| Summary: | Progress Code: completed Statement: No problems with analysis, but there were a lot of problems with GO-FLO bottles during sampling, i.e. bottles either not closing or leaking on arrival on deck. As a result, there is a large number of missing samples (NaN), and we also took some salinity samples for additional data quality control as follows: A subset of salinity samples (n=124) was taken from GO-FLO bottles to check whether bottles had closed at the expected depths and/or whether there were problems with leaking. Salinity samples were compared to CTD salinities, and samples where measured salinity did not match the respective CTD salinity (n=9) were flagged as suspect and are not included in the data sheet. Note that salinity checks were predominantly performed on GO-FLO bottles that were suspicious (e.g. leaking), so they do not represent a random set of samples. Purpose Supply dissolved iron data for the K-axis region. Complimentary to other K-axis data. Sampling was conducted according to GEOTRACES protocols. Samples for trace element analyses, including dissolved iron (dFe), were filtered through acid-cleaned 0.2 um cartridge filters (Pall Acropak) under constant airflow from several ISO class 5 HEPA units. All plastic ware was acid-cleaned prior to use, following GEOTRACES protocols. Samples were collected into low-density polyethylene (LDPE) bottles, acidified immediately to pH 1.7 with Seastar Baseline hydrochloric acid (HCl), double-bagged and stored at room temperature until analysis on shore. Samples for dFe analysis were pre-concentrated offline (factor 40) on a SeaFAST S2 pico (ESI, Elemental Scientific, USA) flow injection system with a Nobias Chelate-PA1 column. Samples were eluted from the column in 10% distilled nitric acid (HNO3), with calibration based on the method of standard additions in seawater (made using multi-element standards in a 10% HNO3 matrix, rather than an HCl matrix). Pre-concentrated samples were analysed using Sector Field Inductively Coupled Plasma Mass Spectrometry ...
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