Award: OCE-1436125

In this project, investigators from University of Hawaii and Columbia University participated in the U.S. Arctic GEOTRACES cruise to the Arctic Ocean aboard the USCGC Healy from August 9 to October 11, 2015. The overall goals of the U.S. Arctic GEOTRACES cruise were to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes (TEIs) in the Arctic Ocean, to determine how likely their distributions will change due to changing environmental conditions, and to establish a baseline of the distributions of TEIs for future reference, since the Arctic is presently undergoing system-scale environmental change at a pace not seen elsewhere on the globe. During the two-month long cruise, as the ship traversed the Arctic Ocean from Dutch Harbor, Alaska to the North Pole and back, samples were taken for measurements of six groups of oceanic tracers, including chlorofluorocarbons (CFCs), sulfur hexafluoride (SF6), tritium, helium isotopes, stable isotopes of water and radiocarbon. These are oceanic tracers that have been used to study of water mass composition, circulation, and mean residence times on short (less than one year) to long (several hundred years) time scales, and allow us to better understand oceanic water movement in the Arctic Ocean. They also allow other investigators to interpret their own TEIs data. Some of these elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. The data we produced on the stable isotopes of water are being used by several groups in their interpretation of TEIs to understand the freshwater sources. The transient tracers (CFCs, SF6, tritium, helium isotopes) are being used to advance our understanding of circulation patterns, spreading velocities and stability of circulation patters. Radiocarbon, in combination with transient tracers are shedding light on renewal of deep water (steady renewal versus ?fossil? deep water body). The final CFCs and SF6data have been posted on publicly accessible databases at The Biological and Chemical Oceanography Data Management Office (BCO-DMO) and CLIVAR and Carbon Hydrographic Data Office (CCHDO). Last Modified: 05/14/2019 Submitted by: David T Ho