G02_P05

Radiocarbon in the ocean: ensuring high quality results

Hansman R¹,  Key R², McNichol A¹, Sonnerup R³

¹Woods Hole Oceanographic Institution, Woods Hole, United States, ²Princeton University, Princeton, United States, ³University of Washington, Seattle, United States

Repeat open ocean radiocarbon measurements of dissolved inorganic carbon (DIC) have led to a better understanding of key ocean processes such as mixing, ventilation rates, air-sea gas exchange, and ocean biogeochemistry.  Until recently, only a few laboratories had the ability to make the precise ¹⁴C analyses necessary to document ocean circulation and the oceanic uptake of anthropogenic CO₂, but technological advances have reduced sample size requirements, brought new methods online, and made it easier for more laboratories to collect and analyze DI¹⁴C in the ocean.  However, as there are presently no recognized standards or reference materials for radiocarbon in seawater, it is critical to ensure the quality and data comparability of these measurements across laboratories and over time.  To this end, a three-day virtual workshop sponsored by the Ocean Carbon & Biogeochemistry program was held in November 2021 to discuss best practices for the measurement, data handling, and reporting of carbon isotopes in the ocean.  While the workshop included the analysis of both DI¹³C and DI¹⁴C, an immediate need for an inter-laboratory comparison exercise of radiocarbon in seawater DIC was determined.  We will present a summary of the workshop discussion and outcomes, including imminent plans for this DI¹⁴C inter-comparison, as well as work towards establishing reference materials for the community.