1 research outputs found
Source Apportionment Using Radiocarbon and Organic Tracers for PM<sub>2.5</sub> Carbonaceous Aerosols in Guangzhou, South China: Contrasting Local- and Regional-Scale Haze Events
We
conducted a source apportionment and investigated the atmospheric
behavior of carbonaceous aerosols during hazy and normal days using
radiocarbon (<sup>14</sup>C) and biomass burning/secondary organic
aerosol (SOA) tracers during winter in Guangzhou, China. Haze episodes
were formed either abruptly by local emissions or through the accumulation
of particles transported from other areas. The average contributions
of fossil carbon to elemental carbon (EC), water-insoluble organic
carbon, and water-soluble organic carbon were 71 ± 10%, 40 ±
6% and 33 ± 3%, respectively. High contributions of fossil carbon
to EC (80–90%) were observed for haze samples that were substantially
impacted by local emissions, as were the highest (lowest) ratios for
NO<sub>3</sub><sup>–</sup>/SO<sub>4</sub><sup>2–</sup> (OC/EC), which indicates that these particles mainly came from local
vehicle exhaust. Low contributions of fossil carbon to EC (60–70%)
were found for haze particles impacted by regional transport. Secondary
organic carbon (SOC) calculated using SOA tracers accounts for only
∼20% of the SOC estimated by <sup>14</sup>C, which is probably
because some important volatile organic carbons are not taken into
account in the SOA tracer calculation method and because of the large
discrepancy in ambient conditions between the atmosphere and smog
chambers. A total of 33 ± 11% of the SOC was of fossil origin,
a portion of which could be influenced by humidity