PNNL

Abstract

In January 1991, the world's largest oil spill inundated extensive coastal areas of the Gulf with massive quantities of crude oil. In August 1993, the authors collected sediment samples from eleven beach sites at four tidal elevations in Kuwait and Saudi Arabia. Ten-day static sediment toxicity tests with the marine amphipods Rhepoxynius abronius revealed significant sediment toxicity (reduced survival) at five sites. Infrared spectrometry indicated that the highest concentrations of petroleum hydrocarbons occurred at these same five sites. Other variables such as ammonia concentration, silt and clay content, and total organic matter in the sediment had no effect on amphipod survival. Concentrations of petroleum hydrocarbons greater than about 1 mg g-1 dry sediment cause significant amphipod mortality. Such toxic sediment concentrations occurred at Al Khiran, Kuwait, and along an extensive coastal area of Saudi Arabia from Ras Tanajib to Abu Ali (a distance of over 100 km). The overall area of sediment toxicity corresponds closely to the spill trajectory and presence of sea surface petroleum as recorded on airborne radar soon after the spill (9 March 1991). These results indicate that sediment toxicity from the world's largest oil spill persisted for at least 30 months. Additionally, petroleum hydrocarbon concentrations in the sediments of contaminated sites were sufficiently high to cause continued leaching of oil to the sea surface.