Stable nitrogen and carbon isotope ratios of beach tars on South Texas barrier islands

Abstract

Stable nitrogen and carbon isotope analyses have been used to characterize two major oil spills in the northwestern Gulf of Mexico. Stable isotope ratios were determined on both the crude material and on discrete chemical fractions of the whole oil (aliphatic, aromatic and NOS). A comparison of these isotopic compositions, of the crude materials and their chemical fractions, with those from samples of beach tars collected from south Texas barrier islands has indicated at least sixteen distinct isotopic signatures in the beach tars, excluding those resembling the major spills. This variation may be indicative of multiple sources of oils stemming from exploration and transport activities. Multiple isotope analysis can be a useful tool in the resolution of origins of spilled oils and tars.