PATTERNS OF CHEMICAL-CHANGES DURING ENVIRONMENTAL ALTERATION OF HYDROCARBON FUELS

This paper discusses major environmental alteration processes and desc ribes a set of chemical tests that have been developed to monitor comp ositional changes in hydrocarbon fuels released into the environment. The methods examine various homologous series of hydrocarbons includin g straight chain (paraffins or n-alkanes), branched chain (isoparaffin s or isoprenoids), alicyclic (naphthenes or alkylated cyclohexanes), p olycyclic (steranes and terpanes), and aromatic structures (benzene, t oluene, ethylbenzene, xylenes, alkylated benzenes, polycyclic aromatic hydrocarbons, and aromatic steranes). Each one of these groups of hyd rocarbons has a different tolerance to environmental alteration by eva poration, dissolution (water washing), and biodegradation. When used a s an analytical system on environmental samples, the data obtained pro vide information on fuel type recognition patterns and on degradation levels of the various fuels, allowing for an estimate of residence tim e.