Hotspot detection and spatial distribution of methane emissions from landfills by a surface probe method

• We used a surface probe method to detect hotspots and to measure methane fluxes.
• We tested the method in three landfills and established methane flux maps.
• We developed two direct parameters to describe spatial variation of emissions.
• Approximately 5% of a landfill’s area was responsible for 50% of its total emissions.
• The method and spatial variation parameters allow for better gas recovery planning.

A surface probe method previously developed was used to detect hotspots and to determine spatial variation of methane (CH4) emissions from three landfills located in Mexico, with an intermediate or a final cover, as well as with or without a landfill gas collection system. The method was effective in the three landfills and allowed mapping of CH4 emissions with a resolution of 24–64 measurements per hectare, as well as the detection and quantification of hotspots, with a moderate experimental effort. In the three selected landfills, CH4 emissions were quantified to 10, 72, and 575 g m−2 d−1. Two straightforward parameters describing the spatial distribution of CH4 emissions were also developed. The first parameter provides the percentage of area responsible for a given percentage of total emissions, while the second parameter assigns a numerical value to flux homogeneity. Together, the emissions map and the spatial distribution parameters offer an appropriate tool to landfill operators willing to begin recovering CH4 emissions or to improve the effectiveness of an existing recovery system. This method may therefore help to reduce the greenhouse gas footprint of landfills, which are still the primary option for waste management in developing countries.