@article{liu_wang_beasley_shah_2009, title={Modeling ammonia emissions from broiler litter at laboratory scale}, volume={52}, DOI={10.13031/2013.29131}, abstractNote={The objectives of this study were to develop a mechanistic emission model to estimate ammonia flux from broiler litter and to evaluate the model at laboratory scale. In the proposed model, the ammonia flux is essentially a function of the litter's total ammoniacal nitrogen (TAN) content, moisture content, pH, and temperature, as well as the Freundlich partition coefficient (Kf), mass transfer coefficient (KG), ventilation rate (Q), and emission surface area (A). The Freundlich partition coefficient (Kf) was used as a fitting parameter in the model. A dynamic flow-through chamber system and a wind tunnel were designed to measure ammonia fluxes from broiler litter. The dynamic flow-through chamber experiments evaluated the proposed model with various litter samples under a constant temperature and wind profile. The wind tunnel experiments evaluated the proposed model under various temperatures and wind profiles. Model parameters such as Kf and KG were estimated. The results from the two experiments were consistent with each other. The estimated KG ranged from 1.11 to 27.64 m h-1, and the estimated Kf ranged from 0.56 to 4.48 L kg-1. A regression sub-model was developed to estimate Kf as function of litter pH and temperature, which indicated that Kf increased with increasing litter pH and decreased with increasing temperature. The proposed model was used to estimate the equilibrium gas phase ammonia concentration (Cg,0) in litter, and the model-predicted values were compared with the observed values. The normalized mean error (NME), the normalized mean square error (NMSE), and fractional bias (FB) were calculated to be 25%, 12%, and -0.3%, respectively, for all 94 measurements, and the model was able to reproduce 80% of the variability of the data. Sensitivity analysis of the model showed that ammonia flux is very sensitive to litter pH and to a lesser extent temperature. The relative sensitivity of pH or temperature increases as the pH or temperature increases.}, number={5}, journal={Transactions of the ASABE}, author={Liu, Z. and Wang, L. and Beasley, D. B. and Shah, Sanjay}, year={2009}, pages={1683–1694} }
 @article{hoff_bundy_nelson_zelle_jacobson_heber_ni_zhang_koziel_beasley_2009, title={Real-Time Airflow Rate Measurements from Mechanically Ventilated Animal Buildings}, volume={59}, ISSN={["1047-3289"]}, DOI={10.3155/1047-3289.59.6.683}, abstractNote={Abstract This paper describes techniques used to determine airflow rate in multiple emission point applications typical of animal housing. An accurate measurement of building airflow rate is critical to accurate emission rate estimates. Animal housing facilities rely almost exclusively on ventilation to control inside climate at desired conditions. This strategy results in building airflow rates that range from about three fresh-air changes per hour in cold weather to more than 100 fresh-air changes per hour in hot weather. Airflow rate measurement techniques used in a comprehensive six-state study could be classified in three general categories: fan indication methods, fan rotational methods, and airspeed measurement methods. Each technique is discussed and implementation plans are noted. A detailed error analysis is included that estimated the uncertainty in airflow rate between ±5 and ±6.1% of reading at a building operating static pressure, air temperature, relative humidity, and barometric pressure of 20 Pa, 25 °C, 50%, and 97,700 Pa, respectively.}, number={6}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Hoff, Steven J. and Bundy, Dwaine S. and Nelson, Minda A. and Zelle, Brian C. and Jacobson, Larry D. and Heber, Albert J. and Ni, Jiqin and Zhang, Yuanhui and Koziel, Jacek A. and Beasley, David B.}, year={2009}, month={Jun}, pages={683–694} }
 @inproceedings{liu_wang_beasley_2008, title={Comparison of three techniques for determining ammonia emission fluxes from broiler litter}, volume={51}, DOI={10.13031/2013.25304}, abstractNote={This article reports an experimental study of three techniques in ammonia emission flux determination. Ammonia concentrations in a dynamic flow-through chamber with broiler litter were measured simultaneously by a chemiluminescence ammonia analyzer and an acid scrubber. At the beginning and ending of each test, the litter samples were analyzed for conducting nitrogen mass balance. Ammonia emissions were estimated from the two concentration measurements and the mass balance approach. It was observed that the chemiluminescence analyzer measurements tended to overestimate ammonia concentration compared with the acid scrubber measurements, especially when litter moisture was high. Statistical results indicated that the effect of litter moisture content on the ratios of the average chemiluminescence analyzer measurements over the acid scrubber measurements was significant, and a p-value of 0.0104 was obtained. Great uncertainties were observed for the mass balance approach, especially when the percentages of the total nitrogen losses in litter samples were small (less than 2%). In order to apply the mass balance approach to estimate ammonia emissions and to achieve acceptable accuracy, a substantially long testing period (more than 80 h) is needed under the observed ammonia emission level (104 to 1137 mg N h-1 m-2), and great efforts are needed to reduce the uncertainties associated with sampling and analyzing litter nitrogen content.}, number={5}, booktitle={Transactions of the ASABE}, author={Liu, Z. and Wang, L. and Beasley, D. B.}, year={2008}, pages={1783–1790} }
 @article{jacobson_hetchler_schmidt_nicolai_heber_ni_hoff_koziel_zhang_beasley_et al._2008, title={Quality assured measurements of animal building emissions: Odor concentrations}, volume={58}, DOI={10.3155/1047-3289.S8.6.806}, number={6}, journal={Journal of the Air & Waste Management Association}, author={Jacobson, L. D. and Hetchler, B. P. and Schmidt, D. R. and Nicolai, R. E. and Heber, A. J. and Ni, J. Q. and Hoff, S. J. and Koziel, J. A. and Zhang, Y. H. and Beasley, D. B. and et al.}, year={2008}, pages={806–811} }
 @article{liu_wang_beasley_oviedo_2007, title={Effect of moisture content on ammonia emissions from broiler litter: A laboratory study}, volume={58}, ISSN={["1573-0662"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34548108638&partnerID=MN8TOARS}, DOI={10.1007/s10874-007-9076-8}, number={1}, journal={JOURNAL OF ATMOSPHERIC CHEMISTRY}, author={Liu, Zifei and Wang, Lingjuan and Beasley, David and Oviedo, Edgar}, year={2007}, month={Sep}, pages={41–53} }
 @article{jerez_zhang_mcclure_jacobson_heber_hoff_koziel_beasley_2006, title={Comparison of measured total suspended particulate matter concentrations using tapered element oscillating microbalance and a total suspended particulate sampler}, volume={56}, ISSN={["1047-3289"]}, DOI={10.1080/10473289.2006.10464460}, abstractNote={Abstract A comparison of the concentration of the total suspended particulate (TSP) matter measured by the tapered element oscillating microbalance (TEOM) monitor and the isokinetic TSP samplers developed at the University of Illinois was carried out in several types of confinement livestock buildings. In a majority of the measurements done, the dust concentration measured by the TEOM monitor was lower than the University of Illinois at Urbana-Champaign (UIUC) isokinetic TSP sampler; the TEOM monitor tended to underestimate the total dust concentration by as much as 54%. The difference in measurements can be attributed to the sampling efficiency of the TEOM monitor sampling head and the loss of some semivolatile compounds and particle-bound water because of heating of the TEOM monitor sampling stream to 50 °C. Although several articles in the literature supported the latter argument, this study did not investigate the effect of heating the sampling stream or the effect of moisture on the relative difference in dust concentration measurements. The model that best describes the relationship between the two methods was site specific, that is, the linear regression model was applicable only to four of the sites monitored. The measured total dust concentration in livestock buildings range from ∼300 to 4000 μg/m3; a higher correlation coefficient between TEOM-TSP and UIUC-TSP monitors was obtained in swine facilities than those obtained in a laying facility.}, number={3}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Jerez, SB and Zhang, YH and McClure, JW and Jacobson, L and Heber, A and Hoff, S and Koziel, J and Beasley, D}, year={2006}, month={Mar}, pages={261–270} }
 @article{hoff_bundy_nelson_zelle_jacobson_heber_ni_zhang_koziel_beasley_2006, title={Emissions of ammonia, hydrogen sulfide, and odor before, during, and after slurry removal from a deep-pit swine finisher}, volume={56}, ISSN={["1047-3289"]}, DOI={10.1080/10473289.2006.10464472}, abstractNote={Abstract It is a common practice in the midwestern United States to raise swine in buildings with under-floor slurry storage systems designed to store manure for up to one year. These so-called “deep-pit” systems are a concentrated source for the emissions of ammonia (NH3), hydrogen sulfide (H2S), and odors. As part of a larger six-state research effort (U.S. Department of Agriculture-Initiative for Future Agriculture and Food Systems Project, “Aerial Pollutant Emissions from Confined Animal Buildings”), real-time NH3 and H2S with incremental odor emission data were collected for two annual slurry removal events. For this study, two 1000-head deep-pit swine finishing facilities in central Iowa were monitored with one-year storage of slurry maintained in a 2.4 m-deep concrete pit (or holding tank) below the animal-occupied zone. Results show that the H2S emission, measured during four independent slurry removal events over two years, increased by an average of 61.9 times relative to the before-removal H2S emission levels. This increase persisted during the agitation process of the slurry that on average occurred over an 8-hr time period. At the conclusion of slurry agitation, the H2S emission decreased by an average of 10.4 times the before-removal emission level. NH3 emission during agitation increased by an average of 4.6 times the before-removal emission level and increased by an average of 1.5 times the before-removal emission level after slurry removal was completed. Odor emission increased by a factor of 3.4 times the before-removal odor emission level and decreased after the slurry-removal event by a factor of 5.6 times the before-removal emission level. The results indicate that maintaining an adequate barn ventilation rate regardless of animal comfort demand is essential to keeping gas levels inside the barn below hazardous levels.}, number={5}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Hoff, SJ and Bundy, DS and Nelson, MA and Zelle, BC and Jacobson, LD and Heber, AJ and Ni, JQ and Zhang, YH and Koziel, JA and Beasley, DB}, year={2006}, month={May}, pages={581–590} }
 @article{heber_ni_lim_tao_schmidt_koziel_beasley_hoff_nicolai_jacobson_et al._2006, title={Quality assured measurements of animal building emissions: Gas concentrations}, volume={56}, ISSN={["2162-2906"]}, DOI={10.1080/10473289.2006.10465680}, abstractNote={Abstract Comprehensive field studies were initiated in 2002 to measure emissions of ammonia (NH3), hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), nonmethane hydrocarbons (NMHC), particulate matter <10 µm in diameter, and total suspended particulate from swine and poultry production buildings in the United States. This paper focuses on the quasicontinuous gas concentration measurement at multiple locations among paired barns in seven states. Documented principles, used in air pollution monitoring at industrial sources, were applied in developing quality assurance (QA) project plans for these studies. Air was sampled from multiple locations with each gas analyzed with one high quality commercial gas analyzer that was located in an environmentally controlled on-farm instrument shelter. A nominal 4 L/min gas sampling system was designed and constructed with Teflon wetted surfaces, bypass pumping, and sample line flow and pressure sensors. Three-way solenoids were used to automatically switch between multiple gas sampling lines with ≥10 min sampling intervals. Inside and outside gas sampling probes were between 10 and 115 m away from the analyzers. Analyzers used chemiluminescence, fluorescence, photoacoustic infrared, and photoionization detectors for NH3, H2S, CO2, CH4, and NMHC, respectively. Data were collected using personal computer-based data acquisition hardware and software. This paper discusses the methodology of gas concentration measurements and the unique challenges that livestock barns pose for achieving desired accuracy and precision, data representativeness, comparability and completeness, and instrument calibration and maintenance.}, number={10}, journal={JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION}, author={Heber, Albert J. and Ni, Ji-Qin and Lim, Teng T. and Tao, Pei-Chun and Schmidt, Amy M. and Koziel, Jacek A. and Beasley, David B. and Hoff, Steven J. and Nicolai, Richard E. and Jacobson, Larry D. and et al.}, year={2006}, month={Oct}, pages={1472–1483} }