GCRC Project Summary |
Dissolved Inorganic Nitrogen and Nitrous Oxide Concentrations in the Groundwater of Two Selected Sites in Coastal Georgia and South Carolina
PI: Samantha Joye (Dept of Marine Sciences, Univ of Georgia, Athens, GA, USA)
Support: Sea Grant College Program (R/WQ-6-PD)
Timeframe: 12/10/98 - 2/28/00 (complete)
Project Overview. The
objectives of this project were to:
1. Determine dissolved organic and inorganic nitrogen concentrations in groundwater
and pore water in coastal salt marsh sediments;
2. Determine nitrous oxide concentrations in groundwater;
3. Determine denitrification rates in marsh sediments.
Findings:
Because
we found the nitrous oxide concentrations in ground water to be insignificant,
our work focused on assessing denitrification rates and the controls on denitrification
in the systems.
- The creek bank
sediments illustrated a clear response to increased nitrate availability,
while the ponded marsh sediments appeared to saturate at very low nitrate
concentrations. The potential for nitrogen removal via denitrification appears
to be larger along the creek bank than in the marsh interior.
- Sediment at both sites illustrated reductions in potential denitrification activity in response to hydrogen sulfide addition.
Publications:
Joye, S. B. (submitted) Denitrification in the marine environment. In: Encyclopedia
of Environmental Microbiology, G. Collins (Ed.) John Wiley & Sons, Inc.,
New York.
Joye, S. B., R. Y. Lee, N. B. Weston, W. P. Porubsky and S. Fisher (in prep.) Estimating potential denitrification rates in aquatic sediments: a critical evaluation of the acetylene block technique. Marine Ecology Progress Series.
Lee, R. Y., Wisniewski, R. J., and S. B. Joye (in prep) Interannual variation in intertidal marsh sediment denitrification rates: a reflection of development pressure? Aquatic Microbial Ecology.
Moore, W. S., J. Krest, G. Taylor, E. Roggenstein, S. B. Joye and R. Lee (in prep.) Thermal evidence of water exchange through a coastal aquifer: implications for nutrient fluxes. Nature.
Wisniewski, R.
J., R. Y. Lee, I. Valiela, and S. B. Joye (in prep.) Salt marsh denitrification
rates along natural and manipulated nitrogen loading gradients. Aquatic Microbial
Ecology.