Contents of major components, U, and Th in bones and bone debris

Uranium and thorium contents, as well as their distribution patterns have been studied in biogenic phosphates from the Atlantic and Pacific Oceans. Differently lithified fish remains (bones, scales, teeth) and marine mammal bones (ribs, vertebras, earbones) collected from both reduced shelf sediments and oxidized pelagic ones have been analyzed. U content in the material varies from 0.7 to 700 ppm, and Th content - from <0.5 to 14 ppm. U/Th ratio varies from 0.16 to 400. Contents of both elements increase with lithification of biogenic phosphates. U concentration is more intense on shelves, whereas thorium concentration increases in pelagic areas. Partial positive correlation of U and Th with Fe and negative correlation of U with organic carbon are noted. The latter corresponds to higher lithification of biogenic phosphates. Calcium phosphate transformed from hydroxyapatite to fluorcarbonate-apatite is the main carrier of U, while transformed organic matter is a minor agent. Thorium is mainly bound with Fe.

(Table 1) Population density and biomass of the foraminifer Rupertina, and grain size of cores from the Norwegian continental slope

Rupertina stabilis occupies a depth restricted biotope of suspension feeding animals situated at the Norwegian continental margin. It extends from the Voring plateau northwards for at least 200 - 300 km, in depths between 600 and 800 m. This slope position is known for relatively strong bottom currents and shifting watermass boundaries. - The species is attached to hard substrates, mainly stones or hydroid stalks and obviously prefers an elevated position. It is building a permanent cyst of sponge spicules and debris at the apertural region. The spicules are used to support a pseudopodial network similar to that described from Halyphysema (LIPPS 1983). It is believed to serve as a filter apparatus. - A review of known occurences in the Atlantic is given, suggesting a temperature adaption of the species ranging from 0°C to a maximum of 8°C. Specimens were successfully cultured for about 2-3 weeks.