The carbonate chemistry of Grand Bahama Bank waters: After 18 years another look

Abstract

Major features of the chemistry of northern Grand Bahama Bank waters found in 1981 were similar to those found by Broecker and Takahashi in 1962 and 1963. Measured variations in salinity and extent of CaCO3 removal are close to the same. Our findings indicate a more complex salinity distribution on the northern banks, probably resulting from transport of high salinity waters from the south and higher PCO2 values in the high salinity waters. Inorganic 14CO2 measurements made in this study can be used to calculate very approximate residence times of water on the bank. There is general agreement with the values previously determined by Broecker and Takahashi. Ship, aerial, and satellite observations indicate that “whitings” are not randomly distributed over the bank. They form a halo around the northern and western flanks of the high salinity waters (S greater than 40). The rate of CaCO3 removal is about 1.5 times faster in the waters where the whitings are common than in the high salinity waters. Even though our analytic precision was over 80 times greater than the change predicted in alkalinity if whitings precipitate directly from seawater, no differences could be found between whiting and adjacent waters. In our opinion, the major features responsible for creating whitings, controlling their distribution, and determining CaCO3 removal rates on the Grand Bahama Bank remain largely unresolved.