[Pollution characteristics of carbonaceous aerosols in PM2.5 during typical winter days in Wuxi City ].

The purpose of this study was to investigate the process of haze in winter and the variation of carbonaceous aerosols in haze days. Continuous measurements of PM2.5 and meteorological parameters were conducted from Dec 3rd ,2013 to Jan 3rd, 2014, in Wuxi City. The carbonaceous component was quantified with the thermal/optical transmission (TOT) method. The results showed that: Three times of haze progresses occurred during the sampling period. Cold air, wind and rainfall were the most efficient ways to improve air quality. The mass concentration of PM2.5, OC and EC were (132.38 ± 87.17) µg.m-3, (22.80±9.77) µg.m-3 and (2.08 ± 1. 63) µg.m-3, respectively. The TC accounted for 23.57% of the PM2.5; at the same time, the TC and PM2.5 were found to be strongly correlated (correlation coefficients = 0. 730). There was a negative correlation between the ratio of carbonaceous aerosol in PM2.5 and the concentration of PM2.5, and the ratio in haze days was lower than that in normal days, which suggested that secondary inorganic particles (SO(2-)(4) , NO(-)(3), NH: ) may have a fast growth in haze days. Average OC/EC ratio was 12. 83, and there was a poor correlation between OC and EC, indicating that secondary pollutants might exist. The secondary organic carbon (SOC) was estimated to be 9.04 µg.m -3, accounting for 40. 96% of OC.

[Influence of high humidity in summer on the characteristic of aerosol's size distribution in Beijing].

In order to research the effect of high humidity on the growth of aerosol particles, the APS, TEOM and BC instruments were used to monitor the aerosol in Beijing during August, 2007. The results show that, under steady-state weather condition, the correlation coefficient between the mass concentration of PM10 and BC aerosol is 0.82, but the correlation between the number concentration and the mass concentration of PM10 is not in accordance with that under non-steady-state weather condition. Tie number concentration and the ratio of fine particles less than 1 microm to the whole samples increase obviously. The change of aerosol particles size distribution suggests that the size of aerosol particles increases obviously by moisture absorption under the high humid condition.

[Observational study of black carbon aerosol during straw-burning period].

Black carbon aerosol (BC) has been measured at three sites in Hefei City during May and June, 2007. Analyzing these real-time BC data, the concentration characters and the sources of black carbon aerosol can be found. The average concentrations of BC in normal period and straw-burning period are 4.85 microg/m3 and 8.38 microg/m3, respectively. The significant difference shows that the straw-burning is one of the main sources. The correlation coefficients between daily average concentration of BC and PM10 is 0.74, while the values of BC/PM10 in normal period and straw-burning period are 4.7% and 7.9%, respectively. Through comparing to the BC concentration during straw-burning period in 2004, the results indicated that pollution of BC has reduced after straw-burning was forbidden by the government.