Carrier free 10Be/9Be measurements with low-energy AMS: Determination of sedimentation rates in the Arctic Ocean

For a comparison study, sediment samples from two cores located in the Arctic Ocean (HLY0503-09JPC, HLY0503-14JPC) were used. The authigenic 10Be/9Be ratio of these samples had been determined previously applying the conventional method where 10Be and 9Be concentrations are measured separately by AMS and ICP-MS, respectively. The resulting sedimentation rates are in discrepancy with values derived from biomarkers. To cross check the 10Be/9Be based age model two samples from each core were measured again with the new carrier-free method. The carrier-free results show systematically higher authigenic 10Be/9Be ratios. The calculated sedimentation rates of about 0.2 cm/kyr, however, are consistent for the carrier free and the conventional method.