|Roadman, Megan - UNIV OF DELAWARE|
|Scudlark, Joe - UNIV OF DELAWARE|
|Ullman, William - UNIV OF DELAWARE|
Submitted to: Atmospheric Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2003
Publication Date: May 5, 2003
Citation: ROADMAN, M.J., SCUDLARK, J.R., MEISINGER, J.J., ULLMAN, W.J. VALIDATION OF OGAWA PASSIVE SAMPLERS FOR THE DETERMINATION OF GASEOUS AMMONIA CONCENTRATIONS IN AGRICULTURAL SETTINGS. ATMOSPHERIC ENVIRONMENT. 2003. Interpretive Summary: Ammonia emissions from animal agriculture are a concern to scientists, agriculture advisors, and regulatory agencies. We evaluated a low-cost passive ammonia sampler in a wide range of agricultural settings and compared it to traditional samplers. The passive sampler requires no power and uses acid-coated filter discs to trap ammonia after the ammonia has diffused across a known distance. Results show that the Ogawa sampler can successfully estimate gaseous ammonia concentrations over a wide range of concentrations and conditions, varying from low-level ambient concentrations in natural environments to very high concentrations inside poultry houses. The large operating range is achieved by adjusting the exposure time from 5 minutes to 14 days and assuring that quantifiable amounts of ammonia are trapped. Reproducibility averaged +/- 10% over the range of conditions tested. Ammonia concentrations and ventilation rates were monitored in and around a broiler house and the data summarized into an ammonia emission estimate of 19 +/- 3g of ammonia nitrogen per chicken over a six week grow-out cycle, a value consistent with other published results. The Ogawa samplers, because of their ease of deployment, wide operational range, and low cost could provide a basis for monitoring ammonia management practices in agriculture. Improving ammonia management in broiler production could result in economic benefits for the farmer and environmental benefits for the conservationists.
Technical Abstract: The Ogawa passive sampler (Ogawa USA, Pompano Beach, Florida) is a useful tool for monitoring atmospheric ammonia (NH3(g)) concentrations and assessing the effects of agricultural waste management practices on NH3(g) emissions. The Ogawa sampler, employing filter-discs impregnated with citric acid to trap NH3(g), was used to determine NH3(g) concentrations in a variety of settings within a poultry-producing region in southern Delaware. A wide range of NH3(g) concentrations can be monitored by varying the sampler exposure time, provided that no more than 10 ug of NH3-N are adsorbed on the acid-coated filters. Concentrations less than 1 ug NH3-N m-3 can be detected using long deployments (e.g. 14 days), while concentrations as great as 10 mg NH3-N m-3 may be determined with very short (e.g. 5 min) deployments. Reproducibility averaged 10% over the range of concentrations studied and the results of passive determinations of NH3(g) were indistinguishable from determinations using dilute-acid gas scrubbers. Background levels of NH3(g) at a non-agricultural site in southern Delaware were typically < 1 ug NH3-N m-3. The air entering a chicken house was 10 ug NH3-N m-3, reflecting the background levels in agricultural settings in this region. Within the house, concentrations < 8.5 mg NH3-N m-3 were observed, reflecting the high rates of NH3(g) emission from chicken excreta. Using measured NH3(g) concentrations and poultry-house ventilation rates, we estimate that each broiler grown to production size over 6 weeks contributes approximately 19 + 3 g of NH3-N to the atmosphere, a value consistent with other published values.