Determining ammonia emissions from a cattle feedlot with an inverse dispersion technique

Flesch, Thomas K.; Wilson, John D.; Harper, Lowry A.; Todd, Richard W.; Cole, N. A.

doi:10.1016/j.agrformet.2007.02.006

Cited by 177 publications

(122 citation statements)

References 20 publications

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“…Laser-based criteria are applied to remove potentially inaccurate or unrepresentative line averaged concentration values, especially when observations correspond to <5 min of a 10-min period, R 2 min (a measure of observed concentration relative to internal cell reference) is <98, and/or when reported light levels (an operating, unitless parameter related to the signal level of the returning laser beam) falls outside an operating range; 3000 to 11 000. Criteria applied to the BLS output, intended to remove error-prone periods, have been applied in previous studies and are based on low wind speed periods (Flesch et al, 2014), periods of extreme atmospheric stratification (Flesch et al, 2004), where actual wind conditions violate WindTrax assumptions, and/or when the fractional coverage (footprint) of the downwind OPL measurement relative to the source area is marginal (Flesch et al, 2007). The application of the criteria removes outliers in the emission dataset (WindTrax output) unique to location and conditions during measurement periods.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, unique to each site is the use of an offset value in cardinal degrees relative to true north (0 to 360°) which is applied to sonic anemometer data. The filtering criteria used throughout the studies for pre-and post-simulation (using WindTrax) were similar to that described by Flesch et al (2007) and McGinn et al (2009) and included; 3000 < light level < 11 000, surface roughness (Z; m) 0.0000001 < Z 0 < 0.9, atmospheric stability (L; m), absolute <2, friction velocity (u*; m/s) >0.15 m/s, where <0.15 indicates calm conditions and unsteady wind directions, and fraction covered by touchdown >10% with ΔCH 4 > 10 ppb. In addition, if the wind direction relative to either path varied by >15°then these data was considered unreliable and excluded from modelling.…”

Section: Methodsmentioning

confidence: 99%

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Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Tomkins

Charmley

2015

Animal

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Methane (CH 4 ) emissions associated with beef production systems in northern Australia are yet to be quantified. Methodologies are available to measure emissions, but application in extensive grazing environments is challenging. A micrometeorological methodology for estimating herd-scale emissions using an indirect open-path spectroscopic technique and an atmospheric dispersion model is described. The methodology was deployed on five cattle properties across Queensland and Northern Territory, with measurements conducted during two occasions at one site. On each deployment, data were collected every 10 min for up to 7 h a day over 4 to 16 days. To increase the atmospheric concentration of CH 4 to measurable levels, cattle were confined to a known area around water points from~0800 to 1600 h, during which time measurements of wind statistics and line-averaged CH 4 concentration were taken. Filtering to remove erroneous data accounted for 35% of total observations. For five of the six deployments CH 4 emissions were within the expected range of 0.4 to 0.6 g/kg BW. At one site, emissions were~2 times expected values. There was small but consistent variation with time of day, although for some deployments measurements taken early in the day tended to be higher than at the other times. There was a weak linear relationship ( R 2 = 0.47) between animal BW and CH 4 emission per kg BW. Where it was possible to compare emissions in the early and late dry season at one site, it was speculated that higher emissions at the late dry season may have been attributed to poorer diet quality. It is concluded that the micrometeorological methodology using open-path lasers can be successfully deployed in extensive grazing conditions to directly measure CH 4 emissions from cattle at a herd scale.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Tomkins

Charmley

2015

Animal

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“…At the landscape scale, limited use has been made of plume measurements and inverse modelling of strong sources Flesch et al, 2007;Blackall et al, 2007;Loubet et al, 2009b;Carozzi et al, 2013). However, model evaluation, especially at the regional scale, typically relies on the indirect indicators provided by measured wet deposition of NH x (NH 3 + NH + 4 ) and, wherever available, ambient NH 3 .…”

Section: Ammonia Measurement and Modelling Approachesmentioning

confidence: 99%

Advances in understanding, models and parameterizations of biosphere-atmosphere ammonia exchange

et al. 2013

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Atmospheric ammonia (NH₃) dominates global emissions of total reactive nitrogen (N_r), while emissions from agricultural production systems contribute about two-thirds of global NH₃ emissions; the remaining third emanates from oceans, natural vegetation, humans, wild animals and biomass burning. On land, NH₃ emitted from the various sources eventually returns to the biosphere by dry deposition to sink areas, predominantly semi-natural vegetation, and by wet and dry deposition as ammonium (NH₄⁺) to all surfaces. However, the land/atmosphere exchange of gaseous NH₃ is in fact bi-directional over unfertilized as well as fertilized ecosystems, with periods and areas of emission and deposition alternating in time (diurnal, seasonal) and space (patchwork landscapes). The exchange is controlled by a range of environmental factors, including meteorology, surface layer turbulence, thermodynamics, air and surface heterogeneous-phase chemistry, canopy geometry, plant development stage, leaf age, organic matter decomposition, soil microbial turnover, and, in agricultural systems, by fertilizer application rate, fertilizer type, soil type, crop type, and agricultural management practices. We review the range of processes controlling NH₃ emission and uptake in the different parts of the soil-canopy-atmosphere continuum, with NH₃ emission potentials defined at the substrate and leaf levels by different [NH₄⁺] / [H⁺] ratios (Γ). Surface/atmosphere exchange models for NH₃ are necessary to compute the temporal and spatial patterns of emissions and deposition at the soil, plant, field, landscape, regional and global scales, in order to assess the multiple environmental impacts of airborne and deposited NH₃ and NH₄⁺. Models of soil/vegetation/atmosphere NH₃ exchange are reviewed from the substrate and leaf scales to the global scale. They range from simple steady-state, "big leaf" canopy resistance models, to dynamic, multi-layer, multi-process, multi-chemical species schemes. Their level of complexity depends on their purpose, the spatial scale at which they are applied, the current level of parameterization, and the availability of the input data they require. State-of-the-art solutions for determining the emission/sink Γ potentials through the soil/canopy system include coupled, interactive chemical transport models (CTM) and soil/ecosystem modelling at the regional scale. However, it remains a matter for debate to what extent realistic options for future regional and global models should be based on process-based mechanistic versus empirical and regression-type models. Further discussion is needed on the extent and timescale by which new approaches can be used, such as integration with ecosystem models and satellite observations

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“…Remote sensing path-integrated CH 4 measurement configurations have been employed to estimate emission fluxes (Griffith and Galle 2000) and are commonly coupled with inverse dispersion models (Flesch et al 2007). Open-path Fourier transform infrared (OP/FTIR) spectrometry techniques have shown a precision of 10-20 ppbv CH 4 for 10-s measurements (Griffith and Galle 2000).…”

Section: Introductionmentioning

confidence: 99%

Long-Path Quantum Cascade Laser–Based Sensor for Methane Measurements

Michel

Miller

Sun

et al. 2016

Journal of Atmospheric and Oceanic Technology

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A long-path methane (CH 4 ) sensor was developed and field deployed using an 8-mm quantum cascade laser. The high optical power (40 mW) of the laser allowed for path-integrated measurements of ambient CH 4 at total pathlengths from 100 to 1200 m with the use of a retroreflector. Wavelength modulation spectroscopy was used to make high-precision measurements of atmospheric pressure-broadened CH 4 absorption over these long distances. An in-line reference cell with higher harmonic detection provided metrics of system stability in rapidly changing and harsh environments. The system consumed less than 100 W of power and required no consumables. The measurements intercompared favorably (typically less than 5% difference) with a commercial in situ methane sensor when accounting for the different spatiotemporal scales of the measurements. The sensor was field deployed for 2 weeks at an arctic lake to examine the robustness of the approach in harsh field environments. Shortterm precision over a 458-m pathlength was 10 ppbv at 1 Hz, equivalent to a signal from a methane enhancement above background of 5 ppmv in a 1-m length. The sensor performed well in a range of harsh environmental conditions, including snow, rain, wind, and changing temperatures. These field measurements demonstrate the capabilities of the approach for use in detecting large but highly variable emissions in arctic environments.

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Determining ammonia emissions from a cattle feedlot with an inverse dispersion technique

Cited by 177 publications

References 20 publications

Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Advances in understanding, models and parameterizations of biosphere-atmosphere ammonia exchange

Long-Path Quantum Cascade Laser–Based Sensor for Methane Measurements

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