Annual variations of atmospheric VOC concentrations in a boreal forest

Hannele Hakola, Heidi Hellén, Virpi Tarvainen, Jaana Bäck, Johanna Patokoski, Janne Rinne, H Hakola, V Tarvainen
2009 unpublished
Rinne, J. 2009: Annual variations of atmospheric VOC concentrations in a boreal forest. Boreal Env. Res. 14: 722-730. Ambient atmospheric concentrations of monoterpene compounds were measured above a boreal forest in Hyytiälä, Finland during 2000-2007. For most of the time, two samples per week were collected, although there are some gaps in the data due to analytical or other issues. The monoterpene concentrations reached their maximum in summer, although they were found to be quite high also
more » ... uring winter. The main compounds found during winter were α-pinene, Δ 3-carene, β-pinene and camphene. In summer 1,8-cineol and sabinene were also present in the samples. The concentrations of α-pinene, β-pinene/myrcene, cam-phene, Δ 3-carene increased during the measurement period both in winter and in summer. This increase cannot be explained by meteorological conditions. The possible explanations could be human activities in the vicinity of the sampling site in addition to forest growth. The seasonal cycles of daytime concentrations were found to follow emission fl uxes mod-eled using a simple temperature dependent parameterisation. The measured monoterpene concentrations were used, together with emission rate measurements, for estimating ambient atmospheric β-caryophyllene concentration which cannot be directly measured due to its high reactivity against ozone.