The authors present an ocean model of the natural radioactive isotopes thorium-230 and protactinium-231. They are compared with many concentration measurements, both dissolved and particulate; most are from the GEOTRACES transects GA02, GA03 (Atlantic) and GIPY5 (Southern Ocean). The figure below shows the modelled dissolved thorium-230 activity at four depth levels; the discs present the observations. The activities are simulated well, based on an improved model of the scavengers, biogenic and lithogenic particles. This is an important result, because these isotopes are often used to investigate past ocean circulation and particle transport. The model may be used by anyone to make such investigations.
Figure: Modelled dissolved thorium-230 activity at four depth level (mBqm−3 ); observations are represented as discs on the same colour scale. Click here to view the figure larger.
van Hulten, M., Dutay, J.-C., & Roy-Barman, M. (2018). A global scavenging and circulation ocean model of thorium-230 and protactinium-231 with improved particle dynamics (NEMO–ProThorP 0.1). Geoscientific Model Development, 11(9), 3537–3556. DOI: http://doi.org/10.5194/gmd-11-3537-2018