1Department of Chemistry and Biochemistry, University of Denver, 2190 E. Illif Ave., Denver, CO, 80208, USA
2Max Planck Institute for Chemistry, P.O. Box 3060, 55020, Mainz, Germany
3Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO, 80523, USA
4Department of Chemistry, University of British Columbia, Room D223, 2036 Main Mall, Vancouver, BC, V6T1Z1, Canada
5Centre for Atmospheric Sciences, University of Manchester, Simon Building, Oxford Road, Manchester, M139PL, UK
6Institute for General Botany, Johannes Gutenberg University, Müllerweg 6, 55099, Mainz, Germany
7National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO, 80307, USA
8IISER Mohali, Department of Earth and Environmental Science, Sector 81, S. A. S. Nagar, Manauli PO, 140306, India
9Cooperative Institute for Research in the Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA
Received: 18 Dec 2012 – Discussion started: 16 Jan 2013
Abstract. Bioaerosols are relevant for public health and may play an important role in the climate system, but their atmospheric abundance, properties, and sources are not well understood. Here we show that the concentration of airborne biological particles in a North American forest ecosystem increases significantly during rain and that bioparticles are closely correlated with atmospheric ice nuclei (IN). The greatest increase of bioparticles and IN occurred in the size range of 2–6 μm, which is characteristic for bacterial aggregates and fungal spores. By DNA analysis we found high diversities of airborne bacteria and fungi, including groups containing human and plant pathogens (mildew, smut and rust fungi, molds, Enterobacteriaceae, Pseudomonadaceae). In addition to detecting known bacterial and fungal IN (Pseudomonas sp., Fusarium sporotrichioides), we discovered two species of IN-active fungi that were not previously known as biological ice nucleators (Isaria farinosa and Acremonium implicatum). Our findings suggest that atmospheric bioaerosols, IN, and rainfall are more tightly coupled than previously assumed.
Revised: 25 May 2013 – Accepted: 27 May 2013 – Published: 01 Jul 2013
Huffman, J. A., Prenni, A. J., DeMott, P. J., Pöhlker, C., Mason, R. H., Robinson, N. H., Fröhlich-Nowoisky, J., Tobo, Y., Després, V. R., Garcia, E., Gochis, D. J., Harris, E., Müller-Germann, I., Ruzene, C., Schmer, B., Sinha, B., Day, D. A., Andreae, M. O., Jimenez, J. L., Gallagher, M., Kreidenweis, S. M., Bertram, A. K., and Pöschl, U.: High concentrations of biological aerosol particles and ice nuclei during and after rain, Atmos. Chem. Phys., 13, 6151-6164, doi:10.5194/acp-13-6151-2013, 2013.