Deep-sea mixing along 40oS as seen in radium isotopes and actinium

Walter Geibert, Alan Hsieh, Raja Ganeshram, Gideon M Henderson

Vertical mixing constrained with actinium: Example from D357 (St.11)

Actinium Profiles from 40 S

Actinium and mixing in the South Atlantic

W E

A new method to determine 226Ra in water

Comparison of new method with traditional ϒ-spectrometry

226Ra [dpm]

signal on RadeCC

Very cheap and simple method to determine 226Ra in water

Valenti Rodellas- UA Barcelona (on Thursday)

Summary• Final measurement still stands out (planned for October-

November)

• Preliminary data show vertical mixing in the lower 1000m between ~0.5 and 10 cm2/s

• Data point to an additional source and lateral mixing in ~3000-3500 m- Other data?

• Evaluation has resulted a very promising method to measure 226Ra with a simple counting system.