Dataset: GT10-11 - Hg Aerosol
Deployment: KN199-04

Concentration of atmospheric aerosol total mercury (Hg) from the 2010 and 2011 U.S. GEOTRACES cruises

Co-Principal Investigator:

Chad Hammerschmidt (Wright State University)

Carl Lamborg (Woods Hole Oceanographic Institution, WHOI)

Contact:

Gretchen Swarr (Woods Hole Oceanographic Institution, WHOI)

BCO-DMO Data Manager:

Shannon Rauch (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:

31 Dec 2012

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:

2013-03-05

Data URL:

https://www.bco-dmo.org/dataset-deployment/455719/data

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Description

This dataset includes concentrations of atmospheric aerosol total mercury across the North Atlantic Zonal Transect.

Methods & Sampling

Dataset acquisition description

In general, the cruise path was contained from 15 to 40 N and 19 to 70 W. Aerosols were collected by Tisch high-volume aerosol sampler mounted on the 03 deck of the R/V Knorr, forward of the main stack. Sampling was sector-controlled to collect air only arriving at the ship from over the bow, to avoid sampling stack gases and debris associated with science activities on the back deck.

Samples were frozen and transported to Woods Hole Oceanographic Institution (Woods Hole, MA) where they were analyzed within 3 months of collection. The filter swaths that were provided were digested in acid-cleaned polypropylene containers with 5 mL of 2N HNO3, heated to 60 degrees C and sonicated. Following digestion, 1 mL of BrCl was added directly to the digestate (Lamborg et al., 1995, Morton et al., in press).

Total mercury analysis:
- Fitzgerald & Gill, 1979, Bloom & Fitzgerald, 1988, Bloom, 1989.
- Tekran Model 2500 CVAFS Mercury Detector
- Detection limit: 50 fmoles
- Procedural duplicates: 3 ± 2 percent r.s.d. (n=24)
- Results are presented in filter- and reagent-blank corrected form.

Data Processing Description

Dataset Processing Description

Quality Flags:
2 = ok
3 = questionable
4 = bad analysis
5 = sample lost
6 = mean of replicates
9 = sample was not collected for Hg analysis

'< DL' indicates that a sample was below the method detection limit Sampling metadata (location, flow rates, sampling duration, etc) are courtesy of Rachel Shelley and Bill Landing (FSU).

BCO-DMO made the following edits:
- Replaced 'not available' with 'nd' to indicate 'no data'.
- Separated each original date-time field to month, day, year, and time fields.
- Added the cruise_id column.

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-0927274	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

Instruments

Aerosol Sampler

Supplied Description:

Aerosols were collected by Tisch high-volume aerosol samplers.

Instrument Type

Generic Name: Aerosol Sampler

Acronym: Aerosol_Sampler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/13/

Generic Description:

A device that collects a sample of aerosol (dry particles or liquid droplets) from the atmosphere.

Cold Vapor Atomic Fluorescence Spectrophotometer

Supplied Description:

A Tekran Model 2500 CVAFS Mercury Detector was used. See the manufacturer's product fact sheet (PDF; opens in new window/tab).

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.

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.	text	cruise_id
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 'GEOTRACES #', this parameter name has been changed to conform to BCO-DMO's GEOTRACES naming conventions.	unitless	sample
year_start	4-digit year (GMT) at start of sampling event.	YYYY	year_start
month_start	2-digit month of year (GMT) at start of sampling event.	mm (01 to 12)	month_start
day_start	2-digit day of month (GMT) at start of sampling event.	dd (01 to 31)	day_start
time_start	Time (GMT) in HHMM format at start of sampling event; 24-hour clock.	HHMM	time_start
lat_start	Latitude at start of sampling event. North = Positive.	decimal degrees	lat_start
lon_start	Longitude at start of sampling event. West = Negative.	decimal degrees	lon_start
year_end	4-digit year (GMT) at end of sampling event.	YYYY	year_end
month_end	2-digit month of year (GMT) at end of sampling event.	mm (01 to 12)	month_end
day_end	2-digit day of month (GMT) at end of sampling event.	dd (01 to 31)	day_end
time_end	Time (GMT) in HHMM format at end of sampling event; 24-hour clock.	HHMM	time_end
lat_end	Latitude at end of sampling event. North = Positive.	decimal degrees	lat_end
lon_end	Longitude at end of sampling event. West = Negative.	decimal degrees	lon_end
run_time	Total run time in hours.	hours	no_bcodmo_term
flow_rate	Flow rate in cubic meters per minute.	m^3/min	no_bcodmo_term
vol_tot	Total volume sampled in cubic meters.	m^3	sample_volume
Hg_tot	Total mercury.	pg/m^3	metal_conc_air
Hg_tot_rsd	Relative standard deviation (RSD) of Hg_tot.	%	rsd
Hg_tot_sd	Standard deviation of Hg_tot.	pg/m^3	no_bcodmo_term
Hg_tot_q_flag	Quality flag for Hg_tot.	unitless	q_flag
filter	Filter type.	text	instrument
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).	unitless	station
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).	unitless	event
ISO_DateTime_UTC_start	Date and time (UTC) variable recorded at the start of 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_end	Date and time (UTC) variable recorded at the end of 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

Database

Contribute Data

Dataset: GT10-11 - Hg Aerosol
Deployment: KN199-04

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: GT10-11 - Hg AerosolDeployment: KN199-04

Dataset acquisition description

Dataset Processing Description

Dataset: GT10-11 - Hg Aerosol
Deployment: KN199-04