Vertical profiles of 90Sr activities in seawater in the Greenland Sea, Chukchi Sea and Arctic Ocean

The ⁹⁰Sr activities of seawater were investigated in the high-latitude region of the Arctic Ocean from August-September 2017. The ⁹⁰Sr activities in seawater in the Chukchi Sea, central Arctic Ocean and East Greenland Sea were 0.31-2.42, 0.12-1.86 and 0.13-1.20 Bq m^-3, respectively. The average ⁹⁰Sr activity (0.92 Bq m^-3) below 500 m in the central Arctic Ocean was higher than those in previous reports. Our study provided high-resolution baseline ⁹⁰Sr activity data for the whole water column in the high-latitude region of the Arctic Ocean (~85°N). The inventory of ⁹⁰Sr in the central Arctic Ocean was higher than those in the Chukchi Sea and East Greenland Sea. The results of our study indicated that ⁹⁰Sr could be transported to the deep seawater and remain in the Arctic Ocean for a long time.

Recent oceanic changes in the Arctic in the context of long-term observations

This synthesis study assesses recent changes of Arctic Ocean physical parameters using a unique collection of observations from the 2000s and places them in the context of long-term climate trends and variability. Our analysis demonstrates that the 2000s were an exceptional decade with extraordinary upper Arctic Ocean freshening and intermediate Atlantic water warming. We note that the Arctic Ocean is characterized by large amplitude multi-decadal variability in addition to a long-term trend, making the link of observed changes to climate drivers problematic. However, the exceptional magnitude of recent high-latitude changes (not only oceanic, but also ice and atmospheric) strongly suggests that these recent changes signify a potentially irreversible shift of the Arctic Ocean to a new climate state. These changes have important implications for the Arctic Ocean's marine ecosystem, especially those components that are dependent on sea ice or that have temperature-dependent sensitivities or thresholds. Addressing these and other questions requires a carefully orchestrated combination of sustained multidisciplinary observations and advanced modeling.

On the potential for climate change impacts on marine anthropogenic radioactivity in the Arctic regions

Current predictions as to the impacts of climate change in general and Arctic climate change in particular are such that a wide range of processes relevant to Arctic contaminants are potentially vulnerable. Of these, radioactive contaminants and the processes that govern their transport and fate may be particularly susceptible to the effects of a changing Arctic climate. This paper explores the potential changes in the physical system of the Arctic climate system as they are deducible from present day knowledge and model projections. As a contribution to a better preparedness regarding Arctic marine contamination with radioactivity we present and discuss how a changing marine physical environment may play a role in altering the current understanding pertaining to behavior of contaminant radionuclides in the marine environment of the Arctic region.