177-6 Using Quantum Cascade Lasers to Quantify Ammonia Emissions from Beef Feedlots.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Improving Accuracy and Precision of Soil Carbon and Greenhouse Gas Emission Measurements and Quantification: I

Tuesday, November 17, 2015: 9:15 AM
Minneapolis Convention Center, M101 A

Jianlei Sun, Crop and Soil Science Section, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Burnley, AUSTRALIA, Trevor Coates, Soil and Crop Science Section, University of Melbourne, Strathmore, AUSTRALIA, Jianlin Shen, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, China, Owen Denmead, CSIRO, Canberra, ACT, AUSTRALIA and Deli Chen, School of Agriculture and Food, The University of Melbourne, Parkville, Victoria, Australia
Abstract:
It is difficult to measure ammonia (NH3) accurately in real time from beef feedlots, especially in a closed-path measurement system, mostly due to its tendency of adsorption to surrounding materials. A high flow and high vacuum sample stream in the closed-path measurement regime is ideal to minimise the adsorption and responsiveness issue of NH3. A Quantum Cascade Laser (QCL) trace gas analyser (Aerodyne, Inc.) has no flow restriction on its open-tubular multi-pass absorption cell and can measure NH3 at a 10 Hz rate. In a few recent studies, we combined QCLs with heated Teflon tubing, a high speed vacuum pump and a virtual impactor to create a sampling system to minimise NH3 adhesion and retention, with the purpose to improve NH3 measurement accuracy and responsiveness. In conjunction with this system, we employed integrated horizontal flux (IHF) method to measure NH3 fluxes from a small scale (20 m x 20 m) feedlot; and eddy covariance method in a large commercial open feedlot. The accurate and real time measurements have dramatically improved the confidence of the flux calculations. We detected NH3 fluxes from beef feedlots at an average of 10 g NH3 m-2 day-1 with a Gaussian distribution diurnal pattern.

See more from this Division: ASA Section: Environmental Quality
See more from this Session: Improving Accuracy and Precision of Soil Carbon and Greenhouse Gas Emission Measurements and Quantification: I