Dataset: Barium concentration and isotopic data from SAFe, collected during the 2nd GEOTRACES Intercalibration cruise (R/V Knorr KN195-08) in the eastern North Pacific during May 2009

Samples were collected on the GEOTRACES carousel, filtered to 0.2 μm or 0.45 μm (depending on filter type), acidified to pH ≈ 2 with hydrochloric acid, and stored for several years prior to processing. Aliquots containing five milliliters of seawater were cleanly subsampled from each sample, weighed, and an appropriate quantity of ¹³⁶Ba–¹³⁵Ba double spike added. Following spike–sample equilibration, barium was co-precipitated with calcium carbonate via dropwise addition of sodium carbonate. The resultant precipitate was dissolved in hydrochloric acid and twice passed through cation-exchange columns to purify Ba from matrix elements.

Samples were aspirated, desolvated, and analyzed using a 100 μL/min nebulizer, Aridus II desolvation system, and ThermoFisher Neptune multi-collector ICP-MS, respectively. All instrumentation was sitated at the WHOI Plasma Facility. Barium-isotopic compositions were calculated from simultaneous monitoring of ion beams corresponding to m/z 131 (Xe, xenon), 135 (Ba), 136 (Xe; Ba; Ce, cerium), 137 (Ba), 138 (Ba; La, lanthanum; Ce), 139 (La) and 140 (Ce).

Problem report:
Sample 4722 (surface) unclear if sample was filtered, and—if so—what filter cutoff was used.