Sediment quality survey of the Choctawhatchee Bay system in the Florida panhandle

To assess the overall ecosystem health of Choctawhatchee Bay, located in the western Florida panhandle, sediment samples were collected at 13 different locations over a 2-d period in August 2002 and analyzed for metals, organochlorines, aliphatic hydrocarbons, and PAHs. Dioxin toxicity equivalents were calculated for 17 dioxin and furan metabolic analytes. The resulting data showed that sediment composition in the Bay was comparable to that of other bay systems of the northeastern Gulf of Mexico. Arsenic, copper, lead, mercury, nickel, and silver concentrations were in excess of sediment-quality guidelines at the effects range low (ERL) level, but none exceeded the effects range median criteria. Concentrations of PAHs exceeding ERL occurred in Tom's Bayou, Garnier's Bayou, and Cinco Bayou. Among organochlorine compounds, sediment quality guidelines were exceeded only for PCBs and total DDT. The highest toxicity equivalent value was calculated for Tom's Bayou. The sediment sample taken from Mullet Creek contained substantially more phenoxy herbicide residues, but residues were also relatively high in sediments from Tom's Bayou and Rocky Bayou, which was also found in terms of concentrations of aliphatic hydrocarbons.