Fine-scale in situ measurement of riverbed nitrate production and consumption in an armored permeable riverbed

Research output: Contribution to journalArticlepeer-review


  • Katrina Lansdown
  • Catherine M. Heppell
  • Matteo Dossena
  • A. Louise Heathwaite
  • Andrew Binley
  • Hao Zhang
  • Mark Trimmer

Colleges, School and Institutes

External organisations

  • School of Biological and Chemical Sciences Queen Mary University of London
  • Queen Mary University of London
  • Lancaster University


Alteration of the global nitrogen cycle by man has increased nitrogen loading in waterways considerably, often with harmful consequences for aquatic ecosystems. Dynamic redox conditions within riverbeds support a variety of nitrogen transformations, some of which can attenuate this burden. In reality, however, assessing the importance of processes besides perhaps denitrification is difficult, due to a sparseness of data, especially in situ, where sediment structure and hydrologic pathways are intact. Here we show in situ within a permeable riverbed, through injections of 15N-labeled substrates, that nitrate can be either consumed through denitrification or produced through nitrification, at a previously unresolved fine (centimeter) scale. Nitrification and denitrification occupy different niches in the riverbed, with denitrification occurring across a broad chemical gradient while nitrification is restricted to more oxic sediments. The narrow niche width for nitrification is in effect a break point, with the switch from activity "on" to activity "off" regulated by interactions between subsurface chemistry and hydrology. Although maxima for denitrification and nitrification occur at opposing ends of a chemical gradient, high potentials for both nitrate production and consumption can overlap when groundwater upwelling is strong.


Original languageEnglish
Pages (from-to)4425-4434
Number of pages10
JournalEnvironmental Science and Technology
Issue number8
Early online date16 Mar 2014
Publication statusPublished - 15 Apr 2014

ASJC Scopus subject areas