Developing a Relationship Between Calcium Ion Concentration [Ca 2+] and Salinity in Atlantic Coastal Waters

• Kelsey Staniec, Chemistry, University of Delaware

• Wei-Jun Cai, Marine Science, University of Delaware

This project consisted of finding the concentration of the calcium ion, [Ca 2+], in several hundred seawater samples collected from different locations along the Atlantic Coast. The samples originated from the Gulf of Maine, the Mid-Atlantic Bight, and the South Atlantic Bight, with additional samples collected in the Delaware Bay. Automatized complexometric titration of 1 mL of each seawater sample with EGTA, measured by a calcium ion selective electrode, allowed for a simple and quick determination of the [Ca 2+] in each sample. With this data, we will be able to determine the carbonate mineral saturation state Ω, which is essential for the calculation of the quantity of calcium carbonate precipitation in these areas. Calcium ion concentration data were graphed against salinity data collected from the same water samples to determine a relative trend between the two variables. A strong positive association was found to exist between [Ca 2+] and salinity in the coastal waters of the Atlantic Ocean.