Within the framework of the joint project on remediation of old sites and dumps ("Nutzraum"), a lysimeter experiment was set up at the Austrian Institute of Technology in Seibersdorf, Austria. Three experimental CH4 oxidation biocovers using different substrates to enhance methane uptake as well as one control cover have been installed in parallel in lysimeters. This diploma thesis presents data concerning the relative emission reduction effect of the passive biocovers prior to in-situ aeration. The methane oxdiation efficiency of the biocovers were determined by gas composition and temperature profiles measured within the lysimeters, and by surface flux measurements as well as surface methane concentration screenings. In addition, methane oxidation was quantified on selected dates using stable isotope methods. The surface flux measurements were conducted using a closed dynamic chamber, which was constructed specially for this project. The challenge was to include the aeration pipe (D = 6 cm) of the lysimeter into the design of the accumulation chamber in order to cover the whole lysimeter surface (4 m) without disturbing the measurement procedure. Laboratory tests were conducted to verify the performance and accuracy of the measurement system with different known methane and carbon dioxide fluxes. Among the four biocovers studied, CH4 emission fluxes could only be detected from the biocovers with mineral soil covers (lysimeters C and D), whereas no CH4 emissions were measured on the biocovers with mature sewage sludge compost and sand/compost mixture, respectively (lysimeters A and B). However, the mature sewage sludge compost (SSC) placed in lysimeter A showed, in principle, very promising results regarding the optimal ambient conditions for methanotrophic bacteria. In contrast to the other biocovers, the SSC-cover was capable of retaining the moisture content and the temperature profiles at an optimum level during the investigation period.