Data Processing:
The raw counts from the HR-ICP-MS analyses were first corrected for any instrument blank derived from the 10% nitric acid and In solution repeatedly analyzed during the instrumental analyses. Following this, each sample was corrected for machine drift and variation in instrumental sensitivity during analysis using the added 115In as well as instrument mass bias using elemental standards for Fe, Zn, Ni, Cu, Pb, and Cd. Subsequently, all counts for isotope spiked elements were converted to concentration in nmol/kg based on the weight of the sample and known concentrations of the added isotope spike mixture. The counts for the monoisotopic elements were converted to concentration units using the matrix-matched standard curves, which were run through the SeaFAST themselves as samples. It should be noted that all Cd concentrations are reported based on the 114/111Cd ratio.

For every 40 seawater samples at least 24 "Procedure blanks" were included throughout the run (every 10 seawater samples). These process blanks consisted of freshly acidified milli-Q (MQ) water spiked with a diluted version of the isotope spike mixture. Each blank was processed identically to a sample in an attempt to account for contamination coming from solutions (buffer, eluent) used or the SeaFAST itself. The MQ water is typically collected from various supplies at Texas A&M to ensure that the "procedure blank" is not derived from the MQ water itself. After conversion to concentration units, the most consistent procedure blank values for each metal are used to subtract an average procedure blank from all sample concentrations determined during that run. Each run, an internal standard was analyzed six times and an external standard (such as SAFe water) was analyzed two times as a "check" of our long-term precision and accuracy.

Quality Control:
For detection limits, accuracy, and precision information, refer to the Supplemental File Detection_Limits_Accuracy_Precision_817259 (PDF)

Quality Flags:
Data were flagged using the SeaDataNet quality flag scheme. For more information on SeaDataNet flags, see: https://www.geotraces.org/geotraces-quality-flag-policy/ and https://www.seadatanet.org/Standards/Data-Quality-Control

SeaDataNet quality flag definitions:
0 = No quality control;
1 = Good value;
2 = Probably good value;
3 = Probably bad value;
4 = Bad value;
5 = Changed value;
6 = Value below detection;
7 = Value in excess;
8 = Interpolated value;
9 = Missing value;
A = Value phenomenon uncertain.

BCO-DMO Processing:
- renamed fields;
- added date/time columns in ISO8601 format;
- 2021-04-15 (v2): made the following corrections:
changed Event_ID to 6449 for Sample_ID numbers 12147, 12151, 12155, and 12161;
added Start_Time_UTC, Start_Latitude, and Start_Longitude to Event_ID 6405 (these values were obtained from dataset https://www.bco-dmo.org/dataset/762056)