Approach for Self-Calibrating CO2 Measurements with Linear Membrane-Based Gas Sensors

Lazik, Detlef; Sood, Pramit

doi:10.3390/s16111930

Cited by 3 publications

(7 citation statements)

References 33 publications

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“…The line sensor presented here covers the entire range of typical CO 2 concentrations in soil with high precision. This was demonstrated for <1.6% CO 2 by Lazik and Ebert (2012) and for concentrations <8% by Lazik and Sood (2016) for dry gases. In this study, we demonstrated the applicability of the line sensor for natural, humid soil conditions.…”

Section: Resultsmentioning

confidence: 74%

“…Also, locally incomplete phase equilibrations would result in a reduced mean soil CO 2 concentration. In addition, the measurement uncertainty and bias of the sensors, which was investigated under precisely defined dry‐gas conditions by Lazik and Sood (2016), will have contributed to this 5% difference.…”

Section: Resultsmentioning

confidence: 99%

“…Due to the same environmental conditions within the soil and the water-vapor-saturated stratum (the humid reference), this independence causes the elimination of pressure effects related to water vapor. Thus, the theoretical framework developed by Lazik and Sood (2016) is still valid and enables CO 2 measurement without further calibration as described above.…”

Section: Basicsmentioning

confidence: 99%

“…Based on selective diffusion through tubular gas‐selective membranes, a new sensory principle was introduced for the measurement of CO 2 or O 2 concentrations (Lazik and Geistlinger, 2005; Lazik et al, 2009; Lazik and Sood, 2016). The tubular sensor (called a line sensor ) provides an arithmetic average of fluctuating CO 2 concentrations along its length.…”

Section: Soil Gas Measurementmentioning

confidence: 99%

“…denotes the internal gas standard, subscript x = CO 2 ). This is known and therefore forms an internal standard for a permanent in situ calibration as introduced by Lazik and Sood (2016):

\begin{matrix} left \\ left p_{x}^{ex} = \frac{α - ε}{α - α'} (p_{x}^{i . s .} - p_{x}^{in}) + p_{x}^{in} \\ left ε \approx g P_{x} (p^{ex} - p^{in}) \sum_{j} f_{j x} {normalχ}_{j}^{in} \end{matrix}

…”

Section: Line Sensors For Aerated Humid Soilsmentioning

confidence: 99%

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New Sensor Technology for Field‐Scale Quantification of Carbon Dioxide in Soil

Lazik

Vetterlein

Salas

et al. 2019

Vadose Zone Journal

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Core Ideas This new technology is suitable for field‐scale quantification of CO2 in soil. The measurement scale ranges from decimeters up to decameters. The concentrations from the soil water and air phases are averaged. Transient CO2 production and transport reflect plant growth. Biological activity in soil causes fluxes of O2 into and CO2 out of the soil with significant global relevance. Hence, the dynamics of CO2 concentrations in soil can be used as an indicator for biological activity. However, there is an enormous spatial and temporal variability in soil respiration, which has led to the notion of hotspots and hot moments. This variability is attributed to the spatiotemporal heterogeneity of both plant–soil–microbiome interactions and the local conditions governing gas transport. For the characterization of a given soil, the local heterogeneities should be replaced by some meaningful average. To this end, we introduce a line sensor based on tubular gas‐selective membranes that is applicable at the field scale for a wide range in water content. It provides the average CO2 concentration of the ambient soil along its length. The new technique corrects for fluctuating external conditions (i.e., temperature and air pressure) and the impact of water vapor without any further calibration. The new line sensor was tested in a laboratory mesocosm experiment where CO2 concentrations were monitored at two depths during the growth of barley (Hordeum vulgare L.). The results could be consistently related to plant development, plant density, and changing conditions for gas diffusion toward the soil surface. The comparison with an independent CO2 sensor confirmed that the new sensor is actually capable of determining meaningful average CO2 concentrations in a natural soil for long time periods.

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Section: Resultsmentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Basicsmentioning

confidence: 99%

Section: Soil Gas Measurementmentioning

confidence: 99%

“…denotes the internal gas standard, subscript x = CO 2 ). This is known and therefore forms an internal standard for a permanent in situ calibration as introduced by Lazik and Sood (2016):

\begin{matrix} left \\ left p_{x}^{ex} = \frac{α - ε}{α - α'} (p_{x}^{i . s .} - p_{x}^{in}) + p_{x}^{in} \\ left ε \approx g P_{x} (p^{ex} - p^{in}) \sum_{j} f_{j x} {normalχ}_{j}^{in} \end{matrix}

…”

Section: Line Sensors For Aerated Humid Soilsmentioning

confidence: 99%

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New Sensor Technology for Field‐Scale Quantification of Carbon Dioxide in Soil

Lazik

Vetterlein

Salas

et al. 2019

Vadose Zone Journal

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Modeling and analysis of an Ni:ZnO-based Schottky pattern for NO2 detection

2018

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A New Principle for Measuring the Average Relative Humidity in Large Volumes of Non-Homogenous Gas

Lazik

Rooij

Lazik

et al. 2019

Sensors

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Due to the current extent of arid regions, the pressure on available water resources is increasing. A suitable measure for water availability and dynamics in dry soil is the relative humidity of the soil air. Due to the heterogeneity of soil, water inputs, and root water uptake, the humidity of soil air will vary in space. Therefore, area-representative measurement methods are needed to find a representative measure of the soil water status. Existing sensors for the direct determination of relative humidity only represent a single location with a spatial extent of up to several cm. We introduce a new measuring principle that averages over a spatially heterogeneously distributed relative humidity. It is based on the selective diffusion of water vapor pressure through a tubular semipermeable membrane to/from a closed measurement chamber. A measured pressure change is sensitive to the water vapor pressure and enables, without any external calibration, to estimate an average of the relative humidity. The comparison of our first laboratory prototype of the new sensor with calibrated reference sensors for relative humidity in a range of approx. 4 to 100% proves the linearity of the measuring method and its high accuracy. For further optimization improved reference measurement techniques are necessary. A potential application is the improvement of water use efficiency in irrigated agriculture.

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Approach for Self-Calibrating CO2 Measurements with Linear Membrane-Based Gas Sensors

Cited by 3 publications

References 33 publications

New Sensor Technology for Field‐Scale Quantification of Carbon Dioxide in Soil

New Sensor Technology for Field‐Scale Quantification of Carbon Dioxide in Soil

Modeling and analysis of an Ni:ZnO-based Schottky pattern for NO2 detection

A New Principle for Measuring the Average Relative Humidity in Large Volumes of Non-Homogenous Gas

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