Spatial and temporal characteristics of urban atmospheric methane in Nagoya City, Japan: : an assessment of the contribution from regional landfills

The spatial and temporal behavior of atmospheric methane (CH4) in the Nagoya metropolitan area was investigated in relation to the regional meteorological and topographical characteristics. It was found that the daily maximum CH4 concentrations in the central city area were observed when the northeast wind blew from the foothill of the northeastern mountainous area down into the central city areas, under stable atmospheric conditions. The large and active landfills are the major anthropogenic CH4 sources and are located at the hill sites in the northeast. Therefore, it was considered that the air mass with the high concentration of CH4 flowed from the landfill sites into the urban area, and exerted substantial influences on the spatial and temporal variations of atmospheric CH4 concentrations in the central city area.