[Microbial Properties of Different Size Aerosols at Human Average Respiratory Height During Fog-haze Days].

Size distribution and microbial population structure are typical characteristics of bioaerosols that are relevant to human health. The concentrations and population structure of bioaerosols associated with size-segregated airborne particulate matter at human average respiratory height were studied using a 6-stage Andersen impactor during and after fog-haze days in the area of Beijing. The results showed that the size distribution of the cultured microbial populations was uneven during fog-haze days, and that the microbial concentration and the difference in the population structure of the size-segregated airborne particulate matter were higher during than after the fog-haze days. During the fog-haze days, Bacillus sp. was the dominant bacteria present in bioaerosols of >3.3 µm, whereas Bacillus sp. and Bacillus amyloliquefaciens were the dominant bacteria in bioaerosols of <3.3 µm. In contrast, after the fog-haze days, Bacillus amyloliquefaciens was dominant in all the bioaerosol sizes. Five species (Alternaria sp., Penicillium italicum, Talaromyces stollii, Cladosporium sp., and Davidiella sp.) were detected as the dominant fungi in the bioaerosols >3.3 µm during the fog-haze days, and only Alternaria sp. was detected in the bioaerosols >3.3 µm after fog-haze. Penicillium italicum and Talaromyces stollii were also detected in the bioaerosols of <3.3 µm during and after the fog-haze. There were significant differences in the concentration and population structure of the size-segregated airborne particulate matter at human average respiratory height collected during and after the fog-haze days. The high concentration of microorganisms and the relatively complex population at human average respiratory height on haze days indicate that the potential risks of the microbiological characteristics of the bioaerosols to human health cannot be ignored.

[Characteristics of Bioaerosols Emitted from WWTP with SBR Treatment Process].

Sampling sites were located in a wastewater treatment plant (WWTP) with a sequencing batch reactor activated sludge process to investigate the characteristics of bioaerosol emissions. The results indicated that bioaerosols were detected from each treatment section of the WWTP, and concentrations of bioaerosols were in the range of 82-1525 CFU·m-3. The coarse screen, aeration tank, and sludge dewatering house were the main sources of bioaerosols. The dominant species in each treatment section was Cyanobacteria, and the other main bacterial taxa were Aeromonas, Peptostreptococcaceae, Moraxellaceae, Chroococcidiopsis, Sphingomonas, Arcobacter, and Acinetobacter. Among the identified bacterial genera, Aeromonas, Arcobacter, Acinetobacter, and Sphingomonas were potential pathogens. Bioaerosol concentration and abundance decreased along the vertical and horizontal directions. Appropriate temperature and relative humidity benefited the survival of bioaerosols in the air (P<0.01), whereas a negative relationship between bioaerosol concentration and wind speed was observed (P<0.05). Although exposure risks caused by bioaerosols were negligible in this study, the accumulation of bioaerosols would increase potential health risks. The bioreactor for odor treatment could effectively reduce bioaerosol emissions.