TEMPORAL PATTERNS OF ELEMENTS IN HILLSBOROUGH BAY, TAMPA BAY SEDIMENTS

Abstract

In the late 1980’s, a study was conducted to identify contaminated areas in Tampa Bay sediments, and sections of Hillsborough Bay consistently showed significant levels of toxicity. A study focusing on the broad stratigraphic history and temporal elemental levels of Hillsborough Bay has not since been conducted. To address the gap and determine how elemental levels in the sediments have changed over time, two cores were taken in Hillsborough Bay in May 2024. Analysis of grain size, carbonate and total organic matter, elemental composition by X-Ray Fluorescence (XRF), and gamma spectroscopy for geochronology was conducted. Spikes in concentrations of many terrigenous elements were located at 25 centimeters down-core, which dated to the 1970s, and 50 centimeters down-core, which was beyond the limits of the dating method used. Some elements seem to reflect short-lived events, and others show a long-term transition in the environment, like zinc and zircon. These upticks could be attributed to documented significant waste-water treatment plant dumping in Hillsborough River, Tampa Bay during the 1970s. It is important to document the bottom-sediment record as shifting elemental patterns of sediments in this area due to anthropogenic activity can impact the general environment health.