Capture and Characterization of Particulates Exported from Farm Drainage During a Storm Event: Effect on Phosphorus Loading

Abstract:

Phosphorus (P)-enriched particulates in farms canals within the Everglades Agricultural Area (EAA) are susceptible to transport and contribute to the overall P load. During storm events, the volume of drainage discharge is significantly higher, and with it the mass of particulates exported. The particulates exported in the drainage water associated with tropical storm Isaac contained 47% higher OM, 65% higher TP, and 93% higher labile KCl-P fraction compared to the sediments. Based on the equilibrium P concentrations at the sediment-water interface, surface sediments behave as a source of P to the water column. A seven-day continuous drainage event exported 4.7 to 11.1 metric tons of suspended solids per farm, corresponding to 32 to 63 kg of particulate P being lost to downstream ecosystems. Drainage associated to a single storm event exported up to 64% of the total P load compared to the rest of the year.