Picocyanobacterial cells in near‐surface air above terrestrial and freshwater substrates in Greenland and Antarctica

Abstract

Bioaerosols are an important component of the total atmospheric aerosol load, with implications for human health, climate feedbacks and the distribution and dispersal of microbial taxa. Bioaerosols are sourced from marine, freshwater and terrestrial surfaces, with different mechanisms potentially responsible for releasing biological particles from these substrates. Little is known about the production of freshwater and terrestrial bioaerosols in polar regions. We used portable collection devices to test for the presence of picocyanobacterial aerosols above freshwater and soil substrates in the southwestern Greenland tundra and the McMurdo Dry Valleys of Antarctica. We show that picocyanobacterial cells are present in the nearsurface air at concentrations ranging from 2,431 to 28,355 cells m −3 of air, with no significant differences among substrates or between polar regions. Our concentrations are lower than those measured using the same methods in temperate ecosystems. We suggest that aerosolization is an important process linking terrestrial and aquatic ecosystems in these polar environments, and that future work is needed to explore aerosolization mechanisms and taxonspecific aerosolization rates. Our study is a first step toward understanding the production of bioaerosols in extreme environments dominated by microbial life.

Increasing Freshwater Salinity Impacts Aerosolized Bacteria

“…The measured gc number concentrations in air are within the same order of magnitude with concentrations of bacterial cells in freshly emitted sea spray aerosols (SSAs) in a wave flume, 26 yet they are 3 orders of magnitude higher than the more diluted atmospheric concentrations measured in marine air. 70 The measured gc number concentrations in the tank's headspace are also at least 3 orders of magnitude higher than cyanobacteria concentrations 48,71 measured in the near-surface air layer (20−30 cm) above freshwater lakes in New Hampshire, Greenland, and Antarctica, as well as colonyforming unit (CFU) concentrations 47 measured 50 m above a freshwater lake in Virginia. These discrepancies are expected since the laboratory experimental setup prevents atmospheric dilution observed in field experiments.…”

“…24,26,43 However, recent microbial aerosolization studies focused exclusively on saltwater 24,26,43,46 although aerosolized microorganisms were also detected above freshwater. 47,48 While some studies examined the incorporation of harmful cyanobacteria strains in lake spray aerosols (LSAs), 16,49,50 no previous studies investigated freshwater bacterial community aerosolization from a holistic perspective. Furthermore, the effect of increases in salinity on the aerosolization of freshwater bacterial communities is not well understood.…”

“…More recently, DNA-based approaches, including targeted amplicon sequencing, have become the standard approach for analyzing microbial diversity and community structure . Modern sequence-based community analysis has been recently applied to investigate microbial aerosolization from saltwater, uncovering taxon-specific transfer potential to the aerosol phase. ,, However, recent microbial aerosolization studies focused exclusively on saltwater ,,, although aerosolized microorganisms were also detected above freshwater. , While some studies examined the incorporation of harmful cyanobacteria strains in lake spray aerosols (LSAs), ,, no previous studies investigated freshwater bacterial community aerosolization from a holistic perspective. Furthermore, the effect of increases in salinity on the aerosolization of freshwater bacterial communities is not well understood.…”

Toxic Cyanobacteria: A Growing Threat to Water and Air Quality

“…Picocyanobacteria, the smallest cyanobacterial cells (diameter <3 μm), are most commonly detected in aerosol because of their size. − In the airshed of small lakes around New England, U.S., airborne concentrations of picocyanobacteria were measured in excess of 10 6 cells m –3 , although the precise mechanism promoting the emission of picocyanobacteria remains unclear. Unlike SSA and LSA number concentrations, picocyanobacterial cell concentration in air is not associated with wind speed and direction, disputing findings that wind driven bubble-mediation is necessary for the incorporation of biological material into SA.…”

“…Alternatively, more affordable, high-volume samplers which impact aerosol onto filters, stages, or plates, may be paired with complementary real-time aerosolmeasurements and meteorological conditions. − , Mass concentrations can be detected in situ with Tapered Element Oscillating Microbalances (TEOM), Beta gauges (BAM), Optical Particle Counters (OPC), or nephelometers, , while wave activity and SA emissions may be scaled by correlations of wind speed measurements. However, it is important to note that while wind speed may increase SA production, it may also lead to sample dilution and does not account for other sources of bubble bursting. ,,, …”