Methodology: EqPac TT13, Radionuclides, GloFlo water bottle samples

January 8, 2002
Bob Anderson, Lamont-Doherty Earth Observatory

 
Methods are provided for EqPac seawater samples.

The reported concentrations are for total radionuclides (dissolved plus
particulate).  Thorium isotopes and Pa-231 were measured by isotope
dilution Thermal Ionization mass spectrometry (TIMS).  10Be was measured by
accelerator mass spectrometry.  The EqPac program was the first time we
measured Th and Pa in seawater by TIMS, and we suffered many samples for
which we were unable to obtain good data.  Blank cells (nd) in the data set
indicate that good data were not obtained.  The EqPac program was the first
time that we have attempted to measure Be-10 in seawater, and we were
unable to obtain useful results for several of those samples as well.

The method used to measure Th and Pa in seawater by TIMS is:

Fleisher, M. Q. and R. F. Anderson.  Assessing the Collection Efficiency of
Ross Sea Sediment Traps using 230Th and 231Pa. Deep-Sea Research-II,
submitted.

The method used to measure Be-10 in seawater takes the Be off the first ion
exchange column in the method of Fleisher and Anderson (above) to measure
Th and Pa isotopes, and then follows the purification procedure of:

Y. Lao, R.F. Anderson, W.S. Broecker, H.J. Hofmann and W. Wolfli,
Particulate fluxes of 230Th, 231Pa, and 10Be in the Northeastern Pacific
Ocean, Geochimica Cosmochimica Acta 57(1), 205-217, 1993.