Radiocarbon dating of alkenones from marine sediments: II. Assessment of carbon process blanks

TitleRadiocarbon dating of alkenones from marine sediments: II. Assessment of carbon process blanks
Publication TypeJournal Article
Year of Publication2005
AuthorsMollenhauer, G, Montlucon, D, Eglinton, TI
JournalRadiocarbon
Volume47
Issue3
Pagination413-424
Date Published2005
ISBN Number0033-8222
Keywordsc-14 ams, organic-compounds, records, samples, system, tool
Abstract

We evaluate potential process blanks associated with radiocarbon measurement of microgram to milligram quantities of alkenones at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility. Two strategies to constrain the contribution of blanks to alkenone C-14 dates were followed: 1) dating of samples of known age and 2) multiple measurements of identical samples. We show that the potential contamination associated with the procedure does not lead to a systematic bias of the results of alkenone dating to either younger or older ages. Our results indicate that alkenones record Delta(14)C of ambient DIC with an accuracy of approximately 10 parts per thousand. A conservative estimate of measurement precision is 17 parts per thousand for modern samples. Alkenone C-14 ages are expected to be reliable within 500 yr for samples younger than 10,500 C-14 yr.