Detection of hotspots and rapid determination of methane emissions from landfills via a ground-surface method

We present a method for the rapid determination of methane emissions from landfills based on atmospheric dispersion theory, which suggests that the methane concentration, at a small distance from the soil/atmosphere interface, is proportional to its flux. Thus, after suitable calibration, the determination of methane concentrations close to the ground allows for flux determination in a shorter time than with standard enclosure techniques. This concept was tested using a surface probe in direct contact with the ground. The probe extracts a continuous sample of the air at the probe/ground interface and transports it to a portable methane analyzer. It was observed that stable methane concentrations were measured 30 s after the probe was positioned at the measurement point. These concentrations correlated well with the fluxes measured by standard static chambers. The method was used to determine the fluxes at 217 points within a 90,000 m(2) landfill. These measurements facilitated mapping of the CH4 emissions and the localization of hotspots. We conclude that the method is simple, effective, and relatively quick, compared to existing standard methods.