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A critical review of the 15 N 2 tracer method to measure diazotrophic production in pelagic ecosystems
Author(s) -
White Angelicque E.,
Granger Julie,
Selden Corday,
Gradoville Mary R.,
Potts Lindsey,
Bourbonnais Annie,
Fulweiler Robinson W.,
Knapp Angela N.,
Mohr Wiebke,
Moisander Pia H.,
Tobias Craig R.,
Caffin Mathieu,
Wilson Samuel T.,
Benavides Mar,
Bonnet Sophie,
Mulholland Margaret R.,
Chang Bonnie X.
Publication year - 2020
Publication title -
limnology and oceanography: methods
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.898
H-Index - 72
ISSN - 1541-5856
DOI - 10.1002/lom3.10353
Subject(s) - tracer , extrapolation , environmental science , pelagic zone , diazotroph , statistics , nitrogen fixation , oceanography , mathematics , physics , nitrogen , geology , quantum mechanics , nuclear physics
Dinitrogen (N 2 ) fixation is an important source of biologically reactive nitrogen (N) to the global ocean. The magnitude of this flux, however, remains uncertain, in part because N 2 fixation rates have been estimated following divergent protocols and because associated levels of uncertainty are seldom reported—confounding comparison and extrapolation of rate measurements. A growing number of reports of relatively low but potentially significant rates of N 2 fixation in regions such as oxygen minimum zones, the mesopelagic water column of the tropical and subtropical oceans, and polar waters further highlights the need for standardized methodological protocols for measurements of N 2 fixation rates and for calculations of detection limits and propagated error terms. To this end, we examine current protocols of the 15 N 2 tracer method used for estimating diazotrophic rates, present results of experiments testing the validity of specific practices, and describe established metrics for reporting detection limits. We put forth a set of recommendations for best practices to estimate N 2 fixation rates using 15 N 2 tracer, with the goal of fostering transparency in reporting sources of uncertainty in estimates, and to render N 2 fixation rate estimates intercomparable among studies.