Methane emissions from cattle grazing under diverse conditions: An examination of field configurations appropriate for line-averaging sensors

Flesch, Thomas K.; Basarab, J. A.; Baron, V. S.; Wilson, John D.; Hu, Nan; Tomkins, Nigel; Ohama, Adele J.

doi:10.1016/j.agrformet.2017.10.012

Cited by 15 publications

(16 citation statements)

References 30 publications

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“…Low path-integrated concentrations were chosen because they are critical for many field studies. For example, path lengths in the 10 to 100 m range are often reported in agricultural emissions research, particularly for targeted measurements of biogas systems [1], manure management systems [11][12][13], or grazing cattle [14]. Where the research site permits, longer path lengths are used [2,15], which our data suggest would have lower bias.…”

Section: Discussionmentioning

confidence: 70%

Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations

2020

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The accurate measurement of greenhouse gas emissions is a challenge for atmospheric science. Long-range open-path sensors are flexible enough to be applied to a variety of complex emission sources, and single devices are often used to measure both high and low path-integrated concentrations. As this technology develops, it is important to examine potential sources of inaccuracy. A GasFinder3 open-path laser was tested with a range of path-integrated concentrations from 11.7 to 182 ppm·m CH 4 using certified standard gases. The measured path-integrated concentrations had a positive bias which was higher than 10% at low path-integrated concentrations (<50 ppm·m) with a declining trend expected to be under 2% at 200 ppm·m. A linear equation was used to correct the measured path-integrated concentrations to fit the expected values. After correction, the average bias was reduced to −0.36% and there was no relationship with path-integrated concentration. A relative bias less than ±3% was achieved above ca. 150 ppm·m with or without calibration. Measurement campaigns may reduce error by increasing path lengths to maximize path-integrated concentration. When low path-integrated concentrations are expected, calibration over the expected range is beneficial.

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Section: Discussionmentioning

confidence: 70%

Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations

2020

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“…Therefore, accurate evaluation of the spatio-temporal patterns of CH 4,ef would require more in situ observations to be available. Recent development and setup of observations from non-invasive measurements (Negussie et al 2017, Flesch et al 2018, Rey et al 2019, eddy covariance (Tallec et al 2012, Prajapati andSantos 2018) and isotope signature (Klevenhusen et al 2010, Chang et al 2019 will provide opportunities to better evaluate and benchmark PcMs at large scales. The output will facilitate the enhancement of our ability to predict future CH 4,ef and its impact on the C-climate feedbacks.…”

Section: Discussionmentioning

confidence: 99%

Comparing process-based models with the inventory approach to predict CH₄ emission of livestock enteric fermentation

Zhang

Chen

et al. 2023

Environ. Res. Lett.

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Livestock production is the largest anthropogenic methane (CH4) source globally over the decades. Enteric fermentation of ruminants is responsible for the majority of global livestock CH4 emissions. Both inventory-based models (IvtMs) and process-based models (PcMs) are extensively used to assess the livestock CH4 emission dynamics. However, the model performance and the associated uncertainty have not been well quantified and understood, which greatly hamper our credibility of the regional and global CH4 emission predictions. In this study, we compared the CH4 emissions of livestock enteric fermentation (CH4,ef) predicted by multiple IvtMs and PcMs across Inner Mongolia, a region dominated by typical temperate grasslands that are widely used for animal husbandry. 20 predictions from 5 IvtMs, and 10 predations from 5 PcMs were explicitly calculated and compared for the reference year of 2006. The CH4,ef predicted from PcMs is lower than IvtMs and the variation between PcMs is substantially higher, i.e., 0.34 ± 0.36 g CH4/m2 yr and 0.78 ± 0.14 g CH4/m2 yr for PcMs and IvtMs, respectively. Different model strategies undertaken, i.e., the demand-oriented strategy for IvtMs and the resource-demand co-determined one for PcMs, cause the different predictions of CH4,ef between the two model groups. Using the results from IvtMs as the baseline scalar, we identified and benchmarked the performance of individual PcMs in the study region. The quantitative information provided can facilitate the understanding of key principles and processes of CH4,ef estimations, which will contribute to the future model development of global CH4 emission.

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“…Shipping emissions have been studied in laboratory test engines (e.g., Petzold et al, 2008;Reda et al, 2014), on-board from auxiliary engines operating at berth (Cooper, 2003), onboard from main engines operating at sea (e.g., Agrawal, 2008a, b;Moldanová et al, 2009;Fu et al, 2013;Celo et al, 2015;Zhang et al, 2016), by intercepting plumes from aircraft (e.g., Sinha et al, 2003;Chen et al, 2005; Figure 1. Location of Halifax Harbour within the Halifax Regional Municipality and eastern Canada/northeast USA.…”

Section: Previous Studies Of Shipping Emissionsmentioning

confidence: 99%

Characterization of trace gas emissions at an intermediate port

Wiacek

Tobin

et al. 2018

Atmos. Chem. Phys.

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Abstract. Growing ship traffic in Atlantic Canada strengthens the local economy but also plays an important role in greenhouse gas and air pollutant emissions in this coastal environment. A mobile open-path Fourier transform infrared (OP-FTIR; acronyms defined in Appendix A) spectrometer was set up in Halifax Harbour (Nova Scotia, Canada), an intermediate harbour integrated into the downtown core, to measure trace gas concentrations in the vicinity of marine vessels, in some cases with direct or near-direct marine combustion plume intercepts. This is the first application of the OP-FTIR measurement technique to real-time, spectroscopic measurements of CO2, CO, O3, NO2, NH3, CH3OH, HCHO, CH4 and N2O in the vicinity of harbour emissions originating from a variety of marine vessels, and the first measurement of shipping emissions in the ambient environment along the eastern seaboard of North America outside of the Gulf Coast. The spectrometer, its active mid-IR source and its detector were located on shore while the passive retroreflector was on a nearby island, yielding a 455 m open path over the ocean (910 m two-way). Atmospheric absorption spectra were recorded during day, night, sunny, cloudy and substantially foggy or precipitating conditions, with a temporal resolution of 1 min or better. A weather station was co-located with the retroreflector to aid in the processing of absorption spectra and the interpretation of results, while a webcam recorded images of the harbour once per minute. Trace gas concentrations were retrieved from spectra by the MALT non-linear least squares iterative fitting routine. During field measurements (7 days in July–August 2016; 12 days in January 2017) AIS information on nearby ship activity was manually collected from a commercial website and used to calculate emission rates of shipping combustion products (CO2, CO, NOx, HC, SO2), which were then linked to measured concentration variations using ship position and wind information. During periods of low wind speed we observed extended (∼9 h) emission accumulations combined with near-complete O3 titration, both in winter and in summer. Our results compare well with a NAPS monitoring station ∼1 km away, pointing to the extended spatial scale of this effect, commonly found in much larger European shipping channels. We calculated total marine sector emissions in Halifax Harbour based on a complete AIS dataset of ship activity during the cruise ship season (May–October 2015) and the remainder of the year (November 2015–April 2016) and found trace gas emissions (tonnes) to be 2.8 % higher on average during the cruise ship season, when passenger ship emissions were found to contribute 18 % of emitted CO2, CO, NOx, SO2 and HC (0.5 % in the off season due to occasional cruise ships arriving, even in April). Similarly, calculated particulate emissions are 4.1 % higher during the cruise ship season, when passenger ship emissions contribute 18 % of the emitted particulate matter (PM) (0.5 % in the off season). Tugs were found to make the biggest contribution to harbour emissions of trace gases in both cruise ship season (23 % NOx, 24 % SO2) and the off season (26 % of both SO2 and NOx), followed by container ships (25 % NOx and SO2 in the off season, 21 % NOx and SO2 in cruise ship season). In the cruise ship season cruise ships were observed to be in third place regarding trace gas emissions, whilst tankers were in third place in the off season, with both being responsible for 18 % of the calculated emissions. While the concentrations of all regulated trace gases measured by OP-FTIR as well as the nearby in situ NAPS sensors were well below maximum hourly permissible levels at all times during the 19-day measurement period, we find that AIS-based shipping emissions of NOx over the course of 1 year are 4.2 times greater than those of a nearby 500 MW stationary source emitter and greater than or comparable to all vehicle NOx emissions in the city. Our findings highlight the need to accurately represent emissions from the shipping and marine sectors at intermediate ports integrated into urban environments. Emissions can be represented as pseudo-stationary and/or pseudo-line sources.

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Methane emissions from cattle grazing under diverse conditions: An examination of field configurations appropriate for line-averaging sensors

Cited by 15 publications

References 30 publications

Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations

Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations

Comparing process-based models with the inventory approach to predict CH₄ emission of livestock enteric fermentation

Characterization of trace gas emissions at an intermediate port

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Methane emissions from cattle grazing under diverse conditions: An examination of field configurations appropriate for line-averaging sensors

Cited by 15 publications

References 30 publications

Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations

Assessment of Open-path Spectrometer Accuracy at Low Path-integrated Methane Concentrations

Comparing process-based models with the inventory approach to predict CH4 emission of livestock enteric fermentation

Characterization of trace gas emissions at an intermediate port

Contact Info

Product

Resources

About

Comparing process-based models with the inventory approach to predict CH₄ emission of livestock enteric fermentation