Daily Changes in Atmospheric Microbiology Demonstrated in the Variability of Lipids in Particulate Matter
Abstract
Large dust storms called 'haboobs' provide a mechanism for transferring high concentrations of particulate matter from soils to the atmosphere during short duration events. Haboobs also transfer soil microbes to the atmosphere where they migrate along with aerosol particles. In this study we examined the lipid content of atmospheric particulate matter sampled daily in Tempe, Arizona from July 23 - August 5, 2014. During this interval there were two haboob events followed by 10 consecutive days of relatively stable weather conditions including one rainfall event. The samples were analyzed using high-mass-accuracy mass spectrometry, and we applied a data screening protocol developed for analyzing the lipidomes of marine microbes under oxidative stress. The method identifies thousands of molecular species including phospholipids, betaine lipids, glycolipids, triacylglycerols, free fatty acids, glycosphingolipids, pigments, and oxylipins, many with taxon-specific sources.
There were distinctive features in the lipidomes of fine (PM2.5) and coarse (PM>2.5) particles during haboobs, calm weather, and rainfall that suggest there were at least three distinct microbial populations over the two-week sampling interval. The first population was associated with the haboobs and was derived from desert biocrust. These samples had the highest concentration of scytonemin, a UV-screening pigment from cyanobacteria in desert biocrust. Scytonemin was also elevated two days after the haboobs and associated with a high concentration of pheophytin a, a chlorophyll a degradation product also abundant in biocrust. The second population was associated with maximum chlorophyll a concentration three days after the haboobs and just preceding a rain event, suggesting there were actively photosynthesizing microbes in a humid airmass. After the rain event there was an increase in phospholipids with polyunsaturated fatty acids and fungal glycosphingolipids suggesting a population of fungi (or spores) in the atmosphere. Throughout the sample interval there were also phospholipids associated with heterotrophic bacteria. The rapid screening capability of the method presented here shows great promise as a tool for examining the significant diversity of microbial populations in the atmosphere.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B52D..07F
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0439 Ecosystems;
- structure and dynamics;
- BIOGEOSCIENCES;
- 0452 Instruments and techniques;
- BIOGEOSCIENCES;
- 0465 Microbiology: ecology;
- physiology and genomics;
- BIOGEOSCIENCES;
- 0470 Nutrients and nutrient cycling;
- BIOGEOSCIENCES;
- 0478 Pollution: urban;
- regional and global;
- BIOGEOSCIENCES