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This article in JEQ

  1. Vol. 34 No. 6, p. 2052-2061
     
    Received: Nov 28, 2004
    Published: Nov, 2005


    * Corresponding author(s): dross@uvm.edu
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doi:10.2134/jeq2004.0449

Denitrification as a Nitrogen Removal Mechanism in a Vermont Peatland

  1. Melissa J. Hayden and
  2. Donald S. Ross *
  1. Department of Plant and Soil Science, University of Vermont, Burlington, VT 05405

Abstract

Atmospheric deposition of nitrogenous compounds to ombrotrophic peatlands (i.e., those that have peat layers higher than their surroundings and receive nutrients and minerals exclusively by precipitation) has the potential to significantly alter ecosystem functioning. This study utilized the acetylene inhibition technique to estimate the relative importance of denitrification in nitrogen removal from a primarily ombrotrophic peatland, in an attempt to estimate the threat of increased nitrogen loadings to these areas. Estimates of mean rates of denitrification ranged from −2.76 to 84.0 ng N2O-N cm−3 h−1 (equivalent to −150 to 4800 μg N2O-N m−2 h−1) using an ex situ core technique and from −8.30 to 5.98 μg N2O-N m−2 h−1 using an in situ chamber technique. Core rates may have been elevated over natural field levels due to effects of disturbance on substrate availability, and chamber rates may have been low due to diffusional constraints on acetylene and N2O. Net nitrification was also measured in an attempt to evaluate this process as a source of nitrate for denitrifiers. The low rates of net nitrification measured, in combination with the low rates of in situ denitrification and the very low amounts of free nitrate measured in this peatland, suggests that inorganic N turnover in this wetland is low. Results showed that nitrate was a limiting factor for denitrification in this peatland, with mean rates from nitrate-amended cores ranging from 13.1 to 260 ng N2O-N cm−3 h−1, and it is expected that increases in nitrogen loadings will increase denitrification rates in this ecosystem.

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