What do the first 236-Uranium data reveal in the Arctic Ocean?

Casacuberta and co-authors (2016, see reference below) propose the first set of data for the artificial radionuclide 236-Uranium (236U) in the Arctic Ocean. The novelty of this study compared to the first comprehensive dataset they published in the western North Atlantic Ocean (GEOTRACES GA02 section), is the combination of 236U with 129-Iodine (129I). The 236U/238U and 129I/236U atomic ratios allow them to distinguish the sources of these two artificial radionuclides to the Arctic Ocean, an approach that would not be possible if only using individual concentrations of 236U, 129I or any other anthropogenic radionuclide. For example, using these ratios in a binary mixing model, they could identify Siberian rivers as potential source of artificial radionuclides in the Arctic Ocean, other than the global fallout and the European Reprocessing plants of Sellafield and La Hague. The highly sensitivity of the measurements of these two radionuclides using Accelerator Mass Spectrometry, also allows the detection of very low concentrations of both radionuclides. This dual tracer approach could therefore become an extremely sensitive tool to study isolation ages of deep and bottom waters of the Amerasian Basin.

16 Casacuberta

Figure: 129I/236U atom ratio in surface waters of the Arctic Ocean (2011/2012). Atlantic Waters (dashed black line) have higher ratios showing a greater influence of Reprocessing Plants signal. Pacific Waters (dashed purple line) are more influenced by global fallout.

Reference:

Casacuberta, N., Masqué, P., Henderson, G., Rutgers van-der-Loeff, M., Bauch, D., Vockenhuber C., Daraoui A., Walther C., Synal H.-A., Christl M. (2016). First 236U data from the Arctic Ocean and use of 236U/238U and 129I/236U as a new dual tracer. Earth and Planetary Science Letters, 440, 127–134. doi:10.1016/j.epsl.2016.02.020

Latest highlights

Science Highlights

Loss of old Arctic sea ice increases methylmercury concentrations

Researchers from the SCRIPPS, the Stockholm Natural Museum and the Mediterranean Institute of Oceanography show the importance of sea ice composition on methylmercury budgets

02.09.2020

Science Highlights

Estimating Atmospheric Trace Element Deposition Over the Global Ocean

A recently developed method based on the natural radionuclide Be-7 has provided a means to estimate the bulk atmospheric trace element deposition velocity

Science Highlights

Dissolved gallium unravels Pacific and Atlantic waters in the Arctic Ocean

Whitmore and co-workers demonstrate that the dissolved gallium distribution provide a better water source deconvolution than the nutrient tracers

22.07.2020

Science Highlights

Precise estimate of the mercury export from the Arctic to the Atlantic Ocean

Using new observations acquired during GEOTRACES Arctic cruises, a refined arctic mercury budget has been established

21.07.2020

Rechercher