DISTINGUISHING NATURAL HYDROCARBONS FROM ANTHROPOGENIC CONTAMINATION IN-GROUND WATER

Differentiation between natural and anthropogenic sources of ground-wa ter contamination by petroleum hydrocarbons is necessary in areas wher e natural hydrocarbons may be present in the subsurface. Because of th e similarity in composition between natural and refined petroleum, the use of statistical techniques to discern trends is required. In this study, both multivariate plotting techniques and principal component a nalysis were used to investigate the origin of hydrocarbons from a var iety of study sites. Ground-water and gas samples were collected from the Niagara Falls area and from three gasoline stations where leaking underground storage tanks had been found. Although soil gas surveys ar e used to indicate the presence of hydrocarbons, they were not useful in differentiating between natural and anthropogenic sources of contam ination in ground water. Propane and pentene were found to be the most useful chemical parameters in discriminating between the natural and anthropogenic sources. These chemicals are not usually measured in inv estigations of ground-water contamination, yet analysis can be conduct ed by most environmental laboratories using conventional methods.