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6252425 
Journal Article 
Chilean paraffin dirt—II. Natural gas seepage at an active site and its geochemical consequences 
Crisp, PT; Didyk, BM; Rohrback, BG; Simoneit, BRT 
1980 
Elsevier 
12 
Elsevier 
171-176 
An active “paraffin-dirt” site located in the inter-Andean Plateau (altitude ∼ 4300 m), Antofagasta, Chile, near that studied by Simoneit and Didyk (1978), was sampled for soil-gas and surface sediment. Soil-gases were analyzed by gas chromatography (GC), using both flame ionization and thermal conductivity detectors. Surface sediments were analyzed for their organic carbon and lipid contents and examined for bacteria. Lipids extracted from the sediments were analyzed by GC and GC-MS. High concentratrations of C1C6 alkanes and CO2 were detected in the soil-gas and C2C5 alkenes accumulated in the head space of canned soil. The presence of the full isomeric series of C2C6 alkanes indicates the presence of an active seep; significant concentrations of methane, C2C5 alkenes and CO2 indicate microbiological activity. Microscopic examination of the soil revealed an abundance of rod bacteria. Elemental analyses yielded a high HC ratio for the organic matter and indicated high concentrations of organic or elemental sulfur. The distribution of hydrocarbons appears typical of bacterial lipid residues. The data indicate active bacterial assimilation of seeping natural gas in contrast to the sample site studied earlier, where the seepage had ceased.