Dataset: GP16 Nitrite Isotopes and Concentrations
Deployment: TN303

GP16 Nitrite Isotopes and Concentrations

View Data: For data, See Dataset Metadata Page: https://www.bco-dmo.org/dataset/933707

Principal Investigator:

Karen L. Casciotti (Stanford University)

Student:

Noah Gluschankoff (Stanford University)

BCO-DMO Data Manager:

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

Project:

GEOTRACES Peru-Tahiti Nitrogen Isotope Measurements (EPZT Nitrogen Isotopes)

U.S. GEOTRACES East Pacific Zonal Transect (GP16) (U.S. GEOTRACES EPZT)

Version:

Deployment Synonyms:

GP16, GEOTRACES EPZT, GEOTRACES East Pacific Zonal Transect (EPZT), GT13, 325020131025

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Description

Methods & Sampling

Dataset acquisition description

Seawater samples were collected at sea from Niskin bottles and were immediately analyzed for nitrite concentration. If sufficient nitrite concentrations (>0.1 micromoles per liter (umol/L)) were observed, samples were preserved as nitrous oxide (N2O) using sodium azide and acetic acid to selectively convert nitrite to nitrous oxide (McIlvin and Altabet, 2005). In the laboratory, the resultant N2O was analyzed using a custom purge and trap gas bench connected to an isotope ratio mass spectrometer. Nitrite isotope standards RSIL-N23, -N7373, and -N10219 were analyzed alongside the seawater samples to normalize nitrite d15N and d18O values to reference scales (Casciotti et al. 2007).

Data Processing Description

Dataset Processing Description

Nitrite d15N and δ18O analyses were calibrated against aliquots of the nitrite isotope standards RSIL-N23, RSIL-N7373, and RSIL-N10219 (Casciotti et al., 2007) prepared and analyzed in parallel with each batch of samples. These standards are used to correct for blanks, drift, and to report nitrite isotope data on VSMOW and Air reference scales for d18O and d15N, respectively (Casciotti et al., 2007).

A quality control (QC) flag was also added for each measurement using the SeaDataNet QC guidelines available at https://www.seadatanet.org/Standards/Data-Quality-Control:

1 = good value;
2 = probably good value;
3 = probably bad value;
4 = bad value;
6 = value below detection;
9 = missing value.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-1233339	NSF Division of Ocean Sciences

Instruments

Automated Purge and Trap System

Supplied Name: custom purge and trap gas bench connected to an isotope ratio mass spectrometer

Supplied Description:

This equipment extracts dissolved gases from the water samples, traps the extracted compounds under liquid nitrogen temperature, and then releases the trapped gases into the gas chromatograph and then to the Isotope Ratio Mass Spectrometer via an open split (McIlvin and Casciotti, 2011). It is automated and controlled by a desktop computer and ISODAT 3.0 software.

Instrument Type

Generic Name: Automated Purge and Trap System

Generic Description:

This equipment removes dissolved gases from the water samples, traps the extracted compounds on a cold trap and then heats the trap and injects the trapped gases into the gas chromatograph. It is automated and controlled by a laptop computer.

Isotope-ratio Mass Spectrometer

Supplied Name: Thermo Fisher DeltaPLUS XP Isotope Ratio Mass Spectrometer

Supplied Description:

The Isotope-ratio Mass Spectrometer is used to measure the relative abundance of isotopes in a given sample. The instrument is equipped with faraday cup collectors for determining the ratios of m/z 44, 45, and 46 in N2O generated from samples using the azide method (McIlvin and Altabet, 2005).

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 Description:

A Niskin bottle is a cylindrical, non-metallic water collection device with stoppers at both ends. On GP16, the 12-place 30-liter (L) Niskin rosette was used to collect discrete water samples for nitrite isotope analyses.

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.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
STNNBR	Station number	unitless	station
GEOTRC_EVENTNO	GEOTRACES event number	unitless	event
GEOTRC_SAMPNO	GEOTRACES sample number	unitless	sample
DATE	Date of sampling	unitless	date
LATITUDE	Latitude; South is negative	decimal degrees	lat
LONGITUDE	Longitude; West is negative	decimal degrees	lon
CTDPRS	Pressure	decibars	press
DEPTH	Depth	meters (m)	depth
CTDTMP	Temperature	degrees Celsius	temp
CTDSAL	Salinity	PSU	sal
NITRITE	Nitrite concentration	micromoles per liter (umol/L)	NO2
NITRITE_15_14_D_DELTA_BOTTLE_x5fmqg	Average d15N of nitrite measurements in reference to atmospheric nitrogen gas, expressed in permille notation. (Code at the end of column name is GEOTRACES DOoR identifier.)	permille	d15N
SD1_NITRITE_15_14_D_DELTA_BOTTLE_x5fmqg	Standard deviation d15N of nitrite measurements in reference to atmospheric nitrogen gas, expressed in permille notation. (Code at the end of column name is GEOTRACES DOoR identifier.)	permille	d15N
Flag_NITRITE_15_14_D_DELTA_BOTTLE_x5fmqg	Data quality control flag from Data quality control flag from SeaDataNet: 1 = good value; 2 = probably good value; 3 = probably bad value; 4 = bad value; 9 = missing value.	unitless	q_flag
NITRITE_18_16_D_DELTA_BOTTLE_iqunnm	Average d18O of nitrite measurements in reference to atmospheric nitrogen gas, expressed in permille notation. (Code at the end of column name is GEOTRACES DOoR identifier.)	permille	d18O
SD1_NITRITE_18_16_D_DELTA_BOTTLE_iqunnm	Standard deviation d18O of nitrite measurements in reference to atmospheric nitrogen gas, expressed in permille notation. (Code at the end of column name is GEOTRACES DOoR identifier.)	permille	d18O
Flag_NITRITE_18_16_D_DELTA_BOTTLE_iqunnm	Data quality control flag from Data quality control flag from SeaDataNet: 1 = good value; 2 = probably good value; 3 = probably bad value; 4 = bad value; 9 = missing value.	unitless	q_flag

Database

Contribute Data

Dataset: GP16 Nitrite Isotopes and Concentrations
Deployment: TN303

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: GP16 Nitrite Isotopes and ConcentrationsDeployment: TN303

Dataset acquisition description

Dataset Processing Description

Dataset: GP16 Nitrite Isotopes and Concentrations
Deployment: TN303