Undergraduate Research: An Archive - 2021 Program

Enzo Dominguez ’21
CHEMISTRY
Senior Thesis Research Funding Awardee
THESIS TITLE
Sunlight, Iron and the
Environmental Fate of
Dissolved Organic
Matter in Freshwater
Systems
ADVISER
Satish Myneni,
Professor of
Geosciences
Dissolved organic matter (DOM) constitutes
a significant part of the global carbon cycle.
It is a source of energy and nutrients in
aquatic ecosystems, and it can affect how
pollutants are stored and transported across
large environments. The composition of DOM
is constantly undergoing both inter- and
intramolecular changes driven by a variety
of natural conditions, including exposure
to sunlight and interactions with inorganic
components in water like aqueous iron. However,
little is known about exactly how these forces
and their interactions change specific chemical
and physical qualities of DOM. I investigated how
the concentration and speciation of iron affect
the photochemical reactions that transform and
degrade DOM. I analyzed excitation-emission
matrix fluorescence spectroscopy data through
parallel factor analysis, which is a method of
mathematically deconstructing a sample set
into a small number of fluorescent components.
Parallel factor analysis is especially suited for
describing extremely heterogeneous mixtures of
complex molecules. I also used X-ray absorbance
spectroscopy. The results of a series of irradiation
experiments with variable additions of aqueous
iron demonstrated a number of trends in DOM
composition related to the concentration and
speciation of iron.
CLIMATE AND
ENVIRONMENTAL SCIENCE
22