Paper No. 12
Presentation Time: 11:30 AM
THE EXTENT OF PHOSPHORUS REDOX CHEMISTRY IN WEST CENTRAL FLORIDA WATERS: AN HPLC-ICP-MS STUDY
SAMPSON, Jacqueline M.1, PASEK, Matthew
2, ATLAS, Zachary D.
3 and RAINS, Mark
3, (1)Department of Geology, University of South Florida, 4202 E. Fowler Ave, SCA 528, Tampa, FL 33620, (2)Departmeent of Geology, University of South Florida, 4202 E. Fowler Ave, SCA 528, Tampa, FL 33620, (3)Department of Geology, University of South Florida, 4202 East Fowler Avenue, SCA 528, Tampa, FL 33620, jmsampso@mail.usf.edu
Phosphorus (P) has long been acknowledged as a vital nutrient for living organisms and is a key factor responsible for the eutrophication of fresh waters. Our understanding of the phosphorus cycle has been limited by: (1) the common assumption that all P in the environment occurs primarily as phosphates and (2) by the limited analytical methods available to identify P speciation. In an attempt to understand the distribution and role of phosphorus within a freshwater system we must be able to identify individual P species. To this end, we used a coupled High Performance Liquid Chromatograph (HPLC) - Inductively Coupled Plasma Mass Spectrometer (ICPMS) to determine concentrations of orthophosphate (+5), phosphite (+3) and hypophosphite (+1) in aqueous samples using methods modified from IC techniques developed by Ivey & Foster (2005) and Pech, et al. (2009) after Atlas et al. (in prep). The identification of different P species provides insight pertaining to contamination, bioavailability and sustainability within a freshwater system.
Thirty-two individual water samples were collected from six different bodies of freshwater in the Tampa Bay area between the months of November 2012 to March 2013. The freshwater samples collected were from river, spring and pond/swamp water locations. Two sampling sites were chosen at each location. At each site one, sample was collected from the waters surface and the second sample from the pore water. When depth was sufficient a third sample was obtained from the midpoint between the surface and pore water. Analytical results show that redox reactions of P occur in all freshwater samples collected and can successfully be identified by HPLC-ICP-MS analysis. From the limited data collected it is apparent that the amount of water circulation is related to the pH, type of phosphate and the amount of reduced P in the system. Additional samples must be collected in order to identify the processes controlling P speciation. Future samples must include pH measurements at each location and identification of bacterial communities should be considered.
