Ocean microbes could interact with pollution to influence climate

Date:
August 17, 2020
Source:
American Chemical Society
Summary:
Little is known about how gases and aerosols made by ocean microbes
affect weather and climate, or how pollution could influence this
process. Today, scientists report they've used an 'ocean-in-a-lab'
to show that air pollution can change the makeup of gases and
aerosols that sea spray releases into the atmosphere, potentially
altering weather patterns.



FULL STORY ========================================================================== Oceans cover almost three-quarters of the globe, yet little is known about
how gases and aerosols made by ocean microbes affect weather and climate,
or how human-produced pollution could influence this process. Now,
scientists report they've used an "ocean-in-a-lab" to show that air
pollution can change the makeup of gases and aerosols that sea spray
releases into the atmosphere and, in turn, potentially alter weather
patterns.


==========================================================================
The researchers will present their results today at the American Chemical Society (ACS) Fall 2020 Virtual Meeting & Expo.

"It's surprising that we don't know more about the central role of
ocean microbes in controlling climate," says Kimberly Prather, Ph.D.,
the project's principal investigator. "They have the potential to
influence atmospheric composition, cloud formation and weather. Humans
can alter these natural processes in two ways: by changing the microbial community structure in the ocean, and by producing air pollutants that
react with compounds that the microorganisms produce." Through natural biological processes, ocean microbes -- including bacteria, phytoplankton
and viruses -- produce compounds that enter the atmosphere as gases or
aerosols (tiny water droplets or particles in air that form when waves
crash). In addition, the microorganisms themselves can be ejected from
the ocean in the form of aerosolized droplets. Some of these particles
can seed clouds, absorb or reflect sunlight, or otherwise influence
atmospheric conditions and weather.

"There's a standard belief that one way the ocean can regulate the
temperature of the planet is through emission of gases and particles,"
says Prather, who is at the Scripps Institution of Oceanography at the University of California San Diego. "Some scientists refer to the ocean
as the 'planetary thermostat.'" Prather and colleagues wondered how
humans might influence this thermostat. But first, they needed to learn
how ocean microbes affect climate without humans.

To find out, the researchers built a 108-foot-long wave channel and filled
it with 3,400 gallons of seawater. They caused a phytoplankton bloom -- an overgrowth of microscopic algae that occurs naturally in oceans -- under certain conditions -- in this ocean-in-a-lab. They continuously monitored
the gases and aerosols produced in the air above the water, measuring
things such as aerosol size, composition, shape, enzymatic activity and
pH. They also studied how natural changes in the microbial community,
for example, introducing certain species of bacteria and phytoplankton, affected the cloud- forming potential of the aerosols. "The short
answer is that the biology had very little effect on sea spray aerosol composition," Prather says. "Altering natural biological processes in
seawater resulted in a very small change in the ability of the primary particles to form cloud droplets." In contrast, adding a small amount of
an atmospheric oxidant (hydroxyl radical, which can be generated naturally
and can be enhanced in polluted atmospheres) caused an immediate shift in
the composition and cloud-forming potential of marine aerosols. According
to Prather, the oxidant reacted with microbe- produced gases in the air, transforming them into compounds that changed the composition of the
primary sea spray aerosol and formed new types of particles.

Although the researchers don't know yet how other individual pollutants
affect sea spray aerosols, Prather says that it's important to study
the complete gas phase mixture of pollutants to mimic and understand
real-world chemical reactions.

The team is now also exploring how water pollution -- in particular,
sewage discharge and pollution run-off that empty into coastal estuaries
and oceans - - can restructure microbial communities and affect human
health, climate and air quality. Previous studies have examined how human pollution impacts water quality; however, Prather's are the first studies focusing on how waterborne pollution that enters the surf zone impacts
air quality and human health. Her research group is making measurements
in the ocean and atmosphere in a region known to be impacted by pollution flowing in from a heavily polluted estuary.

This project aims to understand which viruses, bacteria and other
pollutants become airborne in the surf zone.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2020/08/200817104321.htm

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