While there is an overwhelming amount of evidence that supports the global impact that nonbiological particles have following their release into the atmosphere, there has been a minimal amount of research dedicated to understanding how primary biological aerosol particles (PBAPs) can affect our environment.
By combining a variety of combined laboratory and field studies, a team of Researchers from the Program in Atmospheres, Oceans and Clinate (PAOC) at the Massachusets Institute of Technology’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) have developed a way to measure PBAPs present within the atmosphere.
Some major types of PBAPs, otherwise referred to as bioaerosol, include bacteria, fungal spores and fragments, viruses, pollen, algae, cyanobacteria, biological crusts and other relating plant or animal fragments. The first scientific investigations regarding atmospheric aerosols can be dated back to as early as 1847, of which these studies and those that have followed have confirmed the relevance of PBAPs to have the potential to negatively impact a number of major biological processes.
Once emitted into the environment, PBAPs can undergo certain physical, biological and chemical aging processes, of which can include coagulation, surface coating or photo-oxidant reactions, depending upon the surface properties of the specific PBAP, as well as the environment to which they are exposed to1.
The ability of PBAPs to act as ice nuclei (IN) or cloud condensation nuclei (CCN), could account for a significant influence on the formation of clouds in the troposphere, however, the exact measurement of its impact to the atmosphere has yet to be definitively measured, until now.
Previous attempts at measuring the presence of bioaerosols within the atmosphere have employed various laboratory techniques including filter collection combined with either optical microscopy with fluorescent staining or electron microscopy, differential staining, mass spectrometry, spectrophotometry, immunoassays, etc1.
In collaboration with Researchers from the National Oceanic Atmospheric Administration, Dan Cziczo and his team of MIT Researchers developed a technique known as particle analysis by laser mass spectrometry (PALMS). The PALMS system utilizes an aerodynamic lens to analyze obtained samples. At a size-dependent velocity, the biological particles within the collected sample are ablated and ionized by a 193 nanometer (nm) excimer laser that is responsible for breaking the particles into ion fragments that can then be detected by the instrument2.
The range for detectable particle diameter is from a lower threshold hold of approximately 200 nm to 3 micrometer (μm), in which larger particles are more efficiently detected by the laser as compared to those of a smaller diameter.
By studying a variety of ambient sources, of which included laboratory-manufactured phosphorus-containing samples developed from aerosolized bacteria and yeast cultures, natural soil dust samples, as well as ambient air samples that were taken from high-altitude sites in Colorado and California.
By comparing the known emission rates that are present within dusts, combustion products and biological particles, the team of Researchers was better able to classify the release of particles from the ambient sources of interest. With 96% of the total analyzed particles being classified with high confidence, as well as 79% of phosphate-containing particles, Cziczo’s team utilized this new analytical method to determine that less than 1% of the particles found within the atmosphere are phosphorus-based bioaerosols.
This proved to be a significant discovery when considering the historical belief that up to 50% of the atmosphere was thought to be comprised of such types of bioaerosols. The analytical PALMS method utilized for this study provided an important understanding of exactly how PBAPs are present and behave within the environment, further work is needed to develop more efficient and reliable techniques for the precise characterization of bioaerosols in the atmosphere, and their role in influencing important biological processes.
- “Primary biological aerosol particles in the atmosphere: a review” V. Despres, J. Huffman, et al. Tellus B: Chemical and Physical Meteorology. (2012). DOI: 10.3402/tellusb.v64i0.15598.
- “Improved identification of primary biological aerosol particles using single-particle mass spectrometry” M. Zawadowicz, K. Froyd, et al. Atmospheric Chemistry and Physics. (2017). DOI: 10.5194/acp-17-7193-2017.
Vangelis Vassalakis/ Shutterstock.com