Hi! My
name is Gillian and I’m a first-year Master’s student at Queen’s. Dr. Melissa
Lafrenière, co-manager of the Queen’s Facility for Biogeochemical Research on
Environmental Change and the Cryosphere (FABRECC: http://www.queensu.ca/geographyandplanning/fabrecc-lafreniere/home)
is my supervisor. We are working to better understand biogeochemical processes
at the Cape Bounty Arctic Watershed Observatory. In other words, we study the
interactions between the physical, chemical, biological, and geological
processes occurring in the High Arctic permafrost environment.
Specifically,
I study carbon in organic matter. The permafrost of the Arctic stores huge
amounts of organic carbon. In fact, researchers estimate that there is twice as
much carbon stored in the permafrost as there is carbon in the atmosphere right
now. As permafrost degrades due to warming temperatures, some of the permafrost
carbon could be released to the atmosphere as greenhouse gases such as carbon
dioxide and methane.
Why will only some of the carbon be
released? Well, only a portion of the permafrost carbon is decomposable, and
carbon must undergo decomposition to produce greenhouse gases. My job is to
determine what makes the carbon decomposable and identify where the
decomposable carbon is likely to be found on a High Arctic landscape.
Knowing how much carbon is
decomposable, and where it’s located, is important for developing climate
models. Because data on decomposable carbon are limited, carbon stored in
permafrost isn’t well incorporated into current climate models. The results of
our research could change that. For example, if we know there is a lot of decomposable
carbon stored in areas highly susceptible to enhanced permafrost thaw, then we
might conclude there is a high probability of greenhouse gas emissions in those
areas. This increased probability can then be accounted for in climate model
projections, making them more accurate.
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A soil profile at one of
my sampling sites at the Cape Bounty Arctic Watershed Observatory on Melville
Island, NU.
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I collected soil and water samples from sites with varying geomorphology and vegetation at Cape Bounty during the summer of 2016. Back in the lab at Queen’s, I incubated these samples for twenty-eight days. During an incubation, the samples were kept a constant temperature. At specific time points throughout the incubation period, I removed a subset (or aliquot) of each sample and analyzed it to characterize the molecular structure of its carbon compounds and its organic carbon concentration.
Now that the incubation period is
finished, I can calculate how much organic carbon was lost (through
decomposition) over the twenty-eight days. Better yet, I can compare these data
with the molecular structure of the carbon compounds to see if molecular
structure is an indicator of decomposability. If they are related, it would be
really exciting since the methods used to characterize molecular structure are
much easier to perform than the incubations. If molecular structures could be
used to predict carbon decomposability instead of incubations, it would save
researchers a lot of time and money!
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An emission excitation matrix (EEM), like the one shown above, provides insight into the molecular structure of carbon compounds in water samples.
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The next step for my project will
be to look at how the decomposability of carbon varies by sample site. If we
identify a relationship between carbon decomposability and study site
characteristics, we could use this to predict how carbon decomposability will vary
across the broader landscape. For example, if we find that carbon
decomposability is related to a certain vegetation community, we could use
vegetation cover maps to predict how carbon decomposability varies across the
landscape.
The best part about my project is
that I get to go back to Cape Bounty next summer for a second field season. So,
based on what I find out from the lab work I’m doing now, I can tailor my 2017
sampling plan to better address my research questions. Stay tuned for more
results and stories about field season preparations later this winter!
