Dataset: OUTPACE - water column nitrate+nitrite
Deployment: OUTPACE

Water column nitrate+nitrite d15N measurements

Principal Investigator:

Angela N. Knapp (Florida State University, FSU)

International Collaborator:

Sophie Bonnet (Mediterranean Institute of Oceanography, MIO)

Thierry Moutin (Mediterranean Institute of Oceanography, MIO)

Scientist:

Oliver Grosso (Mediterranean Institute of Oceanography, MIO)

Nathalie Leblond (Villefranche Oceanographic Laboratory, LOV)

Student:

Kelly M. McCabe (Florida State University, FSU)

Contact:

Angela N. Knapp (Florida State University, FSU)

BCO-DMO Data Manager:

Mathew Biddle (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Quantifying nitrogen fixation along unique geochemical gradients in the southwest Pacific Ocean (SW Pac N2 fixation)

Current State:

Final no updates expected

Data URL:

https://www.bco-dmo.org/dataset-deployment/733267/data

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Description

This data set includes water column nitrate+nitrite d15N measurements. These measurements were used together with measurements of the d15N of particulate nitrogen collected in floating sediment traps that were deployed for several days to calculate the relative contribution of subsurface nitrate and nitrogen from N2 fixation for supporting export production (“d15N budgets”). The results suggest that N2 fixation supported a majority of export at Long Duration (LD) stations A and B, and a minor fraction of export at LD C. The results at LD stations A and B are unique compared to other d15N budgets from the oligotrophic regions, whereas the results from LD C are similar to prior reports from the eastern tropical South Pacific as well as the North Pacific near Hawaii. Additionally, these data are compared with other metrics of N2 fixation made on the same cruise.

Methods & Sampling

Dataset acquisition description

NO3-+NO2- d15N analysis was by the “denitrifier method” 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 materials described in the Processing Description.

Data Processing Description

Dataset Processing Description

Nitrate+nitrite concentration was measured by others using colorimetric methods, and can be found at:
http://www.obs-vlfr.fr/proof/php/outpace/outpace.php

The average precision of nitrate+nitrite d15N measurements was <0.2 per mil, but with the standard deviation for duplicate analyses of each sample reported here. Samples were calibrated with IAEA N3 and USGS 34 NO3- d15N isotopic reference materials as described in McIlvin and Casciotti, 2011.

BCO-DMO Processing Notes:

added conventional header with dataset name, PI name, version date.
modified parameter names to conform with BCO-DMO naming conventions.
re-formatted date from dd Month yyyy (day month year) to yyyymmdd.
appended date, latitude, and longitude to each data entry.
If an observation did not exist, 'nd' (no data) was inserted.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1537314	NSF Division of Ocean Sciences

Instruments

Isotope-ratio Mass Spectrometer

Supplied Name: Thermo Finnigan Delta V isotope ratio mass spectrometer.

Supplied Description:

Nitrate+nitrite d15N was measured using a Thermo Finnigan Delta V isotope ratio mass spectrometer.

Instrument Type

Generic Name: Isotope-ratio Mass Spectrometer

Acronym: IR Mass Spec; IRMS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB16/

Generic Description:

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).

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Cast	cast number	unitless	cast
Depth	depth of observation	meters	depth
Sigma_theta	potential density	kilograms per meter cubed (kg/m3)	sigma_theta
NO3_NO2	nitrate+nitrite concentration ([NO3-+NO2-])	micromole (uM)	NO3_NO2
NO3_NO2_d15N	nitrate+nitrite d15N (NO3-+NO2- d15N)	per mil	d15N_NO3NO2
NO3_NO2_d15N_1_SD	nitrate+nitrite d15N standard deviation	per mil	d15N_NO3NO2
Date	Date of observation in four digit year; 2 digit month; 2 digit day (yyyymmdd) format	unitless	date
Longitude	Longitude with west negative.	decimal degrees	lon
Latitude	Latitude with south negative.	decimal degrees	lat
Station	name of the station	unitless	station

Database

Contribute Data

Dataset: OUTPACE - water column nitrate+nitrite
Deployment: OUTPACE

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: OUTPACE - water column nitrate+nitriteDeployment: OUTPACE

Dataset acquisition description

Dataset Processing Description

Dataset: OUTPACE - water column nitrate+nitrite
Deployment: OUTPACE