Samples were collected on the GEOTRACES carousel, filtered to 0.2 \u03bcm or 0.45 \u03bcm (depending on filter type), acidified to pH \u2248 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 \u00b9\u00b3\u2076Ba\u2013\u00b9\u00b3\u2075Ba double spike added. Following spike\u2013sample 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.
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Samples were aspirated, desolvated, and analyzed using a 100 \u03bcL/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).
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Problem report:
\nSample 4722 (surface) unclear if sample was filtered, and\u2014if so\u2014what filter cutoff was used.
Data reduction was performed in MATLAB using the baseline-corrected ion beam output from the instrument software. Barium-isotopic compositions were calculated using an iterative, three-dimensional geometric interpretation of the double spike problem, with additional nested loops for interference corrections. All sample compositions are reported as parts per one thousand deviations (i.e., \u2030; per mille) relative to NIST SRM 3104a.
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Quality Control:\u00a0Refer to the Certified Reference Materials (CRMs) supplemental file (PDF).
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\"_FLAG\" columns follow the ODV flag scheme, defined as:
\n1 =\u00a0Good Value: Used when replicate samples were analyzed for a particular concentration/isotopic composition.
\n2 =\u00a0Probably Good Value: Used when the reported value reflects analysis of a single replicate.
\n3 =\u00a0Probably Bad Value: Used when a value appears abnormally high or low (oceanographically inconsistent) based on adjacent depths or typical profile variability and shape using the context of relevant nearby stations.
\n6 =\u00a0Value Below Detection Limit: Used when value is below the detection limit for that given element. Empty values are reported rather than zero or a detection limit value.
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BCO-DMO Processing:
\n- modified parameter names (replaced spaces w/ underscores; removed units);
\n- replaced blanks (no data) with \"nd\";
\n- 06 August 2019: replaced version 1 with version 2 of dataset (corrections made in\u00a0Ba_138_134_D_DELTA_BOTTLE column).