AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Fluorescent Biological Aerosol Particle Concentrations and Size Distributions Measured with the Waveband Integrated Bioaerosol Spectrometer WIBS-4 in Nanjing China
Xiawei Yu, Zhibin Wang, Zhengning Xu, J. Alex Huffman, Christopher Pöhlker, Uwe Kuhn, Aijun Ding, Yafang Cheng, Ulrich Poeschl, Zhouqing Xie, HANG SU, MPIC
Abstract Number: 95 Working Group: Bioaerosols
Abstract Biological aerosol particles are a crucial subset of atmospheric particles. They affect the Earth’s radiation balance directly by absorbing and scattering solar radiation and serve as cloud condensation nuclei and ice nuclei. In addition, some of them can cause human diseases like asthma and allergy. The abundance of bacteria has been found to be correlated with PM2.5 pollution levels, which might pose health threats to the susceptible population. However, most online aerosols measurements were focusing on non-biological compounds while characterization of biological particles was limited to traditional filter-based methods. In order to have a deeper insight into the ambient biological aerosol in China, WIBS-4 was used for on-line biological particle measurements at a sub-urban sampling site at Nanjing University (32.05°N, 118.79°E) in October and November 2013. A 2×2 excitation (280 nm and 370 nm)-emission (310-400 nm and 420-650 nm) matrix is recorded along with the particle optical size and shape factor. The detected fluorescent particles are considered as fluorescent primary biological aerosol particles. Preliminary results show mean number concentration of total particles was 18 cm$^-3, higher than in earlier reports. High number concentrations were observed specifically at size modes of 1µm<=Do<=1.75µm and 2µm<=Do<=3µm. Mean number concentrations of the fluorescent particles detected by channels FL1 (fluorescence exited at 280 nm and recorded at 310-400 nm), FL2 (fluorescence exited at 280 nm and recorded at 420-650 nm) and FL3 (fluorescence exited at 370 nm and detected at 420-650 nm) were 0.6 cm$^-3, 4.2 cm$^-3 and 2.5 cm$^-3, respectively. Strong diurnal cycles were observed. The number concentration of fluorescence particles increased during night and peaked at early morning (FL1: 0.9 cm$^-3, FL2: 5.8 cm$^-3, FL3: 3.6 cm$^-3), then decreased to a minimum in the middle of the afternoon.