Calcium Chemistry and Deposition in Ionically Enriched Onondaga Lake, New York†

The chemistry of aqueous calcium and the deposition of particulate calcium were studied in the epilimnion of calcium-polluted Onondaga Lake, NY, over a productive 7-month period. To evaluate calcium transformations, the water column was monitored for a number of pertinent water-quality parameters, and sediment traps were used to collect particulate material that settled from the epilimnion. Thermodynamic calculations indicate that the epilimnion of Onondaga Lake was oversaturated with respect to the solubility of CaCO3 (pKso = 8.48) for the entire period of summer stratification. The extent of oversaturation with respect to the solubility of CaCO3, and particulate calcium deposition, was significantly correlated with primary productivity. In-lake formation of CaCO3 not only influences calcium transport but also appears to enhance the downward transport of phosphorus and organic carbon, and contributes to light attenuation.