Dissolved inorganic nutrient samples were pre-filtered through 0.45-\u03bcm polycarbonate syringe filters, kept refrigerated, and analyzed onboard the ship within 1 day of sampling. Nitrate (NO3\u2212), nitrite (NO2\u2212), am- monium (NH4+), phosphate (HPO42\u2212), and silicic acid (Si(OH)4) were measured using a five-channel Lachat Instruments QuikChem FIA+ 8000s series autoanalyzer in conjunction with a Lachat Instruments XYZ AutoSampler (ASX-500 Series), two Lachat Instruments RP-100 Series peristaltic Reagent Pumps, and Omnion Software, version 3.0.220.02.\u00a0
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Seawater samples were analyzed for dissolved Fe over the period of January to August 2012, using an automated flow injection ICP-MS method developed at Rutgers University (Lagerstr\u00f6m et al., 2013). Briefly, the automated device loaded a 9 mL aliquot of seawater, buffered online to pH 7.0 with 3 mL of acetic acid/ammonium hydroxide buffer, onto a column packed with Nobias PA1 chelating resin (Hitachi High-Technologies). The column was eluted with 1.5 M nitric acid directly into the nebulizer of an Element-1 sector field ICP-MS (Thermo-Finnigan, Bremen, Germany). The eluate, a 200-fold concentrate of the sample, was analyzed in medium resolution and temporal peak integration was performed in Matlab using a script written in-house. Quantification was carried out using isotope dilution (Fe, Ni, Cu and Zn) or a matrix-matched external standard curve (Mn).\u00a0
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Samples for particulate organic carbon (POC) and nitrogen (PN) were collected by cleanly filtering 100\u2013600 mL of seawater onto a 25-mm diameter, combusted GF/F filter (nominal pore size of 0.7 \u03bcm) which was then folded sample side in and frozen at \u221280\u00b0C. Samples were processed at Rutgers University and analyzed using a Carlo-Erba CHN analyzer (Hedges and Stern, 1984).\u00a0
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Water column Chl a concentration (used as a proxy for algal biomass) was measured onboard ship using acetone extraction and a spectrofluorometer (Alderkamp et al., 2015). Shipboard values were calibrated against a second set of samples collected similarly, flash-frozen in liquid N2, stored at \u221280\u00b0C, and analyzed at Mote Marine Lab using HPLC (Wright et al., 1991; see Alderkamp et al., 2015).
Hydrographic profiles and discrete water samples were collected from each station using a conventional shipboard conductivity-temperature-depth (CTD; Sea-Bird 911+) sensor and a 24 \u00d7 10 L Niskin bottle rosette sampler (General Oceanics). Potential temperature (\u03b8) and salinity (S) were recorded continuously as a function of depth and at the moment of Niskin bottle closure (see Yager et al., 2016).
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Trace-metal samples were collected similarly using a trace-metal-clean CTD-rosette system (see Sherrell et al., 2015) that was deployed at the same location just before or after the conventional CTD.\u00a0
BCO-DMO Processing Notes:
\n\u00a0- combined data files on columns LocalDate, Station, and Depth
\n\u00a0- appended latitude and longitude coordinates for each station
\n\u00a0- sorted data by LocalDate, Station, Depth
\n\u00a0- added conventional header with dataset name, PI name, version date