Dataset: GP16 Lead dissolved
Deployment: TN303

Dissolved Pb data from US GEOTRACES East Pacific Zonal Transect

Principal Investigator:

Arthur Russell Flegal (University of California-Santa Cruz, UCSC)

Contact:

Ralph Till (University of California-Santa Cruz, UCSC)

BCO-DMO Data Manager:

Danie Kinkade (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

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

Current State:

Preliminary and in progress

Deployment Synonyms:

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

Data URL:

https://www.bco-dmo.org/dataset-deployment/646847/data

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Description

Dissolved lead concentrations of the transect in samples taken from the GEOTRACES GO-FLO rosette surface casts and filtered through a 0.2um Acropak capsule filter.

Methods & Sampling

Dataset acquisition description

Sampling:
Sample bottles were LDPE and cleaned in accordance with the GEOTRACES cookbook (http://www.geotraces.org/images/stories/documents/intercalibration/Cookbook.pdf). Sample bottles were stored in weak (~0.1 N) HNO3, and were emptied before shipping.

Samples were collected using the U.S. GEOTRACES sampling system of 24 Teflon-coated GO-FLO bottles (Cutter and Bruland, 2012). At each station, the bottles were deployed open and tripped on ascent at 3 m/min. GO-FLOs were sampled in the GEOTRACES trace metal clean sampling van that contained HEPA-filtered air.

During sampling, the GO-FLO bottles were pressurized to ~0.4 atm with HEPA-filtered air, and their spigots were fitted with an acid-cleaned piece of Bev-a-Line tubing that fed into an Acropak-200 Supor capsule filter (0.2 µm pore size made of polyethersulfone). Before use, this filter had been filled with filtered surface seawater that had been acidifed to pH 2 with trace metal clean HCl and left overnight to rinse. Before collecting any subsamples, at least 500mL of seawater was passed through the filter (while eliminating air bubbles in the capsule reservoir). Sample bottles were rinsed three times with 10% sample volume before filling. Acropak filters were used for at most 3 casts before a new filter was used, and they were stored empty in a refrigerator while not in use. GEOFish surface samples were taken using an all-plastic "towed fish" pumping system as described in Bruland et al. 2005 at approximately 3 m depth and were similarly filtered and sampled.

Samples were acidified at sea with the equivalent of 4mL quartz-distilled 6M HCl per liter of seawater (resulting in pH 1.7-1.8). Samples were sitting acidified for several months before analysis back in the laboratory.

Analysis:
Samples were analyzed using the method of Ndung’u et. al. (2003) with adaptations from Zurbrick, et. al. (2013). Aliquots of samples are poured in to 15mL LDPE bottles for analysis. Samples, blanks, reference materials and standards are all treated equally. They are buffered with trace metal clean ammonium acetate (pH 9) in line and sent across a Toyopearl AF-Chelate 650 M resin column. The column is rinsed with diluted ammonium acetate, and eluted in 1.5N quartz distilled nitric acid (with added bismuth as an internal standard) into the injector of the HR-ICP-MS. Counts of lead are measured throughout the elution, yielding a curve which is then integrated to give our raw values.

Standards are made by spiking lead into low concentration seawater. Blanks are 24mL HCl in Milli-Q. Reference materials used were SAFe S1, SAFe D2, and GEOTRACES reference samples GS and GD. Standard curves are run at the beginning and the end of runs and reference materials and blanks are run throughout (every 10 or less samples).

Data Processing Description

Dataset Processing Description

Flegal Lab Processing:
For every sample, standard, blank and reference, we integrate an elution peak. We used a seawater standard calibration curve for lead. We subtracted a process blank from every sample. We checked that reference samples analyzed and processed in the same way resulted in reasonable values. NOTE: concentration values are in parts per billion units.

BCO-DMO Processing:
- added conventional header with dataset name, PI name, version date
- renamed parameter names to GEOTRACES standard naming conventions
- edited Pb conc. values from 14 decimal precision to 2 decimal precision.
- split GeoFish samples into a separate column from GO-FLO bottle samples.
- sample values were place in station order for all sample numbers.
- nominal depth for GeoFish samples was edited from 'surface' to 3.5 meters
- removed one duplicate sample (8346) entered as both a bottle and GeoFish sample (master event and GeoFish cast logs confirmed the sample to be from GeoFish, therefore the bottle entry was deleted).
- added columns by joining the submitted data with an Events Master file (see Additional GEOTRACES Processing).

Additional GEOTRACES Processing:
As was done for the GEOTRACES-NAT data, 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:

cruise_id, EXPOCODE,SECT_ID, STNNBR, CASTNO, GEOTRC_EVENTNO, GEOTRC_SAMPNO, GEOTRC_INSTR, SAMPNO, GF_NO, BTLNBR, BTLNBR_FLAG_W, DATE_START_EVENT, TIME_START_EVENT, ISO_DATETIME_UTC_START_EVENT, EVENT_LAT, EVENT_LON, DEPTH_MIN, DEPTH_MAX, BTL_DATE, BTL_TIME, BTL_ISO_DATETIME_UTC, BTL_LAT, BTL_LON, ODF_CTDPRS, SMDEPTH, FMDEPTH, BTMDEPTH, CTDPRS, CTDDEPTH.

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 and ODF_Bottle datasets. Non-bottle parameters, including those from GeoFish tows, Aerosol sampling, and McLane Pumps, were taken from the TN303 Event Log (version 30 Oct 2014). Where applicable, pump information was taken from the PUMP_Nuts_Sals dataset.

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-1234213	NSF Division of Ocean Sciences

Instruments

GeoFish Towed near-Surface Sampler

Supplied Name:

Supplied Description:

Instrument Type

Generic Name: GeoFish Towed near-Surface Sampler

Acronym: GeoFish

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/31/

Generic Description:

The GeoFish towed sampler is a custom designed near surface (<2m) sampling system for the collection of trace metal clean seawater. It consists of a PVC encapsulated lead weighted torpedo and separate PVC depressor vane supporting the intake utilizing all PFA Teflon tubing connected to a deck mounted, air-driven, PFA Teflon dual-diaphragm pump which provides trace-metal clean seawater at up to 3.7L/min. The GeoFish is towed at up to 13kts off to the side of the vessel outside of the ship's wake to avoid possible contamination from the ship's hull. It was developed by Geoffrey Smith and Ken Bruland (University of California, Santa Cruz).

GO-FLO Bottle

Supplied Name:

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.

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
cruise_id	Cruise identifier.	dimensionless	cruise_id
EXPOCODE	Unique cruise identifier.	dimensionless	EXPOCODE
STNNBR	Station Number	unitless	station
GEOTRC_EVENTNO	GEOTRACES Event Number. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	event
EVENT_LAT	latitude in decimal degrees at the start of the event (according to the EPZT event log)	decimal degrees	lat
EVENT_LON	longitude in decimal degrees at the start of the event (according to the EPZT event log)	decimal degrees	lon
GEOTRC_SAMPNO	GEOTRACES sample number	unitless	sample
depth_PI	Sample depth as reported by PI.	meters	depth
Pb_D_CONC_FISH	Dissolved lead concentration as measured from the GeoFish sampler	ppb: parts per billion	trace_metal_conc
Pb_D_CONC_BOTTLE	Dissolved lead concentration as measured from GO-FLO bottles	ppb: parts per billion	trace_metal_conc
CASTNO	Cast Number. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	cast
BTLNBR	Bottle number. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	bottle
BTLNBR_FLAG_W	Bottle quality flag: 2 = good; 3 = questionable; 4 = bad; 9 = missing data. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	q_flag
ISO_DATETIME_UTC_START_EVENT	ISO 8601:2004 standard date and time at start of event. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	year, month, day, hour, minute, seconds	ISO_DateTime_UTC
CTDDEPTH	CTD bottle firing depth. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth
CTDPRS	CTD pressure. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	press
ODF_CTDPRS	ODF CTD pressure. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	press
SMDEPTH	Saunders-Mantyla depth (integrated, uses dynamic height). Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth
FMDEPTH	Fofonoff-Millard depth (non-integrated). Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth
BTMDEPTH	Bottom depth. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth_w
DATE_START_EVENT	date of event start	unitless	date
TIME_START_EVENT	time of event start	unitless	time_start

Database

Contribute Data

Dataset: GP16 Lead dissolved
Deployment: TN303

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: GP16 Lead dissolvedDeployment: TN303

Dataset acquisition description

Dataset Processing Description

Dataset: GP16 Lead dissolved
Deployment: TN303