Characteristics Of Biogenic Aerosol And Contributions To Organic Aerosol In Beijing

Biogenic Aerosol is one of the most important pollutants in the atmosphere,influencing human health, the biosphere, atmospheric chemistry, and climate. Biogenicaerosol can be classified into two categories by the formation mechanism, one isbiogenic secondary organic aerosol (BPOA) and the other is biogenic secondary organicaerosol (BSOA). However, the total abundance of BPOA in the atmosphere is extremelyunderestimated by traditional Colony Forming Units (CFU) assays and the formationalmechanism of BSOA is also rather uncertain. Based on long-term and continuoussampling, investigating the physical and chemical characteristics and the sources ofbiogenic aerosol and quantifing the contribution of biogenic aerosol to organic aerosolin Beijing.Based on the newly established high-performance anion exchange chromatographywith pulsed amperometric detection (HPAEC-PAD), the suitable pretreatmentconditions for high concentration PM samples in Beijing were determined and fourteensaccharides were synchronous detected and quantified. The concentrations ofmonosaccharide anhydrides in summer and autumn are obviously higher than that inspring and winter, while the concentrations of sugar and sugar alcohol in winter aresignificantly lower than other seasons. Moreover, the concentrations of monosaccharideanhydrides in urban area are significantly higher than that in rural area, while there is noobvious difference for sugar and sugar alcohol.54.01~66.78%percent of fungal aerosolwas found distributed in fine particle in dry season, while78.66~81.51%percent offungal aerosol was found distributed in coarse particle in wet season. And thecorrelation of fungal aerosol in PM10and PM2.5is high in winter and low in summer,which demonstrated the previous conjecture.Based on optimizing the dye effect and fluorescence intensity of fungal particles,the FCM in combination with fluorescent stains for the rapid counting of ambient fungalaerosol was established. And with complementary quantification of mannitol andarabitol, the molecular tracers for fungal aerosols, the conversion factors from theconcentrations of molecular tracers to the number concentrations of fungal aerosol,especially for high particle concentration samples in Beijing were established. And thencombined with the average carbon content conversion factor of nine airborne fungalspecies, the contribution of fungal aerosols to organic carbon in PM2.5and PM10in Beijing was obtained, which was1.11±0.94%and2.54±2.09%, respectively.High concentration secondary inorganic acid ion (i.e. SO42-、NO3-, NH4+), wereappeared to promote the formation rate of2-methyltetrols from isoprene in the Beijingurban area, verified the simulative results by smog chamber in the atmosphericenvironment. Furthermore, combined with the conversion factor from molecular tracerto isoprene SOA, the contribution of isoprene SOA to organic aerosol in PM2.5andPM10in Beijing was determined, which was0.61±0.67%and0.56±0.61%,respectively.