Dataset: GP16 Mercury particulate
Deployment: TN303

Suspended particulate total mercury and monomethylmercury across the US GEOTRACES East Pacific Zonal Transect, from cruise TN303, 2013

Principal Investigator:

Carl Lamborg (University of California-Santa Cruz, UCSC)

Co-Principal Investigator:

Chad Hammerschmidt (Wright State University)

Contact:

Katlin Bowman (University of California-Santa Cruz, UCSC)

Chad Hammerschmidt (Wright State University)

Carl Lamborg (University of California-Santa Cruz, UCSC)

BCO-DMO Data Manager:

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

Project:

GEOTRACES Pacific Section: Mercury Speciation Along a Zonal Section in the Eastern Tropical South Pacific (EPZT Mercury)

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

Current State:

Final no updates expected

Deployment Synonyms:

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

Version Date:

2016-04-26

Data URL:

https://www.bco-dmo.org/dataset-deployment/643587/data

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Description

This dataset includes concentrations of suspended particulate total mercury and monomethylmercury from 18 full-depth stations (16 depths each), and 4 stations on the South American margin (5–8 depths). Suspended particle samples (1 and 51 µm) were collected with a multiple-unit large-volume in situ filtration system.

Location and timing: October–December, 2013 from Manta, Ecuador to Papeete, Tahiti.

The section included stations between 10–15 °S from the Peru margin to 152 °W north of Tahiti. Samples were collected from the surface at 2 m to the ocean floor, as deep as 5500 meters. The section captured a buoyant hydrothermal vent plume extending over 4000 km west from the East Pacific Rise.

Methods & Sampling

Dataset acquisition description

See Hg Cook Book for full methodology (PDF)
Sample collection: See Bishop et al., 2012
Particulate samples were frozen and transported to Wright State University (Dayton, OH) where they were analyzed within 3 months of collection. Filter punches were digested in acid-cleaned polypropylene containers with 8 mL of 2N HNO₃ (Baker Instra-Analyzed): Hammerschmidt & Fitzgerald, 2001
HgT analysis:
- Fitzgerald & Gill, 1979, Bloom & Fitzgerald, 1988, Bloom, 1989
- Tekran Model 2500 CVAFS Mercury Detector
- Detection limit: 0.03 pM
- Procedural duplicates: 8 ± 8% (n = 10)
- Recovery of known additions: N/A
MMHg analysis:
- Tseng et al., 2004
- Tekran Model 2500 CVAFS Mercury Detector
- Detection limit: 0.002 pM
- Procedural duplicates: 16 ± 11% (n = 16)
- Recovery of known additions: 98 ± 20% (n = 7)

“lt_DL” indicates that a sample was below the method detection limit.

Sample volumes were used to calculate picomolar concentrations of different mercury species.

Related References:

Bishop, J.K.B., Lam, P.J., Wood, T.J. 2012. Getting good particles: Accurate sampling of particles by large volume in-situ filtration.

Bloom, N. 1989. Determination of picogram levels of methylmercury by aqueous phase ethylation, followed by cryogenic gas-chromatography with cold vapor atomic fluorescence detection. Can. J. Fish. Aquat. Sci. 46, 1131–1140.

Bloom, N.S., Fitzgerald, W.F. 1988. Determination of volatile mercury species at the picogram level by low-temperature gas chromatography with cold-vapor atomic fluorescence detection. Anal. Chim Acta 208, 151–161.

Fitzgerald, W.F., Gill, G.A. 1979. Subnanogram determination of mercury by two-stage gold amalgamation applied to atmospheric analysis. Anal. Chem. 51, 1714–1720.

Hammerschmidt, C.R., Fitzgerald, W.F. 2001. Formation of artifact methylmercury during extraction from a sediment reference material. Anal. Chem. 73, 5930–5936.

Tseng, C.-M., Hammerschmidt, C.R., Fitzgerald, W.F. 2004. Determination of methylmercury in environmental matrixes by on-line flow injection and atomic fluorescence spectrometry. Anal. Chem. 76, 7131–7136.

Data Processing Description

Dataset Processing Description

BCO-DMO Processing:

- added conventional header with dataset name, PI name, version date
- renamed parameters to BCO-DMO standard and GEOTRACES convention
- added cruise_id, cruise_name
- replaced blank cells with nd (no data)
- replaced '<' with 'lt_' ('less than')

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-1232760	NSF Division of Ocean Sciences
OCE-1232979	NSF Division of Ocean Sciences

Instruments

Cold Vapor Atomic Fluorescence Spectrophotometer

Supplied Name:

Supplied Description:

Instrument Type

Generic Name: Cold Vapor Atomic Fluorescence Spectrophotometer

Acronym: CVAFS

Generic Description:

A Cold Vapor Atomic Fluorescent Spectrophotometer (CVAFS) is an instrument used for quantitative determination of volatile heavy metals, such as mercury. CVAFS make use of the characteristic of mercury that allows vapor measurement at room temperature. Mercury atoms in an inert carrier gas are excited by a collimated UV light source at a particular wavelength. As the atoms return to their non-excited state they re-radiate their absorbed energy at the same wavelength. The fluorescence may be detected using a photomultiplier tube or UV photodiode.

McLane Pump

Supplied Name:

Supplied Description:

Instrument Type

Generic Name: McLane Pump

Generic Description:

McLane pumps sample large volumes of seawater at depth. They are attached to a wire and lowered to different depths in the ocean. As the water is pumped through the filter, particles suspended in the ocean are collected on the filters. The pumps are then retrieved and the contents of the filters are analyzed in a lab.

Trace Metal Bottle

Supplied Name:

Supplied Description:

Trace metal rosette

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

Supplied Name	Supplied description	Supplied Units	Standard Name
cruise_id	Official cruise identifier	unitless	cruise_id
cruise_name	cruise name used by PI	unitless	cruise_name
STNNBR	station number; provided in original data submission.	integer	sta
GEOTRC_SAMPNO	Unique identifying number for US GEOTRACES sample. PI-supplied values were identical to those in the intermediate US GEOTRACES master file. Originally submitted as 'sample'; this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	integer	sample
GEOTRC_EVENTNO	Unique identifying number for US GEOTRACES sampling events. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	event
CASTNO	Cast identifier numbered consecutively within a station. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	cast
lat	Latitude; north is positive. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	decimal degrees	lat
lon	Lonitude; east is positive. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	decimal degrees	lon
ISO_DATETIME_UTC_START_EVENT	Event start date/time (UTC) formatted to ISO8601 standard. T indicates start of time string; Z indicates UTC. Calculated from original date and time fields.	YYYY-mm-ddTHH:MM:SS.ssZ	ISO_DateTime_UTC
SAMPNO	Sample number; Values were added from the intermediate US GEOTRACES master file (see Processing Description).	unitless	sample
depth_pump	Depth of pump sample as reported by PI (CTD coordinates as included in the Pacific cruise Report.)	meters	depth
Hg_TP_CONC_PUMP	Total particulate concentration of mercury	picomolar	trace_metal_conc
Hg_TP_CONC_PUMP_FLAG_W	Quality flag: 2) ok; 3) questionable; 4) bad analysis; 5) sample lost; 6) mean of replicates; 9) sample was not collected for Hg analysis	unitless	q_flag
MMHg_TP_CONC_PUMP	Total particulate concentration of monomethylmercury	femtomolar	trace_metal_conc
MMHg_TP_CONC_PUMP_FLAG_W	Quality flag: 2) ok; 3) questionable; 4) bad analysis; 5) sample lost; 6) mean of replicates; 9) sample was not collected for Hg analysis	unitless	q_flag

Database

Contribute Data

Dataset: GP16 Mercury particulate
Deployment: TN303

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: GP16 Mercury particulateDeployment: TN303

Dataset acquisition description

Dataset Processing Description

Dataset: GP16 Mercury particulate
Deployment: TN303