Analysis of dissolved methane, ethane, and ethylene in ground water by a standard gas chromatographic technique.

The measurement of dissolved gases such as methane, ethane, and ethylene in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel- or solvent-contaminated aquifer. A simple procedure is described for the collection and subsequent analysis of ground water samples for these analytes. A helium headspace is generated above a water-filled bottle. Gases that are dissolved in the water partition between the gas and liquid phases and equilibrate rapidly. An aliquot of this headspace is analyzed by gas chromatography to determine the gases concentration in this phase. The concentration of the gas dissolved in the water can then be calculated based on its partitioning properties, as indicated by its Henry's Law constant.

Protozoa in subsurface sediments from sites contaminated with aviation gasoline or jet fuel.

Numbers of protozoa in the subsurface of aviation gasoline and jet fuel spill areas at a Coast Guard base at Traverse City, Mich., were determined. Boreholes were drilled in an uncontaminated location, in contaminated but untreated parts of the fuel plumes, and in the aviation gasoline source area undergoing H(2)O(2) biotreatment. Samples were taken from the unsaturated zone to depths slightly below the floating free product in the saturated zone. Protozoa were found to occur in elevated numbers in the unsaturated zone, where fuel vapors mixed with atmospheric oxygen, and below the layer of floating fuel, where uncontaminated groundwater came into contact with fuel. The same trends were noted in the biotreatment area, except that numbers of protozoa were higher. Numbers of protozoa in some contaminated areas equalled or exceeded those found in surface soil. The abundance of protozoa in the biotreatment area was high enough that it would be expected to significantly reduce the bacterial community that was degrading the fuel. Little reduction in hydraulic conductivity was observed, and no bacterial fouling of the aquifer was observed during biotreatment.