@misc{shah_westerman_arogo_2006, title={Measuring ammonia concentrations and emissions from agricultural land and liquid surfaces: A review}, volume={56}, ISSN={["2162-2906"]}, DOI={10.1080/10473289.2006.10464512}, abstractNote={Abstract Aerial ammonia concentrations (C g) are measured using acid scrubbers, filter packs, denuders, or optical methods. Using C g and wind speed or airflow rate, ammonia emission rate or flux can be directly estimated using enclosures or micrometeorological methods. Using nitrogen (N) recovery is not recommended, mainly because the different gaseous N components cannot be separated. Although low cost and replicable, chambers modify environmental conditions and are suitable only for comparing treatments. Wind tunnels do not modify environmental conditions as much as chambers, but they may not be appropriate for determining ammonia fluxes; however, they can be used to compare emissions and test models. Larger wind tunnels that also simulate natural wind profiles may be more useful for comparing treatments than micrometeorological methods because the latter require larger plots and are, thus, difficult to replicate. For determining absolute ammonia flux, the micrometeorological methods are the most suitable because they are nonintrusive. For use with micrometeorological methods, both the passive denuders and optical methods give comparable accuracies, although the latter give real-time C g but at a higher cost. The passive denuder is wind weighted and also costs less than forced-air C g measurement methods, but it requires calibration. When ammonia contamination during sample preparation and handling is a concern and separating the gas-phase ammonia and aerosol ammonium is not required, the scrubber is preferred over the passive denuder. The photothermal interferometer, because of its low detection limit and robustness, may hold potential for use in agriculture, but it requires evaluation. With its simpler theoretical basis and fewer restrictions, the integrated horizontal flux (IHF) method is preferable over other micrometeorological methods, particularly for lagoons, where berms and land-lagoon boundaries modify wind flow and flux gradients. With uniform wind flow, the ZINST method requiring measurement at one predetermined height may perform comparably to the IHF method but at a lower cost.}, number={7}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Shah, Sanjay B. and Westerman, Philip W. and Arogo, Jactone}, year={2006}, month={Jul}, pages={945–960} }
 @article{arogo_westerman_heber_2003, title={A  review of ammonia emissions from confined swine feeding operations}, volume={46}, DOI={10.13031/2013.13597}, abstractNote={Ammonia emissions from swine feeding operations depend on the housing type; animal size, age, and type; manure 
management, storage, and treatment; climatic variables; and manure utilization or land application techniques. Techniques 
or methods for estimating or quantifying NH3 flux from a source to the atmosphere include nitrogen mass balance, 
micrometeorology, flux chambers, models, and emission factors. Of these techniques, emission factors, once established, 
provide the most convenience in estimating emissions. However,it is important to understand how a particular emission factor 
is determined and whether it accurately reflects a composite or average emission for all the variable conditons. Using an 
average ammonia emission factor multiplied by pig inventory to determine a regional or national ammonia emission inventory 
may be misleading, especially in the U.S. where existing emission factors were developed using data from swine facilities in 
Western Europe. 
Housing, manure management practices, and climate vary among different regions of the U.S. and can be very different 
from those in Western Europe. In addition, ammonia concentrations and emission estimations have been determined with a 
variety of methods, making it difficult to compare results. To determine representative ammonia emissions from confined swine 
feeding operations, it is important that emission factors be specific enough to account for animal type and size, housing 
system, manure storage and treatment, land application, and climatic effects. This article describes the strengths and 
limitations of emission factors as currently used and provides recommendations for determining realistic ammonia emission 
factors for swine feeding operations. Because of the limited nature of the data published in the literature, emission factors 
for different animal management systems could not be presented. 
Regulators, consultants, cooperative extension personnel, and other leaders in the agricultural community with interest 
in ammonia emissions should be aware of the lack of reliable U.S. data available for calculating accurate emission factors. 
The scientific research community should standardize methods for measurement, calculation, and reporting of ammonia 
emissions.}, number={3}, journal={Transactions of the ASAE}, author={Arogo, J. and Westerman, P. W. and Heber, A. J.}, year={2003}, pages={805–817} }
 @article{arogo_westerman_liang_2003, title={Comparing ammonium ion dissociation constant in swine anaerobic lagoon liquid and deionized water}, volume={46}, DOI={10.13031/2013.15441}, abstractNote={The dissociation constant of ammonium ion both in deionized water and swine anaerobic lagoon liquid was 
determined experimentally in a convective emission chamber at three temperatures (15.C, 25.C, and 35.C) commonly 
experienced in lagoons in the south and southeastern regions of the U.S. Ammonium chloride (NH4Cl) salt was used to make 
the solution for the deionized water tests. The dissociation constant (Kd) values obtained for NH4Cl in deionized water 
approximately doubled with every 10.C increase in liquid temperature from 15.C to 35.C. A similar trend was obtained for 
lagoon liquid in the 25.C to 35.C liquid temperature range, but the Kd values for the lagoon liquid were ~50% of those for 
NH4Cl in deionized water. However, at 15.C, the Kd value for the lagoon liquid was almost the same as for deionized water, 
and was 0.75 the lagoon liquid value at 25.C. Based on these results, it can be concluded that the Kd values of ammonium 
ion in anaerobic lagoon liquid was 50% of the value in deionized water at 25.C and 35.C, and 94% of the value at 15.C. 
This implies that for lagoons with characteristics similar to those of the anaerobic lagoon liquid reported in this study, the 
Kd values (normally derived from NH4 
+ dissociation in deionized water) used in ammonia volatilization calculations should 
be adjusted to a fraction of that in deionized water. More studies to determine the Kd values for lagoon liquids with different 
total ammonia nitrogen concentrations and solid contents are needed. Studies should include the effects of temperature and 
perhaps distinguish between the effects of dissolved and suspended solids on the dissociation constant.}, number={5}, journal={Transactions of the ASAE}, author={Arogo, J. and Westerman, P. W. and Liang, Z. S.}, year={2003}, pages={1415–1419} }
 @article{de visscher_harper_westerman_liang_arogo_sharpe_van cleemput_2002, title={Ammonia emissions from anaerobic swine lagoons: Model development}, volume={41}, DOI={10.1175/1520-0450(2002)041<0426:aefasl>2.0.co;2}, abstractNote={Concentrated animal production may represent a significant source for ammonia emissions to the environment. Most concentrated animal production systems use anaerobic or liquid/slurry systems for wasteholding; thus, it is desirable to be able to predict ammonia emissions from these systems. A process model was developed to use commonly available measurements, including effluent concentration, water temperature, wind speed, and effluent pH. The developed model simulated emissions, as measured by micrometeorological techniques, with an accuracy that explains 70% of the variability of the data using average daily emissions and explains 50% of the variability of the data using 4-h average data. The process model did not show increased accuracy over a statistical model, but the deviations between model and measurement were distributed more evenly in the case of the process model than in the case of the statistical model.}, number={4}, journal={Journal of Applied Meteorology}, author={De Visscher, A. and Harper, L. A. and Westerman, P. W. and Liang, Z. and Arogo, J. and Sharpe, R. R. and Van Cleemput, O.}, year={2002}, pages={426–433} }
 @article{liang_westerman_arogo_2002, title={Modeling ammonia emission from swine anaerobic lagoons}, volume={45}, DOI={10.13031/2013.8859}, abstractNote={A mathematical model to estimate ammonia emission from anaerobic swine lagoons was developed based on the 
classical two–film theory. Inputs to the model are wind speed and lagoon liquid properties such as total ammonia nitrogen 
(TAN) concentration, pH, and temperature. Predicted emission rates of ammonia increase when any of these parameters are 
increased, but the relationship is linear only with TAN concentration. The dissociation constant (Kd) for ammonia in lagoon 
liquid is also an important factor, with higher flux predictions for higher Kd. The model was validated by comparing the model 
outputs to measured fluxes from two lagoons in North Carolina. The predicted ammonia emission fluxes for the two lagoons 
ranged from 1 to 38 kg NH3–N/ha–d, which was a wider range than the fluxes measured (2.5 to 22 kg N/ha–d) by other 
researchers using the micrometeorological method. 
Compared to measured fluxes at each lagoon, the model tended to predict higher ammonia fluxes at lagoon A and lower 
fluxes at lagoon B when a Kd of 0.5 was used. Additional information is needed regarding ammonia dissociation (Kd) values 
for anaerobic lagoon liquid. Comparison of the model results with a linear regression equation indicated that the model 
predicted much higher fluxes at temperatures above 25 
³ 
C and at upper ranges of pH and wind speed. Finally, the model was 
used with typical lagoon TAN concentration and pH, and average monthly values for wind speed and estimated liquid 
temperature at Raleigh, North Carolina, to predict monthly ammonia emissions for a typical anaerobic swine lagoon in North 
Carolina. The highest and lowest monthly ammonia emission occurred in June and January, respectively. Based on the 
average monthly emissions, it is estimated that the average annual ammonia nitrogen emission rate from the surface of a 
typical lagoon in North Carolina would be 234 g/m 2 or 2340 kg/ha. However, the model and results from other researchers 
indicate that ammonia emission can vary greatly.}, number={3}, journal={Transactions of the ASAE}, author={Liang, Z. S. and Westerman, P. W. and Arogo, J.}, year={2002}, pages={787–798} }
 @article{arogo_westerman_2000, title={Conceptual model for ammonia and odor production and ammonia emission from swine anaerobic lagoons}, ISBN={1892769123}, journal={Air pollution from agricultural operations : proceedings of the 2nd international conference, October 9-11, 2000, Des Moines, Iowa}, publisher={St. Joseph, Mich. : American Society of Agricultural Engineers}, author={Arogo, J. and Westerman, P. W.}, year={2000}, pages={132} }
 @article{arogo_zhang_riskowski_day_2000, title={Hydrogen sulfide production from stored liquid swine manure: A laboratory study}, volume={43}, number={5}, journal={Transactions of the ASAE}, author={Arogo, J. and Zhang, R. H. and Riskowski, G. L. and Day, D. L.}, year={2000}, pages={1241–1245} }
 @article{arogo_zhang_riskowski_day_1999, title={Mass transfer coefficient for hydrogen sulfide emission from aqueous solutions and liquid swine manure}, volume={42}, DOI={10.13031/2013.13309}, abstractNote={Mass transfer coefficient for hydrogen sulfide emission from an aqueous solution and liquid manure into the 
air was determined using a convective emission chamber where air temperature, velocity, turbulence, and relative 
humidity were precisely controlled. The mass transfer coefficient was determined from experimental data and correlated 
to liquid temperature, air temperature, and air velocity using a dimensional analysis method. Typical values of air 
temperature (15-35°C), air velocity (0.1-0.5 m/s), and liquid manure temperature (15-35°C) found in under-floor manure 
storage pits were used. The mass transfer coefficient increased as liquid temperature increased and decreased as the air 
velocity and air temperature increased. When the liquid temperature was higher than the air temperature, the mass 
transfer coefficient increased as the difference between the two temperatures increased. This result implies that higher 
emission rate of H2S is likely to occur in a situation where the liquid temperature is higher than the air temperature. 
Sensitivity analysis showed that the mass transfer coefficient is more sensitive to changes in liquid and air temperature 
than to air velocity above the liquid.}, number={5}, journal={Transactions of the ASAE}, author={Arogo, J. and Zhang, R. H. and Riskowski, G. L. and Day, D. L.}, year={1999}, pages={1455–1462} }