Life in the critical zone: microbial interactions and biogeochemical cycling on the edge
Presenter
Dr.
Allyson
Brady
School
of
Geography
and
Earth
Sciences
McMaster
University
Abstract
Microorganisms
play
a
crucial
role
in
the
underlying
biogeochemical
processes
that
occur
within
the
Critical
Zone
where
the
geosphere,
atmosphere,
hydrosphere,
and
biosphere
intersect.
Yet,
how
these
physical,
chemical,
and
biological
processes
are
coupled
and
at
what
spatial
and
temporal
scales
is
not
well
constrained.
Microbial
activity
and
interactions
governing
the
transport
of
nutrients
and
pollutants,
biogeochemical
cycling
and
weathering
are
still
not
well
understood
and
largely
remain
a
black
box.
Key
questions
persist
regarding,
for
example,
how
microbial
diversity
changes
throughout
Critical
Zone
profiles
and
what
environmental
factors
impact
biotic
weathering
processes.
Extreme
environments
are
model
systems
in
which
to
investigate
these
fundamental
interactions
and
to
identify
biosignatures
that
may
be
used
to
study
microbial
activity.
These
environments
offer
a
glimpse
into
often
extensive
biogeochemical
cycling
that
can
occur
as
well
as
into
the
distinctive
communities
that
drive
these
interactions.
My
research
applies
organic
biomarker
and
natural
abundance
isotope
analysis
(13C,
14C)
to
investigate
biogeochemical
processes
in
dynamic
microbial
ecosystems.
Past
and
current
projects
include
cycling
of
carbon
in
Antarctica,
linking
habitability
and
weathering
of
terrestrial
basalts
in
Hawaii,
and
microbial
ecology
of
terrestrial
geothermal
springs.
Studying
microbial
interactions
and
biogeochemical
cycling
within
the
Critical
Zone
has
important
implications
for
understanding
processes
that
shape
the
surface
of
the
Earth
and
support
life,
including
impacts
of
climate
change
on
soil
health
and
freshwater
resources.