ARS | Publication request: Inverse-dispersion technique for assessing lagoon gas emissions

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: June 22, 2012
Publication Date: July 29, 2012
Citation: Ro, K.S., Johnson, M.H., Stone, K.C., Hunt, P.G., Todd, R.W., Flesch, T. 2012. Inverse-dispersion technique for assessing lagoon gas emissions. In: Proceedings of the American Society of Agricultural and Biological Engineers Annual International Meeting, July 29-August 1, 2012, Dallas, Texas, Paper #12-1337658. 8 pp.

Technical Abstract: Measuring gas emissions from treatment lagoons and storage ponds poses challenging conditions for existing micrometeorological techniques because of non-ideal wind conditions, such as those induced by trees and crops surrounding the lagoons, and lagoons with dimensions too small to establish equilibrated microclimate conditions within the water boundary. This study evaluated the accuracy of the backward Lagrangian stochastic (bLS) inverse-dispersion technique to measure lagoon emissions using a fabricated floating emission source with known emission rates from an irrigation pond that resembled typical treatment lagoon environments. Anemometers were located on the upwind, downwind, side berm parallel to wind or directly above water surface. Path integrated concentrations (PICs) were monitored within the pond and on the downwind berm. The berm surface was deliberately roughened during the summer by placing pine straw bales along the berms to simulate vegetation growth. Generally using an anemometer located on the berm produced the more accurate results than using an anemometer located directly above water surface. The berm location is also the most convenient place for both wind and concentration sensors to be placed in typical lagoon environments. The overall average accuracy of all combinations of the anemometer and the PIC locations for both smooth and rough berm surface conditions was 77%. This lagoon study demonstrated that the bLS inverse-dispersion technique can be effectively used to measure lagoon emission with relatively high accuracy and convenience.