HR: 1340h
AN: B43B-0151    [Abstracts]
TI: Non-methane Hydrocarbon Emissions from a Subarctic Mire in Northern Sweden
AU: * Backstrand, K
EM: kristina.backstrand@geo.su.se
AF: Stockholm University, Dept Geology and Geochemistry, Stockholm, 106 91 Sweden
AU: Crill, P M
EM: patrick.crill@geo.su.se
AF: Stockholm University, Dept Geology and Geochemistry, Stockholm, 106 91 Sweden
AU: Christensen, T R
EM: Torben.Christensen@nateko.lu.se
AF: Lund University, GeoBiosphere Centre, Lund, 223 62 Sweden
AU: Mastepanov, M
EM: mikhail.mastepanov@nateko.lu.se
AF: Lund University, GeoBiosphere Centre, Lund, 223 62 Sweden
AB: Northern peatlands in the Abisko region of northern Sweden are now subjected to climatic warming. In addition to carbon dioxide (CO$_{2}$) and methane (CH$_{4}$), which are intensively studied regarding carbon cycling and climate, there are non-methane hydrocarbons (NMHCs) emitted by plants. NMHC emissions may be a substantial part of the carbon emissions from an ecosystem. They can play a role in tropospheric radiation balance, oxidation chemistry and biogenic aerosol formation. The dynamics of NMHC emissions are not well understood, but impacts of light, temperature and photosynthetic rate and stress have been documented. There has been very little research conducted on NMHCs from vegetation in high latitude ecosystems. We have made high frequency automated chamber measurements of CO$_{2}$ and total hydrocarbon (THC) fluxes from different subhabitats in a subarctic mire underlain by discontinuous permafrost in northern Sweden. Methane fluxes were also measured regularly but less frequently by manual grab sampling from the same chambers. During the summer of 2003-2004, a detailed study of the THC and methane flux rates was conducted in order to resolve patterns of NMHC fluxes. Four different sub-ecosystems are involved in the study. Manual sampling of methane was conducted three times a week during June to August in order to compare the THC to the methane flux. The THC fluxes range from near 0 to greater than 650 mg m$^{-2}$ d$^{-1}$ (calibrated as CH$_{4}$). The highest fluxes are from the wettest sites. NMHCs are often more than 10% of the THC fluxes with a greater proportion of the THC flux from the drier sites with the lowest THC fluxes. The largest emissions were recorded from the wet, minerotrophic sites (E. angustifolium, E. vaginatum) followed by a semiwet site (Sphagnum mosses, C. rotundata). The dry ombrotrophic sites with several types of herbs and dwarf shrubs have much lower emission rates during clear chamber measurements but a distinct dark chamber effect has been detected from this vegetation, showing high rates of NMHC emission when darkened. Preliminary results from the HC analyses will be presented.
DE: 1890 Wetlands
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting