Dataset: GT10-11 - Nitrate isotopes
Deployment: KN199-04

Nitrogen and Oxygen isotope ratios of dissolved nitrate

Principal Investigator:

Daniel M. Sigman (Princeton University)

Co-Principal Investigator:

Karen L. Casciotti (Stanford University)

Contact:

Alexa Weigand (Princeton University)

BCO-DMO Data Manager:

Nancy Copley (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

U.S. GEOTRACES North Atlantic Transect (GA03) (U.S. GEOTRACES NAT)

Current State:

Final no updates expected

Version:

2014-02-2

Deployment Synonyms:

GA03, GT10, USGT-NAT-2010, KN199-4, GNAT, U.S. GEOTRACES NAZT Leg 1, knorr199-4/5, Section Cruise (GA03), 316N20101015

Version Date:

2014-02-21

Data URL:

https://www.bco-dmo.org/dataset-deployment/455958/data

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Description

Isotope Analysis conducted using the Denitrifier Method on all samples received with nitrate concentrations greater than 0.30 uM nitrate. Nitrite removal performed where noted in the comments section.

Results are published in Marconi et al (2015).

DMO Note: Fully unrestricted data, including the dNO3 columns served on 2018-12-26. Previous version of revised data was served on 12 March 2014. Original data were served in March 2013.

Please note that data may not be final, pending intercalibration results and further analysis. If you are interested in following changes to US GEOTRACES data, there is an RSS feed available from the GEOTRACES-NAT project page.

Methods & Sampling

Dataset acquisition description

Sampling and Analytical Methodology: Seawater samples were processed in accordance with the published Denitrifier Method (citation provided below under Related Files and References). All isotopes analyses were performed on a MAT253 Thermo IRMS equipped with a custom-sample preparation system. With this system, we were able to achieve an overall standard deviation of 0.04 per mil for d15N-NO3 analyses and 0.09 per mil for d18O-NO3 analyses.

Data Processing Description

Dataset Processing Description

Data Processing: Individual data points have been averaged with standard deviations reported. Please see papers cited under Related Files and References for equations applied to derive final data.

BCO-DMO Processing Notes:
- Modified parameter names to conform with BCO-DMO naming conventions.
- Replaced blanks with 'nd'.
- Added 'cruise_id' based on the 'cruise_name' provided.
- Moved 2010 above 2011 rows, sorted station and depth low-to-high
- removed 'GT-' from the sample number so it would match the master file

Additional GEOTRACES Processing:
After the data were submitted to the International Data Management Office, BODC, the office noticed that important identifying information was missing in many datasets. With the agreement of BODC and the US GEOTRACES lead PIs, BCO-DMO added standard US GEOTRACES information, such as the US GEOTRACES event number, to each submitted dataset lacking this information. To accomplish this, BCO-DMO compiled a 'master' dataset composed of the following parameters: station_GEOTRC, cast_GEOTRC (bottle and pump data only), event_GEOTRC, sample_GEOTRC, sample_bottle_GEOTRC (bottle data only), bottle_GEOTRC (bottle data only), depth_GEOTRC_CTD (bottle data only), depth_GEOTRC_CTD_rounded (bottle data only), BTL_ISO_DateTime_UTC (bottle data only), and GeoFish_id (GeoFish data only). This added information will facilitate subsequent analysis and inter comparison of the datasets.

Bottle parameters in the master file were taken from the GT-C_Bottle_GT10, GT-C_Bottle_GT11, ODF_Bottle_GT10, and ODF_Bottle_GT11 datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the Event_Log_GT10 and Event_Log_GT11 datasets. McLane pump cast numbers missing in event logs were taken from the Particulate Th-234 dataset submitted by Ken Buesseler.

A standardized BCO-DMO method (called "join") was then used to merge the missing parameters to each US GEOTRACES dataset, most often by matching on sample_GEOTRC or on some unique combination of other parameters.

If the master parameters were included in the original data file and the values did not differ from the master file, the original data columns were retained and the names of the parameters were changed from the PI-submitted names to the standardized master names. If there were differences between the PI-supplied parameter values and those in the master file, both columns were retained. If the original data submission included all of the master parameters, no additional columns were added, but parameter names were modified to match the naming conventions of the master file.

See the dataset parameters documentation for a description of which parameters were supplied by the PI and which were added via the join method.

More information about this dataset deployment

Funding

Award Number	Funding Source
OCE-0960802	NSF Division of Ocean Sciences

Instruments

GO-FLO Bottle

Supplied Description:

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.

Niskin bottle

Supplied Description:

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
cruise_id	Official cruise identifier e.g. KN199-04 = R/V Knorr cruise number 199-04	dimensionless	cruise_id
cruise_name	project designated cruise name	dimensionless	cruise_name
station_GEOTRC	GEOTRACES station number	dimensionless	station
cast_GEOTRC	Cast identifier numbered consecutively within a station. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	cast
lat	latitude; North is positive	decimal degrees	lat
lon	longitude; East is positive	decimal degrees	lon
event_GEOTRC	Unique identifying number for US GEOTRACES sampling events; ranges from 2001 to 2225 for KN199-04 events and from 3001 to 3282 for KN204-01 events. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	event
sample_GEOTRC	Unique identifying number for US GEOTRACES samples	dimensionless	sample
sample_bottle_GEOTRC	Unique identification numbers given to samples taken from bottles; ranges from 1 to 24; often used synonymously with bottle number. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	sample
bottle_GEOTRC	Alphanumeric characters identifying bottle type (e.g. NIS representing Niskin and GF representing GOFLO) and position on a CTD rosette. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	bottle
BTL_ISO_DateTime_UTC	Date and time (UTC) variable recorded at the bottle sampling time in ISO compliant format. Values were added from the intermediate US GEOTRACES master file (see Processing Description). This standard is based on ISO 8601:2004(E) and takes on the following form: 2009-08-30T14:05:00[.xx]Z (UTC time)	YYYY-mm-DDTHH:MM:SS.SSZ	ISO_DateTime_UTC
date	date of sampling; gmt date	unitless	date
sample_id	PI provided sample identification incorporating station-cast-bottle numbers	unitless	sample
d15N_NO3	Nitrogen isotopic composition (15N/14N) of nitrate relative to atmospheric N2	per mil (ppt) vs. air	dN15_NO3
d15N_NO3_sd	standard deviation of measured Nitrogen isotopic composition (15N/14N) of nitrate relative to atmospheric N2	per mil (ppt) vs. air	std_dev
d18O_NO3	Oxygen isotopic composition (18O/16O) of nitrate relative to SMOW (Vienna Standard Mean Ocean Water)	per mil (ppt) vs. SMOW	d18O_NO3
d18O_NO3_sd	standard deviation of measured Oxygen isotopic composition (18O/16O) of nitrate	per mil (ppt) vs. SMOW	std_dev
comment	comments pertaining to the sample	unitless	comment
depth_GEOTRC_CTD	Observation/sample depth in meters; calculated from CTD pressure. PI-supplied values differed those in the intermediate US GEOTRACES master file and are reported as depth_PI	meters	depth

Database

Contribute Data

Dataset: GT10-11 - Nitrate isotopes
Deployment: KN199-04

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: GT10-11 - Nitrate isotopesDeployment: KN199-04

Dataset acquisition description

Dataset Processing Description

Dataset: GT10-11 - Nitrate isotopes
Deployment: KN199-04