Thrust Areas Ecosystem Water Institute Classification Level
Water, Land Use and Ecosystems Water and Climate Water and Society Water Resources Sustainability Springs Wetlands Watersheds Aquifers Lakes Coastal Zone  Water Institute Classification 1  Water Institute Classification 2  Water Institute Classification 3  Water Institute Classification 4

Mechanisms of N Loss in Spring Runs and Rivers
Goals and Objectives
This project makes use of three new analytical techniques to help understand the ways in which N is lost from rivers in north Florida. In particular, we have coupled the use of isotopes of N and O in nitrate (to measure source and process), high resolution nitrate sensors (to measure the diel patterns of nitrate concentration changes), and membrane-inlet mass spectrometry (to measure N2 gas in water compared with concentrations of Ar from which area rates of denitrification can be inferred). We are also developing the first comprehensive analysis of the hydraulics of karst spring-fed rivers in Florida, which has important implications for surface-groundwater mixing and consequently for the fate of N and other contaminants. We are doing these measurements in 8 major spring fed rivers from throughout the state.
Planned Outputs
Final Report
Journal Articles
Available Outputs

Title: Annual Report Year 1: Mechanisms of Nitrogen Loss in Florida’s Spring Fed Rivers
Authors: Cohen MJ, Liebowitz D, Heffernan JB, Korhnak L, Hensley R

Title: Controls on solute transport in large spring-fed karst rivers. Limnology and Oceanography 57:(4), 2012, 912-924.
Authors: Hensley, Robert T., and Matthew J. Cohen.

Title: Direct and indirect coupling of primary production and diel nitrate dynamics in a subtropical spring-fed river. Limnol. Oceanogr. 55(2), 2010, 677-688.
Authors: Heffernan, J.B. and M.J. Cohen

Title: Hydraulic effects on nitrogen removal in a tidal spring‐fed river, Water Resources Research 51 (3), 1443-1456, 2015.
Authors: Hensley, R.T, M.J. Cohen, L.V. Korhnak

Title: Masters Thesis: Direct and indirect effects of terrestrial organic matter on river denitrification. 2011. Florida International University
Authors: Fork. M.L.

Title: Nutrient flux, uptake, and autotrophic limitation in streams and rivers, Freshwater Science 33 (1), 85-98, 2014.
Authors: King, S. A., J.B. Heffernan, M.J. Cohen
Project Lead
Cohen, Matthew J
Project Participants
Cohen, Matthew J
Additional Participants
Jim Heffernam (FIU)
Level 1: WI Affiliated Faculty Project
Water, Land Use and Ecosystems
Partner Name(s)
Florida International University
Grant Award Dates
12/1/2008 to 3/31/2011