ABSTRACT

Ra-226 and Ba data are presented for the NE Atlantic below 2000m depth from a section of stations 8°S to 46°N obtained by F.S. "METEOR" in 1981. The precision of the Ra-226 data (±1%) allows a resolution of structures in the Ra-226 distribution which is comparable to the resolution for Ba and the nutrients considered. Ra-226/Ba correlations as well as correlations with silica and alkalinity are presented. The Ra-226 excess over a linear Ra-226/Ba correlation in the deepest 800 to 1500m is attributed to the Ra-226 primary source by Th-230 decay in the sediment. From the Ra-226 deficit in intermediate depths, a deep water renewal time of 70 years is derived. From the Ra-226 correlations with silica and alkalinity, and from studying the property-property distributions across the Romanche fracture zone, it is concluded that CaCO3 dissolution must be an important process of Ra-226 and Ba regeneration.