A GEOCHEMICAL RECORD OF ANTHROPOGENIC DISTURBANCES IN NAPLES BAY ESTUARY, FLORIDA

Naples Bay, extending 10 km along the southwest coast of Florida, has undergone significant urbanization over the past decade. Characteristic of many watersheds in Florida, the rather shallow (1-8 m) estuarine system experiences dredge & fill operations, channelization, and episodic urban runoff, which alter hydrological cycles and produce eutrophic effects. Previous evidence shows that decreased tidal flushing and increased water column stratification has occurred as a result of these changes, affording the ability to determine how such development is reflected in the geochemistry of a relatively sensitive ecosystem. Radioisotopic (Pb-210 and Cs-137), textural, and bulk elemental analyses are being performed on sediment cores from 5 representative regions of the bay. This information will be used to compare pre-urbanization with present sedimentological and ecological conditions. Current radiogenic isotope data reveal high levels of excess Pb-210 activity deeper than 18 cm below the surface, suggesting that recent accumulation rates faster than sea level rise are a possible effect of shoreline development. Ongoing analyses will help quantify anthropogenic impacts on accumulation rates, organic matter sources, and sedimentary structures in the Naples Bay estuary.