In this study, we present summertime concentrations
and fluxes of biogenic volatile organic compounds
(BVOCs) measured at a sub-arctic wetland in northern Sweden
using a disjunct eddy-covariance (DEC) technique based
on a proton transfer reaction mass spectrometer (PTR-MS).
The vegetation at the site was dominated by Sphagnum,
Carex and Eriophorum spp. The measurements reported
here cover a period of 50 days (1 August to 19 September
2006), approximately one half of the growing season at the
site, and allowed to investigate the effect of day-to-day variation
in weather as well as of vegetation senescence on daily
BVOC fluxes, and on their temperature and light responses.
The sensitivity drift of the DEC system was assessed by
comparing H3O+-ion cluster formed with water molecules
(H3O+(H2O) at m37) with water vapour concentration measurements
made using an adjacent humidity sensor, and the
applicability of the DEC method was analysed by a comparison
of sensible heat fluxes for high frequency and DEC data
obtained from the sonic anemometer. These analyses showed
no significant PTR-MS sensor drift over a period of several
weeks and only a small flux-loss due to high-frequency spectrum
omissions. This loss was within the range expected
from other studies and the theoretical considerations.