Dissolved Cr concentration and stable isotope data presented in “Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and ?53Cr distributions in the ocean interior” (Janssen et al., 2021, EPSL).

***** Dataset abstract *****

This dataset presents all of the dissolved Cr data included and discussed in “Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and ?53Cr distributions in the ocean interior” (Janssen et al., 2021, EPSL). Three primary datasets are included:
(i) Dissolved [Cr], [Cr(III)] and d53Cr in samples from shipboard particle regeneration incubations conducted in the subantarctic Southern Ocean.
(ii) Dissolved [Cr] in porewater samples from a sediment core collected in the Tasman Sea in primarily calcareous sediments, along with [Cr] and ?53Cr in overlying bottom waters.
(iii) A compilation of intermediate and deep water dissolved [Cr] and ?53Cr from seawater samples from the Southern, Pacific and Atlantic Oceans.

***** Sampling and Analysis *****

Dissolved seawater samples were collected from the following oceanographic cruises: RV Investigator expeditions IN2018_V02 (Mar-2018) and IN2018_V04 (Sept-Oct 2018), ACE Legs 1 (Dec-2016 to Jan-2017) and 2 (Jan-2017 to Feb-2017), GEOTRACES section GP13 (Australian leg, May-June 2011), RV Meteor cruise M77/4 (Jan-Feb 2009), Line P cruise 2012-13 (Aug-2012), and RV Discovery cruise DY110 (Oct-Nov 2019) (Figure 1). Further analyses were performed on bottom and pore waters (IN2018V_04) and on samples from shipboard regeneration incubation experiments (IN2018V_02). Specific sampling strategies varied slightly for difference cruises, but included collected with trace metal clean (all expect RV Meteor and RV Discovery) or standard (RV Meteor and RV Discovery) rosette systems, gravity filtering through 0.2 µm or 0.45 µm filter capsules, and acidifying to pH ? 2. Chromium(III) samples were filtered, co-precipitated with Mg(OH)2, centrifuged and decanted at sea. The precipitate, containing Cr(III), was acidified and stored until analysis.

[Cr(III)] data were determined by isotope dilution with a 50Cr spike. Samples were spiked and left to equilibrate. Sample chromium was removed from the sample matrix and purified by chromatographic separation in one step. Samples were analyzed by Multi Collector ICP-MS using a Neptune Plus instrument (ThermoFisher). [Cr] and ?53Cr were determined using a 50Cr-54Cr double spike and were purified with two steps of ion exchange chemistry before analysis with Multi Collector ICP-MS using a Neptune Plus instrument (ThermoFisher).

The reference material NIST SRM 979 was analyzed with each set of [Cr] and ?53Cr samples, as well as standard seawater samples and a secondary ICP-MS standard. Sample purification and analytical procedures are described fully in Rickli et al. (2019) and Janssen et al. (2021).

***** Quality checking *****

Precision is reported as
*[Cr], [Cr(III)]: The standard deviation of replicate analyses for samples where replicates are available, or otherwise external reproducibility determined for the methodologies ([Cr(III)] = 10% RSD, [Cr] from ?53Cr samples = 1% RSD).
* ?53Cr: Internal analytical uncertainties in 2SEM. External reproducibility for the method has been determined to be 0.033‰ (2SD).

Quality checking included the following methods:
-Analysis of reference materials (see below)
-Comparison with literature data from crossover or nearby stations
-Replicate extractions and analyses of samples on different days
-Assessment of oceanographic consistency (i.e. if the data are explained by the known physical, chemical and biological controls on element distributions in the ocean, and if depth profiles transition smoothly between data points rather than erratically jumping between high and low values.

***** Standards *****

Analytical accuracy was determined by analysis of replicate seawater samples (OSIL) and secondary mass spectrometric standards (Merck Cr ICP-MS standard), as well as comparison to previously published data.

***** Further information for interpreting the data and using the dataset *****

Additional details regarding the sampling, sample preparation and analysis, along with figures, comparisons to literature data, and interpretations, are presented in Janssen et al. (2021, https://doi.org/10.1016/j.epsl.2021.117163).

***** Dataset contents *****

- Janssen_etal_CrPorewaterData_Zenodo.txt, data file, tab-delimited values
- Janssen_etal_CrPorewaterData_Zenodo header.txt, metadata, text format
- Janssen_etal_d53CrData_Zenodo header.txt, metadata, text format
- Janssen_etal_d53CrData_Zenodo.txt, data file, tab-delimited values
- Janssen_etal_Incubation1_Zenodo header.txt, metadata, text format
- Janssen_etal_Incubation1_Zenodo.txt, data file, tab-delimited values
- Janssen_etal_Incubation2_Zenodo header.txt, metadata, text format
- Janssen_etal_Incubation2_Zenodo.txt, data file, tab-delimited values
- Janssen_etal_Incubation3_Zenodo header.txt, metadata, text format
- Janssen_etal_Incubation3_Zenodo.txt, data file, tab-delimited values
- Readme.txt, metadata, text format

***** Dataset contact *****

Janssen, David J., University of Bern, Switzerland. ORCID: 0000-0002-9091-8936
Janssen.davej@gmail.com

***** References *****
Janssen, D.J., Rickli, J., Abbott, A.N., Ellwood, M.J., Twining, B.S., Ohnemus, D.C., Nasemann, P., Gilliard, D., Jaccard, S.L. (2021). Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and ?53Cr distributions in the ocean interior. Article in press at EPSL. https://doi.org/10.1016/j.epsl.2021.117163.

Rickli, J., Janssen, D.J., Hassler, C., Ellwood, M.J., Jaccard, S.L. (2019). Chromium biogeochemistry and stable isotope distribution in the Southern Ocean. Geochim. Cosmochim. Act. 262, 188-206. doi: 10.1016/j.gca.2019.07.033.

***** Dataset citation *****

Janssen, D.J., Rickli, J., Abbott, A.N., Ellwood, M.J., Twining, B.S., Ohnemus, D.C., Nasemann, P., Gilliard, D., Jaccard, S.L. (2021). Dissolved Cr concentration and stable isotope data presented in “Release from biogenic particles, benthic fluxes, and deep water circulation control Cr and ?53Cr distributions in the ocean interior” (Janssen et al., 2021, EPSL). (Version 1.0) [Data set]. Zenodo. http://doi.org/10.5281/zenodo.5408613