Helium isotope with helium and neon concentration data from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018 (NCEI Accession 0291766)

This dataset contains data collected on R/V Roger Revelle during cruise RR1814 in the Gulf of Alaska and North Pacific Ocean from 2018-09-24 to 2018-10-21. These data include depth. The instruments used to collect these data include Isotope-ratio Mass Spectrometer, Niskin bottle, and Quadrupole Mass Spectrometer. These data were collected by Christopher R. German and William J. Jenkins of Woods Hole Oceanographic Institution as part of the "Measurement of Helium Isotopes on the U.S. GEOTRACES Alaska-Tahiti Section (GP15) (PMT Helium Isotopes)" and "US GEOTRACES Pacific Meridional Transect (U.S. GEOTRACES PMT)" projects and "U.S. GEOTRACES (U.S. GEOTRACES)" program. The Biological and Chemical Oceanography Data Management Office (BCO-DMO) submitted these data to NCEI on 2021-10-08.

The following is the text of the dataset description provided by BCO-DMO:

GP15 He Isotope C(He) and C(Ne) - Leg 1

Dataset Description:
Acquisition Description:
Water samples were transferred from Niskin bottles and stored in crimped copper tubing. Gases were extracted from the water samples in a shore-based vacuum system and stored in aluminosilicate glass ampoules. The extracted gases were analyzed for helium and neon concentrations using ion counting in a quadrupole mass spectrometer and for helium isotopes using a magnetic sector dual-collecting isotope ratio mass spectrometer. Details are given in Jenkins et al. (2019) and Stanley et al. (2007).

Note: Natural and bomb tritium will decay to 3He in the copper tubing water sample container between the time the water sample was acquired and when the gases were extracted. We account for this using tritium concentrations estimated from a prior (2015) cruise occupation extrapolated in time and interpolated in space to the sample location and time. The size of this effect is significant in shallow, northern waters and vanishingly small in deeper and more southerly waters.