California Current Ecosystem LTER

Total Dissolvable Iron

Title
Measurements, from CCE LTER process cruises in the California Current region, of total dissolvable inorganic concentrations of the nutrient iron, 2017 - (ongoing).

Abstract
Seawater profiles or discrete samples for total dissolvable iron (TDFe) analysis are collected with the trace metal rosette or GO-FLO bottles, respectively, in stations located within the CCE LTER region in the California Current System. The total dissolvable iron concentration is obtained by collecting unfiltered seawater samples in 250 mL LDPE bottles and storing them at pH 1.8 for 6 months or more. The acidified seawater sample is then filtered using acid cleaned 0.4 um PES membrane Titan 3 syringe filters and determined by flow injection chemiluminescent (FI-CL) analysis at Scripps Insitution of Oceanography since 2017 (ongoing).

Keywords
concentration, iron, ocean biogeochemistry, seawater, water column

LTER Data System Record
http://dx.doi.org/10.6073/pasta/8ea00d55556cbcb18473d4764538f4ae
Projects
California Current Ecosystem LTER

Creators
Barbeau, Katherine (kbarbeau@ucsd.edu)
Lead Principal Investigator

Contact
CCE LTER Information Manager (ccelter.im@gmail.com)

Other Personnel
Padilla-Villa, Minerva
Forsch, Kiefer
Weiss, Marley
Fenton, Max

Data

table Dissolvable iron
Primary data table for this dataset containing total dissolvable iron measurements across multiple research cruises
Rows: 165
Columns: 11
View / Download

Methods


Sampling method
Samples were collected with Teflon coated Niskin and GO-FLO bottles mounted on a trace metal clean CTD-Rosette lowered into the water by a coated hydrowire to pre-determined depths. Total dissolvable iron (TDFe) samples were collected, unfiltered, by pressurizing the sampling bottles with filtered air, into acid washed LDPE bottles and acidified to a pH < 2. Samples were stored in boxes at room temperature for at least 6 months until subsequent analysis in the lab.

Analysis method
Samples were analyzed at the Scripps Institution of Oceanography. Filters (0.µm PES membrane Titan 3) were rinsed with Milli-Q deionized water (18.2 MΩ, TOC ≤ 20 ppb) prior to soaking in 3N HCl at room temperature. Before use, filters were rinsed with Milli-Q dionized water. After filtration, TDFe was determined using a flow injection analysis system (Waterville Analytical) with an Fe(III) H2O2 oxidation. Details on the method are provided in "Iron Limitation and Biogeochemical Effects in Southern California Current Coastal Upwelling Filaments" (Forsch et al., 2023).