The Black Sea is the world's largest anoxic basin,
having dissolved organic carbon (DOC) concentration ~2.5 times higher than the open ocean
(Ducklow et al., 2007).
Anoxia may inhibit the mineralization of DOC, causing it to accumulate
(Sexton et al., 2011),
however, net removal is detected in the anoxic, suboxic and sub-euphotic layers of the Black Sea
(Margolin et al., 2016).
Rivers, such as the Danube River, contribute concentrations of 300 μM DOC to the Black Sea
(Cauwet et al., 2002),
and this river input is likely responsible for the Black Sea's relatively high DOC concentrations (Margolin et al., 2016).
Research Chapter II:
Tracing Organic Matter Dynamics in the Black Sea: Insights from Optical Analyses
The Black Sea's DOC concentrations (~120-200 μM)
are higher than in the open ocean and Mediterranean Sea;
previous studies suggested that input of terrigenous DOC from rivers is responsible
for the relatively high concentrations
(Ducklow et al., 2007;
Margolin et al., 2016).
To obtain information on the basin's DOC composition (e.g., humic- or protein-like)
and predominant origin (i.e., terrigenous or marine),
the optical properties (absorption and fluorescence)
of chromophoric dissolved organic matter (CDOM) were measured in
collected across the Black Sea salinity, redox and DOC gradients.
In the basin's oxic layer (upper ~100 m), CDOM correlates with DOC,
suggesting that they are controlled by same processes.
In the underlying anoxic layer (lower ~2000 m),
DOC increases by ~10% with depth while CDOM ~doubles, correlating well with H2S and nutrients.
These findings indicate that a fraction of in situ DOC is transformed by microbes in the anoxic water,
altering its CDOM composition,
and/or that composition changes as a result of external inputs
(e.g., sinking particles) with little net concentration change.
Research Chapter III:
Biogeochemical Distributions and Carbon Exchanges Between the Deep Intra-Americas Seas
The Gulf of Mexico (GoM) and basins of the Caribbean
(i.e., Yucatan, Cayman, Colombia and Venezuela Basins)
are collectively referred to as the Intra-Americas Seas (IAS).
These five basins are separated from each other by
passages with sill depths (at ~2000 m depth) that restrict deep exchanges
between the basins and with the North Atlantic
The distribution of dissolved inorganic carbon
is explored in the deep IAS basins with respect to sill depths.
The Carbon System in the Canadian Basin, Arctic Ocean
In August-October 2015, I participated in the
U.S. GEOTRACES / U.S. Repeat Hydrography Arctic Expedition
to sample and analyze the carbon system in seawater aboard the
I worked with the
Marine Physical Chemistry Group
to analyze seawater for pH, total alkalinity (AT)
and DIC, also collecting DOC samples for the Hansell Lab.
Analysis of DOC samples and data interpretation have recently begun.
This data will expand upon my dissertation topic, however,
will not be included in it since I will be finishing this summer.
Woods Hole Oceanographic Institution Guest Studentship: Cold-Water Coral Paleo-Biogeography in the Drake Passage
During the summer of 2011, I spent 33 days aboard the
RVIB Nathaniel B. Palmer
in the Drake Passage collecting cold-water corals for use as paleoceanographic climate proxies.
To learn more about our cruise, which was featured in
The Antarctic Sun,
visit our "Antarctic Corals"
Following the cruise, I spent the rest of my summer at
Woods Hole Oceanographic Institution (WHOI), as a
to radiocarbon date over 400 coral subsamples at the
National Ocean Sciences Accelerator Mass Spectrometry
The follow summer, I spent three weeks back at WHOI before beginning graduate school,
where I focused on writing about the results from this project.
Since my last summer at WHOI,
the paper has been published in the journal of
Deep-Sea Research Part II: Topical Studies in Oceanography, entitled
Temporal and spatial distributions of cold-water corals in the Drake Passage: Insights from the last 35,000 years.
Shortly after the paper was published,
I received the Continuous Flow Accelerator Mass Spectrometry (CFAMS) Prize from NOSAMS for my work on the paper,
which was recognized as "a significant contribution to the scientific field."
I was advised by Prof.
(University of Bristol/WHOI) for this project.
In addition to the work on my thesis project,
I worked with Profs.
(University of Wisconsin − Madison)
and my advisor, Nicole Lovenduski, to investigate changes in the North Atlantic carbon sink.
I spent the first part of the summer in 2012 working on this project,
exploring satellite chlorophyll a at the ocean surface
and nutrient distributions in the top 1 km of the water column.
Results from my work on this project contributed to presentations at
NASA Applied Sciences'
third biannual Air Quality Applied Sciences Team
and the Integrated Marine Biogeochemistry and Ecosystem Research
ClimECO3 Summer School
My oceanographic research career began in February of 2009,
when I joined the Fox-Kemper Research Group at CU's Cooperative Institute for
Research in Environmental Sciences
as an undergraduate research assistant.
I studied eddy kinetic energy and eddy diffusivity using MATLAB
to analyze data and contribute to other research within the group.
Results from my work on the relationship between eddy diffusivity and eddy kinetic energy
contributed to multiple presentations in 2010, including the
American Geophysical Union's
2010 Ocean Sciences Meeting.
I was advised by Prof.
for this project, who introduced me to Prof. Nicole Lovenduski and
continued to be involved with my research at CU in the Ocean Biogeochemistry Research Group.
This website was designed and is maintained by Andrew R. Margolin,
under the support of the National Science Foundation Graduate Research Fellowship
(grant no. DGE-1451511).
Updated 31 August 2017.