Estimation of areal flux of atmospheric methane in an urban area of Nagoya, Japan, inferred from atmospheric radon-222 data

To clarify the emission of methane (CH4) from area sources, we have adopted atmospheric radon-222 (222Rn) as a natural tracer. The diurnal variation in CH4 concentration is predominantly affected by local meteorological conditions as is the case of 222Rn. Positive correlations are recognized between atmospheric CH4 and 222Rn concentrations. From these correlations, the CH4 flux from urban area in Nagoya, Japan, was estimated to be almost constant at 0.02 gCH4m−2d−1 over a year.