Dataset: TONGA nitrate plus nitrite isotopes

Name: Water column nitrate plus nitrite d15N measurements from seawater collected in November 2019 and November 2020 in the Western Tropical South Pacific
Published: 2023-04-03
Keywords: Nitrate d15N, d15N budget, nitrogen fixation, Western Tropical South Pacific, NO3 d15N, N2 fixation, oceans

Cite This Dataset

DOI:10.26008/1912/bco-dmo.869963.2

Spatial Extent: N:-19.43 E:-179.52 S:-21.16 W:175.81

Temporal Extent: 2019-11-05 - 2020-11-04

Project:

Collaborative Research: Dissolved organic phosphorus controls on marine nitrogen fixation and export production (DOP N2 fixation and export production)

Principal Investigator:

Angela N. Knapp (Florida State University, FSU - EOAS)

International Collaborator:

Sophie Bonnet (Mediterranean Institute of Oceanography, MIO)

Contact:

Heather J. Forrer (Florida State University, FSU - EOAS)

BCO-DMO Data Manager:

Dana Stuart Gerlach (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Shannon Rauch (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Version:

Version Date:

2023-04-03

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Water column nitrate plus nitrite d15N measurements from seawater collected in November 2019 and November 2020 in the Western Tropical South Pacific

Abstract:

Here we present nitrate plus nitrite isotopic data from the TONGA research cruises to the Western Tropical South Pacific in 2019 and a reoccupation in 2020. These data were collected along a transect focusing on the impacts on biological productivity and the biological carbon pump from shallow hydrothermal sources of trace elements. Notably, these data show that the subsurface nitrate plus nitrite isotopes were low, 2 to 3 per mil, in the vicinity of the hydrothermal vents. While subsurface nitrate plus nitrite isotopes were low higher, 4 to 7 per mil, at stations further from the vents.

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Archival Copy

Version Date	Archive	Persistent Identifier	Date Assigned
2023-04-03	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.869963.2	2023-04-04
2022-02-24	Marine Biological Laboratory/Woods Hole Oceanographic Institution Library (MBLWHOI DLA)	10.26008/1912/bco-dmo.869963.1	2022-03-04

Methods & Sampling

Sampling and Analytical Procedures:
Duplicate water column samples were collected by Niskin or GoFlo rosette on one of the following types of casts:

'CTD',
'TMC' (Trace Metal Clean), or
'TWO' (small classical CTD with 12 x Niskin bottles) cast.

Nitrogen isotopic analysis (d15N of NO3-+NO2-) 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, 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 nanomoles N2O, which was then purged from the vial using a helium carrier gas. The d15N of N2O in samples was calibrated with international isotopic reference materials.

Calibration:
NO3-+NO2- d15N analyses were calibrated with IAEA N3 and USGS 34 NO3- d15N isotopic reference materials as described in McIlvin and Casciotti, 2011.

Precision:
The average precision of NO3-+NO2- d15N measurements was <0.2 per mil.

Data Processing Description

BCO-DMO Processing:
Version 1:
- Added a column for Vessel
- Combined date and time columns to format of yyyy-mm-dd hh:mm:ss
- Modified parameter (column) names to conform with BCO-DMO naming conventions. The only allowed characters are A-Z,a-z,0-9, and underscores. No spaces, hyphens, commas, parentheses, or Greek letters.

Version 2:
- Created ISO 8601 date-time field;
- Renamed fields to comply with BCO-DMO naming conventions.

Version History:
- version 1 (date 2022-02-24) - contains only data from 2019 cruise.
- version 2 (date 2023-04-03) - contains data from 2019 and 2020 cruises.

Data Files

File
tonga_no3_d15n.csv (Comma Separated Values (.csv), 12.72 KB) MD5:aad6b02f852e5c359e52318b91dda63b Primary data file for dataset ID 869963; version 2.

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-1829797

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
TONGA RECUP	TONGA2020	2020-10-24	R/V Alis	Cecile Guieu (Chief Scientist)	data info
TONGA2019		2019-10-31	R/V L'Atalante	Sophie Bonnet (Chief Scientist) Cecile Guieu (Chief Scientist)	data info

Instruments

CTD - profiler

Supplied Name: CTD

Supplied Description:

water column samples were collected on a CTD cast

Instrument Type

Generic Name: CTD - profiler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/130/

Generic Description:

The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.

This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934.

GO-FLO Bottle

Supplied Name: GoFlo rosette

Supplied Description:

water column samples were collected by Niskin or GoFlo rosette

Instrument Type

Generic Name: GO-FLO Bottle

Acronym: GO-FLO

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/30/

Generic Description:

GO-FLO bottle cast used to collect water samples for pigment, nutrient, plankton, etc. The GO-FLO sampling bottle is specially designed to avoid sample contamination at the surface, internal spring contamination, loss of sample on deck (internal seals), and exchange of water from different depths.

Isotope-ratio Mass Spectrometer

Supplied Name: Thermo Finnigan Delta V isotope ratio mass spectrometer

Supplied Description:

NO3-+NO2- 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).

Niskin bottle

Supplied Name: Niskin

Supplied Description:

water column samples were collected by Niskin

Instrument Type

Generic Name: Niskin bottle

Community Identifier: http://vocab.nerc.ac.uk/collection/L22/current/TOOL0412/

Generic Description:

A Niskin bottle (a next generation water sampler based on the Nansen bottle) is a cylindrical, non-metallic water collection device with stoppers at both ends. The bottles can be attached individually on a hydrowire or deployed in 12, 24, or 36 bottle Rosette systems mounted on a frame and combined with a CTD. Niskin bottles are used to collect discrete water samples for a range of measurements including pigments, nutrients, plankton, etc.

Trace Metal Bottle

Supplied Name: Trace Metal Clean (TMC) bottle

Supplied Description:

water column samples were collected on a TMC (Trace Metal Clean) cast

Instrument Type

Generic Name: Trace Metal Bottle

Acronym: TM Bottle

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/30/

Generic Description:

Trace metal (TM) clean rosette bottle used for collecting trace metal clean seawater samples.

Parameters

Date and time formats are described in python strftime() syntax.

Supplied Name	Supplied description	Supplied Units	Standard Name
CruiseID	Cruise name	unitless	cruise_name
ISO_DateTime_UTC	Date and time (UTC) of sampling in ISO 8601 format Format: %Y-%m-%dT%H:%MZ	unitless	ISO_DateTime_UTC
Latitude	Latitude of sample collection	degrees North	lat
Longitude	Longitude of sample collection	degrees East	lon
Cast	Cast number and type (CTD=standard CTD, TMC=Trace Metal Clean, TWO=small classical CTD with 12 Niskin)	unitless	cast
PotentialDensity	Density of water parcel at the surface	kilograms per cubic meter (kg/m^3)	density
Depth	Sample depth	meters (m)	depth
NO3_NO2_d15N	Nitrogen isotopic composition of nitrate plus nitrite with respect to nitrogen in air (NO3- + NO2- d15N vs. N2 in air)	per mil vs. N2 in air	del15N_NO3NO2

Status message

Database

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Dataset: TONGA nitrate plus nitrite isotopes