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Institution Dataset ID
     data   graph     files  public Trial B test of the dissolution method for estimates of the 15N2 atom% of incubations    ?     I   M   background (external link) RSS Subscribe BCO-DMO bcodmo_dataset_778158

The Dataset's Variables and Attributes

Row Type Variable Name Attribute Name Data Type Value
attribute NC_GLOBAL access_formats String .htmlTable,.csv,.json,.mat,.nc,.tsv
attribute NC_GLOBAL acquisition_description String Inocula of 15N2-enriched water were prepared according to either of two
protocols outlined by Klawonn et al. (2015).\u00a0
In a first Trial A, respective 1.9 mL of 15N2 gas aliquots (Cambridge
Isotope Laboratories, Lot #I-21065) were injected into crimped-sealed 120 mL
glass serum vials filled with deionized water. To dissolve the 15N2 bubble,
each of the two serum vials was vortexed for 5 minutes. Two subsamples of each
inoculum were dispensed into Exetainers\u2122 with a peristaltic pump for
analysis on the MIMS. An aliquot of each inoculum (5 % vol/vol) was then
dispensed in replicate 160 mL serum incubation bottles containing air-
equilibrated deionized water (Trials A1-A4), which were then crimped-sealed.
Following homogenization, triplicate subsamples of each incubation were
collected in Exetainers\u2122 for MIMS analysis. The 15N atom % of the inocula
and of the corresponding incubations were measured by MIMS at the University
of Connecticut (Bay Instruments) and computed as follows:\u00a0

Equation 4:\u00a0

In Trial B, duplicate 6 mL, 12 mL, and 24 mL aliquots of enriched seawater,
prepared as per Wilson et al. (2012; Cambridge Isotope Laboratories 15N2 gas
aliquots, Lot #I-19168A), were added to 100 mL glass serum vials, filled with
air equilibrated seawater, and crimp-sealed with no headspace using Teflon-
lined septa. Triplicate subsamples of this dilution series and the enriched
seawater were analyzed at the University of Hawaii on a MIMS (Bay Instruments;
Eq. 4).

In both trials, the concentration of N2 isotopologues (m/z 28, 29, and 30) in
each of the 15N2-enriched inocula was then extrapolated from the ionization
efficiency of N isotopologues in air-equilibrated seawater. We define the
ionization efficiency as the ratio of the isotopologue ion current measured by
MIMS relative to its concentration in air-equilibrated seawater (ASW):\u00a0

Equation S2:\u00a0

For instance, at a temperature of 25\u00baC and salinity of 35 psu, the
solubility coefficients of Hamme and Emerson (2004) predict a N2 concentration
of 388.9 \u03bcmol kg-1. The fraction of 15N in N2 (i.e., 15N/(14N+15N)) for
air-equilibrated seawater is 0.003663 (Mariotti, 1983), such that the expected
fractions of 28N2, 29N2, and 30N2 derived from their binomial probability
distributions are as follows:

\u00a0 = 99.2687 % Equation S3a

= 0.7299 % Equation S3b

= 0.0013 % Equation S3c

Accordingly, air-equilibrated concentrations of 28N2, 29N2, and 30N2 at this
temperature and salinity are 386.0, 2.8, and 0.005 \u03bcmol kg-1,
respectively. The ionization efficiency of the isotopologues is then equal to
the ion current of m/z 28 recorded for ASW divided by the corresponding 28N2
concentration (Eq. S2). We used the ionization efficiency of m/z 28 in ASW to
derive the N2 isotopologue concentrations in the inocula from their respective
MIMS ion currents. We did not derive distinct ionization efficiencies from the
ion current-to-concentration of m/z 29 and 30 in ASW, as these isotopologues
are poorly resolved by the MIMS at natural abundance. Thus, we are assuming
that the ionization efficiency of m/z 29 and 30 isotopologues is roughly
similar to that of m/z 28 (i.e., that ionization isotope effects are
negligible for our purposes). The initial expected AN2 of the
\u201cincubations\u201d was then calculated using a linear mixing model with
N2 isotopologue concentrations in ambient and enriched seawater
attribute NC_GLOBAL awards_0_award_nid String 772538
attribute NC_GLOBAL awards_0_award_number String OCE-1732246
attribute NC_GLOBAL awards_0_data_url String http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=1732246 (external link)
attribute NC_GLOBAL awards_0_funder_name String NSF Division of Ocean Sciences
attribute NC_GLOBAL awards_0_funding_acronym String NSF OCE
attribute NC_GLOBAL awards_0_funding_source_nid String 355
attribute NC_GLOBAL awards_0_program_manager String Henrietta N Edmonds
attribute NC_GLOBAL awards_0_program_manager_nid String 51517
attribute NC_GLOBAL cdm_data_type String Other
attribute NC_GLOBAL comment String Trial b test of the dissolution method
PI: Julie Granger
Version: 2019-09-30
attribute NC_GLOBAL Conventions String COARDS, CF-1.6, ACDD-1.3
attribute NC_GLOBAL creator_email String info at bco-dmo.org
attribute NC_GLOBAL creator_name String BCO-DMO
attribute NC_GLOBAL creator_type String institution
attribute NC_GLOBAL creator_url String https://www.bco-dmo.org/ (external link)
attribute NC_GLOBAL data_source String extract_data_as_tsv version 2.3 19 Dec 2019
attribute NC_GLOBAL date_created String 2019-09-30T19:25:34Z
attribute NC_GLOBAL date_modified String 2019-10-02T18:52:25Z
attribute NC_GLOBAL defaultDataQuery String &time<now
attribute NC_GLOBAL doi String 10.1575/1912/bco-dmo.778158.1
attribute NC_GLOBAL infoUrl String https://www.bco-dmo.org/dataset/778158 (external link)
attribute NC_GLOBAL institution String BCO-DMO
attribute NC_GLOBAL instruments_0_acronym String IR Mass Spec
attribute NC_GLOBAL instruments_0_dataset_instrument_description String continuous flow Delta V Isotope Ratio Mass Spectrometer (Smith et al. 2015), and continuous flow-GV Isoprime IRMS (Charoenpong et al., 2014)
attribute NC_GLOBAL instruments_0_dataset_instrument_nid String 778166
attribute NC_GLOBAL instruments_0_description String The Isotope-ratio Mass Spectrometer is a particular type of mass spectrometer used to measure the relative abundance of isotopes in a given sample (e.g. VG Prism II Isotope Ratio Mass-Spectrometer).
attribute NC_GLOBAL instruments_0_instrument_external_identifier String https://vocab.nerc.ac.uk/collection/L05/current/LAB16/ (external link)
attribute NC_GLOBAL instruments_0_instrument_name String Isotope-ratio Mass Spectrometer
attribute NC_GLOBAL instruments_0_instrument_nid String 469
attribute NC_GLOBAL instruments_0_supplied_name String Isotope Ratio Mass Spectrometer
attribute NC_GLOBAL instruments_1_acronym String MIMS
attribute NC_GLOBAL instruments_1_dataset_instrument_description String Membrane Inlet Mass Spectrometer (Bay Instruments)
attribute NC_GLOBAL instruments_1_dataset_instrument_nid String 778165
attribute NC_GLOBAL instruments_1_description String Membrane-introduction mass spectrometry (MIMS) is a method of introducing analytes into the mass spectrometer's vacuum chamber via a semipermeable membrane.
attribute NC_GLOBAL instruments_1_instrument_name String Membrane Inlet Mass Spectrometer
attribute NC_GLOBAL instruments_1_instrument_nid String 661606
attribute NC_GLOBAL instruments_1_supplied_name String Membrane Inlet Mass Spectrometer
attribute NC_GLOBAL keywords String atom, atom_pcnt_15N, bco, bco-dmo, biological, chemical, data, dataset, dmo, erddap, management, mass, Mass_z_28, Mass_z_29, Mass_z_30, Mass_z_32, Mass_z_40, O2, O2_Ar, oceanography, office, oxygen, pcnt, preliminary, ratio, ratio_30_28, sample, Sample_ID, time, time2
attribute NC_GLOBAL license String https://www.bco-dmo.org/dataset/778158/license (external link)
attribute NC_GLOBAL metadata_source String https://www.bco-dmo.org/api/dataset/778158 (external link)
attribute NC_GLOBAL param_mapping String {'778158': {}}
attribute NC_GLOBAL parameter_source String https://www.bco-dmo.org/mapserver/dataset/778158/parameters (external link)
attribute NC_GLOBAL people_0_affiliation String University of Connecticut
attribute NC_GLOBAL people_0_affiliation_acronym String UConn
attribute NC_GLOBAL people_0_person_name String Julie Granger
attribute NC_GLOBAL people_0_person_nid String 528937
attribute NC_GLOBAL people_0_role String Principal Investigator
attribute NC_GLOBAL people_0_role_type String originator
attribute NC_GLOBAL people_1_affiliation String University of Massachusetts Dartmouth
attribute NC_GLOBAL people_1_affiliation_acronym String UMass Dartmouth
attribute NC_GLOBAL people_1_person_name String Annie Bourbonnais
attribute NC_GLOBAL people_1_person_nid String 778011
attribute NC_GLOBAL people_1_role String Co-Principal Investigator
attribute NC_GLOBAL people_1_role_type String originator
attribute NC_GLOBAL people_2_affiliation String University of Hawaii
attribute NC_GLOBAL people_2_person_name String Samuel Wilson
attribute NC_GLOBAL people_2_person_nid String 51733
attribute NC_GLOBAL people_2_role String Co-Principal Investigator
attribute NC_GLOBAL people_2_role_type String originator
attribute NC_GLOBAL people_3_affiliation String Woods Hole Oceanographic Institution
attribute NC_GLOBAL people_3_affiliation_acronym String WHOI BCO-DMO
attribute NC_GLOBAL people_3_person_name String Mathew Biddle
attribute NC_GLOBAL people_3_person_nid String 708682
attribute NC_GLOBAL people_3_role String BCO-DMO Data Manager
attribute NC_GLOBAL people_3_role_type String related
attribute NC_GLOBAL project String EAGER NitFix
attribute NC_GLOBAL projects_0_acronym String EAGER NitFix
attribute NC_GLOBAL projects_0_description String NSF Award Abstract:
The availability of nitrogen is required to support the growth and production of organisms living in the surface of our global ocean. This element can be scarce. To alleviate this scarcity, a special class of bacteria and archaea, called nitrogen fixers, can derive the nitrogen needed for growth from nitrogen gas. This project would carefully examine one specific method for measuring nitrogen fixation that has been used recently to suggest the occurrence of small amounts of nitrogen fixation in subsurface ocean waters. If these reports are verified, then a revision of our understanding of the marine nitrogen cycle may be needed. The Ocean Carbon and Biogeochemistry program will be used as a platform to develop community consensus for best practices in nitrogen fixation measurements and detection of diversity, activity, and abundances of the organisms responsible. In addition, a session will be organized in a future national/international conference to communicate with the broader scientific community while developing these best practices.
The goal of this study is to conduct a thorough examination of potential experimental and analytical errors inherent to the 15N2-tracer nitrogen fixation method, in tandem with comprehensive molecular measurements, in mesopelagic ocean waters. Samples will be collected and experimental work conducted on a cruise transect in the North Atlantic Ocean, followed by analytical work in the laboratory. The specific aims of this study are to (1) determine the minimum quantifiable rates of 15N2 fixation based on incubations of mesopelagic waters via characterization of sources of experimental and analytical error, and (2) seek evidence of presence and expression of nitrogen fixation genes via comprehensive molecular approaches on corresponding samples. The range of detectable rates and diazotroph activity from the measurements made in this study will be informative for the understanding of the importance of nitrogen fixation in the oceanic nitrogen budget.
attribute NC_GLOBAL projects_0_end_date String 2018-10
attribute NC_GLOBAL projects_0_geolocation String North Atlantic Ocean, Pacific Ocean
attribute NC_GLOBAL projects_0_name String EAGER: Collaborative Research: Detection limit in marine nitrogen fixation measurements - Constraints of rates from the mesopelagic ocean
attribute NC_GLOBAL projects_0_project_nid String 772534
attribute NC_GLOBAL projects_0_start_date String 2017-05
attribute NC_GLOBAL publisher_name String Biological and Chemical Oceanographic Data Management Office (BCO-DMO)
attribute NC_GLOBAL publisher_type String institution
attribute NC_GLOBAL sourceUrl String (local files)
attribute NC_GLOBAL standard_name_vocabulary String CF Standard Name Table v55
attribute NC_GLOBAL summary String The \u201cdissolution\u201d method to measure N2 fixation rates with 15N2 gas tracer involves the preparation of 15N2-enriched water that is then added to each incubation bottle. Investigators typically measure the 15N2 atom% of the 15N2-enriched inoculum by MIMS, and extrapolate the 15N2 atom% in the incubations based on the inoculum value. Here, we demonstrate that such extrapolation yields inaccurate estimates of the 15N2 atom% of incubations. The latter should be measured directly.
attribute NC_GLOBAL title String Trial B test of the dissolution method for estimates of the 15N2 atom% of incubations
attribute NC_GLOBAL version String 1
attribute NC_GLOBAL xml_source String osprey2erddap.update_xml() v1.3
variable Sample_ID   String  
attribute Sample_ID bcodmo_name String unknown
attribute Sample_ID description String sample
attribute Sample_ID long_name String Sample ID
attribute Sample_ID units String unitless
variable time2   double  
attribute time2 _FillValue double NaN
attribute time2 actual_range double 0.4333564814814815, 0.6306365740740741
attribute time2 bcodmo_name String unknown
attribute time2 description String time
attribute time2 long_name String Time
attribute time2 units String unitless
variable Mass_z_28   double  
attribute Mass_z_28 _FillValue double NaN
attribute Mass_z_28 actual_range double 1.659318E-6, 8.301695E-6
attribute Mass_z_28 bcodmo_name String unknown
attribute Mass_z_28 description String mass-to-charge
attribute Mass_z_28 long_name String Mass Z 28
attribute Mass_z_28 units String unitless
variable Mass_z_29   double  
attribute Mass_z_29 _FillValue double NaN
attribute Mass_z_29 actual_range double 1.604068E-8, 5.335568E-8
attribute Mass_z_29 bcodmo_name String unknown
attribute Mass_z_29 description String mass-to-charge
attribute Mass_z_29 long_name String Mass Z 29
attribute Mass_z_29 units String unitless
variable Mass_z_30   double  
attribute Mass_z_30 _FillValue double NaN
attribute Mass_z_30 actual_range double 3.998998E-9, 9.322125E-6
attribute Mass_z_30 bcodmo_name String unknown
attribute Mass_z_30 description String mass-to-charge
attribute Mass_z_30 long_name String Mass Z 30
attribute Mass_z_30 units String unitless
variable Mass_z_32   double  
attribute Mass_z_32 _FillValue double NaN
attribute Mass_z_32 actual_range double 9.379484E-7, 4.042403E-6
attribute Mass_z_32 bcodmo_name String unknown
attribute Mass_z_32 description String mass-to-charge
attribute Mass_z_32 long_name String Mass Z 32
attribute Mass_z_32 units String unitless
variable Mass_z_40   float  
attribute Mass_z_40 _FillValue float NaN
attribute Mass_z_40 actual_range float 3.616499E-8, 2.20631E-7
attribute Mass_z_40 bcodmo_name String unknown
attribute Mass_z_40 description String mass-to-charge
attribute Mass_z_40 long_name String Mass Z 40
attribute Mass_z_40 units String unitless
variable O2_Ar   double  
attribute O2_Ar _FillValue double NaN
attribute O2_Ar actual_range double 9.909134E-4, 9.938847
attribute O2_Ar bcodmo_name String unknown
attribute O2_Ar description String O2 to Ar ratio
attribute O2_Ar long_name String O2 Ar
attribute O2_Ar units String unitless
variable ratio_30_28   float  
attribute ratio_30_28 _FillValue float NaN
attribute ratio_30_28 actual_range float 4.825058E-4, 5.618047
attribute ratio_30_28 bcodmo_name String unknown
attribute ratio_30_28 description String ratio 30/28
attribute ratio_30_28 long_name String Ratio 30 28
attribute ratio_30_28 units String unitless
variable atom_pcnt_15N   double  
attribute atom_pcnt_15N _FillValue double NaN
attribute atom_pcnt_15N actual_range double 0.37, 84.84
attribute atom_pcnt_15N bcodmo_name String unknown
attribute atom_pcnt_15N description String 15N atom %
attribute atom_pcnt_15N long_name String Atom Pcnt 15 N
attribute atom_pcnt_15N units String unitless

The information in the table above is also available in other file formats (.csv, .htmlTable, .itx, .json, .jsonlCSV1, .jsonlCSV, .jsonlKVP, .mat, .nc, .nccsv, .tsv, .xhtml) via a RESTful web service.

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