Dataset: GT10-11 - Hg Speciation

Name: Mercury speciation across the US GEOTRACES North Atlantic Zonal Section from R/V Knorr KN199-04, KN204-01 in the subtropical North Atlantic Ocean from 2010-2011 (U.S. GEOTRACES NAT project)
Published: 2017-04-11
Keywords: oceans

Cite This Dataset

Spatial Extent: N:39.7 E:-9.6601 S:17.3502 W:-69.8

Temporal Extent: 2010-10-16 - 2011-12-09

Project:

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

Program:

U.S. GEOTRACES (U.S. GEOTRACES)

Principal Investigator:

Carl Lamborg (Woods Hole Oceanographic Institution, WHOI)

Co-Principal Investigator:

Chad Hammerschmidt (Wright State University)

Contact:

Katlin Bowman (Wright State University)

Chad Hammerschmidt (Wright State University)

Carl Lamborg (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

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

Version:

Version Date:

2017-04-11

Restricted:

Validated:

Yes

Current State:

Final no updates expected

Mercury speciation across the US GEOTRACES North Atlantic Zonal Section from R/V Knorr KN199-04, KN204-01 in the subtropical North Atlantic Ocean from 2010-2011 (U.S. GEOTRACES NAT project)

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Description

This dataset includes concentrations of filtered total mercury, elemental mercury, monomethylmercury and dimethylmercury from 11 demi stations (surface to 1000 meters) and 21 full stations (surface to bottom water) across the cruise path.

GT10 depths match GTC bottles. G11 depths are nominal.

Methods & Sampling

Detailed method descriptions can be found in Hammerschmidt et al. (2011), Lamborg et al. (2012), Hammerschmidt & Bowman (2012)
Sample collection: Cutter & Bruland, 2012
Sample bottles/cleaning: Hammerschmidt et al., 2012
HgT analysis:
     Fitzgerald & Gill (1979), Bloom & Fitzgerald (1988)
     Tekran Model 2500 CVAFS Mercury Detector
     Detection limit: 0.02 pM for a 200-mL sample
     Procedural duplicates: 4.8 ± 4.4 relative percent difference
     Recovery of known additions: 99 ± 5% recovery of Hg2+ addition
     Reference material: Recovery of total Hg from BCR-579 = 10.3 ± 0.6 pM (certified range = 9.5 ± 2.5 pM)
Hg0 analysis:
     Fitzgerald & Gill (1979), Bloom & Fitzgerald (1988)
     Tekran Model 2500 CVAFS Detector
     Detection limit: 0.01 pM for a 2-L sample
      Procedural duplicates: 9.5 ± 5.8 relative percent difference
     Recovery of known additions: not conducted
MMHg analysis:
     Bowman & Hammerschmidt (2011), Tseng et al. (2004), Bloom (1989)
     Tekran Model 2500 CVAFS Mercury Detector
     Detection limit: 2 - 30 fM (2-L samples)
     Procedural duplicates: 13 ± 13 relative percent difference (n = 14)
     Recovery of known additions: 105 ± 6% recovery of CH3Hg+ addition (n = 3)
DMHg analysis:
    Bowman & Hammerschmidt (2011), Tseng et al. (2004)
    Tekran Model 2500 CVAFS Mercury Detector
    Detection limit: 2 fM (2-L samples)
    Procedural duplicates: 16 ± 18 relative percent difference (n = 16)

Data Processing Description

"lt_DL" indicates that a sample was below the method detection limit

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

BCO-DMO added ISO_DateTime_UTC from the original date and time field provided by PI.

Related files and references:
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.

Bowman, K.L., Hammerschmidt, C.R. 2011. Extraction of monomethylmercury from seawater for low-femtomolar determination. Limnol. Oceanogr.: Methods 9, 121-128.

Cutter, G.A., Bruland, K.W. 2012. Rapid and noncontaminating sampling system for trace elements in global ocean surveys. Limnol. Oceanogr.: Methods 10, 425-436.

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., Bowman, K.L. 2012. Vertical methylmercury distribution in the subtropical North Pacific Ocean. Mar. Chem. 132, 77-82.

Hammerschmidt, C.R., Bowman, K.L., Tabatchnick, M.D., Lamborg, C.H. 2011. Storage bottle material and cleaning for determination of total mercury in seawater. Limnol. Oceanogr.: Methods 9, 426-431.

Lamborg, C.H., Hammerschmidt, C.R., Gill, G.A., Mason, R.P., Gichuki, S. 2012. An intercomparison of procedures for the determination of total mercury in seawater and recommendations regarding mercury speciation during GEOTRACES cruises. Limnol. Oceanogr.: Methods, 10, 90-100.

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.

Additional GEOTRACES Processing:
Version 2017-04-11 replaced version 2013-03-05.
Data version 2013-03-05 was revised with corrected sample_GEOTRC and station_GEOTRC values for duplicates of 6963 and 6971:
Changed sample_GEOTRC 6971 to 6871; station_GEOTRC 11 to 10
Changed sample_GEOTRC 6963 to 6991; station_GEOTRC 10 to 11

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.

Data Files

File
Hg_filt_joined.csv (Comma Separated Values (.csv), 95.87 KB) MD5:1b2bba06a01f5a1bc540ed14cd933d72 Primary data file for dataset ID 3860

More Information about this dataset

Funding Sources

Funding Source	Award Number
NSF Division of Ocean Sciences	OCE-0928191
NSF Division of Ocean Sciences	OCE-1132480
NSF Division of Ocean Sciences	OCE-1132515
NSF Division of Ocean Sciences	OCE-0927274

Deployments

Deployment	Synonyms	Start Date	Platform	Investigator
KN199-04	GA03 GT10 USGT-NAT-2010 KN199-4 GNAT U.S. GEOTRACES NAZT Leg 1 knorr199-4/5 Section Cruise (GA03) 316N20101015	2010-10-15	R/V Knorr	William J. Jenkins (Chief Scientist) Edward A. Boyle (Co-Chief Scientist) Gregory A. Cutter (Co-Chief Scientist)	data info
KN204-01	GA03 GT11 KN204-01A KN204-01B USGT-NAT-2011 USGNAZT GNAT 316N20111106 KN204-1	2011-11-06	R/V Knorr	Edward A. Boyle (Chief Scientist) Gregory A. Cutter (Co-Chief Scientist)	data info

Instruments

Cold Vapor Atomic Fluorescence Spectrophotometer

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.

Pump surface

Supplied Name: Underway towed fish

Supplied Description:

Instrument Type

Generic Name: Pump surface

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

Generic Description:

A source of uncontaminated near-surface seawater pumped onto the deck of the research vessel that can be sampled and analyzed. This pumped seawater supply is from an over-the-side pumping system, and is therefore different from the vessel underway seawater system.

Trace Metal Bottle

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

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

Supplied Name	Supplied description	Supplied Units	Standard Name
cruise_id	Official cruise identifier e.g. KN199-04 = R/V Knorr cruise number 199-04.	text	cruise_id
cruise_part	identifier for a segment of a leg of a cruise, where a leg may have been broken into parts: For KN204-01: part A = 11/6/2011 to 11/18/2011 (Woods Hole to Bermuda) part B = 11/19/2011 to 12/11/2011 (Bermuda to Praia, Cabo Verde)	text	cruise_part
sta	station number; provided in original data submission.	integer	sta
sample_GEOTRC	Unique identifying number for US GEOTRACES samples; ranges from 5033 to 6078 for KN199-04 and from 6112 to 8148 for KN204-01. 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
lat	latitude; north is positive	decimal degrees	lat
lon	longitude; east is positive	decimal degrees	lon
date	UTC date of sample collection	yyyymmdd	date_utc
time	UTC time	HHMM	time_utc
instrument	sample collection instrument: TMR-trace metal rosette; FISH-underway towed fish	text	instrument
depth	sample depth	meters	depth
Hg_total	concentration of total mercury	picomoles/liter	trace_metal_conc
Hg_total_flag	total mercury quality flag: 2) ok 3) questionable 4) bad analysis 5) sample lost 6) mean of replicates	integer	flag
Hg0	concentration of gaseous elemental mercury	picomoles/liter	trace_metal_conc
Hg0_flag	gaseous elemental mercury quality flag: 2) ok 3) questionable 4) bad analysis 5) sample lost 6) mean of replicates	integer	flag
MMHg	concentration of monomethylmercury	femtomoles/liter	trace_metal_conc
MMHg_flag	monomethylmercury quality flag: 2) ok 3) questionable 4) bad analysis 5) sample lost 6) mean of replicates	integer	flag
DMHg	concentration of dimethylmercury	femtomoles/liter	trace_metal_conc
DMHg_flag	dimethylmercury quality flag: 2) ok 3) questionable 4) bad analysis 5) sample lost 6) mean of replicates	integer	flag
station_GEOTRC	GEOTRACES station number; ranges from 1 through 12 for KN199-04 and 1 through 24 for KN204-01. Stations 7 and 9 were skipped on KN204-01. Some GeoFish stations are denoted as X_to_Y indicating the tow occurred between stations X and Y. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	station
depth_GEOTRC_CTD	Observation/sample depth in meters; calculated from CTD pressure. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	meters	depth
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
cast_GEOTRC	Cast identifier numbered consecutively within a station. Values were added from the intermediate US GEOTRACES master file (see Processing Description).	dimensionless	cast
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	bot_Nis
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[.xx][+/-TZ]	ISO_DateTime_UTC
ISO_DateTime_UTC	Cast 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

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Dataset: GT10-11 - Hg Speciation