PETROLEUM HYDROCARBONS DISTRIBUTION IN SEDIMENTS FROM THE THAMES ESTUARY, UK

Abstract

Sediment cores were collected from the Stanford-Le-Hope mudflats within 1 km distance from the Petroplus-Coryton BP and Shell Haven refineries located on the north shore of the Thames Estuary in Essex, 40 km east of Central London, UK (51 °30´N, 0 °27´E). The BTEX compounds (benzene, toluene, ethylbenzene, o-, m-, and p-xylenes) in surface sediment samples were non-detectable within the linear calibration range of 0 – 50 mg l-1.  n-Alkanes (C11 - C40) and polycyclic aromatic hydrocarbons (PAHs) quantified at different sediment depths (2 cm core portions up to a total depth of 18 cm) indicated a high distribution of n-alkanes in subsurface sediments at the 10 – 12 cm depth; up to an average concentration of 1353.4 µg g-1 dry weight. The highest summed PAH (∑PAH) concentration of 2.95 µg g-1 dry weight was also found at the 10 – 12 cm depth. Source identification based on the ratio of low-molecular weight (LMW) to high-molecular weight (HMW) n-alkanes and the pristane/phytane ratio (Pr/Phy) indicated n-alkane input from biogenic sources. Nevertheless, the dominance of C1-naphthalene among ∑PAH concentrations suggested possible input from petroleum-related sources.