Phosphorus Flux From Canal Sediments of the Everglades Agricultural Area.

Phosphorus (P) discharge from the Everglades Agricultural Area (EAA), located in south Florida between Lake Okeechobee and the Everglades National Park, has been attributed to the ecosystem changes in the Everglades. Due to years of P loading, the EAA canal sediments can function as a P source to the water column through internal loading. The objectives of the study were to determine the P release characteristics of sediments from three main canals of EAA: Miami Canal, West Palm Beach Canal (WPB) and Ocean Canal. Phosphorus releases over each of three floodwater exchanges were the greatest for Miami canal with average values of 8.23, 2.89 and 3.43 mg m-2 for 1st, 2nd and 3rd exchange respectively. The high P release from Miami Canal may be due to high total P, NaOH-Pi and NaOH-Po contents (1197, 106, and 88 mg kg-1) compared to WPB and Ocean Canals sediments. Mean P release values for WPB Canal and Ocean Canal were 6.31, 1.23, & 1.93 mg m-2 and 1.12, 0.68 & 0.55 mg m-2 for 1st, 2nd and 3rd exchanges respectively. Sediment equilibrium phosphorus concentration (EPC) values varied from 0.08 – 0.28 mg L-1 for Miami Canal, 0.01 – 0.06 mg L-1 for WPB Canal and 0.03 - 0.07 mg L-1 for Ocean Canal. High EPC and high P release values of Miami Canal may be due to high Fe&Al extractable P that can be released under fluctuating redox conditions and organic P which upon mineralization can be released to the water column.