Hostname: page-component-76fb5796d-dfsvx Total loading time: 0 Render date: 2024-04-25T17:29:27.575Z Has data issue: false hasContentIssue false
  • English
  • Français

Reproducibility of Seawater, Inorganic and Organic Carbon 14C Results at NOSAMS

Published online by Cambridge University Press:  18 July 2016

Kathryn L. Elder ,
Ann P. McNichol  and
Alan R. Gagnon
Kathryn L. Elder
Affiliation:
National Ocean Sciences, Accelerator Mass Spectrometry (NOSAMS) Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 USA
Ann P. McNichol
Affiliation:
National Ocean Sciences, Accelerator Mass Spectrometry (NOSAMS) Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 USA
Alan R. Gagnon
Affiliation:
National Ocean Sciences, Accelerator Mass Spectrometry (NOSAMS) Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543 USA
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The majority of samples processed at the National Ocean Sciences AMS Facility (NOSAMS) thus far were collected as part of the World Ocean Circulation Experiment (WOCE). Due to the long storage time (2–3 yr) required to analyze thousands of samples on the accelerator mass spectrometer (AMS), a test was designed and implemented to determine the effects, if any, of storage time on 14C concentration. We find no systematic offsets in AMS measurements made over a 5-yr period between a total of 16 replicate sets from surface and deep water collected at the same locality. Furthermore, the average δ14C value from the deepwater AMS replicates (-213.1%, std. dev. 7.3) agrees very closely with the conventional 14C results published for GEOSECS (-212.7%) from station 320 taken 20 yr earlier.

A total of 73 WOCE shipboard replicate sets (162 AMS measurements) were analyzed with a mean precision of 4.3%. AMS results from 20 more shipboard replicate sets (44 AMS measurements) submitted as CO2 from the Stable Isotope Laboratory (SIL) at the University of Washington were analyzed with a mean precision of 3.4%. These results suggest no significant difference between water stripping methods used in each preparation lab.

To assess reproducibility, we calculate a pooled estimate of σ for replicates called s, which we use as an approximation of σTOT for a given sample type. The s for WOCE seawater replicates is 4.9% and 5.8% for SIL gas replicates. These numbers demonstrate an overall reproducibility of seawater AMS results at NOSAMS that is in line with reported errors. We take the difference between total error s and machine error as the overall standard deviation of combined uncertainties associated with preparation of samples and with AMS. For seawater samples processed at NOSAMS, σSPL is calculated to be 2.4%, and for the SIL gas replicates it is 4.8%.

Reproducibility of samples prepared with an acid hydrolysis technique is demonstrated using 24 coral samples submitted in triplicate by Dr. R. G. Fairbanks of Lamont Doherty Earth Observatory. Seventy-two replicates were prepared and analyzed at NOSAMS with a mean reported precision of 1.2%. The pooled estimate s for the Fairbanks triplicates is 2.6%. We calculate a laboratory reproducibility uncertainty for coral hydrolysis samples of 2.2%.

In 1993, NOSAMS participated in the Third International Radiocarbon Intercomparison (TIRI) Study. We report here 60 AMS analyses of the six TIRI test materials, five of which are organic carbon samples, to validate sample-processing methods for organic carbon sample AMS analyses at NOSAMS.

Type
Part 1: Methods
Information
Radiocarbon , Volume 40 , Issue 1: 16th International Radiocarbon Conference 16-20,1997 Groningen , 1997 , pp. 223 - 230
Copyright
Copyright © The American Journal of Science 

References

Cohen, G. J., Hutton, D. L., Osborne, E. A., von Reden, K. F., Gagnon, A. R., McNichol, A.P. and Jones, G. A. 1994 Automated sample processing at the National Ocean Sciences AMS Facility. Nuclear Instruments and Methods in Physics Research B92: 129–133.CrossRefGoogle Scholar
McNichol, A. P., Gagnon, A. R., Osborne, E. A., Hutton, D. L., von Reden, K. F. and Schneider, R. J. 1995 Improvements in procedural blanks at NOSAMS: Reflections of improvements in sample preparation and accelerator operation. In Cook, G. T., Harkness, D. D., Miller, B. F. and Scott, E. M., eds., Proceedings of the 15th International 14C Conference. Radiocarbon 37(2): 683–691.Google Scholar
McNichol, A. P. and Jones, G. A. 1991 WOCE Operations Manual. WOCE Report No. 68. Woods Hole, Massachusetts, Woods Hole Oceanographic Institution.Google Scholar
McNichol, A. P., Jones, G. A., Hutton, D. L. and Gagnon, A. R. 1994 The rapid preparation of seawater ∑CO2 for radiocarbon analysis at the National Ocean Sciences AMS Facility. Radiocarbon 36(2): 237–246.Google Scholar
Osborne, E. A., McNichol, A. P., Gagnon, A. R., Hutton, D. L. and Jones, G.A. 1994 Internal and external checks in the NOSAMS sample preparation laboratory for target quality and homogeneity. Nuclear Instruments and Methods in Physics Research B92: 158–161.Google Scholar
Östlund, H.G., et al. 1987 GEOSECS Atlantic, Pacific and Indian Ocean Expeditions. Vol. 7. Shorebased Data and Graphics. Washington, D.C., National Science Foundation: 200 p.Google Scholar
Schneider, R. J., Jones, G. A., McNichol, A. P., von Reden, K. F., Elder, K. L., Huang, K. and Kessel, E. D. 1994 Methods for data screening, flagging and error analysis at the National Ocean Sciences AMS Facility. Nuclear Instruments and Methods in Physics Research B92: 172–175.Google Scholar
Skoog, D. A. and West, D. M. 1916 Fundamentals of Analytical Chemistry. 3rd ed. New York, Holt, Rinehart, and Winston: 804 p.Google Scholar
Vogel, J. S., Southon, J. R. and Nelson, D. E. 1987 Catalyst and binder effects in the use of filamentous graphite for AMS. In Gove, H. E., Litherland, A. E. and Elmore, D., eds., Proceedings of the 4th International Symposium on Accelerator Mass Spectrometry. Nuclear Instruments and Methods in Physics Research B29: 50–56.Google Scholar
von Reden, K. F., McNichol, A. P., Peden, J. C., Elder, K. L., Gagnon, A. R. and Schneider, R. J. 1997 AMS measurements of the 14C distribution in the Pacific Ocean. Nuclear Instruments and Methods in Physics Research B123: 438–442.Google Scholar