Advances in Radiocarbon Measurement of Water Samples

In this paper two very different and novel methods for the 14C measurement of water samples are presented. The first method uses direct absorption into a scintillation cocktail and a following liquid scintillation measurement. Typical sample size is 20-40 L and overall uncertainty is ± 2% for modern samples. It is a very cost effective and easy to use method based on a novel and simple static absorption process for the CO2 extracted from groundwater. The other very sensitive method is based on accelerator mass spectrometry (AMS) using a gas ion source. With a MICADAS type AMS system we demonstrated that you can routinely measure the 14C content of 1 mL of water sample with better than 1% precision (for a modern sample). This direct 14C AMS measurement of water takes less than 20 minutes including sample preparation. (author)