HYDROCARBONS AND RELATED PHOTOOXIDATION PRODUCTS IN SAUDI-ARABIAN GULF COASTAL WATERS AND HYDROCARBONS IN UNDERLYING SEDIMENTS AND BIOINDICATOR BIVALVES

Saudi Arabian coastal waters near sandy beaches, severely contaminated with crude oil released in Kuwait during the 1991 Gulf War, as well a s underlying sediments and a few bivalves, were analysed to assess con centrations and composition of petrogenic hydrocarbon mixtures and str ucturally related oxidation products. Concentrations of dissolved oil residues determined by UV spectrofluorometry (UVF) near oil deposits o n beaches did not exceed 3.5 mug l-1; concentrations dropped to approx imately 1/10th of this value a few miles offshore. Gravimetric concent rations of unfractionated lipophilic material extracted from large vol umes of seawater at the same stations were up to 10 times those determ ined by UVF. After chromatography on silica gel, individual petroleum hydrocarbons in the low polarity fractions and oxidation products in t he polar fractions were characterized by their spectra (GC/MS) and qua ntitated by Selected Ion Monitoring (SIM) GC/MS. Concentrations of oxi dation products (ketones, aldehydes, alcohols) of aromatic hydrocarbon s exceeded those of their parent compounds by more than an order of ma gnitude. Significant concentrations were also found of the presumably pyrogenic triplett sensitizer anthraquinone. Contributions to polar fr actions of water extracts by biosynthesized lipids were negligible. UV F determinations appear to underestimate concentrations of dissolved o il residues, because many oxidation products have lower fluorescence q uantum yields than the respective parent hydrocarbons. Their ecotoxico logical properties are unknown. Concentrations measured in sediments b y UVF ranged from 13 to 540 mug g-1 dry wt and 0.5 to 103 mug g-1 as m easured by gas chromatography with flame ionization detection (FID GC) . Bivalves ranged from 0.8 to 1.5 mug mg-1 extractable organic matter (EOM) by UVF, and 0.1 to 0.3 mug mg-1 EOM by GC analysis. PAHs were id entified in sediment and bivalve extracts by GC/MS and quantitated by SIM GC/MS. None or the relatively water soluble alkylbenzene photo-oxi dation products found in water samples nor any higher molecular weight quinones could be detected in sediment extracts. However, ion chromat ograms strongly suggest the presence of numerous high molecular weight aromatics in that matrix.