Dissolved trace metal concentrations from a GO-FLO rosette collected during the R/V Thomas G. Thompson cruise TN303 from Peru to Tahiti in 2013 (U.S. GEOTRACES EPZT project) (NCEI Accession 0277472)

Acquisition Description:
Sampling:
Sample bottles were Low Density Polyethylene (LDPE) bottles and cleaned in accordance with the GEOTRACES cookbook ( http://www.geotraces.org/images/stories/documents/intercalibration/Cookbook.pdf ). Sample bottles were stored in weak (~0.1 N) HNO 3 , and were emptied before shipping.

Samples were collected using the U.S. GEOTRACES sampling system of 24 Teflon-coated GO-FLO bottles (Cutter and Bruland, 2012). At each station, the bottles were deployed open and tripped on ascent at 3 m/min. GO-FLOs were sampled in the GEOTRACES trace metal clean sampling van that contained HEPA-filtered air.

During sampling, the GO-FLO bottles were pressurized to ~0.4 atm with HEPA-filtered air, and their spigots were fitted with an acid-cleaned piece of Bev-a-Line tubing that fed into an Acropak-200 Supor capsule filter (0.2 µm pore size made of polyethersulfone). Before use, this filter had been filled with filtered surface seawater that had been acidifed to pH 2 with trace metal clean HCl and left overnight to rinse. Before collecting any subsamples, at least 500mL of seawater was passed through the filter (while eliminating air bubbles in the capsule reservoir). Sample bottles were rinsed three times with 10% sample volume before filling. Acropak filters were used for at most 3 casts before a new filter was used, and they were stored empty in a refrigerator while not in use. GEOFish surface samples were taken using an all-plastic "towed fish" pumping system as described in Bruland et al . 2005 at approximately 3 m depth and were similarly filtered and sampled.

Samples were acidified at sea with the equivalent of 4mL quartz-distilled 6M HCl per liter of seawater (resulting in pH 1.7-1.8). Samples were sitting acidified for several months before analysis back in the laboratory.