The status of oil pollution in the Arabian Gulf by the end of 1993

Abstract

Measurements of total organic carbon (TOC) and concentrations of total petroleum hydrocarbons (TPHs) and trace metals (Pb, V, and Ni) in 40 body (lower 13 cm) - and top (upper 2 cm) - sediment core subsamples collected in December 1993 were used to delineate the status of chronic and recent oil pollution levels in the Arabian Gulf. These measurements were first compared with those made on subsamples collected in 1992 from the same sampling stations and correlated with previously identified oil-polluted areas in the region. The similarity of the grain-size distribution and chronic TPH, Pb, V, and Ni contents of the two sets of samples verifies the stability of chronic pollution levels in the Gulf and implies that bioturbation has a diminishing effect on bottom sediments in the region below 2 cm depth. Differences between the recent TPH contents of the two sets of samples were recorded in three polluted areas, including Area C (offshore Bahrain, Qatar, and the United Arab Emirates) polluted by the Kuwait oil slick. The relatively small increase in the 1993 TPH content of sediments in Area C suggests that, three years after the oil spill, the remaining smaller quantities of oil floating from tidal areas along the Saudi Arabian coastline had enough time to reside in the bottom sediments of the area without changing its state of oil pollution. By the end of 1993, the recent concentrations of Pb, V, and Ni in the sediment of Area C remained within the natural background levels, and hence verified that the Kuwait oil slick, as a whole (i.e., the spilled oil and the airborne fallouts), still has a minimal effect on the state of pollution by trace metals in the Arabian Gulf. The invalidity of V Ni ratios and TOC content of bottom sediments as indicators for oil pollution in the Arabian Gulf is emphasized.