Dataset: nutrients metals and ctd
Deployment: KN192-05

Three transects were sampled using the Trace Metal Rosette (TMR) on the CoFeMUG cruise aboard R/V Knorr in 2007. Refer to Noble et al. (2012) for detailed information on acquisition and processing.

Nutrient Analyses: Technicon AutoAnalyzer II components were used to measure phophate and ammonium. Alpkem rapid flow analyzer (RFA) 300 components were used to measure silicic acid, nitrate+nitrite, and nitrite.

Cobalt Analyses: Total dissolved and labile cobalt concentrations were determined using cathodic stripping voltammetry, previously described by Saito and Moffet (2001) and Saito et al. (2004). Measurements were made using Eco-Chemie uAutolab-III systems connected to Metrohm 663 VA Stands with hanging mercury drop electrodes and Teflon sampling cups.

Iron and Manganese Analyses: Total dissolved iron and manganese concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). SAFe seawater intercalibration standards were analyzed at the beginning of each analysis day with iron concentrations of 0.96 ± 0.095 nmol L-1 for D2 and 0.125 ± 0.046 nmol L-1 for S1 (n = 10), which are within the reported ranges of 0.91 + 0.17 nmol L-1 and 0.097 + 0.043 nmol L-1 (Johnson et al. 2007).

CTD: Two CTD packages were employed on KN-192-5, the Knorr's Seabird 911+ CTD package and the science party's Seabird-19 sensor package. The Seabird-19 was deployed on the science party's trace metal rosette for the deep casts to ~5000m, while the ship's CTD was deployed to 800m for upper water casts. The two packages were needed due to wire time constraints, as there was insufficient time to send both rosettes deep at each station. Oxygen data for the two CTD were calibrated with shipboard winkler titrations as described in Noble et al. Limnol. Oceanogr. 2012. The Seabird-19 was calibrated in the factory immediately prior to the cruise. 

References:
Johnson, K.S. et al. 2007. Developing iron standards for seawater. EOS Trans. 88: 11, 131-132. doi: 10.1029/2007EO110003

Saito, M. A., and J. W. Moffett. 2001. Complexation of cobalt by natural organic ligands in the Sargasso Sea as determined by a new high-sensitivity electrochemical cobalt speciation method suitable for open ocean work. Marine Chemistry. 75 (49-68). doi: 10.1016/S0304-4203(01)00025-1.

Saito, M. A.,  J. W. Moffett, and G. DiTullio. 2004. Cobalt and Nickel in the Peru Upwelling Region: a Major Flux of Cobalt Utilized as a Micronutrient. Global Biogeochemical Cycles. 18 GB4030, doi: 10.1029/2003GB002216.