Airborne Bacteria over Thawing Permafrost Landscapes in the Arctic

Rapid
warming in the Arctic, outpacing global rates, is driving
significant changes in cryospheric landscapes, including the release
of long-preserved microorganisms. This study focuses on thawing permafrost
in Northern Alaska, where microbes previously preserved in frozen
soils are introduced into thermokarst lakes, rivers, and coastal waters
and may also become airborne as bioaerosols. We present the first
microbial composition measurements of bioaerosols in Alaska, identifying
their local sources, such as soils, water bodies, and vegetation.
Although sea/brackish water is the dominant bioaerosol contributor,
we provide the first evidence of permafrost microbial signatures in
bioaerosols from permafrost-laden regions. Permafrost is highly enriched
with ice nucleating particles (INPs), which play a crucial role in
cloud formation, precipitation processes, and radiation budget despite
their relatively low atmospheric concentrations. With rising Arctic
temperatures, increased permafrost thaw could result in higher levels
of airborne permafrost-derived microbes and biological INPs active
at warmer subzero temperatures. This, in turn, could enhance precipitation,
further accelerating the permafrost thaw. Our findings emphasize the
complex interactions between terrestrial changes and atmospheric processes,
revealing a potential feedback loop that could intensify permafrost
thaw and its broader environmental impacts.