Dataset: Seawater Beryllium-7 activity concentration from submersible pump samples from USCGC Healy cruise HLY1502 in the Canada and Makarov Basins of the Arctic Ocean from August to October 2015 (US GEOTRACES Arctic)

A weighted sampling hose, attached to a submersible pump with a portable ctd was deployed over the aft of the ship to collect seawater for Be-7 analysis. The seawater was collected in plastic 700 liter holding tanks and then passed through iron-oxide impregnated acrylic fiber filters (adsorbs Be-7). The efficiency of the fiber for extraction of Be from seawater was determined by adding stable Be atomic absorption standards to a drum containing seawater, pumping the water through an iron fiber cartridge, and at every 100 L measuring the Be content of the cartridge effluent. Based on several trials, it was found that for sample volumes in the range 400-700L, extraction efficiencies are respectively, 82 ± 3% to 76 ± 2%. Some water was also collected from ice occupations, where water was pumped directly through fibers by means of a centrifugal pump on the ice. This was performed in a heated tent. Sample sizes varied from 1-3 fibers, each processing 400-700 L of seawater.

All fibers were returned to the lab where they were dried and ashed. Single fiber samples were pressed into pellets, and the combined ash from multi-fiber samples placed in Marinelli beakers. All samples were then placed over a low background germanium gamma detector. 7Be has a readily identifiable peak at 478keV. The detector is calibrated for these samples by adding a commercially prepared mixed solution of known gamma activities to ashed fiber and counting in the the appropriate geometry.

Please refer to: Kadko & Olson (1996) and Kadko et al. (2016) (full citations below).