Masaaki Hosomi*, Yuji Sakai**, Noriyoshi Usui**, Gen Inoue***, and Mamoru Kobayashi**

*Tokyo University of Agriculture and Technology
(2-24-16 Nakamachi, Koganei, Tokyo 184 Japan)
**Tsukuba Univeristy
***National Institute for Environmental Studies

Abstract

We investigated methane emissions from a municipal solid waste landfill site. The landfill site was closed in 1983 and part of the site has been used for recreation and a parking lot. Gas generated from landfilled waste has been emitted naturally into the atmosphere through venting pipes. We set up a gas chamber to measure methane emissions from a gas venting pipe under natural conditions in November of 1990. The gas chamber was equipped with a blower and ducts in order to ventilate the inside air of the chamber with a outside fresh air. Part of the gas withdrawn from the chamber was measured every ten minutes through a non-methane hydrocarbon analyzer. Additionally, a meteorological parameters were monitored at the site every ten minutes. Gas emission rates were affected by changes in atmospheric pressure. This phenomenon was also observed during the periods of diurnal changes in atmospheric pressure by the atmospheric tides on clear days. Auto-correlation analysis showed that there was a cycle of 12 hours and 24 hours, or both emission rate and atmospheric pressure during clear days.

Key words: methane, emissions, cycle change, MSW landfill site, meteorological parameters