The West Falmouth Oil Spill after Thirty Years:  The Persistence of Petroleum Hydrocarbons in Marsh Sediments

Abstract

The long-term fate of petroleum hydrocarbons in marsh sediments (West Falmouth, MA) contaminated in 1969 by the spill of the barge Florida was investigated. A 36-cm-long sediment core was collected in August 2000, and sediment extracts were analyzed by gas chromatography (GC) and comprehensive two-dimensional gas chromatography (GC x GC). The latter technique is capable of separating 1 order of magnitude more compounds than the former and was used to observe whether any compositional changes in the unresolved complex mixture (UCM) occurred. No evidence of petroleum residues was detected in the top 6 cm (0-6 cm) and the lower 8 cm (28-36 cm) of the core. However, the central sections 16-28 cm) were dominated by a UCM in the boiling range of n-C13-n-C25 alkanes, consistent with a No. 2 fuel oil source. The 12-14- and 14-16-cm sections had the highest concentrations of UCM approximately 8 mg g(-1)). These values are similar to concentrations observed shortly after the spill. Initial GC x GC analysis revealed that only the n-alkanes were completely degraded, and contrary to previous studies, pristane and phytane as well as numerous other branched alkanes are still present in the sediments. These results suggestthatatthis site hydrocarbon contamination will persist indefinitely in the sedimentary record.

Long-term biological effects of petroleum residues on fiddler crabs in salt marshes

“…Despite slight differences in analytical methods, the concentrations of residual total petroleum hydrocarbons (TPHs) within the 8 to 20 cm layer, for sediment collected in 2000, were in roughly the same range as those measured in 1973 in surface sediments (Reddy et al, 2002). The petroleum hydrocarbons present at depth are moderately degraded: volatile and water-soluble compounds and nalkanes 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, 2005). In particular, total PAHs (mostly alkylated naphthalenes and phenanthrenes/anthracenes) in a core collected in 2000 were 134 _g g -1 in the 14-16 cm horizon (White et al, 2005b); such levels are very similar to concentrations of PAHs found in the 1970s (Blumer and Sass, 1972).…”

“…The oiled sediments are now overlain by subsequent accretion, about 0.35 cm yr -1 , of salt marsh sediments devoid of oil (White et al, 2005a). Despite slight differences in analytical methods, the concentrations of residual total petroleum hydrocarbons (TPHs) within the 8 to 20 cm layer, for sediment collected in 2000, were in roughly the same range as those measured in 1973 in surface sediments (Reddy et al, 2002). The petroleum hydrocarbons present at depth are moderately degraded: volatile and water-soluble compounds and nalkanes 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, 2005).…”

“…2 fuel oil was still present 8 to 20 cm below the salt marsh surface (Fig. 3b) across Wild Harbor (Frysinger et al, 2003;Reddy et al, 2002;Slater et al, 2005;White et al 2005a, b;Peacock et al, 2005). The oiled sediments are now overlain by subsequent accretion, about 0.35 cm yr -1 , of salt marsh sediments devoid of oil (White et al, 2005a).…”

Influence of Petroleum Deposit Geometry on Local Gradient of Electron Acceptors and Microbial Catabolic Potential

“…While petroleum hydrocarbons themselves are rich source of organic carbon and are readily biodegradable [19], particularly under aerobic conditions, their extreme hydrophobicity and low solubility [20][21][22][23] complicates accurate predictions of natural attenuation rates. One potentially critical factor governing persistence in coastal environments that has generally been overlooked in models is geometry of the contaminant source.…”

“…It is known to cause significant shifts in microbial communities of oceans and coasts [14, 17, 56, 57] and negatively impacts most of the higher life forms [5,7,16,22,23,49,58].…”