Biogeochemistry

, Volume 33, Issue 3, pp 197–215

Estimating denitrification rates in estuarine sediments: A comparison of stoichiometric and acetylene based methods

Authors

  • Samantha B. Joye
    • Institute of Marine SciencesUniversity of North Carolina at Chapel Hill
    • Center for Environmental StudiesSan Francisco State University
  • Smith Stephen V. 
    • Department of OceanographyUniversity of Hawaii
  • Hollibaugh James T. 
    • Center for Environmental StudiesSan Francisco State University
  • Paerl Hans W. 
    • Institute of Marine SciencesUniversity of North Carolina at Chapel Hill
Article

DOI: 10.1007/BF02181072

Cite this article as:
Joye, S.B., Smith, S.V., Hollibaugh, J.T. et al. Biogeochemistry (1996) 33: 197. doi:10.1007/BF02181072

Abstract

We compared denitrification rates obtained using an adaptation of the acetylene block technique to rates estimated from benthic flux nutrient stoichiometry in the subtidal sediments of Tomales Bay, California (USA). By amending whole cores with acetylene and saturating nitrate concentrations, we obtained potential denitrification rates, which ranged between 4 and 30 mmol N m−2 d−1. We determined the apparent Michaelis constant (Kapp) and the maximum potential rate (Vmp) of the denitrifying community and used these constants in a rectangular hyperbola to estimatein situ denitrification rates. Both the Kapp and Vmp of the denitrifying community exhibited significant variation over both depth in the sediment column and time of sampling.

Estimates ofin situ denitrification obtained using our ‘kinetic-fix’ adaptation of the acetylene block ranged between 1.8 (March) and 9 (Sept.) mmol N m−1 d−1. Denitrification rates obtained using benthic flux stoichiometry ranged between 0.7 and 4.1 mmol N m−2 d−1. Average denitrification rates obtained using the ‘kinetic-fix’ acetylene block approach exceeded those obtained from net benthic flux stoichiometry; however, these differences were not significant. We conclude that our ‘kinetic-fix’ adaptation of the acetylene block technique provides realistic estimates of denitrification in sediments, even when pore water nitrate concentrations are low and nitrification and denitrification are closely coupled.

Key words

acetylene blockdenitrificationnitrificationsedimentsstoichiometry

Copyright information

© Kluwer Academic Publishers 1996