Bioconcentration of Creosote Compounds in Snails Obtained from Pensacola Bay, Florida, Near an Onshore Hazardous-Waste Site

Snails were collected from two areas offshore in Pensacola Bay near an onshore hazardous-waste site. The hazardous-waste site involved creosote contamination of ground water, resulting from activities at a wood-preserving facility. Because concentrations of creosote compounds in the water from Pensacola Bay may be too low for detection, snails, which are detritus feeders, were chosen as a preliminary indicator of bioconcentration. The snails, Thais haemostoma, were deshelled and the tissue homogenized. The tissue was then hydrolyzed for 2 hours with ethanolic potassium hydroxide. After extraction with isooctane and further cleanup with dimethyl-sulfoxide to eliminate cholesterol, the snail-tissue extracts were analyzed by gas chromatography-mass spectrometry. Along with naturally occurring compounds, the snail tissue contained large concentrations of polycyclic aromatic compounds, such as naphthalene, phenanthrene, acridine, dibenzothiophene, dibenzofuran, and benzo[a]pyrene. Many of these compounds are characteristic of the creosote contamination associated with the onshore hazardous-waste site. In the snail tissue, 23 compounds indicative of creosote contamination were quantitated. The compounds selected included four chemical classes: 13 polycyclic aromatic hydrocarbons (indane to benzo[a]pyrene); seven nitrogen heterocycles (2,4-dimethylpyridine to acridinone); two sulfur heterocycles (benzoand dibenzo-thiophene) ; and an oxygen heterocycle (dibenzofuran). Concentrations of the selected compounds in the snail tissue were higher at one site than the other site; however, when the concentrations were normalized to phenanthrene, the distributions of the compounds were similar, indicating a common source. Based on the n-octanol-water partition coefficient, the expected bioconcentration was compared to the actual concentration of each compound. An absence of a correlation between the bioconcentration and the n-octanol-water partition coefficient suggested an anthropogenic source. The low concentration and pattern of alkylated polycyclic aromatic hydrocarbons indicated that the source of these compounds was not petroleum. Many of the compounds studied (naphthalene versus 1- and 2-methylnaphthalene, acenaphthene versus biphenyl, phenanthrene versus anthracene), had similar n-octanol-water partition coefficients, yet the concentration of the compounds in the snail tissue varied considerably. Compounds with a n-octanol-water partition coefficient less than three were not bioconcentrated except for 2-quinoi i none. The concentration profiles of these compounds in the snail tissue were more closely correlated with profiles from nearby onshore ground water near the source of the contamination and near the shore. The concentration profiles in the snails resemble the creosote-contaminated ground-water profile rather than that predicted by the n-octanol-water partition coefficient. The anomaly of the 2-quinolinone present in the snail tissue was the result of extremely high concentrations of 2-quinoi i none present in the ground water. An evaluation of the snail-tissue extracts provided an excellent preliminary indication that the contaminated ground water was indeed impacting the food chain in Pensacola Bay.