Soil Flux Chamber Measurements with Five Species CRDS and New Real-time Chamber Flux Processor Sascha Reth1 & Renato Winkler2
1UGT GmbH, Lise-Meitner-Str.30, 85354 Freising; 2Picarro, Inc., 3105 Patrick Henry Drive, Santa Clara, California 95054
Abstract
Flexible Measurement Specifications GUI
Soil flux chamber measurements remain a key tool for determining production and sequestration of direct and indirect greenhouse gases. The Picarro G2508 Cavity Ring-down Spectrometer has radically simplified soil flux studies by providing simultaneous measurements of five gases: CO2, CH4, N2O, NH3, and H2O, and by lending itself to field deployment. Picarro has now developed a real-time processing software to simplify chamber measurements of soil flux with the G2508 CRDS. This new chamber-based Soil Flux Processor is designed to work with all chamber types and sizes, and to provide real-time flux values.
Flux Analysis GUI
Multiple fit attempts listed for comparison
Specify and Save Measurement Session
Specify multiple Chamber Types or Different Tubing Dimensions
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Also view traces from environmental sensors
Tab between traces of all five gas species
Flexible Measurement Specification GUI Interface
Provides ability to switch between multiple chamber types, dimensions Flexible data tagging – up to three run identifiers User-defined chamber condition thresholds and length of run-time Provides ability to save/re-deploy measurement protocols
Specify up to three identifying variables; Run duration; Alarm Thresholds
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Practical Real-time Measurement GUI Interface Provides monitoring of all five species and environmental sensors Manual flux measurement start/stop override.
Easy left click to set start
Real-time Measurement GUI:
Sophisticated Chamber Flux Analysis GUI interface Three standard flux algorithms, and potential for user defined. Advancement in Soil Error Analysis possible with high frequency data.
Tab between Realtime concentration traces of all five gas species
Picarro G2508 analyzer N2O: < 25 ppb + 0.05 % (raw 1σ) < 5 ppb + 0.008 % (5 min 1σ)
Measurement of five greenhouse gas species in one single instrument
Separate “start” run and “measurement” provides control for chamber placement
CH4: < 10 ppb + 0.05 % (raw 1σ) < 5 ppb + 0.02 % (5 min 1σ) CO2: < 600 ppb + 0.05 % (raw 1σ) < 200 ppb + 0.05 % (5 min 1σ) NH3: < 5 ppb + 0.05 % (raw 1σ) < 1 ppb + 0.05 % (5 min 1σ)
Coupled with YOUR CHAMBER:
H2O: < 500 ppm (raw 1σ) < 100 ppm (5 min 1σ)
Reth, S. Verbesserte Schätzungen von CO2- und N2O-Flussraten von Böden mitteleuropäischer Ökosysteme Entwicklung konzeptioneller Neuerungen
von Bodenemissionsmodellen. 2004 Dissertation, Universität Bayreuth, 172pp
Serial interface with users external datalogger allows Realtime monitoring of chamber environment; Sensor indicators turn red when values go out of range.
http://www.edf. org/blog/2013/ 11/14/ how-can-wegrow-morericeless-landwater-andpollution
Dr.Serena Moseman-Valtierra’s Lab http://mosemanvaltierralab.weebly.com
Finally, convenient .csv export of all derived fluxes and fit terms by the three identifying variables.
Picarro High Frequency Measurements Provide New Opportunities in Soil Chamber Flux Error Analysis: 1. Error is calculated on the assumption that the selected model is correct, and attributes misfit to procedural and instrument variability.
Use run-time count down or stop run early, or restart same run again
Three Standard Soil Flux Algorithms Included: Exponential: Linear: C(t) = m * t + b, Fluxo = Ve/A * m
C(t) = Bck + Asat [1− 𝒆−𝒕/𝝉 ],
Fluxo = Ve/A * (slope = Asat / 𝝉 ) “Hutchinson and Mosier (1991)”
Quadratic Polynomial: C(t) = at2 + m * t + b, Fluxo = Ve/A * m
Borhan et al. 2011 Department of Biological and Agricultural Engineering, Texas A&M University
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Easy right click to set end
Where Ve = effective chamber volume corrected for actual temperature and pressure; A = area of chamber footprint; m = slope; b = intercept; t = time elapsed; Bck = background concentration; Asat =saturation concentration; 𝜏 = concentration saturation rate (s-1)
2. Bootstrap method used to estimate the uncertainties in each model parameter within the bounds of variability computed from the misfit 3. Graph shows uncertainly in flux estimate defined by the band of variability estimated from the misfit between the model and the data.
For further information please visit www.ugt-online.de or contact
[email protected] 