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Alkylcyclohexanes in environmental geochemistry

Environmental Forensics

By:
,
DOI: 10.1006/enfo.2002.0100

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Abstract

The n-alkylated cyclohexanes (CHs) are a homologous series of hydrocarbon compounds that are commonly present in crude oil and refinery products such as diesel fuel. These compounds exhibit specific distribution patterns for different fuel types, providing useful fingerprints for characterizing petroleum products, especially after degradation of n-alkanes has occurred. However, there are no published data to show how these compounds are altered in the environment after long-term spillage of petroleum products. This paper presents two case studies of oil spills that demonstrate the changing distribution patterns resulting from long-term anaerobic microbial degradation. These spills are the 1979 crude-oil spill in Bemidji, Minnesota, and a chronic diesel-fuel spillage from 1953-1991 at Mandan, North Dakota. The alkyl CHs in both spilled oil products are affected by similar biodegradative processes in which the compounds undergo a consistent pattern of loss from the high molecular weight end of the homolog distribution. Degradation results in a measurable increase in the concentrations of the homologs in the lower molecular weight range, a gradual lowering in carbon number of the homolog maximum, and a gradual decrease of the total homolog range from the high molecular weight end. This pattern is the opposite of low-end loss expected with weathering and aerobic biodegradation. The enhancement of the low molecular mass alkyl CH homologs, if not recognized as a degradative pathway of diesel fuel in an anaerobic environment, can potentially be misinterpreted in fuel-oil fingerprinting as deriving from lower distillation-range fuels or admixture of diesel with other fuels.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Alkylcyclohexanes in environmental geochemistry
Series title:
Environmental Forensics
DOI:
10.1006/enfo.2002.0100
Volume
3
Issue:
3-4
Year Published:
2002
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
293
Last page:
301
Number of Pages:
9