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Dynamic Chamber Technique

NOx chambers in the field
NOx chambers in the field
Plant Cuvette
Plant Cuvette
NOx chamber
NOx chamber

The dynamic chamber technique is applied for quantification of surface fluxes of reactive gaseous compounds (e.g. NO, NO2, O3, BVOC, CO2) at the biosphere-atmosphere interface.

Obligatory for the use of the dynamic chamber technique for calculation of flux rates of NO, NO2 is the simultaneous determination of the mixing ratios of NO, NO2 and O3, due to their rapid internal chemical reaction velocity [NO fluxes must be corrected for gas phase reactions of the NO-NO2-O3 triad which occur in the air sample while passing through the chamber]. Furthermore a so called reference chamber that is sealed to the ground has to be used in order to account for potential effects of chamber wall losses and for determination of mixing ratios of NO, NO2, and O3 in ambient air. In contrast to static chambers dynamic chamber are open at one side while from the other side ambient air is sucked over the entire area of the chamber at a minimum flux rate that the entire volume of the chamber is replace once in a minute. Fluxes of NO, NO2, and O3 were calculated by the differences in mixing ratios of the measuring chamber vs. the reference chamber.

In combination with an automatic sampling system dynamic chambers can be used for continuous measurements in high temporal resolution (hourly resolution). Dynamic chamber technique can be applied to many environmental in-situ studies in different ecosystems (agriculture, forest, even aquatic systems) as well as laboratory experimental setups for simultaneous detection of concentration as well as fluxes of trace gases (e.g. NO, NO2, O3, BVOC).
Dynamic chamber technique is cost-effective as compared to other techniques for quantification of surface fluxes and is ideal for determination of spatial heterogeneity. Disadvantage of dynamic chamber technique is - as compared to other techniques - their reduced areal representativeness (scale: 0,25 m2 per chamber). Due to large spatial and temporal variability of net exchange of trace gases at the soil/atmosphere interface a large number of replicate chambers are often required.
The IMK-IFU has outstanding expertise in applying dynamic chamber technique since it constructs and operates for more than two decades different types of dynamic chambers that have been adapted to the different experimental demands.

 

Contacts: Rainer Gasche,  Georg WillibaldHans Papen

 

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