Dataset: Radiocarbon in methane at ocean margins
Deployment: RC0026

View Data: For data, See Dataset Metadata Page: https://www.bco-dmo.org/dataset/861576

Principal Investigator:

John D. Kessler (University of Rochester)

Scientist:

DongJoo Joung (University of Rochester)

Contact:

DongJoo Joung (University of Rochester)

BCO-DMO Data Manager:

Dana Stuart Gerlach (Woods Hole Oceanographic Institution, WHOI BCO-DMO)

Project:

Characterizing Ocean Acidification and Atmospheric Emission Caused by Methane Released from Gas Hydrate Systems along the US Atlantic Margin (Gas Hydrate Methane)

Constraining Global Coastal Ocean Methane Emissions to the Atmosphere (Coastal Methane Emissions)

Version:

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Description

Data collection in 2017 was carried out under DOE Project Award DE-FE0028980: Characterizing Ocean Acidification and Atmospheric Emission Caused by Methane Released from Gas Hydrate Systems along the US Atlantic Margin

Data collection in 2019 was carried out under NSF Project Award OCE-1851402. Subsequent analyses and data compilation were also funded by this award: Constraining Global Coastal Ocean Methane Emissions to the Atmosphere

Methods & Sampling

Dataset acquisition description

Please see the Related Publications (Methods) section for references with additional acquistion and processing details.

Radiocarbon Sample Collection at Sea:
Gases dissolved in seawater were extracted following the procedures outlined in Sparrow and Kessler (2017) and Joung et al (2019 and 2020). As detailed in these prior publications, waters were pumped through a suction hose with a discharge pump and were passed through multiple filters for removing particles. This water was then continuously passed through a gas-permeable membrane to vacuum extract the dissolved gases in the seawater.

Radiocarbon Sample Preparation in the Laboratory:
Extracted gas samples were purified and analyzed using vacuum line procedures and Accelerator Mass Spectrometry as previously detailed in Sparrow and Kessler, (2017). The volume of the whole gas sample needed for processing in the laboratory using vacuum-line techniques was determined by the CH4 concentration and the amount of carbon necessary for the Accelerator Mass Spectrometry (AMS) analysis. Careful monitoring of standards and blanks was done to ensure efficiency of purification and combustion performance.

Dissolved Methane Concentration Measurement:
Dissolved methane concentration measurements were conducted using a headspace equilibration. The concentration of CH4 in the headspace was determined using an Agilent 6850 gas chromatograph with a flame ionization detector (GC-FID), which was then translated into the original dissolved gas concentration using headspace and water volumes, along with the gas solubility.

Instrument notes:
*All apparatus and their detail specifications for the 14C-CH4 measurements can be found in Sparrow and Kessler (2017) and Joung et al. (2019).
*GC-CH4 measurements references are Weinstein et al., (2016) and Leonte et al (2017)
*14C was measured by Accelerator Mass Spectrometer (AMS) at the Keck-Carbon Cycle AMS facility at UC Irvine
*Temperature, salinity, and dissolved oxygen were measured by the CTD sensors

Data Processing Description

Dataset Processing Description

BCO-DMO Processing:
- added columns for cruise and vessel name
- combined date and time fields into ISO8601 format
- added a conventional header with dataset name, PI names, version date
- adjusted parameter names to comply with database requirements
- units removed and added to Parameter Description metadata section

More information about this dataset deployment

Funding

Award Number	Funding Source
DE-FE0028980	US Department of Energy
OCE-1851402	NSF Division of Ocean Sciences

Instruments

Accelerator Mass Spectrometer

Supplied Name: UC-Irvine Keck-Carbon Cycle AMS

Supplied Description:

14C was measured by Accelerator Mass Spectrometer (AMS) at the Keck-Carbon Cycle AMS facility at UC Irvine

Instrument Type

Generic Name: Accelerator Mass Spectrometer

Acronym: AMS

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB17/

Generic Description:

An AMS measures "long-lived radionuclides that occur naturally in our environment. AMS uses a particle accelerator in conjunction with ion sources, large magnets, and detectors to separate out interferences and count single atoms in the presence of 1x1015 (a thousand million million) stable atoms, measuring the mass-to-charge ratio of the products of sample molecule disassociation, atom ionization and ion acceleration." AMS permits ultra low-level measurement of compound concentrations and isotope ratios that traditional alpha-spectrometry cannot provide. More from Purdue University: http://www.physics.purdue.edu/primelab/introduction/ams.html

CTD - profiler

Supplied Name: CTD sensors

Supplied Description:

Temperature, salinity, and dissolved oxygen were measured by the CTD sensors

Instrument Type

Generic Name: CTD - profiler

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/130/

Generic Description:

The Conductivity, Temperature, Depth (CTD) unit is an integrated instrument package designed to measure the conductivity, temperature, and pressure (depth) of the water column. The instrument is lowered via cable through the water column. It permits scientists to observe the physical properties in real-time via a conducting cable, which is typically connected to a CTD to a deck unit and computer on a ship. The CTD is often configured with additional optional sensors including fluorometers, transmissometers and/or radiometers. It is often combined with a Rosette of water sampling bottles (e.g. Niskin, GO-FLO) for collecting discrete water samples during the cast.

This term applies to profiling CTDs. For fixed CTDs, see https://www.bco-dmo.org/instrument/869934.

Flame Ionization Detector

Supplied Name: Agilent 6850 GC-FID

Supplied Description:

Methane concentration measurements were performed in the Kessler laboratory at the University of Rochester using an Agilent 6850 gas chromatograph with a flame ionization detector (GC-FID).

Instrument Type

Generic Name: Flame Ionization Detector

Acronym: FID

Generic Description:

A flame ionization detector (FID) is a scientific instrument that measures the concentration of organic species in a gas stream. It is frequently used as a detector in gas chromatography. Standalone FIDs can also be used in applications such as landfill gas monitoring, fugitive emissions monitoring and internal combustion engine emissions measurement in stationary or portable instruments.

Flow Meter

Supplied Name: Digital flowmeter

Supplied Description:

Seawater is pumped through a digital flowmeter then on to filter housings before flowing through gas extractors

Instrument Type

Generic Name: Flow Meter

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/388/

Generic Description:

General term for a sensor that quantifies the rate at which fluids (e.g. water or air) pass through sensor packages, instruments, or sampling devices. A flow meter may be mechanical, optical, electromagnetic, etc.

Gas Chromatograph

Supplied Name: Agilent 6850 GC-FID

Supplied Description:

Methane concentration measurements were performed in the Kessler laboratory at the University of Rochester using an Agilent 6850 gas chromatograph with a flame ionization detector (GC-FID).

Instrument Type

Generic Name: Gas Chromatograph

Community Identifier: http://vocab.nerc.ac.uk/collection/L05/current/LAB02/

Generic Description:

Instrument separating gases, volatile substances, or substances dissolved in a volatile solvent by transporting an inert gas through a column packed with a sorbent to a detector for assay. (from SeaDataNet, BODC)

Pump

Supplied Name: Water pump

Supplied Description:

Seawater is pumped up to the deck by a gasoline-powered, chemical-resistant water pump
A high-performance discharge pump was used to pump water onto the vessel

Instrument Type

Generic Name: Pump

Generic Description:

A pump is a device that moves fluids (liquids or gases), or sometimes slurries, by mechanical action. Pumps can be classified into three major groups according to the method they use to move the fluid: direct lift, displacement, and gravity pumps

Parameters

Supplied Name	Supplied description	Supplied Units	Standard Name
Location	Ocean body	unitless	region
Vessel	Cruise vessel	unitless	ship
Cruise	Cruise identification	unitless	cruise_id
Station	Station identification	unitless	station
Latitude	Latitude of sample collection	decimal degrees	lat
Longitude	Longitude of sample collection	decimal degrees	lon
ISO_DateTime_UTC	Date and Time in ISO8601 format	unitless	ISO_DateTime_UTC
StnDepth	Depth of water column at the station	meters (m)	depth
SamDepth	Water depth where sample was collected	meters (m)	depth
Temperature	Temperature measured by CTD	degrees Celsius	temp
Salinity	Salinity measured by CTD	practical salinity unit (psu)	sal_ctd
DO	Dissolved oxygen measured by CTD	micromole per liter (umol/L)	O2
Water_filtered	Volume of water filtered	liter (L)	vol_filt
CH4	Dissolved methane concentrations measured by GC-FID	nanoMolar (nM)	CH4
C14_in_CH4	Radiocarbon in methane measured by Accelerator Mass Spectrometry	percent modern (pMC)	14C
Std_Dev_C14_in_CH4	Standard deviation of 14C in CH4	percent modern (pMC)	std_dev
D14C	Radiocarbon in methane measured by Accelerator Mass Spectrometry	per mil	14C
Std_Dev_D14C	Standard deviation of 14C in CH4	per mil	std_dev

Database

Contribute Data

Dataset: Radiocarbon in methane at ocean margins
Deployment: RC0026

Dataset acquisition description

Dataset Processing Description

Database

Contribute Data

Dataset: Radiocarbon in methane at ocean marginsDeployment: RC0026

Dataset acquisition description

Dataset Processing Description

Dataset: Radiocarbon in methane at ocean margins
Deployment: RC0026