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Title Sum-
Institution Dataset ID
     data   graph     files  public Water column nitrate+nitrite d15N and d18O from samples collected during R/V Pelican and R/V
F.G. Walton Smith cruises in the Gulf of Mexico and Florida Straits between 2011 and 2018
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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,.esriCsv,.geoJson
attribute NC_GLOBAL acquisition_description String Water column samples were collected by Niskin bottle on a CTD rosette
(\u201cCTD profile\u201d). NO3-+NO2- concentration was measured using a
chemiluminescent method described by Braman and Hendrix, 1989, with a
detection limit of 0.1 \u00b5M. NO3-+NO2- d15N and d18O analyses were by the
\u201cdenitrifier method\u201d and followed the methods described by Sigman et
al., 2001, Casciotti et al., 2002, McIlvin and Casciotti, 2011, and Weigand et
al., 2016. Briefly, NO3-+NO2- was quantitatively reduced to N2O by Pseudomonas
aureofaciens and Pseudomonas chlororaphis, which was then cryogenically
focused and analyzed on an isotope ratio mass spectrometer. A volume of sample
was added to each bacterial vial to achieve a final quantity of 10 or 20 nmols
N2O, which was then purged from the vial using a helium carrier gas. The d15N
of N2O in samples was calibrated with the international isotopic reference

The average precision of the nitrate+nitrite concentration measurement was
<0.2 \u00b5M. The average precision of nitrate+nitrite d15N measurements was
<0.2 per mil and for d18O was <0.3 per mil, but with the standard deviation
for duplicate analyses of each sample reported here. NO3-+NO2- \u03b415N
\u03b418O analyses were calibrated with IAEA N3 and USGS 34 NO3- d15N isotopic
reference materials as described in McIlvin and Casciotti, 2011. NO3-+NO2-
d18O were also calibrated with the USGS 35 isotopic reference material as
described in McIlvin and Casciotti, 2011.
attribute NC_GLOBAL awards_0_award_nid String 710561
attribute NC_GLOBAL awards_0_award_number String OCE-1537314
attribute NC_GLOBAL awards_0_data_url String http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=1537314 (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 Gulf of Mexico NO3 isotopes
PI(s): Angela N. Knapp
Data Version 1: 2019-11-21
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 2019-11-21T20:42:09Z
attribute NC_GLOBAL date_modified String 2019-11-26T21:22:23Z
attribute NC_GLOBAL defaultDataQuery String &amp;time&lt;now
attribute NC_GLOBAL doi String 10.1575/1912/bco-dmo.782518.1
attribute NC_GLOBAL Easternmost_Easting double -79.5
attribute NC_GLOBAL geospatial_lat_max double 27.0
attribute NC_GLOBAL geospatial_lat_min double 25.866
attribute NC_GLOBAL geospatial_lat_units String degrees_north
attribute NC_GLOBAL geospatial_lon_max double -79.5
attribute NC_GLOBAL geospatial_lon_min double -92.0401
attribute NC_GLOBAL geospatial_lon_units String degrees_east
attribute NC_GLOBAL geospatial_vertical_max double 2805.0
attribute NC_GLOBAL geospatial_vertical_min double 1.0
attribute NC_GLOBAL geospatial_vertical_positive String down
attribute NC_GLOBAL geospatial_vertical_units String m
attribute NC_GLOBAL infoUrl String https://www.bco-dmo.org/dataset/782518 (external link)
attribute NC_GLOBAL institution String BCO-DMO
attribute NC_GLOBAL instruments_0_acronym String Mass Spec
attribute NC_GLOBAL instruments_0_dataset_instrument_description String Nitrate+nitrite d15N was measured using a Thermo Finnigan Delta V isotope ratio mass spectrometer.
attribute NC_GLOBAL instruments_0_dataset_instrument_nid String 782731
attribute NC_GLOBAL instruments_0_description String General term for instruments used to measure the mass-to-charge ratio of ions; generally used to find the composition of a sample by generating a mass spectrum representing the masses of sample components.
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 Mass Spectrometer
attribute NC_GLOBAL instruments_0_instrument_nid String 685
attribute NC_GLOBAL instruments_0_supplied_name String Thermo Finnigan Delta V isotope ratio mass spectrometer
attribute NC_GLOBAL instruments_1_acronym String Gas Analyzer
attribute NC_GLOBAL instruments_1_dataset_instrument_description String Nitrate+nitrite concentration was measured on a Thermo 42i NOx analyzer.
attribute NC_GLOBAL instruments_1_dataset_instrument_nid String 782730
attribute NC_GLOBAL instruments_1_description String Gas Analyzers - Instruments for determining the qualitative and quantitative composition of gas mixtures.
attribute NC_GLOBAL instruments_1_instrument_name String Gas Analyzer
attribute NC_GLOBAL instruments_1_instrument_nid String 720
attribute NC_GLOBAL instruments_1_supplied_name String Thermo 42i NOx analyzer
attribute NC_GLOBAL keywords String altimetry, bco, bco-dmo, biological, chemical, chemistry, concentration, cruise, Cruise_ID, data, dataset, date, density, depth, dmo, earth, Earth Science > Oceans > Ocean Chemistry > Nitrate, Earth Science > Oceans > Salinity/Density > Density, erddap, laboratory, latitude, longitude, management, mole, mole_concentration_of_nitrate_in_sea_water, n02, nitrate, no3, NO3_NO2, NO3_NO2_d15N, NO3_NO2_d18O, ocean, oceanography, oceans, office, preliminary, sal, salinity, sampling, satellite, science, sea, sea_water_sigma_theta, seawater, sigma, SigmaTheta, temperature, theta, time, water
attribute NC_GLOBAL keywords_vocabulary String GCMD Science Keywords
attribute NC_GLOBAL license String https://www.bco-dmo.org/dataset/782518/license (external link)
attribute NC_GLOBAL metadata_source String https://www.bco-dmo.org/api/dataset/782518 (external link)
attribute NC_GLOBAL Northernmost_Northing double 27.0
attribute NC_GLOBAL param_mapping String {'782518': {'Latitude': 'flag - latitude', 'Depth': 'flag - depth', 'Longitude': 'flag - longitude'}}
attribute NC_GLOBAL parameter_source String https://www.bco-dmo.org/mapserver/dataset/782518/parameters (external link)
attribute NC_GLOBAL people_0_affiliation String Florida State University
attribute NC_GLOBAL people_0_affiliation_acronym String FSU
attribute NC_GLOBAL people_0_person_name String Angela N. Knapp
attribute NC_GLOBAL people_0_person_nid String 555499
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 Woods Hole Oceanographic Institution
attribute NC_GLOBAL people_1_affiliation_acronym String WHOI BCO-DMO
attribute NC_GLOBAL people_1_person_name String Amber York
attribute NC_GLOBAL people_1_person_nid String 643627
attribute NC_GLOBAL people_1_role String BCO-DMO Data Manager
attribute NC_GLOBAL people_1_role_type String related
attribute NC_GLOBAL project String SW Pac N2 fixation
attribute NC_GLOBAL projects_0_acronym String SW Pac N2 fixation
attribute NC_GLOBAL projects_0_description String NSF Award Abstract:
The availability of nitrogen in the surface ocean plays a critical role regulating rates of primary productivity in the ocean, and thus through modification of the carbon cycle, nitrogen has the capacity to influence climate. The dominant source of biologically available nitrogen to the ocean is through a process known as di-nitrogen (N2) fixation, which involves the reduction of N2 gas dissolved in seawater to ammonium by microbes referred to as diazotrophs. While significant progress has been made identifying a diversity of marine diazotrophs in recent years using molecular tools, quantifying global rates of N2 fixation, and identifying which ocean basin supports the highest fluxes, has remained a vexing question. This research will quantify rates of N2 fixation as well as its importance for supporting production in the southwest Pacific Ocean. Results from this research will shed light on the sensitivities of N2 fixation (temperature, iron concentrations) as well as the extent of spatial and temporal coupling of nitrogen sources and sinks in the ocean. The work will be carried out by an early career scientist, and involve mentoring of young women, middle school girls and minorities, training of undergraduate and graduate researchers, and international collaborations.
Identifying the spatial distribution of the largest di-nitrogen (N2) fixation fluxes to the ocean remains a critical goal of chemical oceanography. The spatial distribution can inform our understanding of the environmental sensitivities of N2 fixation and the capacity for the dominant marine nitrogen (N) source and sink processes to respond to each other and thus influence the global carbon cycle and climate. In addition to temperature, two factors are at the heart of the current debate over what influences the spatial distribution of N2 fixation in the ocean: 1) the presence of adequate iron to meet the needs of N2 fixing microbes, and, 2) the absolute concentrations as well as ratios of surface ocean nitrate and phosphate concentrations that are low relative to the "Redfield" ratio, which are thought to favor N2 fixing microbes. This project will test the effects of gradients in atmospheric dust deposition on N2 fixation rates when surface waters have relatively constant but favorable nitrate to phosphate concentrations. The work will be carried out in the southwest Pacific, a region highlighted by new modeling work for its unique geochemical characteristics that are expected to favor significant N2 fixation fluxes. Nitrate+nitrite d15N as well as total dissolved nitrogen (TDN) concentration and d15N will be measured in water column samples collected on a French cruise and sediment traps were deployed to capture the sinking particulate N flux. The results will be compared with published work to evaluate which ocean regions support the largest N2 fixation fluxes.
More information:
This project was part of the Oligotrophy to UlTra-oligotrophy PACific Experiment (OUTPACE) cruise in the Southwest Pacific between New Caledonia (166°28' E; 22°14' S) and Tahiti (149°36' W; 17°34' S) 0-2000 m​
* OUTPACE cruise (doi: https://dx.doi.org/10.17600/15000900)
* OUTPACE website: https://outpace.mio.univ-amu.fr/?lang=en
attribute NC_GLOBAL projects_0_end_date String 2018-07
attribute NC_GLOBAL projects_0_geolocation String Southwest Pacific Ocean between New Caledonia and Tahiti along ~18 deg S
attribute NC_GLOBAL projects_0_name String Quantifying nitrogen fixation along unique geochemical gradients in the southwest Pacific Ocean
attribute NC_GLOBAL projects_0_project_nid String 710562
attribute NC_GLOBAL projects_0_project_website String http://scope.soest.hawaii.edu/data/lava/lava.html (external link)
attribute NC_GLOBAL projects_0_start_date String 2015-08
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 Southernmost_Northing double 25.866
attribute NC_GLOBAL standard_name_vocabulary String CF Standard Name Table v55
attribute NC_GLOBAL summary String This data set includes water column nitrate+nitrite d15N and d18O measurements from the Gulf of Mexico and Florida Straits. These measurements were used to address whether Mississippi River nitrate is entrained in Loop Current waters and potentially exported from the Gulf of Mexico to the North Atlantic. Water samples were collected during R/V Pelican and R/V F.G. Walton Smith cruises in the Gulf of Mexico and Florida Straits between 2011 and 2018.
attribute NC_GLOBAL title String Water column nitrate+nitrite d15N and d18O from samples collected during R/V Pelican and R/V F.G. Walton Smith cruises in the Gulf of Mexico and Florida Straits between 2011 and 2018
attribute NC_GLOBAL version String 1
attribute NC_GLOBAL Westernmost_Easting double -92.0401
attribute NC_GLOBAL xml_source String osprey2erddap.update_xml() v1.3
variable Cruise_ID   String  
attribute Cruise_ID bcodmo_name String cruise_id
attribute Cruise_ID description String Rolling Deck Repository or other cruise identifier
attribute Cruise_ID long_name String Cruise ID
attribute Cruise_ID units String unitless
variable Sampling_Date   String  
attribute Sampling_Date bcodmo_name String date
attribute Sampling_Date description String Date on which the sample was collected
attribute Sampling_Date long_name String Sampling Date
attribute Sampling_Date nerc_identifier String https://vocab.nerc.ac.uk/collection/P01/current/ADATAA01/ (external link)
attribute Sampling_Date source_name String Sampling_Date
attribute Sampling_Date time_precision String 1970-01-01
attribute Sampling_Date units String unitless
variable latitude   double  
attribute latitude _CoordinateAxisType String Lat
attribute latitude _FillValue double NaN
attribute latitude actual_range double 25.866, 27.0
attribute latitude axis String Y
attribute latitude bcodmo_name String latitude
attribute latitude colorBarMaximum double 90.0
attribute latitude colorBarMinimum double -90.0
attribute latitude description String latitude at which the sample was collected
attribute latitude ioos_category String Location
attribute latitude long_name String Latitude
attribute latitude nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/LATX/ (external link)
attribute latitude standard_name String latitude
attribute latitude units String degrees_north
variable longitude   double  
attribute longitude _CoordinateAxisType String Lon
attribute longitude _FillValue double NaN
attribute longitude actual_range double -92.0401, -79.5
attribute longitude axis String X
attribute longitude bcodmo_name String longitude
attribute longitude colorBarMaximum double 180.0
attribute longitude colorBarMinimum double -180.0
attribute longitude description String longitude at which the sample was collected
attribute longitude ioos_category String Location
attribute longitude long_name String Longitude
attribute longitude nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/LONX/ (external link)
attribute longitude standard_name String longitude
attribute longitude units String degrees_east
variable depth   double  
attribute depth _CoordinateAxisType String Height
attribute depth _CoordinateZisPositive String down
attribute depth _FillValue double NaN
attribute depth actual_range double 1.0, 2805.0
attribute depth axis String Z
attribute depth bcodmo_name String depth
attribute depth colorBarMaximum double 8000.0
attribute depth colorBarMinimum double -8000.0
attribute depth colorBarPalette String TopographyDepth
attribute depth description String Depth at which the sample was collected
attribute depth ioos_category String Location
attribute depth long_name String Depth
attribute depth nerc_identifier String https://vocab.nerc.ac.uk/collection/P09/current/DEPH/ (external link)
attribute depth positive String down
attribute depth standard_name String depth
attribute depth units String m
variable SigmaTheta   float  
attribute SigmaTheta _FillValue float NaN
attribute SigmaTheta actual_range float 22.53, 27.77
attribute SigmaTheta bcodmo_name String sigma_theta
attribute SigmaTheta description String Potential Density of depth at which sample was collected
attribute SigmaTheta long_name String Sea Water Sigma Theta
attribute SigmaTheta units String unitless
variable NO3_NO2   float  
attribute NO3_NO2 _FillValue float NaN
attribute NO3_NO2 actual_range float 0.0, 31.22
attribute NO3_NO2 bcodmo_name String NO3_NO2
attribute NO3_NO2 colorBarMaximum double 50.0
attribute NO3_NO2 colorBarMinimum double 0.0
attribute NO3_NO2 description String Concentration of nitrate+nitrite in a sample
attribute NO3_NO2 long_name String Mole Concentration Of Nitrate In Sea Water
attribute NO3_NO2 units String micro molar (µM)
variable NO3_NO2_d15N   float  
attribute NO3_NO2_d15N _FillValue float NaN
attribute NO3_NO2_d15N actual_range float 2.39, 5.8
attribute NO3_NO2_d15N bcodmo_name String d15N
attribute NO3_NO2_d15N colorBarMaximum double 50.0
attribute NO3_NO2_d15N colorBarMinimum double 0.0
attribute NO3_NO2_d15N description String Nitrogen isotopic composition of nitrate+nitrite in a sample
attribute NO3_NO2_d15N long_name String Mole Concentration Of Nitrate In Sea Water
attribute NO3_NO2_d15N units String per mil (0/00) vs. N2 in air
variable NO3_NO2_d18O   float  
attribute NO3_NO2_d18O _FillValue float NaN
attribute NO3_NO2_d18O actual_range float 0.67, 3.75
attribute NO3_NO2_d18O bcodmo_name String d18O_NO3
attribute NO3_NO2_d18O colorBarMaximum double 50.0
attribute NO3_NO2_d18O colorBarMinimum double 0.0
attribute NO3_NO2_d18O description String Oxygen isotopic composition of nitrate+nitrite in a sample
attribute NO3_NO2_d18O long_name String Mole Concentration Of Nitrate In Sea Water
attribute NO3_NO2_d18O units String per mil (0/00) vs. VSMOW
variable sal   float  
attribute sal _FillValue float NaN
attribute sal actual_range float 34.9, 36.81
attribute sal bcodmo_name String sal
attribute sal description String salinity of the sample
attribute sal long_name String Sal
attribute sal nerc_identifier String https://vocab.nerc.ac.uk/collection/P01/current/PSALST01/ (external link)
attribute sal units String Practical Salinity Units (PSU)
variable temp   float  
attribute temp _FillValue float NaN
attribute temp actual_range float 4.24, 29.45
attribute temp bcodmo_name String temperature
attribute temp description String temperature of the sample
attribute temp long_name String Temperature
attribute temp nerc_identifier String https://vocab.nerc.ac.uk/collection/P01/current/TEMPP901/ (external link)
attribute temp units String degrees Celsius

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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