Emission and Transport of Carbonaceous Aerosols in Urbanized Coastal Areas in China
Elemental and organic carbon (EC and OC), the principal short-lived climate forcers, were measured in fine particulate matter (PM2.5) collected at urban and rural sites in continental edge in Southern China. The carbonaceous matter (CM) contributed an average of 28.5 ± 7.2% (1 SD) of the mass of PM2.5 in urban areas and 30.3 ± 8.2% in rural areas. The annual average OC concentrations in PM2.5 in urban and rural areas were 7.6 ± 4.3 and 5.7 ± 3.1 μg/m3, respectively; and the annual average EC concentrations were 2.4 ± 0.8 and 1.3 ± 0.7 μg/m3, respectively. The higher EC concentration in urban area than in
rural area showed significant anthropogenic emissions to the urban atmosphere. EC and OC concentrations displayed good correlation in samples collected in urban area during winter monsoon season,suggesting a dominant emission source (mostly traffic-related) in urban area. The carbonaceous aerosol pollution in the rural coastal receptor area can be attributed to the local emission and transport of air pollutants from urbanized areas in the eastern part of China. The surface observation together with backward trajectory analysis, satellite imaging, and meteorological simulation indicate that air pollutants transported from emission hotspots in the urbanized Eastern China area had caused an increase in the concentration of carbonaceous aerosols in the rural continental edge by a factor of 2–3. This significant aerosol forcing of the Chinese outflow plume should be paid attention in the study of air quality and climate changes in Eastern/Southern Asia.
