating were important contributors to carbonaceous particles, along with a significant impact from variable meteorological conditions. High emissions coupled with unfavorable meteorological conditions led to the maximum weekly carbonaceous concentration the week of November 18-25, 1999. The weekly mass ratios of OC:EC ranged between 2 and 4 for most samples and averaged 2.9, probably suggesting that secondary OC (SOC) is present most weeks. The range of contemporary carbon fraction, based on the C14 analyses of eight samples collected in 2001, is 0.330-0.479. Estimated SOC accounted for {approximately}38% of the total OC at the two sites. Average OC and EC concentrations at Tsinghua University were 25% and 18%, respectively, higher than those at Chegongzhuang, which could be attributed to different local emissions of primary carbonaceous particles and gaseous precursors of SOC, as well as different summer photochemical intensities between the two locations. Main carbonaceous sources are from coal combustion, vehicles and cooking. 44 refs., 5 figs., 2 tabs.
- OSTI ID:
- 20638632
- Journal Information:
- Journal of the Air and Waste Management Association, Vol. 55, Issue 7; ISSN 1047-3289
- Country of Publication:
- United States
- Language:
- English
Similar Records
Measurements of OC and EC in coarse particulate matter in the southeastern United States
Evaluation of the carbon content of aerosols from the burn- ing of biomass in the Brazilian Amazon using thermal, op- tical and thermal-optical analysis methods