Das Projekt "Biogene Emissionen im Mittelmeerraum (BEMA)" wird vom Umweltbundesamt gefördert und von Fraunhofer-Gesellschaft zur Förderung der Angewandten Forschung, Fraunhofer-Institut für Atmosphärische Umweltforschung durchgeführt. Objectives: Quantification and parameterisation of emission rates of C5 to C10 hydrocarbons from orange trees and from the soil in an orange plantation on the basis of key environmental and plant physiological parameters. - Quantification and parameterisation of emission rates of C5 to C10 hydrocarbons from Quercus ilex and Quercus coccifera in the autumn period of the year on the basis of key environmental and plant physiological parameters. - Determination of the 3D- variability of the surface temperature of a Q. ilex tree. - Determination of the leaf area index (LAI) and biomass index (BI) for Q. coccifera ecosystems. - Development of a chemical mechanism for the degradation of biogenic volatile organic compounds (BVOC) emitted by plants at the BEMA locations. - Intercomparison of canopy emission rates calculated by enclosure techniques and/or Gradient-/REA-technique. - Application and test of new chemical mechanisms for the degradation of BVOC in the troposphere in collaboration with the JRC group within three dimensional mesoscale models. Main Results Obtained: Buriana Field Experiment: In spring, near Buriana (Valencia area), Spain, cuvette measurements were performed to determine isoprenoid emission rates from orange trees and from the soil. The main compound emitted from orange twigs with flowers was myrcene with a maximum of 350 pmol m-2 s-1 (7755 ng g-1dw h-1) followed by limonene (58 pmol m-2 s-1 (1348 ng g-1dw h-1)). During night-time, isoprenoid emission was negligible. In a first screening study the emission rates from soil were investigated in an orange plantation. Isoprenoid emission rates from bare soil reached values of up to 323 pmol m-2 s-1 for limonene, followed by myrcene (22 pmol m-2 s-1) and alpha-pinene and beta-pinene/sabinene in traces. The emission rate from planted soil was in the same order.