Radium inputs into the Arctic Ocean from rivers a basin‐wide estimate

Radium isotopes have been used to trace nutrient, carbon, and trace metal fluxes inputs from ocean margins. However, these approaches require a full accounting of radium sources to the coastal ocean including rivers. Here, we aim to quantify river radium inputs into the Arctic Ocean for the first time for Ra-226 and to refine the estimates for Ra-228. Using new and existing data, we find that the estimated combined (dissolved plus desorbed) annual Ra-226 and Ra-228 fluxes to the Arctic Ocean are [7.0-9.4] x 10(14) dpm y(-1) and [15-18] x 10(14) dpm y(-1), respectively. Of these totals, 44% and 60% of the river Ra-226 and Ra-228, respectively are from suspended sediment desorption, which were estimated from laboratory incubation experiments. Using Ra isotope data from 20 major rivers around the world, we derived global annual Ra-226 and Ra-228 fluxes of [7.4-17] x 10(15) and [15-27] x 10(15) dpm y(-1), respectively. As climate change spurs rapid Arctic warming, hydrological cycles are intensifying and coastal ice cover and permafrost are diminishing. These river radium inputs to the Arctic Ocean will serve as a valuable baseline as we attempt to understand the changes that warming temperatures are having on fluxes of biogeochemically important elements to the Arctic coastal zone.