Phosphorus Retention and Forms in Stormwater Treatment Area Wetlands of the Everglades.

The Stormwater Treatment Areas (STAs) of the Everglades were designed and are operated to retain phosphorus (P) and reduce P concentrations of surface water in accordance with water quality standards. One way to reduce P concentrations in surface water is assimilation and retention into soil, however various factors including vegetation type and soil conditions influence P retention potential. Our study characterized the relative lability or recalcitrance of assimilated P in soils of various STAs. The objective of this study was to determine the forms of phosphorus in soils of an emergent aquatic vegetation (EAV) dominated and submerged aquatic vegetation (SAV) dominated subtropical wetland ecosystem.Intact soil cores were collected from STA-2 Cell 1 & Cell 3 (from inflow, midflow, and outflow) along transects parallel to flow direction. Soil cores were sectioned into floc, recently accreted Soil (RAS), pre-STA 1, and pre-STA 2.The SAV-dominated cell has exhibited more inorganic P enrichment in floc and soils than organic P, while the EAV-dominated cell has exhibited relatively more organic P enrichment than inorganic P. The SAV P enrichment was primarily driven by abiotic factors, possibly from high calcium and magnesium activity in this system. The EAV P enrichment was primarily driven by litter production and accretion of organic matter.