1 Revisions by MEF, WK, DW. Radiocarbon determination of particulate organic carbon in non- temperated, Alpine glacier ice

Dating ice samples from cold glaciers via radiocarbon is still a challenge, still calling for systematic investigations. This work describes an approach towards extraction and AMS radiocarbon analysis of the particulate organic carbon (POC) fraction in ice samples. First measurements were performed at VERA (Vienna Environmental Research Accelerator) on ice samples mainly obtained from the non-temperated ablation zone of the Grenzgletscher system (Monte Rosa massif, Swiss Alps). The samples were obtained from two sampling sites situated roughly on a common flow line. The sample masses used were between 0.3 and 1.4 kg ice, yielding between 18 and 307 µg carbon as POC. The carbon contamination introduced during sample processing varied between 5.4 and 33 µg C, and is shown to originate mainly from the quartz filters and the rinsing liquids used. Minimum sample sizes for successful graphitization of carbon dioxide in our laboratory could be reduced to less than 10 µg carbon with a background in the graphitization process of approximately 0.5 µg carbon of 40 pMC. Evaluation of the whole procedure via 11 Grenzgletscher samples revealed a surprisingly large scatter of the pMC values. We obtain a mean calibrated age of 2100