Whalen lab members:
Ken Fortino
My
research investigates the local
and landscape scale factors that affect carbon cycling and organic
matter
storage in arctic lake sediments. I
focus my work on the northern foothills
of the Brooks Range on the
Alaskan
North Slope. The region is characterized
by tundra vegetation and numerous small kettle lakes. The lakes
are
typically very unproductive and
are trophically supplemented by organic matter washed in from the
watershed. Once entering the lake, this
organic matter is exported from the lake, buried in
the sediments, or consumed
and respired as CO2
by the lake biota. The
relative magnitude of each of these fates
will determine the extent to which a lake is source or a sink of
atmospheric CO2.
In general, the lakes tend
to be a net source
of atmospheric CO2, however
considerable amounts of
organic matter
may be stored in lake sediments. The
processes that affect whether organic matter will be consumed or stored
in lake
are affected by local environmental factors (i.e., temperature and
oxygen availability)
and landscape scale factors (i.e., lake morphometry and organic matter
transport). My research is designed to
elucidate how these factors interact to affect
carbon cycling and organic
matter storage in the lake sediments and how they may change with
climate
warming.
Joelene Diehl
I am a second
year
graduate student working toward a Master’s Degree in Environmental
Science. My
research project is on nitrogen cycling and
transformations that occur in
agricultural soil treated with UAN fertilizer amended with urease and
nitrification inhibitors. A majority of my work
is spent in the lab conducting experiments on soil that I collected
from Open
Grounds Farm in Beaufort,
NC.
As a part of this research I conduct nutrient
analyses on the soils and look at changes in the microbial community. Before
entering the graduate program at UNC-CH, I received a BS in
Biology/Zoology
from Eastern
Washington University
and spent a couple of years in
the Peace Corps.
Dendy Lofton
My research examines
benthic production of methane in Arctic Alaskan lakes and how methane
derived
carbon may be made available to pelagic organisms. I am
particularly
interested in the factors controlling methane production and
oxidation.
Methane is produced in anaerobic sediments as a byproduct of organic
matter degradation. As this methane diffuses from the
sediments, it becomes
available
to methane oxidizing bacteria where it is oxidized to carbon
dioxide.
This methane derived carbon can be an important source of carbon
for
pelagic
food webs. Methanogenesis and subsequent oxidation represent an
important
link between benthic and pelagic food webs that has until recently been
overlooked in limnological studies. This study also has important
implications
for global warming because methane is a powerful greenhouse gas.
Any methane that is not oxidized in the lake
can diffuse into the atmosphere where it will contribute to the global
methane
budget. It is important to establish a foundation for these
processes in
the Arctic region in order to understand how they will be affected
as
global warming continues.
Lindsay
Dubbs
My Ph.D. research is primarily conducted at the FACTS-1
research facility in the Duke
Forest
where the atmospheric concentration of carbon dioxide within forest
plots is
maintained at present (control) and two-times preindustrial (elevated)
concentrations via free air carbon exchange (FACE) technology. My
research investigates whether the
previously observed reduction in net methane consumption by forest
soils is a
sustained response to elevated carbon dioxide, and examines reasons for
the observed decline. I am interested in physical,
chemical, and microbial
community composition differences between elevated and control plots
that may
influence rates of methane consumption or
production. I am also interested in
reconciling problems arising from heterogeneity in soil properties and
processes, and anoxic microsites. I conducted my MS thesis research as
a member
of the Whalen lab as well, and attended Tufts
University for my BS. My MS thesis
is entitled Seasonal
Analysis of the Influence of Nutrient Reduction on
Phytoplankton
Biomass and Primary Production in the Middle Cape Fear River, NC.
Gina
Trevino
My
research deals with nitrogen
transport and fate in a
large, precision managed, agro ecosystem. More specifically in
determining
rates of transport and eventual fate of N at Open Grounds Farm (OGF)
which is a
45,000 acre farm located along the coast of North Carolina and is the largest farm east of
the Mississippi
River. I am
particularly
interested in trying to develop a nitrogen mass balance for the
agricultural
ecosystem and determining the relative quantities and forms of N
(specifically
NO3, NH4 and urea) found in both the agricultural soil and
groundwater. Also in trying to determine if differences
exist between management practices that control moisture
levels and in
determining rates of N loss via volatilization and plant uptake to use
in
conjunction with N quantities found in soil and groundwater to
estimate the
amount of N being transported to the estuary.
It is my intention to use the data from the prior objectives to model
the transport, transformation, and attenuation of NPS
N from the
agroecosystem
(both soil and groundwater nutrient data) using GIS analysis in
conjunction
with BME/MATLAB modeling
software and create a management
budget for the
ecosystem. Determining nitrogen
quantities in ecosystems is important because inorganic
forms of nitrogen that
are not taken up by plant matter can be leached out into the system or
nitrified back into the atmosphere promoting pollution in ground and
surface
water and an increase in the greenhouse effect.
Determining rates of fate and flux of N at OGF is important because it
does use precision agriculture (sometimes called best
management
practices) and
it is essential to see if BMPs allow for efficient plant production and
nitrogen uptake without promoting excess N in
the
environment and if these practices
can be applied to future management.