Dataset: Beryllium-7 (Be-7) measurements from samples collected on R/V Thomas G. Thompson (TN303) in the Eastern Tropical Pacific from October to December 2013 (U.S. GEOTRACES EPZT project)

A weighted sampling hose with a portable CTD was deployed over the side of the ship to collect seawater for Beryllium-7 (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%.

All fibers were returned to the lab where they were dried, ashed, and pressed into pellets, which in turn were 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 an ashed fiber and counting it in the pellet geometry.

Please refer to:
Kadko, D. and D. Olson (1996) Be-7 as a tracer of surface water subduction and mixed layer history. Deep Sea Res. 43, 89-116. doi:10.1016/0967-0637(96)00011-8