Water Chemistry and Nutrient Dynamics in the Lower Flint River

Research Team: Dr. Stephen P. Opsahl (Assistant Scientist), Christopher Wheeler (Research Technician III), and Joanna Jenkins (Research Technician)

The lower Flint River is characterized by high quality water, abundant riparian flood plains, and dynamic water exchanges with the Upper Floridan aquifer. The region contains an impressive diversity of plants and animals and many threatened or endangered species. Natural springs along the river corridor sustain a breeding population of striped bass by providing a thermal refuge during the warm summer months. Underwater caverns along the river corridor are also home to a number of unique dark-adapted vertebrate and invertebrate animals. The Flint River system is increasingly stressed during dry periods due to a growing demand for groundwater and surface water for urban development, agricultural practices, and coastal resource needs. This region suffers from an obvious lack of monitoring efforts and scientific studies. We are carrying out a number of short- and long-term scientific studies in order to understand the lower Flint River as an ecosystem and how human activities are affecting this system at different scales.

Water Chemistry of the Lower Flint Water chemistry and microbial respiration in the lower Flint River, tributary streams, and natural springs are being measured regularly. We hope to better understand how water chemistry varies as a function of aquifer discharge into the river at various stages of the hydrograph and during storm/recharge events. We also hope that a suite of inorganic (Ca⁺², Mg⁺², Na⁺, K⁺, SO4^-, Cl^-) and organic (d¹³C, lignin phenols, UV/visible absorbance) tracers, and other parameters will provide us the means to chemically distinguish surface water from groundwater. Understanding the unique chemical environment of the lower Flint River will also help us to understand the controls on microbial respiration and to what extent natural processing of nutrients and organic matter can occur. New microscopic techniques and generic processes such as oxygen consumption are being used to evaluate microbiological activity. Ultimately, we also hope to understand how large inputs of aquifer water and microbial activity help to maintain the healthy status of the river. Specific questions include:

What are the major controls on water chemistry in the lower Flint River?
How significant are the effects of point and non-point source pollution?
What are baseline levels of microbial respiration and how do they vary along the river corridor?
Which essential nutrients limit microbial growth and how does this vary among habitats?
How active are microbial populations in aquifer springs along the river?

Additional Information:

Opsahl, S. P., K. Wheeler, R. A. Lane, and J. C. Jenkins. (in review). Effects of Upper Floridan Aquifer Groundwater on Water Chemistry and Microbial Metabolism in the Lower Flint River. In: Proceedings of the 2003 Georgia Water Resources Conference. K. J. Hatcher, editor. Institute of Ecology, The University of Georgia, Athens, Georgia.

Funded by: The Joseph W. Jones Ecological Research Center