Adsorption and desorption of phosphate on limestone in experiments simulating seawater intrusion

Authors

René M. Price, Southeast Environmental Research Center and Department of Earth and Environment, Florida International UniversityFollow
M. Reza Savabi, US Department of Agriculture, Agricultural Research ServiceFollow
Jean L. Jolicoeur, Southeast Environmental Research Center and Department of Earth and Environment, Florida International University
Srikumar Roy, Southeast Environmental Research Center and Department of Earth and Environment, Florida International University

Abstract

This study investigates the potential release of from carbonate aquifers exposed to seawater intrusion. Adsorption and desorption of in the presence of deionized water (DIW) and seawater were conducted on a large block of Pleistocene age limestone to simulate the effects of seawater intrusion into a coastal carbonate aquifer at the laboratory scale. The limestone showed strong adsorption of in DIW, while adsorption was significantly less in the presence of seawater. Dissolution of CaCO₃ was found to prevent adsorption at salinities less than 30 psu. Adsorption of was limited at higher salinities (30–33 psu), due to competition with ions for adsorption sites. At a salinity3 precipitated. Concentrations of between 2 and 5 μmol/L were released by desorption when the limestone was exposed to seawater. The results of this study suggest that as seawater intrudes into an originally freshwater coastal aquifer, adsorbed may be released into the groundwater. Consequently, adsorbed is expected to be released from coastal carbonate aquifers world-wide as sea level continues to rise exposing more of the freshwater aquifer to seawater.

Comments

Post-Print Version.

Copyright © 2010 Elsevier.

The definitive publisher-authenticated version is available online at http://dx.doi.org/10.1016/j.apgeochem.2010.04.013

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Price, R.M., M.R. Savabi, J.L. Jolicoeur, S. Roy. 2010. Adsorption and desorption of phosphate on limestone in experiments simulating seawater intrusion. Applied Geochemistry 25(7): 1085-1091.