Unresolved complex mixture

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 chroma tography (GC×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 (6−28 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 (∼8 mg g-1). These values are similar to concentrations observed shortly after the spill. Initial GC×GC analysis revealed that only the n-...

Abstract: The spatial and temporal distribution of aliphatic and polycyclic aromatic hydrocarbons (PAHs) and sulfur/oxygen derivatives in sediments from the NW Mediterranean basin were investigated. Along the Continental Shelf and slope, an unresolved complex mixture (UCM) of aliphatic hydrocarbons and alkylated PAHs, indicative of petrogenic inputs, were predominant. Long-chain n-alkanes derived from terrestrial plant waxes (n-C27, n-C29, and n-C31) and parent PAHs, which are typical of high-temperature combustion processes, were evenly distributed in the whole basin and largely prevailing in the deepest areas. Perylene, a geochemically derived PAH, was found highly abundant in the areas influenced by river discharges. The highest anthropogenic hydrocarbon inputs were found near the cities of Marseille and Barcelona, being the contribution of the Rhone River ca. 25 times higher than that of the Ebro. Fluxes of PAHs in the deep basin were consistent with a predominant atmospheric input. These results account for an...