Methodological underestimation of oceanic nitrogen fixation rates.

The two commonly applied methods to assess dinitrogen (N(2)) fixation rates are the (15)N(2)-tracer addition and the acetylene reduction assay (ARA). Discrepancies between the two methods as well as inconsistencies between N(2) fixation rates and biomass/growth rates in culture experiments have been...

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Autores principales:	Wiebke Mohr, Tobias Grosskopf, Douglas W R Wallace, Julie LaRoche
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2010
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/b74950089fcf47f08f6fb14bfb602d64
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spelling	oai:doaj.org-article:b74950089fcf47f08f6fb14bfb602d642021-11-18T06:35:26ZMethodological underestimation of oceanic nitrogen fixation rates.1932-620310.1371/journal.pone.0012583https://doaj.org/article/b74950089fcf47f08f6fb14bfb602d642010-09-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/20838446/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203The two commonly applied methods to assess dinitrogen (N(2)) fixation rates are the (15)N(2)-tracer addition and the acetylene reduction assay (ARA). Discrepancies between the two methods as well as inconsistencies between N(2) fixation rates and biomass/growth rates in culture experiments have been attributed to variable excretion of recently fixed N(2). Here we demonstrate that the (15)N(2)-tracer addition method underestimates N(2) fixation rates significantly when the (15)N(2) tracer is introduced as a gas bubble. The injected (15)N(2) gas bubble does not attain equilibrium with the surrounding water leading to a (15)N(2) concentration lower than assumed by the method used to calculate (15)N(2)-fixation rates. The resulting magnitude of underestimation varies with the incubation time, to a lesser extent on the amount of injected gas and is sensitive to the timing of the bubble injection relative to diel N(2) fixation patterns. Here, we propose and test a modified (15)N(2) tracer method based on the addition of (15)N(2)-enriched seawater that provides an instantaneous, constant enrichment and allows more accurate calculation of N(2) fixation rates for both field and laboratory studies. We hypothesise that application of N(2) fixation measurements using this modified method will significantly reduce the apparent imbalances in the oceanic fixed-nitrogen budget.Wiebke MohrTobias GrosskopfDouglas W R WallaceJulie LaRochePublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 5, Iss 9, p e12583 (2010)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Wiebke Mohr Tobias Grosskopf Douglas W R Wallace Julie LaRoche Methodological underestimation of oceanic nitrogen fixation rates.
description	The two commonly applied methods to assess dinitrogen (N(2)) fixation rates are the (15)N(2)-tracer addition and the acetylene reduction assay (ARA). Discrepancies between the two methods as well as inconsistencies between N(2) fixation rates and biomass/growth rates in culture experiments have been attributed to variable excretion of recently fixed N(2). Here we demonstrate that the (15)N(2)-tracer addition method underestimates N(2) fixation rates significantly when the (15)N(2) tracer is introduced as a gas bubble. The injected (15)N(2) gas bubble does not attain equilibrium with the surrounding water leading to a (15)N(2) concentration lower than assumed by the method used to calculate (15)N(2)-fixation rates. The resulting magnitude of underestimation varies with the incubation time, to a lesser extent on the amount of injected gas and is sensitive to the timing of the bubble injection relative to diel N(2) fixation patterns. Here, we propose and test a modified (15)N(2) tracer method based on the addition of (15)N(2)-enriched seawater that provides an instantaneous, constant enrichment and allows more accurate calculation of N(2) fixation rates for both field and laboratory studies. We hypothesise that application of N(2) fixation measurements using this modified method will significantly reduce the apparent imbalances in the oceanic fixed-nitrogen budget.
format	article
author	Wiebke Mohr Tobias Grosskopf Douglas W R Wallace Julie LaRoche
author_facet	Wiebke Mohr Tobias Grosskopf Douglas W R Wallace Julie LaRoche
author_sort	Wiebke Mohr
title	Methodological underestimation of oceanic nitrogen fixation rates.
title_short	Methodological underestimation of oceanic nitrogen fixation rates.
title_full	Methodological underestimation of oceanic nitrogen fixation rates.
title_fullStr	Methodological underestimation of oceanic nitrogen fixation rates.
title_full_unstemmed	Methodological underestimation of oceanic nitrogen fixation rates.
title_sort	methodological underestimation of oceanic nitrogen fixation rates.
publisher	Public Library of Science (PLoS)
publishDate	2010
url	https://doaj.org/article/b74950089fcf47f08f6fb14bfb602d64
work_keys_str_mv	AT wiebkemohr methodologicalunderestimationofoceanicnitrogenfixationrates AT tobiasgrosskopf methodologicalunderestimationofoceanicnitrogenfixationrates AT douglaswrwallace methodologicalunderestimationofoceanicnitrogenfixationrates AT julielaroche methodologicalunderestimationofoceanicnitrogenfixationrates
_version_	1718424439509483520

Methodological underestimation of oceanic nitrogen fixation rates.

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