Pre–treatment method to avoid contamination for radiocarbon dating of organic–rich coastal deposits

Establishing an accurate chronology for coastal sediment profiles using radiocarbon dating has been a challenging task for scientists around the world. In this study, we present a step-by-step procedure of an optimized pre-treatment method to remove roots, shell hashes, and other contaminants from organic-rich bulk sediments for radiocarbon dating. This procedure first applies loss-on-ignition analysis throughout the sediment profile to locate the ideal sampling intervals that have high organic and low carbonate contents, and then uses a two-step sieving procedure to remove contaminants from the bulk sediments. During the past five years, we have prepared a total of 64 samples for radiocarbon dating using this pre-treatment method, and 59 of them were deemed valid, a success rate of 92.2%. Thus, we believe this procedure can successfully remove contamination and optimize the sample pre-treatment for radiocarbon dating of organic-rich deposits from coastal and other environments. • Use loss-on-ignition analysis to locate the ideal sampling intervals. • Sieve each sample with 200 µm and then 100 µm sieve to remove roots and organic debris. • Acid-leach each of the sieved sediment samples (100-200 µm) with HCL to remove carbonates.