Assessing the sources of organic matter in sediments from the Gulf of Batabano (Cuba) using stable isotopes, aliphatic and polycyclic aromatic hydrocarbons

Samples of superficial sediments collected along the Gulf of Batabano<acute accent>, Cuba were analysed for the first time to characterize contents of biogenic and anthropogenic hydrocarbon biomarkers aiming to understand sources of hydrocarbon contamination that might contribute to biodiversity loss and fisheries decline. Total Petroleum Hydrocarbon (TPH) levels, ranging from 7.8 to 54 mu g g- 1 dry weight, fall within the range typical for non- polluted areas, suggesting minimal anthropogenic impact. The sediment's aliphatic hydrocarbon profile further supports this, showing no signs of petrogenic contamination and a variation in total & sum;n-alkanes concentration between 0.31 and 8.2 mu g g- 1 dry weight. The presence of high concentrations of highly branched isoprenoids (HBIs), (3(3 hopanoid compounds, and the absence of the C32-C35 extended hopane doublets, which are indicative of crude oil pollution, point to a dominance of natural organic sources. This is corroborated by delta 13C isotopic values of specific aliphatic biomarkers, which trace back to biogenic origins such as terrestrial plant waxes, seagrass beds, and marine plankton, with the seagrass beds being the primary contributor to the organic matter in offshore sediments. Lastly, the low-level presence of polycyclic aromatic hydrocarbons (PAHs) and their pyrolytic origin pattern suggest limited contamination, likely from combustion processes rather than direct petroleum input. This comprehensive analysis underscores the importance of ongoing monitoring to preserve the ecological integrity of such marine environment.