2nd UF Water Institute Symposium Abstract

Submitter's Name Krystal Walker
Session Name Poster Session: Hydrologic, Biogeochemical and Ecological Processes 1
Category Hydrologic, biogeochemical and ecological processes
Poster Number 245
Author(s) Krystal Walker,  Graduate Student UF
  Trevor Boyer,  Assistant Professor, Environmental Engineering Sciences, University of Florida
  Christine Overdevest, Assistant Professor, Sociology, University of Florida
  Evaluating the Chemistry of Halides and Dissolved Organic Matter in the St. Johns River
  Although studies have been conducted on the St. Johns River to understand the effects of surface water withdrawals on environmental outcomes, there is a gap in knowledge pertaining to the chemistry of halides and dissolved organic matter (DOM). For example, it is not known how the concentration of bromide and iodide vary with respect to chloride. This is important because understanding the speciation of halides is expected to provide new insights into the geochemistry of the river. In addition, bromide and iodide are precursors to harmful disinfection byproducts that can be formed during water treatment. Although the concentration of DOM in the St. Johns River is known, there is little information on its chemistry. Understanding the chemistry of DOM is fundamental to understanding the numerous reactions that DOM takes part in, such as oxidation-reduction, photochemistry, contaminant binding, and impact on engineered treatment processes. The goal of this work is to understand the concentration and speciation of halides and DOM in the St. Johns River. The objectives of this work are: (1) to evaluate temporal trends in the ratios of bromide to chloride and iodide to chloride; (2) to couple bromide to chloride and iodide to chloride ratios with chloride flux from hydrologic modeling scenarios; (3) to evaluate temporal trends in the ultraviolet absorbance and fluorescence spectra of DOM; and (4) to discuss the implications of the chemistry of halides and DOM on natural and engineered processes. The proposed work will be accomplished by collecting weekly water samples, over the course of one year, from the St. Johns River near Deland. This location was chosen because it is downstream of proposed withdrawal locations, and has a stream gauge maintained by the U.S. Geological Survey. Water samples will be analyzed for a wide range of inorganic and organic water quality parameters.