PARENT SESSION
Oral Session #57: Aquatic Ecology: Wetlands, Estuaries, Marine. Presiding: T. Klinger.
Wednesday, August 8, 2001. 1:00 PM to 5:15 PM. Hall of Ideas J.
The effect of drawdown on P flux from soils in the Everglades Nutrient Removal Project wetland.
White, John1, Reddy, Ramesh1, 1
ABSTRACT- A series of flow-through tanks were established at the inflow of the Everglades Nutrient Removal (ENR) Project site. These systems mimic the stormwater treatment areas (STAs), a series of large constructed wetlands to treat high nutrient surface waters before entering the Everglades. The objective of this study was to determine the interactive effects of vegetation and draw down on P retention/release characteristics of ENR soils and surface water quality. There were 4 treatments of; continuously flooded with macrophytes, intermittently flooded with macrophytes, continuously flooded with no macrophytes, intermittently flooded without macrophytes. A P fractionation scheme was completed on the soils at the project initiation and after 1 year and a mass balance of P was performed on each of the treatments. In addition, microbial biomass P and potentially mineralizable P were determined. The P stored in vegetative biomass was significantly greater than stored within algae. The majority of the P within the mesocosms was stored in the Ca and Mg fraction as well as the refractory pool of the soil. Periodic drawdown of the surface water increased release of P from the soil, in particular, resulting in a net release of dissolved organic P. These results point to potential problems with maintaining and managing such large treatment wetlands for improved water quality during periods of fluctuating water levels.
KEY WORDS: organic phosphorus, water quality, biogeochemistry, nutrient cycling