Rapid removal of mining waste-contributed phosphate from estuarine waters by pre-existing apatite in north Manatee County, Florida

In March–April 2021, ~800 million liters of industrial phosphate wastewater, seawater, and rainwater were discharged into Tampa Bay, a central Florida estuary. Phosphate pollution in aquatic systems can drive potentially toxic algal blooms and cause oxygen loss, detrimental to native aquatic plant life. From July 2021 to May 2024, we tracked the mobility of phosphate contributed by the release by sampling estuarine sediments along the eastern Tampa Bay shoreline, both north and south of the discharge site. Extractable phosphate concentrations correlated with distance and the predicted flow of the release, indicating relative phosphate immobility. Further, laboratory simulations using wastewater and seawater analogs, and native sediments and their mineral components, revealed that natural apatite effectively sequesters phosphate onto its surface. These findings suggest that estuarine sediments, especially those rich in apatite, promote rapid removal of waste fluid-contributed phosphate and inhibit its re-release for at least three years following the contamination. Phosphate contributed by the Piney Point stack water release was rapidly attenuated by pre-existing phosphate minerals within the sediment, reducing the environmental impact of the huge quantity of released phosphate, according to sampling analysis within Tampa Bay, a Central Florida estuary.