[Pollution Characteristics and Source of HULIS in the Fine Particle During the Beijing APEC].

In order to investigate the influence of the emission reduction measure during the Beijing APEC on the concentrations and pollution characteristics of humic-like substances (HULIS) in atmospheric fine particles, PM2.5 samples were collected and analyzed for OCEC, WSOC, HULIS and water-soluble ions. The concentration of HULIS in PM2.5 ranged 1 µg · m⁻³-15 µg · m⁻³. HULIS concentrations were 7.99 µg · m⁻³, 5.83 µg · m⁻³ and 7.06 µg · m⁻³ before, during and after APEC, which indicated emission reduction measure had important effect on the reduction of HULlS. The decrease of HULIS during the APEC was significantly faster than those of EC and WSOC, while the increase of HULIS turned out to be much slower than OC, EC, WSOC and PM2.5 after the meeting. The proportions of HULIS to PM2.5 were 13.60%, 13.59%, 14.02% and 12.22% at four different stages, i. e., whole sampling period, before, during and after the APEC, while HULIS-C/OC and HULIS-C/WSOC were 28.95%, 35.51%, 28.37%, 19.93%; and 52.75%, 59.58%, 51.54%, 45.39%, respectively. HULlS was significantly positively correlated with humidity, while significantly negatively correlated with wind speed. Biomass burning and secondary transformation of VOCs might be two important sources of HULlS in Beijing.

[Chemical Characteristics and Sources of Atmospheric Carbonyls During the 2014 Beijing APEC].

Pollution characteristic and variation trend of atmospheric carbonyls were investigated in November during the 2014 Beijing APEC. Formaldehyde, acetaldehyde and acetone were the dominant carbonyls, accounting for 82.66% of total carbonyls, and especially, formaldehyde accounted for 40.12% of total carbonyls. Atmospheric concentrations of total carbonyls decreased by around 64.10% after the clean air policy was carried out during the Beijing APEC, and the variation trend of carbonyls showed a similar pattern to those of other pollutants like PM2.5 during the APEC. Strong correlations (R² of 0.67-0.98) were observed among formaldehyde, acetaldehyde, acetone and total carbonyls during and after the APEC, indicating that they had similar sources; however, poor correlations (R² of -0.11-0.42 and 0.16-0.94, respectively) were observed before the APEC, implying different emission sources for ambient carbonyls. The calculated ratios of C1/C2, C2/C3 and OC/EC indicated that both vehicles and coal emissions were responsible for atmospheric carbonyls before the APEC, and emissions from coal burning were the major contributor to atmospheric carbonyls during and after the APEC, especially after the APEC.