Identification of Large PAHs in Bitumens from Deep-Sea Hydrothermal Vents

Abstract

Bitumens are materials produced when organic matter is exposed to the extremely harsh conditions adjacent to deep-sea hydrothermal vents. The temperature and action of the near critical, and possibly supercritical, water present under such conditions contribute to the production and migration of these bitumens. Bitumens are superficially similar to petroleum, and their composition has been determined by mass spectrometry and GC-MS. In the present work, HPLC with diode-array absorbance detection was used to identify the polycyclic aromatic hydrocarbons (PAHs). Shpol'skii spectrofluorometry was used to confirm the structures. Samples from various sites in the Pacific Ocean; the Red Sea; Yellowstone National Park in Wyoming, U.S.A.; and Lake Tanganyika have been examined.

Several large PAHs of over seven rings have been identified. Different possible production routes are proposed to explain the structures and the variation between samples and locales as well as the effects of hydrothermal conditions.

Key Words:

• Large PAHs
• Hydrothermal Vents