https://data.amerigeoss.org/dataset/46a7ef4b-c5f8-4983-b868-9819c9d1e942
type: Dataset
title: Comparison of methane concentration and stable carbon isotope data for natural samples analyzed by discrete sample introduction module - cavity ring down spectroscopy (DSIM-CRDS) and traditional methods
description: A discrete sample introduction module (DSIM) was developed and interfaced to a cavity ring-down spectrometer to enable measurements of methane and CO2 concentrations and 13C values with a commercially available cavity ring-down spectrometer (CRDS). The DSIM-CRDS system permits the analysis of limited volume (5 - 100-ml) samples ranging six orders-of-magnitude from 100% analyte to the lower limit of instrument detection (2 ppm). We demonstrate system performance for methane by comparing concentrations and 13C results obtained by the DSIM and traditional methods for a variety of sample types, including low concentration (nanomolar) seawater and high concentration (> 90%) natural gas. The expansive concentration range the CRDS is able to analyze while being packaged in a field-portable analytical system greatly enhances functionality for investigating methane and CO2 dynamics, as well as other gases measured by laser absorption spectroscopy.
keyword: amerigeo
keyword: amerigeoss
keyword: biogeochemistry
keyword: carbon-cycle
keyword: carbon-cycling
keyword: carbon-dioxide
keyword: carbon-isotope-analysis
keyword: cavity-ring-down-spectroscopy
keyword: ckan
keyword: eastern-continental-margin-of-india
keyword: environment
keyword: gas-hydrate-resources
keyword: geo
keyword: geochemical-data
keyword: geochemistry
keyword: geoss
keyword: isotope-geochemistry
keyword: marine-chemistry
keyword: methane
keyword: methane-hydrate
keyword: national
keyword: north-america
keyword: northern-cascadia-margin
keyword: northern-u-s-atlantic-margin
keyword: ocean-characteristics
keyword: oceanography
keyword: oceans
keyword: sediment-geochemistry
keyword: stable-isotopes
keyword: temperate-northern-atlantic
keyword: temperate-northern-pacific
keyword: u-s-geological-survey
keyword: united-states
keyword: usgs
keyword: usgs-60d60d72d34e960393674818
issued: 2025-11-21T09:43:32.867998
modified: 20210827
theme: {geospatial}
contact point: Organization
  fn: John W. Pohlman
spatial: Location

US Migrating
type: Agent

Original Metadata
type: Distribution
description: The metadata original format
media type: text/xml
format: XML
access URL: https://data.usgs.gov/datacatalog/metadata/USGS.60d60d72d34e960393674818.xml
issued: 2022-08-06T18:48:53.805490
modified: 2025-11-21T09:43:32.849645

Digital Data
type: Distribution
description: Landing page for access to the data
media type: application/http
format: XML
access URL: https://doi.org/10.5066/P99B34V1
issued: 2022-08-06T18:48:53.805496
modified: 2025-11-21T09:43:32.850061