|Reddy, G - NC A&T STATE UNIV.|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2003
Publication Date: May 1, 2004
Citation: Poach, M.E., Hunt, P.G., Reddy, G.B., Stone, K.C., Matheny, T.A., Johnson, M.H., Sadler, E.J. 2004. Ammonia volatilization from marsh-pond-marsh constructed wetlands treating swine wastewater. Journal of Environmental Quality 33:844-851. Interpretive Summary: The emission of ammonia gas is a potential pollution concern for constructed wetlands that treat liquid animal manure. A system design of particular concern is the marsh-pond-marsh design because the pond may act like an anaerobic lagoon, a known source of ammonia pollution. Previous studies indicated that wetland systems without pond sections had low ammonia emissions. We quantified the amount of ammonia gas given off by marsh-pond-marsh systems receiving liquid swine manure to 1) verify that marsh sections had minor ammonia gas releases, and 2) determine if the presence of the pond section increased the potential for ammonia pollution from constructed wetlands. Investigations were performed on a swine farm in North Carolina where liquid swine manure was applied to six constructed wetlands of the marsh-pond-marsh type. We confirmed that the marsh sections emitted minor amounts of ammonia gas. Also, pond sections did increase the ammonia pollution potential of the systems. Therefore, constructed wetland systems without pond sections should be preferred over those with pond sections for the treatment of liquid animal manure.
Technical Abstract: The objective of this research was to use a steady-state enclosure to quantify ammonia (NH3) volatilization from marsh-pond-marsh, constructed wetlands treating liquid swine manure. Liquid swine manure was added at different nitrogen (N) loads to six constructed wetlands of the marsh-pond-marsh type that were located in Greensboro, North Carolina. Ammonia was volatilized from marsh and pond sections with emission rates ranging from 5 to 102 mg N/sq. meter/hour. Pond sections exhibited a significantly greater increase in the rate of NH3-N volatilization (p < 0.001) than did both marsh sections as N load increased. Ammonia volatilization rates greater than 36 mg N/sq. meter/hour were measured on pond sections. A consequence of the pond sections was that NH3 volatilization was an important contributor to the N budget of marsh-pond-marsh systems at N loads greater than 16 kg/hectare/day and was a dominant N removal mechanism at N loads greater than 27 kg/hectare/day. Results indicated that NH3 volatilization would have been a minor N removal mechanism from these wetlands if the pond sections were not present.