Archives

New science emerges to measure air emissions from livestock

Laser technology provides a new tool in accurately measuring emissions of gaseous compounds and other particles from beef cattle operations, say Agriculture and Agri-Food Canada (AAFC) researchers in Lethbridge, Alberta. Data collected with a laser can provide information on everything from specific compound concentrations in the air to whether a particular source is responsible for certain emissions.

"Laser technology itself is not a new concept, but the applications for measuring air emissions in agriculture are," says Dr. Sean McGinn, a research scientist with the Environmental Health Program at the Lethbridge Research Centre. "The laser data, combined with other physical and/or biological data, is providing essential information in numerous livestock research applications."

Nuisance emissions, particularly dust and odour, have become an issue of conflict between farming operations and neighbouring communities in recent years, says McGinn. Because the magnitude of a nuisance is subjective, scientifically sound regulations and standardized methods are necessary to assess these problems fairly. Laser technology can prove essential in the development of these methods.

"Lasers are not very valuable on their own," says McGinn. They are measuring tools that provide information on gas concentration over time and space. However, when combined with other data, the information can be very useful.

Laser technology can be used to evaluate the effect of diet treatments on gas emissions from cattle, he says. It can also be used to determine the effect of bedding material, animal density and weather conditions on the release and dispersion of gases from cattle pens.

"To measure concentrations, and changes in concentration, of a particular compound over time, the laser has to be 'tuned' to a wavelength specific to that compound," explains McGinn. The laser sends a beam through the air above the animals that are being monitored. Because of the matching wavelength, the beam agitates molecules of the target compound. This is similar to how microwaves selectively agitate water molecules to warm food.

It takes energy to agitate molecules, he says. The amount of energy that the laser beam loses along its path can be quantified and is equivalent to the concentration of the target compound in the air.

Using several lasers, gas concentration can be measured upwind and downwind from a pen, says McGinn. This provides information on incoming and outgoing gas and determines the extent to which the cattle contribute to the observed gas concentration in the air.

Dispersion modeling is another application for laser technology that is gaining recognition around the world, he adds. It involves measuring plumes of air particles and creating models of the degree to which a specific source contributes to total air particles at various distances from the source.

"As an analogy, imagine a cloud of smoke from a forest fire," says McGinn. "The smoke plume gets bigger and more diluted the farther it drifts from the fire. A similar dispersion pattern exists for invisible gases like methane. In this case we rely on detecting the size of the plume using tools such as lasers."

Agriculture and Agri-Food Canada’s Lethbridge Research Centre has a mandate to promote innovation for growth, maintain security of the food system and protect the health of the environment.

© 2003 Meristem Information Resources Ltd.
Meristem® is a registered trademark of Meristem Information Resources Ltd. All rights reserved.
Legal Disclaimer