COMPOUND-SPECIFIC RADIOCARBON, STABLE CARBON ISOTOPE AND BIOMARKER ANALYSIS OF MIXED MARINE/TERRESTRIAL LIPIDS PRESERVED IN ARCHAEOLOGICAL POTTERY VESSELS

At archaeological sites located on islands or near the coast, the potential exists for lipid extracts of potsherds to contain fatty acids (FA) from both aquatic and terrestrial organisms, meaning that consideration must be given to marine reservoir effects (MRE) in radiocarbon (C-14) analyses. Here we studied the site of Bornais (Outer Hebrides, UK) where a local MRE, Delta R of -65 +/- 45 yr was determined through the paired C-14 determinations of terrestrial and marine faunal bones. Lipid analysis of 49 potsherds, revealed aquatic biomarkers in 45% of the vessels, and delta C-13 values of C-16:0 and C-18:0 FAs revealed ruminant and marine product mixing for 71% of the vessels. Compound-specific C-14 analysis (CSRA) of FAs yielded intermediate C-14 ages between those of terrestrial and marine bones from the same contexts, confirming an MRE existed. A database containing delta C-13 values for FAs from reference terrestrial and marine organisms provided endmembers for calculating the percentage marine-derived C (%(marine)) in FAs. We show that lipid C-14 dates can be corrected using determined %(marine) and Delta R values, such that pottery vessels from coastal locations can be C-14 dated by CSRA of FAs.