A RADIOGEOCHEMICAL, LAND-USE ARCHIVE OF THE MANATEE RIVER WATERSHED, FL

The Manatee River Watershed, located southeast of Tampa Bay, Florida has experienced heavy anthropogenic development over the last one hundred years. This development has led to depletion in natural resources, nutrient loading, coastal erosion, and increased pollution. This project utilized sediment records retrieved near the mouth of the Manatee River to determine the anthropogenic land-use history of the Manatee River Watershed for the last one hundred years. The first phase of the project established the radiogeochemical and sedimentological history of the Manatee River. Radionuclide dating techniques using ¹³⁷Cs and ²¹⁰Pb were used to establish the accumulation rates and the timeline of the environmental evolution determined by grain size, total organic content, and carbonate content throughout each core. The second phase of this project examined the enrichment factors of several heavy metals including arsenic, lead, and copper. The enrichment factors of these heavy metals have been assigned to potential land-use changes throughout the history of the Manatee River Watershed such as growth of agricultural pesticide use and consumption of lead gasoline. This study provides a land-use archive that documents the significant anthropogenic and natural changes made to the Manatee River Watershed over the last one hundred years, which significantly increases our understanding of how the watershed reacts to anthropogenic land use change and how to manage those changes to prevent deleterious events in the future.