Molecular-level investigation of soils contaminated by oil spilled during the Gulf War

In this study, molecular-level chemical compositions of soils contaminated by oil spilled during the Gulf War were studied. Two soil samples, respectively collected at 0.1 m and between 0.5 and 1 m below the surface from an oil spill site, were extracted with organic solvents and water. The extracts were analyzed via ultrahigh resolution FT-ICR and two-dimensional gas chromatography/high resolution mass spectrometry. The data showed that the spilled oil was significantly affected by vaporization due to high surface temperatures in the desert. The data obtained with (+) atmospheric pressure photo ionization (APPI) and (-) electrospray ionization (ESI) coupled with ultrahigh resolution–mass spectrometry (UHR-MS) indicated that the degradation of aromatic compounds and increase in oxygen-containing classes occurred in the following order: surface soil > below surface soil > crude oil. The oxygenated compounds were confirmed by principal component analysis. The score and loading plots of O_x and SO_x showed that they were the major contributors to differentiate the samples. However, a comparison with previously reported oceanic oil spills showed that less significant degradation occurred even after almost 30 years. Our data can provide an information basis for designing a strategy for clean-up and restoration efforts of Gulf War oil spills.