NATURAL SEEPAGE IN THE GULF OF PARIA AND ITS RELATION WITH BEACH TAR ALONG THE SOUTHEASTERN COAST OF THE PARIA PENINSULA, VENEZUELA

Abstract

Tar residues are frequent on the south-eastern coastline of the Paria Peninsula. Here we studied tarballs along approximately 14 km of shoreline by means of a systematic monthly sampling conducted over a two-year period on beaches between the villages of Macuro and Mapire. More than 70% of the tarballs sampled were included in the same group on the basis of their physical and organoleptic properties. This group was then fingerprinted using biomarkers (hopanes, steranes, alkanes, aromatic steroids, phenanthrenes, and dibenzothiophenes) by gas chromatography coupled to flame ionization detection, and by gas chromatography/mass spectrometry. Sulfur and trace elements were also determined to complete the geochemical characterization. Our results showed that these beach tar residues do not have an anthropogenic origin and that they may have originated from carbonate source rocks within the Naparima Hill Formation via shallow offshore seepage. Therefore, we have established a geochemical background for tar residues that will be very helpful to distinguish natural from anthropogenic beach tar contamination along the south–eastern shoreline of the Paria Peninsula.