Skip to main content
Duke University Libraries
DukeSpace Scholarship by Duke Authors
  • Login
  • Ask
  • Menu
  • Login
  • Ask a Librarian
  • Search & Find
  • Using the Library
  • Research Support
  • Course Support
  • Libraries
  • About
View Item 
  •   DukeSpace
  • Duke Scholarly Works
  • Scholarly Articles
  • View Item
  •   DukeSpace
  • Duke Scholarly Works
  • Scholarly Articles
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

Hydrologie and biotic influences on nitrate removal in a subtropical spring-fed river

Thumbnail
View / Download
1.8 Mb
Date
2010-01-01
Authors
Heffernan, JB
Cohen, MJ
Frazer, TK
Thomas, RG
Rayfield, TJ
Gulley, J
Martin, JB
Delfmo, JJ
Graham, WD
Show More
(9 total)
Repository Usage Stats
209
views
216
downloads
Abstract
We use a long-term chemical and hydrologic record in combination with longitudinal sampling and highfrequency nitrate (NO3-) measurements from in situ sensors to describe temporal and spatial patterns of nitrogen (N) inputs and removal in the spring-fed Ichetucknee River (Columbia County, Florida) and to determine the hydrological, geomorphic, and biological factors that influence those dynamics. Over a 20-yr period of record, NO 3-N removal averaged 118 kg N d-1 (0.77 g N m-2 d-1 ) over the upper 5 km of the Ichetucknee River. Three independent estimates of gross autotrophic N assimilation (from gross primary production, diel NO3- variation, and standing biomass) agreed closely but accounted for less than 20% of observed N removal. Longitudinal surveys indicate negligible or negative dissolved organic nitrogen and ammonium (NH4+) production, suggesting that denitrification is the predominant mechanism of N removal in this river. A positive relationship between discharge and the magnitude of NO3-N removal shows that interactions with the surrounding floodplain exert considerable influence at high flows, and longitudinal NO3- patterns indicate that N removal may be influenced by channel morphology. These results suggest a greater role for dissimilatory processes and hydrologic connectivity with hyporheic and floodplain sediments than has been previously recognized in highly productive spring-fed rivers of north Florida. While hydrologic variation is the primary determinant of variation in NO 3- removal within the Ichetucknee River, comparison across systems indicates that biotic characteristics can cause significant deviation from predictions based on purely physical models of relationships between river size and N removal. © 2010 by the American Society of Limnology and Oceanography, Inc.
Type
Journal article
Permalink
https://hdl.handle.net/10161/8364
Collections
  • Scholarly Articles
More Info
Show full item record

Scholars@Duke

Heffernan

James Brendan Heffernan

Associate Professor of Ecosystem Ecology and Ecohydrology
I am interested in major changes in ecosystem structure, particularly in streams, rivers and wetlands. My work focuses on feedbacks among ecological, physical, and biogeochemical processes, and uses a wide range of tools and approaches. I am particularly interested in projects that address both basic ecological theory and pressing environmental problems. Increasingly, we are applying tools and theories developed for local ecosystems to better understand ecological patterns and mechanisms at regi
Open Access

Articles written by Duke faculty are made available through the campus open access policy. For more information see: Duke Open Access Policy

Rights for Collection: Scholarly Articles


Works are deposited here by their authors, and represent their research and opinions, not that of Duke University. Some materials and descriptions may include offensive content. More info

Make Your Work Available Here

How to Deposit

Browse

All of DukeSpaceCommunities & CollectionsAuthorsTitlesTypesBy Issue DateDepartmentsAffiliations of Duke Author(s)SubjectsBy Submit DateThis CollectionAuthorsTitlesTypesBy Issue DateDepartmentsAffiliations of Duke Author(s)SubjectsBy Submit Date

My Account

LoginRegister

Statistics

View Usage Statistics
Duke University Libraries

Contact Us

411 Chapel Drive
Durham, NC 27708
(919) 660-5870
Perkins Library Service Desk

Digital Repositories at Duke

  • Report a problem with the repositories
  • About digital repositories at Duke
  • Accessibility Policy
  • Deaccession and DMCA Takedown Policy

TwitterFacebookYouTubeFlickrInstagramBlogs

Sign Up for Our Newsletter
  • Re-use & Attribution / Privacy
  • Harmful Language Statement
  • Support the Libraries
Duke University