T04_P09

Capabilities, Procedures, and Summary Statistics of the MICADAS and GIS at ACE Isotope Laboratory, Northern Arizona University

Ebert C¹, Schuur E¹, Kaufman D¹, Brown J¹, Propster J¹, Kelley A¹, Bright J¹, Carbone M¹, McKay N¹, Koch G¹

¹Northern Arizona University, Flagstaff, United States

The Arizona Climate and Ecosystems (ACE) Isotope Laboratory at Northern Arizona University brought a MICADAS online on June 1, 2021. Our lab includes a Gas Ion Source (GIS) with a Carbonate Handling System (CHS2) and Automated Graphitization Equipment (AGE3), as well as manual graphitization equipment and a wet lab for sample pretreatment. In one year since measurement of unknown samples began, we have analyzed 1,553 graphite samples (including 967 unknown graphite samples) and 1098 gas samples (including 647 unknown gas samples). These unknowns include a variety of sample types: plant materials, atmosphere, ecosystem respiration samples, carbonates, megafauna coprolites, organic and inorganic soils, and dissolved organic carbon.

Our facility supports specific research projects of the coauthors and other NAU researchers, with a particular focus on Arctic carbon and its potential as a feedback to climate change. Other research includes: geochronology of sediment and lake cores, tree physiology, and ecosystem science.

Our MICADAS laboratory has performed similar to other AMS laboratories. During 202 graphite replications of SRM 4990C (Oxalic Acid II), the standard deviation is 2.3 permil. After running 107 OX-II replicates with the GIS, the standard deviation is 7.8 permil. Other SRMs demonstrate similar precision. Across 112 graphite radiocarbon blank repetitions, the average age is 50,200 years. 154 GIS blank replicates had an average age of 38,900 years.