Wednesday, November 15, 2006

Organic Phosphorus Speciation in a Range of Wetlands.

Alexander Cheesman1, Benjamin Turner2, K. R. Reddy1, Sue Newman3, and William T. Cooper III4. (1) Univ of Florida, Soil & Water Science Dept, 106 Newell Hall, PO Box 110510, Gainesville, FL 32611, (2) Smithsonian Tropical Research Inst, Unit 0948, APO, AA 34002-0948, (3) South Florida Water Management District, Marsh Ecology Research Group, Everglades Div, West Palm Beach, FL 33416, (4) Florida State Univ, Dept of Chemistry and Terrestrial Waters Institute, Talahassee, FL 32306

Treatment wetlands sequester phosphorus from polluted runoff and store it organic forms, yet the long-term stability of organic phosphorus in wetland soils remains poorly understood. We are addressing this by utilizing phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy and sequential fractionation to determine the chemical nature and stability of organic phosphorus in a range of wetlands from the continental US. Initial results from a limited number of sites in Florida indicate that phosphate diesters (such as DNA and phospholipids) dominate the organic phosphorus in wetland soils. This is in direct contrast to most other soil types, in which the organic phosphorus is dominated by inositol phosphates in stable associations with soil components. The abundance of what are routinely thought of as unstable organic phosphates raises concern over the long-term efficacy of treatment wetlands, given the likelihood of future perturbation. Current studies are investigating whether patterns detected across nutrient and concomitant vegetation gradients within the Florida Everglades extend across a climatic and geomorphic range of wetland types.