Qianfeng Li

Ammonia concentrations and modeling of inorganic particulate matter in the vicinity of an egg production facility in Southeastern USA

Ammonia (NH3) is an important base gas and can react with acidic species to form atmospheric aerosols. Due to the rapid growth of poultry and swine production in the North Carolina Coastal Plain, atmospheric NH3 concentrations across the region have subsequently increased. Ammonia concentrations and inorganic particulate matter (PM) at four ambient stations in the vicinity of an egg production facility were measured for 1xa0year using PM2.5 speciation samplers with honeycomb denuders and ion chromatography (IC). Meanwhile, concentrations of NH3 and inorganic PM in one of the egg production houses were also simultaneously measured using a gas analyzer for NH3 and the filter pack plus IC method for inorganic PM. An equilibrium model-ISORROPIA II was applied to predict the behavior of inorganic aerosols in response to precursor gas concentrations and environmental parameters. Average ambient NH3 concentrations varied from 10.0 to 27.0xa0μg/m3, and they were negatively correlated with the distances from the ambient location to the nearest egg production house exhausts. Ambient NH3 concentrations were higher in warm seasons than in cold seasons. Measured NH3 concentrations agreed well with ISORROPIA II model predictions at all sampling stations. For the ambient stations, there was a good agreement in particle phase NH4+ between the model simulation and observations. For the in-house station, the model simulation was applied to correct the overestimation of particle phase NH4+ due to gas phase NH3 breaking through the denuders. Changes in SO42−, NO3−, and Cl− yield proportional changes in inorganic PM mass. Due to the abundance of NH3 gas in the vicinity area of the monitored farm, changes in NH3 concentrations had a small effect on inorganic PM mass. Aerosol equilibrium modeling may be used to assess the influence of precursor gas concentrations on inorganic PM formation when the measurements for some species are unavailable.

Field evaluation of particulate matter measurements using tapered element oscillating microbalance in a layer house

The tapered element oscillating microbalance (TEOM) is one type of continuous ambient particulate matter (PM) monitor. Adsorption and desorption of moisture and semivolatile species may cause positive or negative artifacts in TEOM PM mass measurement. The objective of this field study was to investigate possible uncertainties associated with TEOM measurements in the poultry operation environment. For comparisons of TEOM with filter-based gravimetric method, four instruments (TEOM-PM10, low-volume PM10 sampler, TEOM-PM2.5, and PM2.5 speciation sampler) were collocated and tested inside a poultry house for PM2.5 and PM10 (PM with aerodynamic equivalent diameter ≤2.5 and ≤10 μm, respectively) measurements. Fifteen sets of 24-hr PM10 concentrations and 13 sets of 24-hr PM2.5 measurements were obtained. Results indicate that compared with filter-based gravimetric method, TEOM gave significantly lower values of both PM10 and PM2.5 mass concentrations. For PM10, the average ratio of TEOM to the gravimetric method was 0.936. For PM2.5, the average ratio of TEOM to the gravimetric method was 0.738. Particulate matter in the poultry houses possibly contains semivolatile compounds and moisture due to high levels of relative humidity (RH) and gas pollutants. The internal heating mechanism of the TEOM may cause losses in mass through volatilization. To investigate the effects of TEOM settings on concentration measurements, the heaters of two identical TEOMs were set at 50 °C, 30 °C, or no heating at all. They were collocated and tested for total suspended particle (TSP), PM10, and PM2.5 measurements in layer house for 6 weeks. For all TSP, PM10, and PM2.5 measurements, the internal TEOM temperature setting had a significant effect (P < 0.05). Significantly higher PM mass concentrations were measured at lower temperature settings. The effects of environmental (i.e., temperature, RH, NH3 and CO2 concentrations) and instrumental (i.e., filter loading and noise) parameters on PM measurements were also assessed using regression analysis. Implications Because of its potential health and environmental effects, particulate matter (PM) emissions from animal feeding operations (AFOs) have been a great concern to the public and to the regulatory agencies. The tapered element oscillating microbalance (TEOM) PM monitor has been was adapted for continuous PM measurements in some AFO air quality studies. This study investigated possible uncertainties associated with TEOM measurements in an egg production environment. It was discovered that there was a significant bias in TEOM measurements of PM10 as compared with federal reference method. Internal temperature settings of a TEOM have significant impact on its PM measurement.

Fine Particulate Matter in a High-Rise Layer House and Its Vicinity

Fine particulate matter (PM2.5) is one of many air pollutants emitted from animal feeding operations (AFOs). Knowledge about PM2.5 in AFO production facilities and their vicinity is important for studies of its impact on health, animal welfare, and the environment. However, very little information is available about PM2.5 concentrations and emissions, and their spatial and temporal variations, associated with egg production facilities. In this study, Partisol 2300 PM2.5 speciation samplers were used to take daily PM2.5 samples in a high-rise layer house and at four ambient stations. The sampling period covered four seasons, with a total of 300 samples. The results showed that none of the ambient PM2.5 concentrations exceeded the 35 µg m-1 (24 h) and 15 µg m-1 (annual) PM2.5 National Ambient Air Quality Standards (NAAQS). The ambient stations and the in-house station showed strong seasonal variations; the ambient stations had the highest PM2.5 concentrations in summer, and the in-house station had the highest concentration in winter. Based on the gamma distribution, 95% confidence intervals of PM2.5 emissions (mg PM2.5 d-1 hen-1) were [7.86, 11.4]. The downtime PM2.5 concentration mean was one-tenth that of the occupied house. PM2.5 concentrations were negatively correlated with ambient RH, egg production, and ventilation rate. Statistical tests did not show a strong correlation between ambient PM2.5 concentrations and emissions from the layer house. This study adds to a growing body of research assessing the environmental impact, air quality, emissions of AFOs and the relationship between PM2.5 and the environmental and farm management inventory information.

Particle Size Distribution of Particulate Matter Emitted from a Layer Operation in Southeast U.S.

This paper reports a field study on characterizing particle size distribution (PSD) of particulate matter (PM) emitted from a commercial layer operation in Southeast U.S. across three seasons from October of 2008 to April of 2009. Six low-volume (1m3/hr) total suspended particulate (TSP) samplers were used to collect PM samples in two high-rise layer houses. Laser diffraction particle size analyzer (LS13 320) was applied to measure PSD of PM samples collected by the TSP samplers. Results of the study indicate that TSP concentrations across the three seasons ranged from 888 to 5333 µg/m3. TSP concentration was affected by season, animal activity, floor and equivalent air flow rate factor. It was observed that TSP concentration in winter was higher than that in spring; concentration on the second floor was higher than that on the first floor; the more active the animals were, the higher the TSP concentration; the more the fans on, the lower the concentration. Compared with PM concentration, PSD (characterized by the mass medium diameter, MMD, & geometric standard deviation, GSD) was much less affected by season, animal activity, floor and equivalent flow rate factor. The MMD was affected by floor and equivalent flow rate factor, but the degree of affection was within the range of one standard deviation. Overall MMDs of PM samples collected in fall, winter and spring were 15.80±1.05µm, 17.13±0.81µm and 18.44±1.44µm, respectively. The difference of MMD among three seasons was within the range of one standard deviation. GSD was relatively constant and not affected by those factors. The overall GSD was 2.65±0.08.

Particulate Matter in the Vicinity of an Egg Production Facility: Concentrations, Statistical Distributions, and Upwind and Downwind Comparison

Animal feeding operations (AFOs) satisfy the demand for meat, dairy, and eggs; however, they may negatively impact air quality. In this study, the concentrations of PM2.5 and PM10 were simultaneously monitored at four ambient locations in the vicinity of a commercial egg production farm for over two years. Overall, concentrations and temporal patterns were similar to other rural sites in the southeast U.S. Concentrations near the farm property line did not exceed the 24 h National Ambient Air Quality Standards (NAAQS) for PM2.5 (35 µg m-3) or PM10 (150 µg m-3). Daily average ambient PM concentrations were best described by a lognormal distribution. Downwind concentrations were statistically significantly higher than upwind concentrations, but differences were <1.0 µg m-3 for PM2.5 and <5.0 µg m-3 for PM10. Relationships between ambient PM concentrations and rates of PM emission from the poultry houses were statistically significant; however, the strength of the linear relationships (Pearson correlation) was relatively weak (r = 0.15 for PM10 and r = 0.33 for PM2.5). On a diurnal time scale, variability was consistent with expected patterns of mobile source emissions, with observed higher concentrations of PM10 on weekdays attributed to on-farm vehicle activity. The observation of higher ambient PM concentrations during summer months was attributed primarily to seasonal variability in non-local primary PM emissions, as well as regional secondary PM precursor emissions and formation mechanisms. Results of this study provide helpful information for understanding the influence of emissions from egg laying facilities on local PM concentrations.

Could Ozonation Technology Really Work for Mitigating Air Emissions from Animal Feeding Operations

Abstract Among various mitigation technologies for ammonia (NH3) emission control at animal feeding operations (AFOs), room ozonation technology is the most controversial. This paper aims to present full perspectives of ozonation techniques through a literature review and a series of laboratory experiments. In the literature review, ozone chemistry was summarized to address (1) ozone and NH3 reactions, (2) ozone and odor reactions, (3) ozone and particulate matter reactions, and (4) ozone and microorganism reactions. A series of laboratory experiments were conducted in a dual large outdoor aerosol smog chamber (270 m3). NH3 and fine particle number concentrations from ozone-treated and control experiments were compared. The experimental results indicated that (1) ozone has no significant effect on NH3 emissions concentrations or NH3 decay of an outdoor chamber; and (2) with ozone treatment, high concentration of particles in the “high-risk” respiratory fraction (in submicron range) are generated.

Chemical Characterization of Particulate Matter Emitted from Animal Feeding Operations

This paper reports a field study of concentration and chemical characterization of PM2.5 emitted from a large egg production facility. PM2.5 samples were taken at five sampling locations covering emission source (in a layer barn) and four ambient stations at four wind directions surrounding the facility. Eight particulate matter (PM) sampling events were conducted from December 2008 to February 2009, through which 117 filter based PM samples were collected and analyzed for PM2.5 mass concentration, organic/elemental carbon (OC/EC), ionic species (nitrate, sulfate, ammonium, sodium, and potassium) and chemical elements (sodium through lead). PM2.5 concentrations in house were found in the range of 143.85 to 396.48 µg/m3, and four ambient stations were in range of 5.94-16.27 µg/m3 (station 2), 5.54-13.97 µg/m3 (station 3), 5.15-14.20 µg/m3 (station 4), and 4.05-16.71 µg/m3 (station 5) respectively. These winter data didn’t show spatially significant difference in ambient PM2.5 mass concentrations among different locations. Na and K concentrations in house PM2.5 samples were higher than that in ambient locations and they were highly correlated with each other. Aerosol NH4+ showed no difference in samples from house to ambient locations. Majority components in PM2.5 were organic compounds, and all PM2.5 samples had EC/TC ratio less than 0.1. PM2.5 samples in house had much higher concentrations of Ca, Cl, K, Mg, Na, P, S, Si and Zn than those of ambient PM2.5 samples. Both ambient and house stations had very low concentrations of Ag, Al, As, Ba, Cd, Ce, Co, Cr, Cs, Cu, In, Ni, Pb, Rb, Sb, Se, Sn, Sr, Ti, V, and Zr.

Major ionic compositions of fine particulate matter in an animal feeding operation facility and its vicinity.

Animal feeding operations (AFOs) produce particulate matter (PM) and gaseous pollutants. Investigation of the chemical composition of PM2.5 inside and in the local vicinity of AFOs can help to understand the impact of the AFO emissions on ambient secondary PM formation. This study was conducted on a commercial egg production farm in North Carolina. Samples of PM2.5 were collected from five stations, with one located in an egg production house and the other four located in the vicinity of the farm along four wind directions. The major ions of NH4+, Na+, K+, SO42−, Cl−, and NO3− were analyzed using ion chromatography (IC). In the house, the mostly abundant ions were SO42−, Cl−, and K+. At ambient stations, SO42−, and NH4+ were the two most abundant ions. In the house, NH4+, SO42−, and NO3− accounted for only 10% of the PM2.5 mass; at ambient locations, NH4+, SO42−, and NO3− accounted for 36–41% of the PM2.5 mass. In the house, NH4+ had small seasonal variations indicating that gas-phase NH3 was not the only major force driving its gas–particle partitioning. At the ambient stations, NH4+ had the highest concentrations in summer. In the house, K+, Na+, and Cl− were highly correlated with each other. In ambient locations, SO42− and NH4+ had a strong correlation, whereas in the house, SO42− and NH4+ had a very weak correlation. Ambient temperature and solar radiation were positively correlated with NH4+ and SO42−. This study suggests that secondary PM formation inside the animal house was not an important source of PM2.5. In the vicinity, NH3 emissions had greater impact on PM2.5 formation. Implications The chemical composition of PM2.5 inside and in the local vicinity of AFOs showed the impact of the AFO emissions on ambient secondary PM2.5 formation, and the fate and transport of air pollutants associated with AFOs. The results may help to manage in-house animal facility air quality, and to develop regional air quality control strategies and policies, especially in animal agriculture-concentrated areas.

Biological Characteristics of Aerosols Emitted From A Layer Operation In Southeastern U.S.

This preliminary study was to investigate biological characteristics of aerosols emitted from a commercial layer farm (egg production farm). Bioaerosol samples were taken on this farm at five sampling locations covering emission source (inside a layer barn) and four ambient stations at four wind directions. All glass impingers (AGI) were used for the field sampling. The AGI fluid samples were plated in duplicate on Trypticase Soy Agar (TSA) for growth of bacteria and Sabouraud Dextrose Agar (SDA) for growth of fungi. The most prominent bacterial colony types were identified using a combination of methods that include recording characteristics of colony morphology; performing a Gram staining method and metabolic analyses using the Biolog system. Results from one group of bioaerosol samples at the five stations indicate that the sampling duration played an important role in accurately determining bacteria concentration in air samples; there were significant reductions in total bacteria concentrations in the samples collected from ambient stations compared to the sample collected in the layer house; the most prominent bacteria species differed among all five stations and three of the most prominent bacteria from samples taken at all five stations were gram-positive; fungal type differed from station to station.

Response of PM Characteristics to NH3 and Other Gaseous Emissions at a southeast Layer Operation

Animal feeding operations (AFOs) contribute directly to primary particular matter (PM) in the atmosphere, and they can also emit large amount of ammonia and other gaseous pollutants. The objective of the study is to investigate the response of PM characteristics to the precursor concentrations in vicinity of a southeast layer operation.PM and gas samples were collected inside the layer houses and around the vicinities. This paper reports the preliminary results for the samples collected from Dec 16, 2008 to April 19. It was observed that, the percentage of both NO3- and NH4+ were higher at ambient than that at source, which indicate the response of particulate matter (PM) to NH3 gas and the formation of NH4NO3. The average molar ratios of NH4+ to SO42- were calculated to be in the range from 2.25 to 2.78, which indicated an ammonia rich environment and complete neutralization of sulfate. The molar concentrations of free ammonia in particulate phase were obviously correlated with the gas phase NH3 concentrations at the ambient stations. It was also found that the mass concentrations of PM increased as NH3 gas concentration increased at the ambient stations. And the increase of PM in response to NH3 gas was mainly due to the neutralization of NH3 by other acid gases besides NO3- and SO42-. The molar ratios of NH3/NH4+ were influenced by the availability of acid gases in the environment. The influences of temperature on gas particulate equilibrium were also observed.