ARS | Publication request: Gas Emissions from an Anaerobic Swine Waste Treatment Lagoon: Bowen Ratio and Heat Fluxes in Summer Time

Submitted to: ASABE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: January 1, 2009
Publication Date: June 20, 2009
Citation: Lovanh, N.C., Quintanar, A., Loughrin, J.H., Mahmood, R., Motley, M. 2009. Gas Emissions from an Anaerobic Swine Waste Treatment Lagoon: Bowen Ratio and Heat Fluxes in Summer Time. ASABE Annual International Meeting.

Technical Abstract: Anaerobic lagoons are effective and low-cost tools to treat swine manure but they are also responsible for emissions of numerous atmospheric pollutants such as ammonia, greenhouse gases, and odors. The emissions of these pollutants are controlled by the interactions between the atmosphere, biochemical and physical processes occurring inside and at lagoon surfaces. Thus, any study on swine operations needs to address the issue of anaerobic lagoons as a source of atmospheric pollutants and the potential for devising emission reduction techniques. Despite their relatively small size, compared to lakes or estuaries for instance, these lagoons exhibit a considerable amount of complexity due to atmospheric interactions. Therefore, the aims of this work were to deploy a system to estimate Bowen ratio, an index in climatological and meteorological studies to evaluate energy partitions under a variety of conditions which could affect emission, and to carry out sensitivity analysis on various parameters that could potentially affect Bowen ratio estimates. Based on data obtained during the summer, Bowen ratios showed diurnal behavior near the lagoon surface characterized by negative values during the day and positive ones at night. Lagoon heating was driven by the diurnal cycle of solar radiation and net radiation. This suggested that Bowen ratios had an inverse relationship with lagoon heating and its thermal stratification. This also indicated that there was an increase in latent heat flux and evaporation during the daytime. Based on sensitivity analysis, however, we found that while there were differences in Bowen ratio of about 20 to 30 % between different methods, the differences in sensible and latent heat fluxes did not have such sensitivity due to the energy balance constraint. Thus, these results are important for characterizing the thermal behavior of the lagoon leading to a better representation of processes responsible for emissions.