Physical and chemical characterization of bioaerosols – Implications for nucleation processes

Abstract

The importance of organic compounds in the oxidative capacity of the atmosphere, and as cloud condensation and ice-forming nuclei, has been recognized for several decades. Organic compounds comprise a significant fraction of the suspended matter mass, leading to local (e.g. toxicity, health hazards) and global (e.g. climate change) impacts. The state of knowledge of the physical chemistry of organic aerosols has increased during the last few decades. However, due to their complex chemistry and the multifaceted processes in which they are involved, the importance of organic aerosols, particularly bioaerosols, in driving physical and chemical atmospheric processes is still very uncertain and poorly understood. Factors such as solubility, surface tension, chemical impurities, volatility, morphology, contact angle, deliquescence, wettability, and the oxidation process are pivotal in the understanding of the activation processes of cloud droplets, and their chemical structures, solubilities and even the molecular configuration of the microbial outer membrane, all impact ice and cloud nucleation processes in the atmosphere. The aim of this review paper is to assess the current state of knowledge regarding chemical and physical characterization of bioaerosols with a focus on those properties important in nucleation processes. We herein discuss the potential importance (or lack thereof) of physical and chemical properties of bioaerosols and illustrate how the knowledge of these properties can be employed to study nucleation processes using a modeling exercise. We also outline a list of major uncertainties due to a lack of understanding of the processes involved or lack of available data. We will also discuss key issues of atmospheric significance deserving future physical chemistry research in the fields of bioaerosol characterization and microphysics, as well as bioaerosol modeling. These fundamental questions are to be addressed prior to any definite conclusions on the potential significance of the role of bioaerosols on physico-chemical atmospheric processes and that of climate.

Global fungal spore emissions, review and synthesis of literature data

“…Interest in bioaerosols is mainly related to their health effects, agriculture, ice nucleation and cloud droplet activation or atmospheric chemistry (Ariya et al, 2009). In the present study, the focus lies on fungal aerosols.…”

Primary biological aerosol particles in the atmosphere: a review

“…How active particles are as cloud condensation nuclei (CCN) depends on their size and hygroscopicity (Petters and Kreidenweis, 2007). Primary biological aerosol particles are generally assumed to be efficient CCN, provided that their surfaces are wettable (Andreae and Rosenfeld, 2008;Ariya et al, 2009). It has been suggested that the largest PBAP (e.g.…”

Laboratory Study of Effects of Atmospheric Pollutants on Ice Nucleation Activity of Bacteria

“…Ice nucleation-active bioaerosols have widely been found in different regions and climates (Schnell and Vali, 1976;Christner et al, 2008a;Christner et al, 2008b;Pratt et al, 2009;Conen et al, 2011;Garcia et al, 2012;Burrows et al, 2013;Huffman et al, 2013;Monteil et al, 2014;O'Sullivan et al, 2014). Recent numerical studies show that ice nucleation-active bioaerosols can trigger the ice multiplication in the warmbased precipitating shallow cumulus clouds (Ariya et al, 2009;Sun et al, 2010;Sun et al, 2012). Therefore, Ice nucleation-active bioaerosols may play an important role in precipitation and even in climate change.…”