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Abstract:
Fluorescence characteristics of aerosol particles in a polluted atmosphere were studied using a wideband integrated bioaerosol spectrometer (WIBS-4A) in Nanjing, Yangtze River Delta area of China. We observed strong diurnal and day-to-day variations of fluorescent aerosol particles (FAPs). The average number concentrations of FAPs (1-15 mu m) detected in the three WIBS measurement channels (FL1: 0.6 cm(-3), FL2: 3.4 cm(-3), FL3: 2.1 cm(-3)) were much higher than those observed in forests and rural areas, suggesting that FAPs other than bioaerosols were detected. We found that the number fractions of FAPs were positively correlated with the black carbon mass fraction, especially for the FL1 channel, indicating a large contribution of combustion-related aerosols. To distinguish bioaerosols from combustion-related FAPs, we investigated two classification schemes for use with WIBS data. Our analysis suggests a strong size dependence for the fractional contributions of different types of FAPs. In the FL3 channel, combustion-related particles seem to dominate the 1-2 mu m size range while bioaerosols dominate the 2-5 mu m range. The number fractions of combustion-related particles and non-combustion-related particles to total aerosol particles were similar to 11 and similar to 5%, respectively.
