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Soil Gas Flux Solutions

Grounded in Science, Designed for Research

From idea to understanding, LI-COR has your soil gas flux research covered. No other solution is as flexible or delivers the same level of proven hardware, gas analyzers, and advanced data analysis software.

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What makes LI-COR different?

LI-COR offers hardware, software, and analyzers for soil gas flux research all based on extensive scientific research and testing. Patented designs minimize disruption of natural soil gas transport across the soil surface and record high-precision flux measurements to evaluate spatial and temporal variability.

The result is an integrated system and an ideal soil gas flux research experience.

Designed for flexibility and convenience

LI-COR soil gas flux systems combine more than 20 years of experience with the latest innovations for flexibility and convenience.

LI-CR Soil Flux System with Smart Chamber, LI-8250 Multiplexer, LI-7810 Trace Gas Analyzer and LI-870 Gas Analyzer.
LI-COR long-term soil gas flux multiplexer flexibility

On-site, processed fluxes

When the Smart Chamber or LI-8250 are connected to a LI-COR analyzer, embedded software provides on-site, real-time fluxes of CO2 and CH4.

Extended connectivity options

A built-in Wi-Fi web server allows you to manage your survey or long-term instruments from a mobile device or laptop using an intuitive browser-based interface. With a cellular modem added to your long-term system, you can receive daily summary files and remotely monitor your site.

Research flexibility

Because unique research requires flexibility, LI-COR soil gas flux systems are designed to adapt and grow with your research. Both survey and long-term systems can integrate a variety of gas analyzers, including third-party analyzers, and long-term systems can also integrate with custom chambers.

LI-COR soil chambers reduce artificial impact

Engineered to reduce artificial impact

The importance of soil gas flux chambers to accurate measurements is often underestimated. An inherent challenge to chamber design is the influence the chamber may have on measurements.

All LI-COR chambers are designed to minimize chamber interference on the natural soil gas flux, and gas production and consumption, leading to accurate, consistent measurements.

Minimize instrument influence

The perforated base of LI-COR long-term chambers allows for the natural exchange of gas, sunlight, and precipitation between the atmosphere and soil surrounding the chamber, minimizing the effect of the deployment of soil chambers.

LI-COR soil chambers minimize instrument influence
Figure 1. Diffusion simulation, using Fick's Law, showing a representation of CO2 flux rates at the soil-air interface. Red indicates low flux rate and blue indicates high flux rate. A) A solid baseplate shows suppressed flux rates with a nearly uniform effect under the baseplate. B) Perforations in the baseplate greatly reduce this effect.

Equalize chamber pressure

Any difference between the air pressure inside a soil chamber and ambient air will affect the flux rate. If the chamber is not properly vented, under windy conditions the Venturi effect can cause a mass flow of air from the soil into the chamber, leading to significant overestimation of soil gas flux.

To maintain pressure equilibrium, all LI-COR soil chambers feature a patented pressure vent.

LI-COR pressure vent equalizes chamber pressure
Figure 2. Cross section of the patented pressure vent used on all LI-COR chambers. As air is forced into the vent by wind, the average wind speed drops. As a result, most of the dynamic pressure is converted to static pressure, virtually eliminating the Venturi effect. The patented vent (U.S. Patent 7,856,899) is radially symmetric to eliminate sensitivity to wind direction.1, 2

Minimize soil disturbance

Any soil disturbance can artificially influence natural gas fluxes. LI-COR chambers are placed over soil collars that are inserted before measuring. An automated mechanism seals the chamber around the collar. Because the chamber never touches the collar directly, any soil disturbance is negligible and fluxes are minimally affected.

LI-COR chambers minimize soil disturbance
Figure 3. All LI-COR chambers feature a gasket seal around the soil collar with a second gasket on the chamber bowl to minimize disturbances to the soil collar when the chamber is placed or moved.

Recognize the altered diffusion gradient

Once the chamber is placed over the collar, increasing gas concentrations reduce the gas diffusion gradient—suppressing the efflux. A linear regression will lead to a significant flux underestimation, particularly in porous soil.

LI-COR uses an exponential function to account for the altered diffusion gradient to estimate flux at the time of chamber closing—when gas concentration is nearest to ambient levels.

LI-COR chamber design recognizes the altered diffusion gradient
Figure 4. Chamber CO2 concentration begins to increase the moment the chamber closes. As a result, the flux begins to decrease with time, as indicated by the slope of dCO2/dt. The blue line (A) represents the pre-measurement CO2 concentration, while the green line (B) represents the concentration at the start of the measurement. Flux is suppressed (C) as gas concentration within the chamber increases.

Optimize mixing of chamber air

Air mixing is critical for accurate flux measurement, but fans create pressure gradients within the chamber that may suppress or enhance flux.

All LI-COR soil chambers are designed without fans and mixing is achieved through a bowl-shaped chamber and air inlet/outlet positioning.

LI-COR soil chambers optimize mixing of chamber air
Figure 5. The shape of the chamber along with the placement of the air inlet and air outlet ensure that the air within the chamber is well mixed.

References

  1. Xu, L., et.al. (2006). On maintaining pressure equilibrium between a soil CO2 flux chamber and ambient air. Journal of Geophysical Research, 111(D8). DOI: 10.1029/2005JD006435
  2. Furtaw, M.D., McDermitt, D.K., and Xu, L., “Vent and soil flux measurement system,” U.S. Patent 7,856,899, December 28, 2010.

SoilFluxPro Software

SoilFluxPro Software simplifies the management and processing of large soil gas flux datasets. SoilFluxPro is a powerful, free software included with all LI-COR soil gas flux solutions to view, revise, and recompute flux data, to perform quality assurance and quality control, and much more.

SoilFluxPro Screenshot
  • Recompute fluxes from both long-term and survey datasets.
  • Perform quality assurance and quality control checks using revised parameters, such as deadband start and stop time.
  • Built-in tools provide guidance for choosing parameter alterations.
  • Quickly plot results and statistics to evaluate measurements individually or in groups.
  • Compute statistics for individual measurements or whole datasets.
  • Create .kml files to map concentrations and fluxes on Google Earth.
  • Generate fluxes from measurements made by third-party analyzers.
Learn more about SoilFluxPro
LI-COR Soil Gas Flux Mapping Screenshot

Where will your research take you?

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