Geochemistry and isotope systematics of sulphur in the mixing zone of Bahamian blue holes

Abstraet -A profile of aqueous S species concentrations and stable isotope compositions is presented for the mixing zone of Cousteau's Blue Hole, North Andros, Bahamas, together with similar, but less detailed results from two other blue holes. These data show that S o and S 2are produced by bacterially mediated sulphate reduction near the base of the mixing zone and that these species are reoxidized at shallower levels. Acidity generated by oxidation can contribute to corrosiOn of limestone walbrock. Estimated rates of such corrosion range up to 1200 mm wall-rock recession per 10 ka at Cousteau's Blue Hole (equivalent to 16% porosity generation per l0 ka) and are comparable with rates of dissolution caused by inorganic mixing corrosion.