High Concentrations of Biological Aerosol Particles and Ice Nuclei Open Access During and After Rain Biogeosciences Biogeosciences Discussions J
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EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Natural Hazards Natural Hazards and Earth System and Earth System Sciences Sciences Discussions Open Access Open Access Atmos. Chem. Phys., 13, 6151–6164, 2013 Atmospheric Atmospheric www.atmos-chem-phys.net/13/6151/2013/ doi:10.5194/acp-13-6151-2013 Chemistry Chemistry © Author(s) 2013. CC Attribution 3.0 License. and Physics and Physics Discussions Open Access Open Access Atmospheric Atmospheric Measurement Measurement Techniques Techniques Discussions Open Access High concentrations of biological aerosol particles and ice nuclei Open Access during and after rain Biogeosciences Biogeosciences Discussions J. A. Huffman1,2, A. J. Prenni3, P. J. DeMott3, C. Pohlker¨ 2, R. H. Mason4, N. H. Robinson5, J. Frohlich-Nowoisky¨ 2, Y. Tobo3, V. R. Despres´ 6, E. Garcia3, D. J. Gochis7, E. Harris2, I. Muller-Germann¨ 2, C. Ruzene2, B. Schmer2, 2,8 9 2 9 5 3 4 Open Access B. Sinha , D. A. Day , M. O. Andreae , J. L. Jimenez , M. Gallagher , S. M. Kreidenweis , A. K. Bertram , and Open Access U. Poschl¨ 2 Climate 1 Climate Department of Chemistry and Biochemistry, University of Denver, 2190 E. Illif Ave., Denver, CO, 80208, USA of the Past 2Max Planck Institute for Chemistry, P.O. Box 3060, 55020, Mainz, Germany of the Past 3Department of Atmospheric Science, Colorado State University, 1371 Campus Delivery, Fort Collins, CO, 80523, USA Discussions 4Department of Chemistry, University of British Columbia, Room D223, 2036 Main Mall, Vancouver, BC, V6T1Z1, Canada Open Access 5Centre for Atmospheric Sciences, University of Manchester, Simon Building, Oxford Road, Manchester, M139PL, UK Open Access 6Institute for General Botany, Johannes Gutenberg University, Mullerweg¨ 6, 55099, Mainz,Earth Germany System Earth System 7National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO, 80307, USA Dynamics 8IISER Mohali, Department of Earth and Environmental Science, Sector 81, S. A. S. Nagar, ManauliDynamics PO, 140306, India Discussions 9Cooperative Institute for Research in the Environmental Sciences and Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, USA Open Access Geoscientific Geoscientific Open Access Correspondence to: J. A. Huffman ([email protected]), A. J. Prenni ([email protected]), A. K. Bertram ([email protected]), and U. Poschl¨ ([email protected]) Instrumentation Instrumentation Methods and Methods and Received: 18 December 2012 – Published in Atmos. Chem. Phys. Discuss.: 16 January 2013Data Systems Data Systems Revised: 25 May 2013 – Accepted: 27 May 2013 – Published: 1 July 2013 Discussions Open Access Open Access Geoscientific Abstract. Bioaerosols are relevant for public health and may 1 Introduction Geoscientific Model Development play an important role in the climate system, but their at- Model Development mospheric abundance, properties, and sources are not well Discussions understood. Here we show that the concentration of air- Biological particles suspended in the atmosphere (bioaerosols) are key elements in the life cycle of many Open Access borne biological particles in a North American forest ecosys- Open Access tem increases significantly during rain and that bioparticles organisms and ecosystems,Hydrology and they may and influence the water Hydrology and cycle as cloud condensation and ice nuclei (IN) (Morris et are closely correlated with atmospheric ice nuclei (IN). The Earth System Earth System greatest increase of bioparticles and IN occurred in the size al., 2008; Despres´ et al., 2012). Laboratory studies have range of 2–6 µm, which is characteristic for bacterial aggre- shown that certain species of bacteria,Sciences fungal spores, and Sciences gates and fungal spores. By DNA analysis we found high pollen are highly efficient IN (Maki et al., 1974; Diehl et Discussions Open Access diversities of airborne bacteria and fungi, including groups al., 2001; Morris et al., 2013), and bioparticlesOpen Access have been containing human and plant pathogens (mildew, smut and detected in clouds, fog, rain, and snowfall (Christner et al., 2008; Pratt et al., 2009). On a global scale bioaerosols may Ocean Science rust fungi, molds, Enterobacteriaceae, Pseudomonadaceae). Ocean Science In addition to detecting known bacterial and fungal IN (Pseu- be only a minor fraction of the total IN population (Hoose Discussions domonas sp., Fusarium sporotrichioides), we discovered two et al., 2010; Sesartic et al., 2013), but regionally bioaerosols species of IN-active fungi that were not previously known could play an important role in the evolution of clouds and Open Access as biological ice nucleators (Isaria farinosa and Acremo- precipitation (Mohler¨ et al., 2007), especiallyOpen Access in pristine regions like the Amazonian rainforest (Prenni et al., 2009; nium implicatum). Our findings suggest that atmospheric Solid Earth bioaerosols, IN, and rainfall are more tightly coupled than Poschl¨ et al., 2010; Pohlker¨ etSolid al., 2012b). Earth previously assumed. So far, however, direct evidence linking bioaerosols Discussions with increases in IN, especially during and following Open Access Open Access Published by Copernicus Publications on behalf of the European Geosciences Union. The Cryosphere The Cryosphere Discussions 6152 J. A. Huffman et al.: High concentrations of biological particles and ice nuclei during rain precipitation, has been limited. For example, splash-induced beachon/). The measurements were located in a part of the emission of fungal spores during rain has been well docu- Manitou Experimental Forest in a montane pine zone in mented (e.g., Hirst, 1953; and Allitt, 2000). Bigg and Miles the central Rocky Mountains 35 km northwest of Colorado (1964) observed a correlation between rainfall and IN con- Springs, Colorado, and 15 km north of Woodland Park, Col- centrations when comparing extensive measurements in Aus- orado (2370 m elevation, lat. 39◦60000 N, long. 105◦503000 W). tralia, and Constantinidou et al. (1990) observed a down- The forest canopy at the site is sparse and highly variable. ward flux of ice-active Pseudomonas syringae bacteria dur- Clusters of ponderosa pine trees approximately 10–20 m in ing rain. However, real-time measurements directly linking height are separated by large open spaces of grass and forb ambient bioaerosols and ice nuclei have been missing. Fur- understory. Grasses are generally ∼ 20 cm tall, with seed ther, there is an apparent disconnect between concentrations shocks occasionally reaching as high as 1 m. The leaf area of IN-active biological particles commonly found on vegeta- index (LAI) is also highly variable and was estimated to be a tion and concentrations in the air above them. For example, mean of approximately 1.9 (DiGangi et al., 2011), with trees Garcia et al. (2012) recently reported that variations in the covering ∼ 60 % of the site. number concentrations of airborne IN did not correlate with Aerosol measurements were performed using inlets strong variations in the numbers of biological IN on underly- mounted 1–4 m above ground level, unless otherwise spec- ing vegetation. ified and as detailed below. Relative locations of samplers Airborne bioparticles are also major vectors for human, are shown in Fig. 1. During rain periods, all measurements animal, and plant diseases (Poschl,¨ 2005; Despres´ et al., discussed refer to particles not embedded in rain droplets. 2012). Specifically, pollen and spores have been suggested Below is a brief discussion of materials and methods of sam- to enhance asthma, allergies and other respiratory conditions pling and analysis utilized. Additional details are presented during thundershowers (e.g., Packe and Ayres, 1985; Celenza in the Supplement. The local time (LT) used for data anal- et al., 1996; and Taylor and Jonsson, 2004; Denning et al., ysis and plotting refers to Mountain Daylight Time (MDT). 2006; Dales et al., 2012), but the mechanism for this is not All times reported here are listed as LT. understood. During the BEACHON-RoMBAS (Bio-hydro-atmosphere 2.2 Meteorological and leaf moisture measurements interactions of Energy, Aerosols, Carbon, H2O, Organ- ics, and Nitrogen – Rocky Mountain Biogenic Aerosol Precipitation occurrence, rate, and microphysical state (i.e., Study) intensive field campaign we performed comprehen- rain versus hail) was measured using a laser-optical dis- sive bioaerosol measurements during summertime in a semi- drometer (PARticle SIze and VELocity “PARSIVEL” sen- arid North American pine forest (20 July to 23 August 2011). sor; OTT Hydromet GmbH, Kempton, Germany). The instru- The biological, chemical and physical measurement tech- ment senses a falling hydrometeor by measuring the magni- niques applied include online fluorescence detection (ultra- tude and duration of attenuation of a temporally continuous violet aerodynamic particle sizer, UV-APS; waveband in- 2-dimensional laser beam (780 nm) through which the hy- tegrated bioaerosol sensor, WIBS); scanning electron mi- drometeor passes. It, therefore, directly detects the presence croscopy (SEM) and epifluorescence microscopy (FM); real- of falling hydrometeors without the time delay of typical tip- time IN counting in a continuous flow diffusion chamber ping bucket gauges and with greater particle size sensitivity (CFDC) and microscopic IN activation experiments; aerosol than typical weighing gauges. The stated accuracy of liquid filter