Seawater Oxygen Isotopes Community

The oxygen isotope ratio (δ18O) of seawater is a powerful tracer of the global water cycle. Seawater δ18O provides valuable information on the exchange of water between the ocean and atmosphere, ocean upwelling and advection, and continental ice sheet volume (on glacial-interglacial and longer timescales). As such, observational seawater δ18O data are essential for tracking hydrologic changes in the modern ocean, benchmarking isotope-enabled Earth system models, and calibrating paleoclimate proxies of past ocean variability based on the δ18O of marine carbonates.

In recognition of the value of seawater δ18O data to the Earth science community and the growing number of new seawater δ18O data sets, this EarthChem community was created to serve as a dedicated and actively-curated data repository for seawater δ18O data. The submission template contains descriptive and standardized metadata fields that align with FAIR data principles.

This effort was initiated in 2020 by the Past Global Changes (PAGES) CoralHydro2k team with support from the PAGES Data Stewardship Scholarship.

It builds on earlier activities in the 1990s to gather δ18Osw data that resulted in the NASA Goddard Institute for Space Studies (GISS) Global Seawater Oxygen-18 Database.

The PAGES CoralHydro2k Seawater δ18O Database Project is a community-led effort to recover hidden seawater oxygen isotope datasets from the global ocean and develop a new, machine-readable, and metadata-rich database for seawater δ18O data. Questions about the project can be directed to Alyssa Atwood ( or Kristine DeLong (

Submission Guidelines

We recommend reviewing the general ECL submission Guidelines Page for more information on best practices when submitting a dataset.

For improved discovery of your dataset, please include  ‘seawater d18O’ under keywords in the online submission form.

The following information is considered the minimum required metadata that should be included with all seawater δ18O data upon submission to this community.

  • Collection date
  • Latitude
  • Longitude
  • Depth
  • Delta 18O
  • Reference standard (e.g. VSMOW, SMOW)
  • Sample ID
  • Delta 18O analysis technique (e.g. cavity ring-down spectroscopy or isotope ratio mass spectrometry)
  • Delta 18O analysis location (university or institute name)
  • Publication citation and DOI (if published data)
  • Submitter information (name, affiliation, contact information)

Additional recommended metadata includes but is not limited to:

  • Site name or geographic area
  • Collection time
  • Delta 18O error (analytical precision)
  • Cruise ID
  • Cruise report
  • Delta 2H
  • Temperature
  • Salinity
  • Location type (e.g. open ocean, bay, lagoon, estuary)
  • Location description (E.g. coral reef site, groundwater or riverine input, depth and geometry of bay or lagoon, distance from coastline, major currents)

Data Template

Download Template