HYDROCARBON CONTAMINATION OF THE RHONE DELTA AND WESTERN MEDITERRANEAN

The distribution and origin of non-aromatic hydrocarbons (NAH) and polycyclic aromatic hydrocarbons (PAH) were investigated in superficial sediments from the Rhone delta and from the open Western Mediterranean Sea. Hydrocarbons extracted from sediments were fractionated by high performance liquid chromatography and analysed by gas chromatography and GC/mass spectrometry. NAH concentrations ranged 6.5-348.9-mu-g g-1 of dry sediment and from 1.7-20.2 mg g-1 of organic carbon (OC) in sediment. PAH concentrations ranged 179-2427 ng g-1 and 43.8-237.9-mu-g g-1 OC, respectively. Higher concentrations were observed at stations close to the river mouth and in the Gulf of Fos. Lower background levels of hydrocarbons were found in deep sediments from the north and central western Mediterranean. Different diagnostic criteria, such as unresolved/resolved compounds ratio, carbon preference index of n-alkanes, pristane/n-C-17 ratio, and distribution patterns of PAH were used to distinguish between natural and mixed anthropogenic inputs, underlining the utility of a multi-diagnostic criteria approach. The amount of hydrocarbons deposited in this part of the Mediterranean Sea is estimated at 416 t yr-1.