BVOC fluxes above mountain grassland

[摘要] Grasslands comprise natural tropical savannah over managed temperate fieldsto tundra and cover one quarter of the Earth's land surface. Plantgrowth, maintenance and decay result in volatile organic compound (VOCs)emissions to the atmosphere. Furthermore, biogenic VOCs (BVOCs) are emittedas a consequence of various environmental stresses including cutting anddrying during harvesting. Fluxes of BVOCs were measured with aproton-transfer-reaction-mass-spectrometer (PTR-MS) over temperate mountaingrassland in Stubai Valley (Tyrol, Austria) over one growing season (2008).VOC fluxes were calculated from the disjunct PTR-MS data using the virtualdisjunct eddy covariance method and the gap filling method. Methanol fluxesobtained with the two independent flux calculation methods were highlycorrelated (y = 0.95×−0.12, R² = 0.92). Methanol showed strong daytimeemissions throughout the growing season – with maximal values of9.7 nmol m⁻² s⁻¹, methanol fluxes from the growing grassland wereconsiderably higher at the beginning of the growing season in June comparedto those measured during October (2.5 nmol m⁻² s⁻¹). Methanol wasthe only component that exhibited consistent fluxes during the entiregrowing periods of the grass. The cutting and drying of the grass increasedthe emissions of methanol to up to 78.4 nmol m⁻² s⁻¹. In addition,emissions of acetaldehyde (up to 11.0 nmol m⁻² s⁻¹), and hexenal(leaf aldehyde, up to 8.6 nmol m⁻² s⁻¹) were detected during/afterharvesting.

[学科分类] 地球化学与岩石