Evaluation of a portable chamber system for soil CO2 efflux measurement and the potential errors caused by internal compensation and water vapor dilution

Abstract

A portable, easy-to-install chamber system for rapid measurement of soil CO2 efflux is needed for the immediate analysis of CO2 flushes after events such as tillage and grassland renovation. We conducted field measurements and simple simulations to validate the effectiveness of a portable chamber system with an infrared CO2 gas analyzer (IRGA) and a temperature/humidity sensor (the SIR system). We confirmed that a measurement period of 60-180 s after the closure of the chamber was sufficient for the calculation of soil CO2 efflux. We compared the SIR system with a closed static chamber system and an automated open/closed chamber system. The efflux data obtained with the SIR system were linearly related to the data obtained with the other systems, and the relationships between the soil temperature and efflux were similar in the three systems. These results show that the SIR system provided soil CO2 efflux values with a reasonable accuracy relative to the other systems. We also examined how the calculated efflux values were affected by the internal compensation of the IRGA for environmental parameters and water vapor dilution in the chamber. The potential error caused by the default internal compensation of the IRGA was within 3.1 under general environmental conditions. The effect of water vapor dilution was large ( 20 ) for small CO2 effluxes. The combined effects of the default internal compensation and water vapor dilution were larger for small CO2 effluxes than for large CO2 effluxes, and the effects became larger under low air pressure conditions. We recommend that accurate environmental compensation and water vapor correction be applied for analysis of small CO2 effluxes when there is a rapid increase in water vapor, especially under low air pressure conditions.

The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content

“…Only in advective high-T. Eickenscheidt et al: The greenhouse gas balance of a drained fen peatland flux situations when the rate of increasing water vapor is less than 1 % of the rate of increasing chamber CO 2 may dilution effects be ignored. This finding was also confirmed by Matsuura et al (2011). However, neither corrections for cross-sensitivity and band broadening nor a dilution correction were applied in the present study.…”

Blanket bog CO2 flux driven by plant functional type during summer drought

“…Both linear and quadratic rates are calculated, and model parameters are stored for the following model-selection steps. Subsequently, rates are corrected for an increase of water vapour concentrations as dilution by water molecules can significantly reduce CO 2 flux estimates (Matsuura et al, 2011).…”

Short-term effects of grassland renovation on CO<SUB>2</SUB> exchange of grasslands in a temperate humid region

“…Details of the system were presented previously by Matsuura et al 2011 . Briefly, the system consisted of an infrared CO 2 gas analyzer GMP343 diffusion model, Vaisala, Helsinki, Finland and a temperature/humidity sensor HMP75, Vaisala that penetrated through a chamber lid white acrylic disk, diameter 465 mm ; a data-logging device MI70, Vaisala for collecting data of CO 2 concentration, air temperature, and relative humidity inside a chamber; a temperature/pressure sensor RS-12P, Espec Mic, Oguchi, Japan ; and cylindrical stainless-steel chambers inside diameter 390 -415 mm, height 300 mm .…”