ENRICH 2019 Trace element data (RV Investigator IN2019_V01 Southern Ocean voyage)

• Other Authors: Smith, Abigail (pointOfContact), Institute for Marine and Antarctic Studies (IMAS), University of Tasmania (UTAS) (hasAssociationWith)
• Format: Dataset
• Language: unknown
• Published: University of Tasmania, Australia
• Subjects: oceans; TRACE METALS; EARTH SCIENCE; TERRESTRIAL HYDROSPHERE; WATER QUALITY/WATER CHEMISTRY; in2019_v01; RV Investigator; Southern Ocean; Canada; Pacific; Mertz Glacier; glacier*
• Online Access: https://researchdata.edu.au/enrich-2019-trace-ocean-voyage/1713702; https://metadata.imas.utas.edu.au:443/geonetwork/srv/en/metadata.show?uuid=956a2c2f-ecfe-423d-bfa9-cc9d9770f846; https://www.marine.csiro.au/data/trawler/survey_details.cfm; https://mnf.csiro.au/en/Voyages/IN2019_V01; https://www.marine.csiro.au/data/underway/

Trace element data collected from 18 stations near the Mertz Glacier on the 2019 ENRICH voyage. Sea water was collected using a 12-bottle trace metal rosette (TMR) and acidified for analysis back in Hobart. Samples were measured using an offline seaFAST pre-concentration system and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) at the University of Tasmania. This data contributed to Smith et al., Circumpolar Deep Water and shelf sediments support late summer microbial iron remineralisation in Global Biogeochemical Cycles (2021). Cleaning: All trace metal sampling and analyses techniques were based on the international GEOTRACES program’s cookbook (Cutter et al., 2017). Briefly, new 60 mL LDPE sample bottles were cleaned in 2% v:v Decon-90 for one week to remove any residue from manufacturing, after which bottles were rinsed four times with deionised water and thrice in ultra-high purity (UHP) water. The bottles were filled with 6M hydrochloric acid (HCl) and placed in a 1.2M HCl bath for one month. Bottles were rinsed again with UHP water, filled with trace metal grade 1.2M HCl and triple-bagged for transportation. Bottles were rinsed thrice with freshly collected seawater prior to sampling. Dissolved trace elements: Water profiles were sampled using a purpose-built Trace Metal Rosette (TMR; General Oceanics Inc.), comprising twelve 10L Teflon-lined Niskin bottles, each equipped with an external spring and automatic firing mechanism. The TMR was deployed from the ship with a Dyneema™ line to a maximum depth of 1,200 m. Bottles were programmed to fire at predetermined depths to sample the water column during the ascent. Once onboard, Niskin bottles were carefully transported to a trace-metal-clean laboratory equipped with an ISO 5 HEPA filtered air system. Sixty mL of seawater from each depth was sampled using acid-washed AcroPak 0.2 µm filters and acidified to pH 1.8 with ultrapure HCl (Seastar Baseline) for trace element analysis in Australia. Seawater samples were analysed for a suite of dissolved trace elements (including Fe, Mn, and Ti, among others) using a commercially available, offline seaFAST preconcentration system (SC-4 DX seaFAST S2/pico, ESI, USA) with sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) detection. Briefly, samples were loaded onto a Nobias PA1 resin column (200 µL) to retain metals of interest. Trace metals were then eluted with 0.75 mL of 1.6 M ultrapure nitric acid (HNO3; Seastar Baseline). This method allowed the seawater matrix to be removed and trace metals of interest to be concentrated to levels more reliably measurable by ICP-MS. Samples were typically pre-concentrated 40 times, and 10 times where sample volume was low. An internal standard of 10 µg L-1 rhodium (Rh) was added to the eluent to monitor instrument drift. Samples were quantified using commercially-prepared multi-element mixes for internal (on-column) and external (off-column, ICP-MS) calibrations. Further details of the seaFAST method are outlined in Wuttig et al. (2019). Following preconcentration, trace element concentrations were determined typically within 24 h using a Thermo Fisher Scientific ELEMENT 2 SF-ICP-MS (Central Science Laboratory, Tasmania), employing medium resolution mode. Precise dTi concentrations used in this work require some caution as extraction conditions (pH) used to preconcentrate dFe may be sub-optimum for dTi extraction (Wuttig et al., 2019); however trends and ratios between elements may still be used to identify potential sources of dFe across a broad scale. Analytical precision and accuracy were monitored throughout the seaFAST and SF-ICP-MS processing sequences using globally inter-calibrated seawater consensus materials including GSP (2009 GEOTRACES Pacific surface seawater), GSC (2009 GEOTRACES coastal surface seawater), NASS-6 and NASS-7 (National Research Council of Canada), in addition to regularly measured in-house seawater reserves. A full outline of CRM analyses, blanks and detection limits are provided in the supplementary information (Tables S1 & S2). Full intercalibration of this data is provided with the GEOTRACES Intermediate Data Product (IDP) 2021.