THE BIOGEOCHEMICAL IMPORTANCE OF REACTIVE IRON IN FLORIDA BAY SEDIMENTS: BENTHIC-PELAGIC COUPLING AND SEASONAL SULFIDE DYNAMICS

Iron and manganese redox chemistry are important drivers of sulfur cycling in marine sediments. Florida Bay sediments are extremely sulfidic, having been attributed to mass mortality of seagrass and oxygen depletion in the water column. This research used conventional sediment analyses and a diagenetic model to infer the overall capacity for Florida Bay sediments to eliminate hydrogen sulfide and prevent high rates of sediment dissolved oxygen consumption via hydrogen sulfide reoxidation. Previous studies have suggested that iron is important for buffering hydrogen sulfide in Florida Bay sediments, while the results of this project show for the first time that this phenomenon is relevant only in specific locations and times of the year. However, my research indicates that Fe has the potential to sequester sulfides and minimize hypoxia in the Everglades system. Thus, under a scenario that greater amounts of Fe are delivered to Florida Bay sediments from freshwater flows under Everglades restoration, Fe could be a component of ecosystem management.