Nonpolar lipid tracers in sediments from the Shatt al-Arab River of Iraq and the northwestern Arabian Gulf

Abstract

Surface sediment samples from the Shatt al-Arab River of Iraq and northwestern coast of the Arabian Gulf were collected and analyzed to determine the characteristics, concentrations, distribution, and sources of nonpolar lipid compounds. The sediments were collected using a Van Veen grab sampler, dried, extracted with a mixture of dichloromethane/methanol, and analyzed by gas chromatography–mass spectrometry. The lipid compounds included n-alkanes (24.55 ± 44.35 μg g−1), methyl n-alkanoates (11.45 ± 9.45 μg g−1), hopanes (13.31 ± 13.46 μg g−1), steranes (15.63 ± 28.40 μg g−1), phthalates (36.99 ± 53.62 μg g−1), and unresolved complex mixture (315.84 ± 435.87 μg g−1). The major sources of these lipids were from anthropogenic petroleum inputs and plasticizers with lesser amounts from natural waxes of higher plants and microbial residues. Anthropogenic inputs from petroleum products ranged from 53 to 92 % of the total lipid compounds, whereas biogenic inputs were from 1.8 to 6.9 % for terrestrial plant wax and from 2.0 to 10.0 % for microbial detritus.