Soil magnetic susceptibility anomalies at a landfill: Investigating their occurrence and origin

The purpose of this study is to test for the presence of anomalous soil magnetic susceptibilities (SMS) in the methane producing environment of a landfill and to determine whether such anomalies originate in authigenic magnetite. Previous studies have proposed a connection between the presence of hydrocarbons and authigenesis of magnetite. If such an association exists, magnetic susceptibility can be used as a rapid, nearly non-invasive and inexpensive tool for the tracing of methane seepage at and around landfills.;Several cores extracted from the clay cap of a landfill show high SMS values in the lower part compared with control samples. Rock magnetic and optical observations suggest the addition of magnetite and possibly greigite in the cap soil when compared to the original magnetic mineralogy of the soil. Gas chromatographic analyses within the lower part of a core indicate that methane is present in the zone of elevated magnetic susceptibility. Methane is produced within the sand layer underneath the cap and is probably seeping into the cap. The results suggest that soil magnetic susceptibility measurements may be successfully used as indirect indicators for the presence of microseeping methane penetrating landfill caps. (Abstract shortened by UMI.)...