| Carbonaceous aerosol is one of the major components of atmospheric aerosol, mainly contains organic carbon and elemental carbon, it has the highest quality ratio in PM2.5 and a significant influence on climate, environment and human health. In order to understand the pollution characteristics of carbonaceous matters and the characteristics ofconcentration and size distribution during haze process in Tianjin, the particle samples were collected by an Andersen cascade impactor from June 19 to July 19 in 2013 in Summer, from October 24 to November 3 in 2013 in Autumn, from January 8 to 18 in 2014 in winter, from April 19 to 29 in 2014 in Spring. Organic carbon (OC) and elemental carbon (EC) in atmospheric particles were analyzed with the DRI carbon analyzer which use thermal optical reflection(TOR) method. Combined with the water-soluble inorganic ions and metal elements data, we use principal method to analysis the sources of fine particles in Summer and Autumn in Tianjin. we obtain the following conclusions:(1) The annual average concentration of OC and EC in fine particles(PM2.1) were (26.8±14.0)μg·m-3and (2.3±1.1)μg·-3 during sampling period. The concentration of OC from high to low is Winter> Summer> Autumn> Spring, while EC is Winter> Spring> Autumn> Summer. OC pollution is serious and the precipitation has obvious effect on the removal of carbonaceous aerosol.(2) Both of the Log-normal size distribution of OC and EC showed a bi-modal with peaks. The peak of OC in fine particles appear in 0.65-1.1 μm in winter and 0.43-0.54μm in three other seasons. The peak of EC in fine particles appeared in <0.43μm in Summer, Autumn and 0.43-0.65 in Spring and 1.1-2.1 in Winter. The peaks of OC and EC in coarse particles both appear in 4.7-5.8 in the four seasons. In the fine particulate matter, The concentration of SOC from high to low is Winter> Autumn> Summer> Spring, the production of SOC is highest in Summer.(3) There is a serious haze pollution in January 2014 in Tianjin, the mean value of PM2.5 is (140.2±100.1)μg·m-3 with the highest value of 421.4μg·m-3 the mean value of PM10 is (222.0±145.4)μg·m-3. The concentrations of OC and EC have been increased with the increase of the particulate pollution. Definite it is a good air quality day when PM2.5 is below 75, the highest concentration of OC and EC were exited in size of 0.43-0.65μm,then they thansfer to the size of 0.65-1.1μm and 1.1-2.1μm with the increasing degree of pollution. The percentage of 8 parts of carbon indicated that the main origins of carbonaceous aerosols in fine particles were attributed to automobile exhaust fumes and biomass burnings, while the coal combustion were the main sources of coarse particles.(4)The source apportionmentresults show that there are five sources congtribute to fine particles, mixed source of sea salt and construction dust, accounted for 27.5%; mixed source of coal combustion and vehicle exhaust emissions, accounting for 24.36%; mixed source of metallurgical industry and the secondary source pollution, accounting for 13.94%;soil dust, accounting for 9.99%; biomass burning, accounted for 5.83%. |
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