Plant and Soil

, Volume 343, Issue 1, pp 171–185

Assessing the effects of chamber placement, manual sampling and headspace mixing on CH4 fluxes in a laboratory experiment

Authors

    • Division of Forest & Landscape Ecology, Forest & Landscape DenmarkUniversity of Copenhagen
  • Janne F. J. Korhonen
    • Department of PhysicsUniversity of Helsinki
  • Radoslaw Juszczak
    • Meteorology DepartmentPoznan University of Life Sciences
  • Michael Giebels
    • Institute of Landscape Matter DynamicsLeibniz-Centre for Agricultural Landscape Research
  • Mari Pihlatie
    • Department of PhysicsUniversity of Helsinki
Regular Article

DOI: 10.1007/s11104-010-0701-y

Cite this article as:
Christiansen, J.R., Korhonen, J.F.J., Juszczak, R. et al. Plant Soil (2011) 343: 171. doi:10.1007/s11104-010-0701-y

Abstract

A laboratory experiment was conducted with two types of closed static chambers to estimate the effects of chamber placement, manual headspace sampling and headspace mixing on methane (CH4) fluxes. Chamber fluxes were compared to a known reference flux in a chamber calibration system. The measurements were conducted with three types of soils (coarse dry, fine dry and fine wet quarts sand) at five flux levels ranging from 60 to 2000 μg CH4 m−2 h−1. We found that the placement of a non-vented chamber disturbed the initial CH4 concentration development within the chamber headspace for 10 to 30 s. Excluding this short period from the flux calculation resulted in a lower flux estimate (mean±SE) of 126 ± 26 μg CH4 m−2 h−1 compared to 134 ± 26 μg CH4 m−2 h−1 if data from time zero of the enclosure were included. We also found that in non-mixed chambers (no fan mixing) the gas sampling by syringes or gas bottles disturbed the development of CH4 concentration during the enclosure. Furthermore, flux estimates in non-mixed chambers were significantly underestimated (on average 36%) compared to the measured reference fluxes. However, the use of fans to constantly mix the chamber headspace during enclosure significantly improved the goodness-of-fit of the regression analysis used to calculate the flux and further eliminated the disturbance of the manual sampling on the concentration development. We recommend that chambers should be vented during the placement of the chamber, and that fans are used as an integrated part of static chambers while headspace mixing with syringes should be avoided.

Keywords

MethaneClosed static chamberGreenhouse gasHeadspace mixingFansManual sampling

Abbreviations

CO2

Carbon dioxide

FL

Flux level

GHG

Greenhouse gas

CH4

Methane

N2O

Nitrous oxide

NRMSE

Normalised root mean square error

RMSE

Root mean square error

Copyright information

© Springer Science+Business Media B.V. 2011