Seal Tightly and Store in a Cool Dry Place: Exploring Soil Phosphorus Storage in a Subtropical Treatment Wetland.

Abstract

Oligotrophic wetlands of the Everglades are often the final recipients of nutrients from adjacent ecosystems and tend to accumulate phosphorus (P) in their soils. Understanding P source and sink dynamics in wetlands are critical for managing wetland ecosystems and protecting downstream resources. In this study, soil P storage capacity (SPSC) was evaluated within two treatment flow-ways of the Everglades Stormwater Treatment Areas (STAs). This study hypothesized that SPSC will vary between flow-ways, soil depth, and spatially along the inflow-to-outflow gradient. The P storage capacity in the STAs depend on the proportion of iron, aluminum, calcium, and magnesium (Fe, Al, Ca, and Mg, respectively) to P with floc and recently accreted soils (RAS) being associated more with Ca and Mg and pre-STA soils being associated more with Fe and Al. Phosphorus loss, as indicated from SPSC values would vary between systems and soil depths suggesting a variable condition of P sink and source within and along flow-ways. This result, while limited, demonstrates the applicability of SPSC to wetlands systems and provides information that will aid operational or management decisions associated with improving P retention of the Everglades STAs.