Baseline physicochemical investigations on waters from three blue holes, San Salvador Island, Bahamas

Abstract

Physicochemical parameters have been studied in the water column of Inkwell, Church, and Watling's Blue Holes (San Salvador Island, Bahamas). Water samples were collected from multiple depths at the three blue holes to identify and characterize changes of physical and chemical parameters. The values were compared to the average ocean concentrations in order to assess how connectivity to the ocean, evaporation, freshwater input, and Inkwell and Church blue holes are inferred from changes in the concentration of chloride. The degree of variation is a mixed signal resulting from changes of the precipitation/evaporation balance and tidal driven water-rock interaction.-) from 300 to 9591.8 mg/L, and total hardness (9 to 293 mg/L) within the mixing zone. This location is the only site that may have a true halocline. Watlings's geochemical parameters have the smallest range (i.e. Cl-Cl-values between surface and-2 m suggests mixing is occurring. The lack of other parameter variations within the SO4 2-) concentration at the same depth reach its maximum value (4009 mg/L). The high sulfate values throughout the column (2634 to 4009 mg/L) are characteristic of seawater (>2700 mg/L), thus indicating seawater seepage into the blue hole. We assume the elevated salinity values at the surface and-1 m are pointing towards evaporative processes.