The first full transarctic section of 228Ra in surface waters measured during GEOTRACES cruises PS94 and HLY1502 (2015) shows a consistent distribution with maximum activities in the transpolar drift. Activities in the central Arctic have increased from 2007 through 2011 to 2015. The increased 228Ra input is attributed to stronger wave action on shelves resulting from a longer ice-free season. A concomitant decrease in the 228Th/228Ra ratio likely results from more rapid transit of surface waters depleted in 228Th by scavenging over the shelf. The 228Ra activities observed in intermediate waters (
Rutgers van der Loeff, M., Kipp, L.E., Charette, M.A., Moore, W.S., Black, E.E., Stimac, I., Charkin, A., Bauch, D., Valk, O., Karcher, M., Krumpen, M., Casacuberta, N., Smethie, W., Rember, R. (2018) Radium isotopes across the Arctic Ocean show time scales of water mass ventilation and increasing shelf inputs. Journal of Geophysical Research: Oceans. DOI: 10.1029/2018JC013888
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