Alkanes, Terpanes, and Aromatic Hydrocarbons in Surficial Sediments of Halifax Harbor

Hydrocarbons were quantified it? sulficial sediments of Halifax Harbor. Alkanes ranging from nC-15 to nC-33 were detected in all samples at a mean concentration of 23.2 +/- 12.3 mug/g, dry. A lower mean concentration of 7.0 +/- 3.3 mug/g, dry, was observed for the smaller nC-15 to nC-22 alkanes, which represented between 15% and 60% of summed alkanes. The site with the highest sum of alkanes (46.4 mug/g, dry) also had the highest carbon preference index for the nC-15 to nC-33 alkanes (1.41), and lowest ratios of C-17 to pristane (1.23) and C-18 to phytane (0.83), reflecting terrestrial inputs, both biogenic and petrogenic. The latter source was confirmed by the profile of terpanes, including the hopanes. The ratio of tricyclic to summed terpanes remained relatively constant at all sites 0.26 +/- 0.04, revealing a chronic petrogenic input, with a moderate degree of degradation, because they were present in a concentration range (i.e., 15.0 +/- 10.0 mug/g) similar to that of alkanes. A site adjacent to a sewage treatment plant displayed lower levels of alkanes, terpanes, and unresolved complex mixture as well as PACs compared to the two closest sites. Two sites at the entrance to the harbor consistently displayed lower levels of all hydrocarbons.