Measurements of radium isotopes (224Ra, 228Ra and 226Ra) in water column samples collected aboard R/V Point Sur cruise PS19_14 in the Gulf of Mexico from 2019-01-27 to 2019-01-28

This dataset contains measurements of radium isotopes (224Ra, 228Ra and 226Ra) in water column samples collected aboard R/V Point Sur cruise PS19_14 in the Gulf of Mexico from 2019-01-27 to 2019-01-28. The dataset also includes the location, date, time, and depth of the sample collection. Water samples were collected from Niskin bottles during a CTD cast at the Megaplume site as well as via bucket sampling from the sea surface in a transect extending both up current and down current of the hydrocarbon seep. Sample volumes varied between 19.4 and 41.4 L. Sample volumes were passed slowly over acrylic fibers impregnated with MnO2 to quantitatively sorb dissolved radium isotopes, then counted immediately on a Radium Delayed Coincidence Counter (produced by Scientific Computer Instruments) for total 224Ra and subsequently three weeks later for supported 224Ra. The difference between these measurements represents the excess 224Ra, serving as our tracer of hydrocarbons in the marine environment. The samples were later analyzed for 226Ra on a radon emanation line and for 228Ra via a gamma spectrometer (produced by Ortec). These data are used to understand the distribution of radium isotopes in and around an area of the water column that is actively discharging hydrocarbons. The cruise documentation was provided for the R/V Point Sur cruise PS19_14, led by chief scientist Dr. Richard Peterson.