Hydrocarbon seeps

Zande, J. M. (1999). An ascomycete commensal on the gills of Bathynerita naticoidea, the dominant gastropod at Gulf of Mexico hydrocarbon seeps. Invertebrate Biology, 118, 57-62. 

Eu B. (1998) A study of pore fluids and barite deposits from hydrocarbon seeps deepwater Gulf of Mexico. PhD Thesis, Louisiana State University. 

Wade T. L., Kennicutt M. C., and Brooks J. M. (1989) Gulf of Mexico hydrocarbon seep communities Part 111. Aromatic hydrocarbon concentrations in organisms, sediments, and water. Mar. Environ. Res. 27, 19-30. 

Hornafius J. S., Quigley D., and Luyendyk B. P. (1999) The world s most spectacular marine hydrocarbon seeps (Coal Oil Point, Santa Barbara Channel, California) quantification of emissions. J. Geophys. Res.-Oceans 104, 20703—20711. 

Among the classes of compounds in crude oil, the alkanes, cycloalkanes, and aromatic fractions contain compounds that are volatile and are described in more detail in this chapter. The NSO compounds, resins and asphaltenes, and organometalhc compounds are nonvolatile and, in general, are less mobile in the environment. A discussion of these compounds is beyond the scope of this chapter. Examples of some of the volatile hydrocarbons present in cmde oil for the major compound classes are shown in Figure 6. Benzene, toluene, xylenes, ethylbenzene, isopropylbenzene, naphthalene, methyl- and dimethyl-naphthalenes are among the most important volatile aromatic hydrocarbons, because they are widely used and, once released into the environment, their mobility and toxicity make them a significant environmental threat (Merian and Zander, 1982). The occurrence of these compounds in the environment is almost exclusively anthropogenic, with the exception of natural hydrocarbon seeps. 

There is abundant field evidence for the existence of SP cells over petroleum reservoirs. Indeed this evidence itself was used to find petroleum reservoirs for almost 100 years before the cells were recognised. It includes gaseous and liquid hydrocarbon seeps, paraffin deposits, halo-type metal anomalies, iron and manganese deposition, carbonate cementation, hard-drilling areas, magnetic anomalies (associated with magnetite mineralisation) and elevated uranium concentrations (Tomkins, 1990). Chapters 5-7 of this volume and references provided therein document many of these features. 

The occurrence at surface of hydrocarbon seeps suggests that an oil or gas reservoir leaks even though it acts as a trap for hydrocarbons. Macroseepage is the visible presence of oil and gas seeping to the surface. Macroseeps have been documented in various parts of the world (Davidson, 1963 Sittig, 1980 Hunt, 1981 Davis, 1967 Tedosco, 1995). Microseeps are invisible trace quantities of hydrocarbons seeping to the... 

Pirkle, R.J., 1985. Hydrocarbon seeps in the Gulf of Mexico. Presented at 189 Annual Meeting, Amer. Chem. Soc., Miami Beach, Florida. 

Williams, J.C., Mousseau, R.J. and Weismann, T.J., 1981. Correlation of well gas analysis with hydrocarbon seeps (abs). Proc. Meeting American Chemical Society, Atlanta, GA, March 29-April 3. 

For example, natural hydrocarbon seeps (oil and gas flow out of the ocean floor) have been reported to support dense biological communities. Hydrocarbon seeps produce methane and hydrogen sulfide. Certain bacteria can live on compounds like methane and hydrogen sulfide. Certain species (e.g., tube worms and mussels) can establish a symbiotic relationship with these bacteria and not only survive, but thrive in deep sea seeps. These populations may provide the basis for diverse community in the seep environment. The following are examples of life in areas that have naturally high levels of hydrogen sulfide. 

The most compelling evidence for microbial utilisation of seep hydrocarbons as energy and nutritional carbon sources, and of the pathway of carbon flow through the seep fauna and carbonates, comes from the distribution of stable carbon isotopes at hydrocarbon seeps in the Gulf of Mexico (Aharon, 2000). 

Aharon, P., Schwarcz, H.P. and Roberts, H.H. (1997) Radiometric dating of submarine hydrocarbon seeps in the Gulf of Mexico. Bulletin Geological Society America, 109, 568—579. 

Sen Gupta, B. K., Platon, E., Bernhard, J. M. Aharon, P. 1997. Foraminiferal colonization of hydrocarbon-seep bacterial mats and underlying sediment, Gulf of Mexico slope. Journal of Foraminiferal Research, 27, 292 -300. 

Bauer J. E., Spies R. B., Vogel J. S., Nelson D. E. and Southon J. R. (1990) Radiocarbon evidence of fossil-carbon cycling in sediments of a near shore hydrocarbon seep. Nature 348, 230-232. 

Yan, T, Ye, Q., Zhou, I, Zhang, C.L. 2006. Diversity of functional genes for methanotrophs in sediments associated with gas hydrates and hydrocarbon seeps in the Guff of Mexico. FEME Microbiol... 

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