03/02012 Photo-oxidation products of petroleum hydrocarbons in the Eastern Red Sea coastal waters: Al-Lihaibi, S. S. Environment International, 2003, 28, (7), 573–579

Abstract

The level of dissolved oil residues as well as the oxygenated petroleum hydrocarbons in the seawater of the affected area of Jeddah coast, Red Sea was estimated. The dissolved/dispersed petroleum hydrocarbons concentration was found minimal. The minimum level may be attributed to the action of the weathering processes. Selected samples of the dichIoromethane extracts of seawater were fractionated, using silica gel columns, into four fractions eluted with solvents of increasing polarity. The fluorescence intensity of these fractions was measured at three different pairs of excitation and emission wavelengths using ultraviolet fluore;;cence spectrofluorophotomelly (UVF). The total fluorescence intensity of the fractions at 280 run excitation, 327 run emission wavelengths and 310 om excitation, 360 nm emission wavelengths exceeds the fluorescence intensity of the whole extract by more than two orders of magnitude. The estimation of higher molecular mass oxygenated compounds in the fourth fractions, read at 380 run excitation, 430 run emission wavelengths. indicates rather Iow concentrations of < I ).!g 1- I hydroxypyrene equivalents. However, the polar fractions (eluted with acetone) account for more than 25% of the total fluorescence intensity of all fractions combined at eacb pair of wavelengths. The characterization of the products causing the fluorescence particularly the high molecular mass compounds still presents difficulties. Preliminary GCIMS results revealed some evidence for petroleum hydrocarbon oxidation products. Alkyl isobenzofumnones bave been found in some seawater extracts. This is an ongoing project to characterize and identifY additional compounds from these extracts.