Laboratory experiments show that the U/Ca ratios in foraminifera tests are proportional to the ratios in sea water. Thus, based on the analysis of form tests, the ocean has increased by about 20 percent and V decreased by a factor of 2 since the peak of the last glacial period. Three approaches are offered to test the hypothesis that these changes are related to variation in the rates of exchange at the sediment.water interface through the oxidation condition of bottom waters: 1) test the mechanism of the incorporation of U and V into form tests; 2) investigate V speciation in seawater; 3) look at the changes in an Atlantic core over the past 250 thousand years as well as long.term changes of U from the mid.Miocene.
