[AT50-12 IC Data] - Porewater geochemical data from sediment pushcores collected from Southern California Seeps in July 2023 on R/V Atlantis cruise AT50-12 (Collaborative Research: Redefining the footprint of deep ocean methane seepage for benthic ecosystems)

Cores were sectioned into 1-3 centimeter (cm) horizons, and porewater was extracted shipboard using an argon-pressurized squeezer. Porewater samples were frozen at sea and thawed just before analysis.

We report concentrations of fluoride, acetate, formate, chloride, bromide, nitrate, sulfate, thiosulfate, and phosphate anions and lithium, sodium, potassium, magnesium, and calcium cations. Measurements were made using the Thermo Dual Dionex Integrion HPIC ion chromatography system with either a 250 millimeter (mm) Dionex IonPac AS19-4 micrometer (um) column (anions) or a 250 mm Dionex IonPac CS16-4um column (cations), in the Resnick Water and Environment Laboratory at the California Institute of Technology (Caltech).