Georgia
Assessing the impact of residential development and recreational land use on
shallow groundwater quality in coastal environments.
Principal Investigator: Samantha B. Joye, Department of Marine Sciences, The
University of Georgia
ABSTRACT
Groundwater is a potentially important source of dissolved nutrients and organic matter
to coastal systems. The proposed research will provide basic information on the
concentrations of nutrients and organic matter in surface water and groundwater
samples and of rates of microbially-mediated processing of groundwater-derived
materials in the aquifer and in sediments along the groundwater flow path.
Groundwater will be collected from established monitoring wells and piezometers
located along upland to tidal creek transects at Dover Bluff (Satilla River, Georgia) and
Moses Hammock (Sapelo Island, Georgia). Samples from the adjacent surface waters
will be collected at the same time.
This project will address the following objectives: (1) to compare and contrast
groundwater and surface water nutrient and organic matter concentrations; (2) to
determine transformation rates of groundwater-derived dissolved inorganic nitrogen
within the aquifer using push-pull experiments; and, (3) to determine transformation
rates of groundwater-derived dissolved organic matter, nitrogen and phosphorus within
marsh and creek sediments using plug-flow bioreactor incubations. Groundwater and
surface water samples will be collected to quantify concentrations of dissolved
constituents, including nutrients (nitrogen, phosphorus, silica), salts (chloride, sulfate),
redox indicators (pH, hydrogen sulfide, dissolved inorganic carbon, methane and
ferrous iron), and organic material (dissolved organic carbon, nitrogen and phosphorus).
These data will document spatial and temporal variability in groundwater geochemistry
and will aid in evaluating the impact of septic-inputs and recreational land use on
groundwater nutrient and organic content. Push-pull tests will be conducted to
determine rates of within aquifer N cycling. Replicated bioreactors will be used to
quantify the transformation(s) of groundwater-derived carbon, N, and P by sediments
along the groundwater flow path.
The proposed work will generate fundamentally new data regarding the microbial
processing of groundwater-derived materials within coastal aquifers and sediments.
Since our work will be conducted at sites impacted by human activity, the data will
improve our understanding of the effects of such activity on groundwater quality. We
will communicate our results to the scientific community by publishing articles in peerreviewed scientific journals, reporting to the NSF, and presenting papers at national and
international scientific meetings. The work described here complements ongoing
studies of the Georgia Coastal Ecosystems Long Term Ecological Research program
and will provide data that can be used in a regional comparison of groundwater
biogeochemistry in southeast coastal ecosystems. This human resources impact is to
support a Ph.D. level graduate student and an undergraduate student in the Department
of Marine Sciences.