9402263 BROECKER Scenarios designed to explain the 80 ppm glacial to interglacial difference in atmospheric CO2 content recorded in ice cores can be placed into tow categories, those involving the ocean's biologic pump and those involving the ocean's CaCO3 cycle. The former group received most attention; but cadmium concentration and carbon isotope measurements on foraminifera appear to rule against them. The latter group have, to some extent, been rejected out of hand because the dissolution record for deep sea sediments appears to dictate against the rather large CO32 content changes required to accomplish the observed atmospheric CO2 change. Recently Archer and Maier-Reimer have found a way around the dissolution record constraint. They show that because of the influence of respiration CO2 released to the upper centimeter of sediment it is possible to have a rather large change in the steady state lysocline depth. This study will employ the boron isotope method to determine whether the Archer and Maier-Reimer scenario is feasible. Preliminary measurements on paired glacial and holocene foraminifera (both benthic and planktonic) suggest that the ocean's pH was, as required by the Archer and Maier-Reimer scenario, 0.2 to 0.3 units higher during glacial time. The thrust of this research is to make more such measurements with the highest attainable accuracy and also to explore the validity of the numerous assumptions on which the boron isotope pH method as applied to marine CaCO3 is based.
