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- Title
Controlled environment chamber system for gas exchange measurements: setup and operating principles.
- Authors
Pihlatie, Mari; Polvinen, Tatu; Kohl, Lukas; Rissanen, Kaisa; Pohja, Toivo; Aalto, Juho; Koskinen, Markku
- Abstract
Field-scale measurements rarely allow separating parallel processes behind gas exchange ofplants or soil. There is an urgent need to construct controlled measurement setups to separateprocesses and their responses to environmental drivers. Such a setup allows for testing ofe.g. dark-light-cycles, drought, freeze-thaw and different temperatures and CO2levels. Important applications for controlled-environment setups include partitioningof emissions to different parts of plants and soil, parameter isolation, tracer tests,improvement of models and tests where easy access to different parts of the test subject isbeneficial. In this presentation we introduce a chamber setup that can be used for trace gasmeasurements under controlled environmental conditions. The system includes temperature,moisture and CO2 control in the measurement chambers and PAR, temperature and relativehumidity (RH) control of the general environment. The system can operate in eitherflowed-through or closed-loop setup. CO2 concentration in the sample chamber is controlledwith a mass flow controller and a PID algorithm. In order to keep the measured objects under controlled conditions, we use aFITOCLIMA D 1200 plant growth chamber. To keep the measurement system safefor VOC-measurements, we use PTFE tubing and stainless steel connectors andvalves. The setup is tested for gas exchange from shoots and root-soil compartment of treesaplings. For shoot measurements, we use a rectangular chamber made of aluminium andtransparent polyacrylic with a volume of 1 l. The chamber includes a small fan atone end to enable efficient mixing of air and a peltier cooling element to preventtemperature rise due to the light. The shoot is secured into place by a supportingframe with a fishing line bed. There is an LM-35 temperature sensor inside theshoot chamber. The chamber is hung inside the growth chamber with cords attachedto each corner of the chamber so that its placement and stance can be preciselycontrolled. We conduct soil gas exchange measurements using a chamber that is large enough tohouse the pot in which the sapling is placed. The chamber has vents that can be opened andclosed using pneumatic actuators to enable ventilation between measurement cycles. Fansinside the chamber keep the air mixed. The chamber is also equipped with a temperaturesensor. Preliminary data from test measurements will be presented to demonstrate theapplicability of the system, and to give more insight to the process-level understanding thatsuch a setup can provide for the research community. The design and controlling softwarewill be made freely available to the public.
- Subjects
GAS chambers; SOIL air; PID controllers; PLANT-soil relationships; FISHING lines; MIXING; PNEUMATIC actuators
- Publication
Geophysical Research Abstracts, 2019, Vol 21, p1
- ISSN
1029-7006
- Publication type
Article