By comparing expected ratios of thorium and protactinium
in those ocean sediments to observed amounts, the authors showed that protactinium
was being swept out of the Arctic before it could settle to the ocean bottom.
2004) was the ratio of the concentration of protactinium
(Pa) to thorium (Th) in a sedimentary core (recovered near Bermuda) that was well-placed to measure the impact of changes in the strength of the western boundary undercurrent--the return flow to the south produced by deep-water formation in the Greenland, Icelandic and Norwegian seas, as well as the Labrador Sea.
In addition to the uranium, the ore usually also contains traces of almost a dozen other elements, including lead, polonium, bismuth, thorium, radium, protactinium
, and radon gas (these are radioactive decay products from uranium) and nickel, cadmium, molybdenum, vanadium, arsenic, and mercury.
They therefore named the new element protactinium
(meaning "before actinium").
Scientists announced that they had succeeded in splitting uranium, thorium, and protactinium
atoms by bombarding them with neutrons.