The global impact of bacterial processes on carbon mass
<p>Many recent studies have identified biological material as a major fraction of ambient aerosol loading. A small fraction of these bioaerosols consist of bacteria that have attracted a lot of attention due to their role in cloud formation and adverse health effects. Current atmospheric model...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/20/1777/2020/acp-20-1777-2020.pdf |
| Summary: | <p>Many recent studies have identified biological material as a major
fraction of ambient aerosol loading. A small fraction of these bioaerosols
consist of bacteria that have attracted a lot of attention due to their role
in cloud formation and adverse health effects. Current atmospheric models
consider bacteria as inert quantities and neglect cell growth and
multiplication. We provide here a framework to estimate the production of
secondary biological aerosol (SBA) mass in clouds by microbial cell growth
and multiplication. The best estimate of SBA formation rates of 3.7 Tg yr<span class="inline-formula"><sup>−1</sup></span> is comparable to previous model estimates of the primary emission
of bacteria into the atmosphere, and thus this might represent a previously
unrecognized source of biological aerosol material. We discuss in detail the
large uncertainties associated with our estimates based on the rather sparse
available data on bacteria abundance, growth conditions, and properties.
Additionally, the loss of water-soluble organic carbon (WSOC) due to
microbial processes in cloud droplets has been suggested to compete under
some conditions with WSOC loss by chemical (OH) reactions. Our estimates
suggest that microbial and chemical processes might lead to a global loss of
WSOC of 8–11 and 8–20 Tg yr<span class="inline-formula"><sup>−1</sup></span>, respectively. While
this estimate is very approximate, the analysis of the uncertainties
and ranges of all parameters suggests that high concentrations of
metabolically active bacteria in clouds might represent an efficient sink
for organics. Our estimates also highlight the urgent need for more data
concerning microbial concentrations, fluxes, and activity in the atmosphere
to evaluate the role of bacterial processes as net aerosol sinks or sources on
various spatial and temporal scales.</p> |
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| ISSN: | 1680-7316 1680-7324 |