2013 Articles

Capabilities of the Lamont–Doherty Earth Observatory in situ¹⁴C extraction laboratory updated

Goehring, Brent M.; Schimmelpfennig, Irene Lois; Schaefer, Joerg M.

We report on the status and capabilities of the Lamont–Doherty Earth Observatory in situ¹⁴C extraction laboratory. In late 2006 we began, in collaboration with the AMS group at the University of Arizona, construction of a new laboratory to extract in situ cosmogenic ¹⁴C from terrestrial silicates. Long-term measurements of the process blank over the last two years give an arithmetic mean and standard deviation of 125 ± 43 × 10³ atoms ¹⁴C (n = 9) and show significant improvement in the number of atoms, as well as stability compared to initial measurements of the process blank. We report long-term measurements of the intercomparison material CRONUS-A, which has been developed as part of the CRONUS-Earth effort to characterize inter- and intra-laboratory variability. We interpret the standard deviation (5%) of six replicate measurements of CRONUS-A as the reproducibility of in situ¹⁴C extractions in our laboratory.