Abundance, Composition, and Vertical Transport of PAHs in Marsh Sediments

Abstract

Petroleum-derived hydrocarbons continue to persist in Wild Harbor, West Falmouth, MA, following a spill of No. 2 fuel oil in 1969 from the barge Florida. Recent analysis of marsh sediments revealed that residues of degraded oil are present with concentrations of total petroleum hydrocarbons as high as approximately 9 mg g(-1). Polycyclic aromatic hydrocarbons (PAHs) constitute only a minor fraction of these residues with maximum concentrations of 134 mirog g(-1), but their fate is of interest because of their potential toxicity to organisms. As compared to typical unweathered No. 2 fuel oil, the current distribution of PAHs in the sediments reflects substantial weathering by abiotic and biotic processes, specifically a preferential loss of naphthalenes relative to phenanthrenes, as well as isomer-specific biodegradation of alkylated PAHs. Based on comparison to results from an earlier study, it appears that little or no change has occurred to the distribution of PAHs since 1989, indicating that weathering at this site has stalled or is now proceeding at a significantly slower rate. To assess whether sediment-water partitioning and molecular diffusion in the interstitial medium are now the dominant processes controlling the vertical distribution of PAHs, downcore profiles were compared to a numerical model. While in some cases the model accurately reproduced the measured data, there were instances where the distribution of PAHs was slightly under or overestimated. Reasons for these discrepancies are discussed and are likely due to bioturbation, colloid-facilitated transport, or both. Assessment of the influence of these processes on the spilled oil expands our understanding of the overall fate of these compounds and their potential long-term effects on the environment.

Effect of field exposure to 38-year-old residual petroleum hydrocarbons on growth, condition index, and filtration rate of the ribbed mussel, Geukensia demissa

“…The petroleum hydrocarbons present at depth are moderately degraded: volatile and water-soluble compounds and n-alkanes have been removed, concentrations of acyclic isoprenoids have been reduced, but alkyl cyclohexanes, alkylbenzenes, and polycyclic aromatic hydrocarbons (PAHs) as well as many other unidentified hydrocarbons still persist (Reddy et al, 2002;Frysinger et al, 2003;White et al, 2005b). Total PAHs (mostly alkylated naphthalenes and phenanthrenes/anthracenes) in a core collected in 2000 were 134 µg g -1 in the 14-16 cm horizon (White et al, 2005b).…”

Status of organic pollutants in surface sediments of Barnegat Bay-Little Egg Harbor Estuary, New Jersey, USA

“…The higher values were attributed in part to catastrophic oil spill events as well as diffuse pollution sources . Similarly, downcore TPH profiles tracking an oil spill event in 1969 at salt marsh in Wild Harbor, West Falmouth, MA, showed TPH values as high as 9000 mg/kg (White et al, 2005).…”

Spatially Explicit Analysis of Metal Transfer to Biota: Infl uence of Soil Contamination and Landscape

“…Sediment cores can be used to study the pollution history of aquatic ecosystem [48,49]. Within an individual sediment core, differences in pollutant concentrations at different depths reflect how heavy metal input and accumulation changes over time [50,51]. The purpose of this study is (1) to quantify and explain the spatial distribution of heavy metal contaminants in modern sediments of Jinzhou bay, NE China; (2) to investigate the natural and anthropogenic processes controlling sediment chemistry; and (3) to identify the potential ecological risks of such heavy metals.…”