Description
Wavelength modulation spectroscopy (WMS), employing a 1654-nm tunable diode laser and an annular polygon-reflector multi-pass optical cell, has been developed to study enteric emissions of methane (a key greenhouse gas) from ruminant livestock. This molecule-specific technique can quantitatively measure sub-parts-per-million concentrations of methane in ambient air at atmospheric pressure. A pulsed solenoid valve has been used to simulate such animal emissions in the laboratory. This approach demonstrates the feasibility of implementing WMS to time-resolve individual simulated eructations of methane in cattle breath [1]. This approach is the precursor to subsequent field-ready instruments. The bulky laboratory-based WMS system has been replaced by more compact, rugged instruments with miniaturised digital electronics, customised software, and remote online instrument control and data transmission. One such WMS unit has been installed in an open-circuit respiration chamber operated by the Ruminant Research Group at the University of New England (Armidale, NSW), where time-resolved eructation patterns from individual cattle can be continuously recorded [2]. Ongoing research, supported by the Cooperative Research Centre for Zero Net Emissions from Agriculture (ZNE-Ag CRC) [3], will study methane-reduction measures such as in-paddock cattle-feed additives and mid-infrared analysis of dairy-cow milk.
[1] B. J. Orr, Y. He, and J. Hill, “Time-resolved measurement of simulated methane emissions from livestock, using wavelength modulation spectroscopy,” submitted to Applied Optics (2026).
[2] Y. He, B. J. Orr, F. Cowley, et al., “Measurement of methane emissions from ruminant livestock in a rural respiration chamber,” manuscript in preparation (2026).
[3] https://zneagcrc.com.au
| I am the presenting author | Yes |
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