Improvements to 232-thorium, 230-thorium, and 231- protactinium analysis in seawater arising from GEOTRACES intercalibration
Auro, Maureen E.
Robinson, Laura F.
Bradtmiller, Louisa I.
Fleisher, Martin Q.
Anderson, Robert F.
MetadataShow full item record
The GEOTRACES program requires the analysis of large numbers of seawater samples for 232Th, 230Th, and 231Pa. During the GEOTRACES international intercalibration exercise, we encountered unexpected difficulties with recovery and contamination of these isotopes, 232Th in particular. Experiments were carried out to identify the source of these issues, leading to a more streamlined and efficient procedure. The two particular problems that we identified and corrected were (1) frits in columns supplied by Bio-Rad Laboratories caused loss of Th during column chemistry and (2) new batches of AG1-X8 resin supplied by Bio-Rad Laboratories released more than 100 pg of 232Th during elution of sample. To improve yields and blanks, we implemented a series of changes including switching to Eichrom anion exchange resin (100-200 μm mesh) and Environmental Express columns. All Th and Pa samples were analyzed on a Neptune multi-collector inductively-coupled-plasma mass spectrometer (MC-ICP-MS) using peak hopping of 230Th and 229Th on the central SEM, with either 232Th, 236U (or both) used to monitor for beam intensity. We used in-house laboratory standards to check for machine reproducibility, and the GEOTRACES intercalibration standard to check for accuracy. Over a 1-y period, the 2 s.d. reproducibility on the GEOTRACES SW STD 2010-1 was 2.5% for 230Th, 1.8% for 232Th, and 4% for 231Pa. The lessons learned during this intercalibration process will be of value to those analyzing U-Th-Pa and rare earth elements as part of the GEOTRACES program as well as those using U-series elements in other applications that require high yields and low blanks, such as geochronology.
Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography: Methods 10 (2012): 464-474, doi:10.4319/lom.2012.10.464.
Suggested CitationLimnology and Oceanography: Methods 10 (2012): 464-474
Showing items related by title, author, creator and subject.
Dissolved thorium-230 and thorium-232 from R/V Pelican cruise PE17-24 in the deep Northern Gulf of Mexico during June 2017 Hayes, Christopher T. (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: firstname.lastname@example.org, 2020-07-31)Dissolved thorium-230 and thorium-232 from the deep Northern Gulf of Mexico collected on R/V Pelican cruise PE17-24 during June 2017. For a complete list of measurements, refer to the full dataset description in the ...
Dissolved thorium-230 and thorium-232 from R/V Point Sur cruise PS1718 at the site of the former Deepwater Horizon in April 2017 Hayes, Christopher T. (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: email@example.com, 2020-07-31)Dissolved thorium-230 and thorium-232 from R/V Point Sur cruise PS1718 at the site of the former Deepwater Horizon in April 2017. For a complete list of measurements, refer to the full dataset description in the supplemental ...
Lerner, Paul (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2018-09)Many chemical constituents are removed from the ocean by attachment to settling particles, a process referred to as “scavenging.” Radioisotopes of thorium, a highly particle-reactive element, have been used extensively ...