Subpollen Particles as Atmospheric Cloud Condensation Nuclei
Bioparticles constitute a significant fraction of atmospheric aerosol. Their size range varies from nanometers (macromolecules) to hundreds of micrometers (plant pollen and vegetation residues). Like other atmospheric aerosol particles, the degree of involvement of bioaerosols in atmospheric processes largely depends on their hygroscopic and condensation properties. This paper studies the ability of subpollen particles of pine, birch, and rape to serve as cloud condensation nuclei. Secondary particles are obtained by the aqueous extraction of biological material from pollen grains and the subsequent solidification of atomized liquid droplets. The parameters of cloud activation are determined in the size range of 20–270 nm and water-vapor supersaturations of 0.1–1.1%. Measurement data were used to determine the hygroscopicity parameter that characterizes the effect of the chemical composition of subparticles on their condensation properties. The hygroscopic parameter varies in the range from 0.12 to 0.13. In general, the results of measurements have shown that the condensation activity of subpollen particles is comparable with the condensation activity of secondary organic aerosols and depends weakly on the type of primary pollen.
Keywords:bioaerosol subpollen particles condensation activity of aerosols spectrometer of cloud condensation nuclei hygroscopicity parameter
This study was supported by the Russian Foundation for Basic Research, project no. 16-05-00717a, and the Geomodel and Innovative Technologies of Composite Materials resource centers. The results of experimental measurements discussed in Section 5 were obtained with support from the Russian Science Foundation, project no. 18-17-00076.
- 1.R. Jaenicke, “Abundance of cellular material and proteins in the atmosphere,” Science 308, 73– (2005).Google Scholar
- 3.H. E. Manninen, J. Back, S.-L. Sinto-Nissila, et al., “Patterns in airborne pollen and other primary biological aerosol particles (PBAP), and their contribution to aerosol mass and number in a boreal forest,” Boreal Environ. Res. 19B, 383–405 (2014).Google Scholar
- 22.D. Rose, S. S. Gunthe, E. Mikhailov, et al., “Calibration and measurement of a continuous-flow cloud condensation nuclei counter (DMT-CCNC): CCN activation of ammonium sulfate and sodium chloride aerosol particles in theory and experiment,” Atmos. Chem. Phys. 8, 1153–1179 (2008).CrossRefGoogle Scholar
- 25.D. Rose, A. Nowak, P. Achtert, et al., “Cloud condensation nuclei in polluted air and biomass burning smoke near the megacity Guangzhou, China. Part 1: Size-resolved measurements and implications for the modeling of aerosol particle hygroscopicity and CCN activity,” Atmos. Chem. Phys. 10, 3365–3383 (2010).CrossRefGoogle Scholar
- 28.E. J. T. Levin, A. J. Prenni, M. D. Petters, et al., “An annual cycle of size-resolved aerosol hygroscopicity at a forested site in Colorado,” J. Geophys. Res. 117 (D6) (2012).Google Scholar