The distribution of 227Ac along the GA01 section in the North Atlantic

Actinium-227 is a powerful tool to study vertical mixing in the ocean, and was more recently proposed as a tracer of hydrothermal plumes. However, because 227Ac activities are especially low in the ocean, relatively few studies have been conducted to date, and none has been done on the large scale, as is reported in the present study. Here, we report a section of dissolved 227Ac in the North Atlantic Ocean between Portugal-Greenland-Canada based on nine full-depth profiles obtained in the framework of the international GEOTRACES program (GA01 section - GEOVIDE cruise, May–July 2014). The simultaneous determination of 231Pa, the parent nuclide of 227Ac, along the section allowed us to report a section of excess 227Ac activities (227Acex).