Researcher(s)
- Chanelle Rahbany, Plant Science, University of Delaware
Faculty Mentor(s)
- Deb Jaisi, Environmental Biogeochemistry Laboratory, University of Delaware
Abstract
Florida Everglades is a nutrient-saturated wetland ecosystem in Southern Florida. Highly
elevated phosphorus (P) in the Everglades and the inability of current nutrient management plans
to meet target results in the state court order that the phosphorus load decrease below 1 part
per billion (PPB) by 2026. However, not all P forms in soils are bioavailable, and those that are
not bioavailable do not impact water quality. This project aimed to investigate the bioavailable
portion of total P in Everglade. Further, seasonal variations and hydrological changes influence
the concentrations and bioavailability of organic phosphorous in different ecological zones of the
Florida Everglades. For this reason, soil samples from different hydrological regimes of the
Everglade were collected. The selected sites include the TREC field, next to a canal at 272 ST,
within the canal at 272 ST, and the canal at Krome Ave, all sites near Homestead, Florida. From
each soil, four different inorganic phosphate pools (H 2 O-Pi, NaHCO 3 -Pi, NaOH-Pi, and
HCl-Pi) were extracted using the sequential extraction method and quantified through
absorbance using UV-Vis Spectroscopy. Our data revealed the relative order of inorganic
phosphorus concentrations was as follows: HCl-Pi>NaHCO 3 -Pi>NaOH-P i>H2O-Pi. The
HCl-Pi pool concentration ranged from 17 to 35 uM/g, while all other pools were much below 10
uM/g. The substantially high HCl-Pi pool indicates a large portion of phosphorus is present in
the most unavailable form in the soils. These results emphasize the need for high-resolution
studies on the bioavailable fraction of phosphorus and how this fraction changes with seasons,
hydrogeological conditions, and land use practices. Such information will be helpful and
contribute to the continued efforts to support soil health and fertility, water management, and
pollution reduction to maintain the vitality of the Everglade’s unique ecosystem.