In situ quantification of methane oxidation in soils using Gas Push-Pull Tests

The Gas Push-Pull Test (GPPT) is a tool for measuring in situ soil processes including methane oxidation. To quantify methane oxidation, methane and non-reactive gases selected based on transport behaviour similar to methane, were injected into soil above a petroleum hydrocarbon contaminated aquifer and gas samples were extracted over time. The rate of loss of methane was compared to the loss of tracer gases and differences in the concentrations were attributed to microbial activity. To further support the evidence for microbial methane consumption, tests were also performed under conditions of inhibited microbial activity.