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Agricultural and Environmental Chemistry
Using a Vegetative Environmental Buffer to Reduce the Concentrations of Volatile Organic Compounds in Poultry House Atmospheric Emissions Qi Yao, Alba Torrents, Hong Li, Michael Buser, Laura L. Mcconnell, Peter M Downey, and Cathleen Joan Hapeman J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b00088 • Publication Date (Web): 29 Jun 2018 Downloaded from http://pubs.acs.org on June 29, 2018
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Journal of Agricultural and Food Chemistry
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Using a Vegetative Environmental Buffer to Reduce the Concentrations of Volatile Organic
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Compounds in Poultry House Atmospheric Emissions
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Qi Yao1, Alba Torrents1, Hong Li2, Michael D. Buser3, Laura L. McConnell1, Peter M. Downey4,
5
Cathleen J. Hapeman4,*
6 7
1
8
Martin Hall, College Park, Maryland, 20742, USA
9
2
Department of Civil and Environmental Engineering, University of Maryland,1173 Glenn L.
Department of Animal and Food Sciences, University of Delaware, 046 Townsend Hall,
10
Newark, DE 19716, USA
11
3
12
Hall, Stillwater, OK 74078, USA
13
4
14
Avenue, Beltsville, MD 20705, USA
Biosystems and Agricultural Engineering Department, Oklahoma State University, 223 Ag
US Department of Agriculture, Agricultural Research Service (USDA-ARS), 10300 Baltimore
15 16
*
Corresponding author: Tel: 301-504-6451, e-mail address:
[email protected]
17 18
DISCLAIMER
19
Mention of trade names or commercial products in this publication is solely for the purpose of
20
providing specific information and does not imply recommendation or endorsement by
21
University of Maryland, Oklahoma State University, University of Delaware, or United States
22
Department of Agriculture (USDA). University of Maryland, Oklahoma State University,
23
University of Delaware, and USDA are equal opportunity providers and employers.
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KEYWORDS
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volatile organic compound (VOC), VOC emission, poultry production, vegetative environmental
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buffer (VEB), ozone formation potential (OFP)
27 28 29
ABSTRACT Ground-level ozone is formed when volatile organic compounds (VOCs) react with
30
hydroxyl radicals and nitrogen oxides in the presence of ultraviolet light. Research has typically
31
focused on the release and control of VOCs from hydrocarbon processing, however, agricultural
32
activities, such as poultry production, can also be VOC sources and potentially contribute to
33
ozone pollution. Therefore, this study examines the emission of C2 - C6 VOCs emitted from
34
poultry houses and the use of a vegetative environmental buffer (VEB) as a potential mitigation
35
strategy. Sampling campaigns were conducted at two farms, one with and one without a VEB. Of
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the nine compounds measured, methanol, ethanol, and acetone were the primary VOCs emitted
37
and had the largest ozone formation potential (OFP). A significantly larger decrease in the OFP
38
for methanol was observed as a function of distance from the poultry house at the farm with the
39
VEB as compared to the farm without the VEB. These results suggest that besides a visual
40
barrier and particulate screen, VEBs can provide some control of VOCs emitted from poul try
41
production.
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Journal of Agricultural and Food Chemistry
INTRODUCTION
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Ozone is one of the six criteria air pollutants identified in the Clean Air Act by the United
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States Environmental Protection Agency (US EPA) and is a major component in photochemical
46
smog. Ground-level ozone is a concern because it can cause severe respiratory problems among
47
older adults and young children and can negatively affect vegetation including agricultural crops
48
and seed production1-5. Ozone concentrations can reach unhealthful levels when the temperature
49
is high and few or no clouds are present with little or no wind. Typically in the US, average
50
ozone concentration levels are the highest during April to October. In 2015, the US EPA
51
strengthened the National Ambient Air Quality Standards (NAAQS) for ground-level ozone. The
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current NAAQS for ground-level ozone is an eight-hour average concentration of 70 ppb (0.14
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µg/m3 at 25 °C)6.
54
Ground-level ozone is formed in the atmosphere when volatile organic compounds
55
(VOCs) react with hydroxyl radicals and nitrogen oxides in the presence of ultraviolet light.
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However, some VOCs react quickly with hydroxyl radicals (e.g., xylenes) and are referred to as
57
reactive organic gases, while other VOCs (e.g., methane) are virtually non-reactive with
58
hydroxyl radicals. Short chain alcohols are moderately reactive7,8. Therefore, decreasing the
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amount of VOCs released to the atmosphere can lead to reducing ozone formation.
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Ground-level ozone concentrations in the Chesapeake Bay region have become a
61
concern. Over 30 counties in this area did not meet the new US EPA ground-level ozone
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requirement during 2012 to 2014, and those areas are likely to be designated as nonattainment
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areas9. In addition, high levels of NOx primarily due to massive electric power plants and large
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traffic volumes are released to the atmosphere in this region1. With the increasing encroachment
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of urbanization into agricultural lands, the ozone formation potential of the VOCs released from
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agriculture needs to be considered. Previous experiments have shown that the ozone formation
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potential (OFP) of VOCs emitted from poultry waste was more than twice the OFP associated
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with VOC emissions from swine, beef cattle, or dairy cattle farms10.
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The Chesapeake Bay region and Delmarva Peninsula have become one of the major
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poultry-producing areas because of the large markets from New York to Washington, DC11, 12.
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Nearly 600 million broilers were produced on the Delmarva Peninsula in 201711. This rapid
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expansion and consolidation of industrialized poultry operations has raised concerns about the air
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pollutants emitted from these facilities and the negative impacts that these pollutants can have on
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the public health and the surrounding environment. Generally, odorous compounds emitted by
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concentrated animal feeding operations (CAFOs) can be a social problem and can negatively
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affect rural and state economies13. Inside the poultry house, the most abundant VOCs observed
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were acetic acid, 2,3-butanedione, methanol, acetone, and ethanol, and the largest concentrations
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were around ventilation areas14. Furthermore, the primary VOC sources in poultry production
79
were identified as manure, waste bedding, fertilizer and crop residues, and feathers15. Although
80
studies have been conducted measuring and identifying the VOCs inside poultry houses, little
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VOC emission data are available for outside the poultry houses.
82
Vegetative environmental buffers (VEB) have been introduced to poultry producers as a
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cost-efficient practice for air pollutant remediation. VEBs are rows of grasses, shrubs, and trees
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purposefully planted surrounding the CAFOs, which also can provide a more appealing visual
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for the facilities. Although previous studies have reported that VEBs can reduce VOCs in swine
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farms16,17, no specific research has been carried related to poultry houses. Vegetation is also a
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known VOC source. For example, Miscanthus x giganteus is known to release isoprene18,19,
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however this compound was not observed inside poultry houses in previous work14.
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The objectives of this study are to develop VOC specific concentration profiles which
90
began near the sidewall ventilation fans and extended perpendicularly outward from the poultry
91
houses, to examine the ability of VEBs to decrease the concentration of the emitted VOCs, and
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to evaluate the ozone formation potential (OFP) from the poultry-emitted VOCs. Time-integrated
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air samples were collected at multiple locations and heights outside of two poultry facilities, one
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with a VEB and one without, in two air sampling campaigns between very late spring to summer.
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This time period has higher temperatures relative to fall and winter, which leads to increased
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poultry house ventilation and presumably to higher levels of VOC emissions. Air samples were
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analyzed and quantified for nine non-methane VOCs (C2 - C6 molecular weight range): propene,
98
methanol, ethanol, acetone, acetonitrile, propanol, hexane, butanol, and butanal. These VOCs
99
were previously reported with relatively large concentrations inside the poultry houses,
100
especially during warmer and active feeding periods14, and readily react with hydroxyl radicals7.
101 102
MATERIALS AND METHODS
103 104
Site descriptions. Two commercial poultry farms were chosen for the field air sampling
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campaigns (Fig. 1, Fig. S1). Farm 1 was located in southeastern Pennsylvania and consisted of
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two poultry houses (152 m length * 15 m width) with approximately 25,000 boilers per house.
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This facility is a certified organic commercial poultry farm that uses organic-approved feed and
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litter amendments. The farm produces free-range chickens by providing them with fenced-in
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outdoor access. Each flock was raised for 50 days with a 10-day down time in between flocks
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when the litter was removed and new bedding was placed in the house. The house included five
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1.2-m tunnel fans on both sides of the houses at one end of each house. Four 0.9-m sidewall fans
112
(35 m apart) were located on the south sidewall, but were not used during any experiments. A
113
vegetative environmental buffer (VEB) was located parallel to the first house. This VEB
114
consisted of a row of switch-grass (Panicum virgatum) and miscanthus (Giant Miscanthus
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Miscanthus x giganteus and Miscanthus x giganteus), which were planted in 2012, and a row of
116
Austree hybrid willow trees (Salix matsudana x alba), which was planted in 2007. The species
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chosen were consistant with recommendations for this area20 The height of the grasses and the
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willow trees were approximatedly 3 m and 10 m, respectively. The distance between the grass
119
portion of the VEB and the tunnel fans was approximately 5 m.
120
Farm 2 was located in Delaware and consisted of two poultry houses (122 m length * 21
121
m width) with approximately 28,000 boilers per house. This facility is a typical CAFO poultry
122
farm, where each flock was raised on used litter for 60 days with a 10-day inactive time between
123
flocks. Mechanical ventilation of the poultry house was accomplished by five 1.2-m tunnel fans
124
on both sides of the houses at one end of each house. As with Farm 1, the sidewall fans were not
125
used in during any experiments.
126
Air sampling. Two air sampling campaigns were carried out, one at Farm 1 in August
127
2015 and one at Farm 2 in late May 2015. Five daytime and five nighttime field experiments
128
were conducted at each farm, and 13 and 12 2-hr-composite air samples were collected at Farm 1
129
and Farm 2, respectively. At Farm 1, three 10-m sampling towers with multiple sampling heights
130
were deployed perpendicularly to the tunnel fans of house one at distances of 2, 6, and 20 m. The
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sampling heights above ground level for Tower 1 (T1) were 1, 2, 4.5, 7.25, and 10 m; Tower 2
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(T2) were 1, 2, 4.5, and 7.25 m; and Tower 3 (T3) were 2, 4.5, 7.25, and 10 m (Fig. 1). There
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was a ground-level elevation drop of about 1 m between T1 and T2 and a drop of about 3 m
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between T1 and T3. A background sampler was deployed at approximately 150 m away
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northwest of the tunnel fans. At Farm 2, three 10-m sampling towers with multiple sampling
136
heights were deployed perpendicularly to the tunnel fans of house one at distances of 2, 23, and
137
47 m. The sampling heights above ground level for all towers (T1, T2, and T3) were 2, 4.5, 7.25,
138
and 10 m (Fig. 1). There was no elevation change between T1 and T3. A background sampler
139
was deployed at approximately 70 m away east of the tunnel fans.
140
US EPA Method TO-15 was modified to collect VOCs using 1-L amber glass canisters
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(Bottle-Vac) coupled with a filtered restrictor to afford 2-hr integrated air samples (Entech
142
Instruments, Inc., Simi Valley, California)21. The filter of the restrictor ensured that particulates
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were not collected. All canisters were cleaned and evacuated for 20 cycles and reached a final
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evacuation of -1.04 atm using an Entech 3100A canister cleaner automatic system (Entech
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Instruments, Inc., Simi Valley, California). During each experiment, one replicate air sample was
146
collected to evaluate the precision of the VOC measurement procedure.
147
Samples were transported to the laboratory and were analyzed within two weeks after
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collection. Meteorological conditions (temperature, pressure, relative humidity, wind speed, and
149
wind direction) were recorded by HOBO U30 Station 3.0.0 (Onset Computer Corporation,
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Bourne, Massachusetts) (Table SI 1 and S2).
151
Sample analyses. Air samples were analyzed for nine C2 – C6 VOCs (molar mass < 90 g
152
mol-1): propene, methanol, acetone, ethanol, acetonitrile, hexane, propanol, butanol, and butanal.
153
Carbon sulfide, methyl sulfide dimethyl disulfide, dimethyl sulfide, hexanal, toluene, and
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nonanal were also observed, but the concentrations were not quantified. For these compounds,
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the spectra of each peak were identified using the NIST05 Mass Spectral Library, and the peak
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areas were used to construct the emission profile figures.
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A 3400A auto sampler and 7200A pre-concentrator (Entech Instruments, Inc., Simi
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Valley, California) were used to prepare the gas samples prior to injection into an Agilent 6980N
159
gas chromatograph equipped with a 5973 mass spectrometer (Agilent Technologies, Inc.). The
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pre-concentrator used three gas concentrating stages to trap water and CO2 prior to the injection
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onto a GC column (Rxi-1ms, 60m * 0.32mm * 0.1µm Restek Corporation, Bellefonte,
162
Pennsylvania). Instrument settings were as follows: 35 °C hold 5 min, ramp 5 °C /min to 140 °C,
163
ramp 25 °C /min to 220 °C, and hold 5 min; inlet temperature was 175°C, and flow (He) was 1.5
164
mL/min, splitless. The mass spectrometer was operated under both scan and sim modes with
165
electron ionization mode. Calibration gas standards (10 ppm) with a mixture of 8 standard gases
166
were custom made (Restek Corporation, Bellefonte, Pennsylvania). Dilution of calibration gases
167
was performed by a dynamic dilution system 4600A (Entech Instruments, Inc., Simi Valley,
168
California). The detection limit of each VOC was as follow: butanal (6 µg/m3), butanol (6
169
µg/m3), hexane (7 µg/m3), propanol (5 µg/m3), acetone (5 µg/m3), acetonitrile (3 µg/m3), ethanol
170
(4 µg/m3), methanol (3 µg/m3), and propene (3 µg/m3). The replicate precision values for the
171
most abundant VOCs (methanol, ethanol, and acetone) met or exceeded the US EPA TO-15
172
method21.
173
Gradient figures and statistical analyses. Plume figures were constructed using
174
pollutant concentrations and plotted as a function of distance and/or height from the tunnel fans.
175
Figures were created in MATLAB R2016a using the griddata function (The Math Works, Inc.,
176
Natick, MA) to interpolate concentration data linearly. All statistical analyses (student t-test,
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standard variance) were performed using GraphPad Prism, Version 5.01 (GraphPad Software,
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Inc., La Jolla, CA) and Microsoft Excel 2016 (office.microsoft.com).
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Relative VOC concentrations were used in the data analysis, because the range of
180
concentrations was very large between experiments. Relative concentrations ( .)
181
were obtained by normalizing all VOC concentrations to the concentrations observed at the 2-m
182
height of Tower 1 in the same experiment; these samples are referred to as the reference sample.
183
Normalization allowed for comparison of the two campaigns. For VOC concentrations below the
184
limit of detection, 0.5 of the value of the limit of detection was used for statistical analyses and
185
figure construction. VOC levels from background samples varied significantly and were likely
186
influenced by additional sources. These values were not used to correct the sample
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concentrations observed at T1, T2, and T3.
.
188 189 190
RESULTS AND DISCUSSION Composite air samples were collected at multiple heights and distances on three sampling
191
towers during five daytime and five nighttime field experiments at both poultry farms (Fig. 1.).
192
Samples were analyzed for nine C2 – C6 VOCs (molar mass < 90 g mol-1): propene, methanol,
193
acetone, ethanol, acetonitrile, hexane, propanol, butanol, and butanal.
194
During the ten sampling time periods at Farm 1, the daytime and nighttime (mean ±
195
standard deviation) temperatures were 27.2 ± 1.5 °C and 22.0 ± 2.1 °C; atmospheric pressures
196
were 0.89 ± 0.01 atm and 0.94 ± 0.01 atm; relative humidity was 49% ± 4% and 67% ± 3%, calm
197
percentages (wind speed < 0.5 m s-1) were 52% ± 30% and 100% ± 0%, respectively. (SI, Table
198
S1). At Farm 2, daytime and nighttime (mean ± standard deviation) temperatures were 20.2 ± 4.4
199
°C and 22.2 ± 3.0 °C; atmospheric pressures were 0.97 ± 0.02 atm and 0.92 ± 0.03 atm; relative 9 ACS Paragon Plus Environment
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humidity was 73% ± 17% and 76% ± 13%, calm percentages (wind speed < 0.5 m s-1) were 25%
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± 30% and 46% ± 38% during sampling time, respectively (SI, Table S2). The higher
202
temperatures during the campaign at Farm 1 compared to temperatures during the campaign
203
conducted at Farm 2 presumably contributed to the larger VOC concentrations observed, even
204
though the total ventilation rates were significantly higher at Farm 2 (SI, Tables S3, S4, t-test, p
205
< 0.05).
206
Methanol concentrations and sources. Of the VOCs measured in this study, the most
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abundant VOC observed at both farms was methanol, and all samples contained detectable levels
208
of methanol. The methanol concentrations at the same sampling points for each experiment at
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both farms were significantly larger than all the other measured VOCs (t-test, p < 0.05). For
210
Farm 1 at the 2-m height, the average methanol concentrations (ranges) were 182 µg m-3 (128 -
211
226 µg m-3) at T1 and 47 µg m-3 (12 - 110 µg m-3) at T3 during the day, and 207 µg m-3 (174 -
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254 µg m-3) and 76 µg m-3 (48 - 112 µg m-3) for nighttime. The distance between T1 and T3 at
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Farm 1 was 18 m, and the correspondingly-similar distance at Farm 2 was between T1 and T2
214
(21 m). At Farm 2 (2-m height), the average methanol concentrations were 116 µg m-3 (96 - 138
215
µg m-3) and 56 µg m-3 (17 - 127 µg m-3) at T1 and T2 during the day, respectively, and were 106
216
µg m-3 (69 - 137 µg m-3) and 83 µg m-3 (37 - 124 µg m-3) for nighttime. The difference in
217
average methanol concentrations between the two poultry houses may be due to the different
218
house managements and temperatures.
219
To compare the VOC emissions between experiments, relative concentration was used
220
due to the wide range of concentration levels. Relative concentrations were plotted as a function
221
of distance to the primary ventilation fan and the height for each experiment at both farms (Fig.
222
2; SI Figs. S3, S4). A representative relative methanol concentration gradient during daytime at
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Farm 1 shows the emission plume originating from the ventilation fan (Fig. 2a). In some
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experiments, the plume lofted upwards in the relative short distance from T1 to T2 (< 5 m), most
225
likely due to the presence of the VEB (Fig. 2a; SI, Fig. S3). This is consistent with previous
226
studies22,23. Fig. 2c shows an extended plume of more than 40 m observed at Farm 2. Thus, the
227
VEB prevented the VOC plume from moving far beyond the poultry house.
228
A typical methanol emission pattern during the nighttime at Farm 1 is shown in Fig. 2b.
229
It is somewhat similar to the emission plume that emanated from the ventilation fan during the
230
day, however, the plume height was much lower and reached further into the VEB. This is not
231
unexpected as much calmer wind conditions and lower temperatures during the nighttime can
232
create a nocturnal radiation inversion. The ground-level methanol plumes were trapped under the
233
warmer air giving rise to the suppressed and extended plume shape. Similar to Fig. 2b, the
234
nighttime plume of Farm 2 shown in Fig. 2d is suppressed and somewhat extended.
235
For each campaign at ground-level (2-m height), the day and nighttime relative methanol
236
concentration reductions were not significantly different (t-test, p > 0.1). The relative methanol
237
concentrations at Farm 1 decreased by 69% ± 13% over the span of 18 m (T1 to T3) for all ten
238
experiments, whereas, at Farm 2, the decrease in the relative methanol concentrations from T1 to
239
T2 (38% ± 36% over 21 m) for all ten experiments were significantly lower (t-test, p < 0.05).
240
The reduction of methanol concentrations at Farm 2 represents the effect of dispersion as a
241
function of distance only, whereas the methanol concentration decrease at Farm 1 is the result of
242
both dispersion due to distance and interaction the VEB. Furthermore, the relative concentrations
243
at the highest points were not significantly different between both farms (t-test, p > 0.1). Thus,
244
the VEB did not simply push the plume to higher levels above the ground. Although we have no
245
direct evidence, i.e., analyses of plant material, we can surmise that the VEB trapped the VOCs.
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Ethanol and acetone concentrations and sources. The emission patterns of ethanol and
247
acetone were very similar at both farms. The relative ethanol concentrations were plotted as a
248
function of distance from the primary ventilation fan and height for each experiment (Fig. 3, SI
249
Figs. S5 - S8). Results showed that ethanol was emitted from the poultry house (Fig. 3a). The
250
relative concentration gradients for acetone and for ethanol were not significantly different (t-
251
test, p > 0.05). Again, the nocturnal ethanol emission plumes at both farms (Figs. 3b, 3d) was
252
suppressed which is consistent with the inversion pattern observed with methanol. However,
253
high background acetone and ethanol levels observed in some of experiments at both farms
254
suggested that additional sources were present. Dairy and swine facilities have also been reported
255
as significant contributors for both ethanol and acetone emissions24,25, and these types of
256
facilities are within visual distance at both farms.
257
Other VOCs. Acetonitrile, propanol, butanol, hexane, and propene were detected in 40%
258
of the samples collected at Farm 1 (4 experiments), but in less than 5% of the samples from Farm
259
2; thus, the following discussion is for Farm 1 only. For these five VOCs, the ground-level (2-m
260
height) VOC concentrations in front of the ventilation fan were significantly lower (t-test, p <
261
0.05) than at T3 location (20-m distance from the fan and behind VEB). The relative
262
concentration changes as a function of distance for butanol are shown in Fig. 4, and the emission
263
patterns for acetonitrile, propanol, hexane, and propene are shown in SI Fig. S9. Butanol
264
concentrations in front of the poultry ventilation fans were the lowest, whereas larger
265
concentrations were observed much higher levels of T3 indicating that the poultry house is not
266
the primary source for this compound. Acetonitrile, propanol, hexane, and propene had other
267
dominant emission sources as well. Additionally, background samples showed the largest
268
concentrations levels of these VOCs in 2 experiments at Farm 1.
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Journal of Agricultural and Food Chemistry
Dimethyl sulfide, carbon disulfide, dimethyl disulfide, toluene, hexanal, and nonanal,
270
have been reported as malodorous VOCs and have been detected inside poultry houses14. These
271
compounds were also identified in the collected air samples from both farms, but were not
272
quantified against standards. The emission patterns for carbon disulfide, methyl sulfide, dimethyl
273
sulfide, and dimethyl disulfide were similar to the methanol emission patterns (SI Fig. S10-S13),
274
indicating that the poultry houses were the emission source of these compounds. However,
275
hexanal exhibited similar patterns as ethanol and acetone (SI Fig. S14) suggesting that broiler
276
houses are an emission source, but not the only source. Nonanal and toluene presented same
277
concentration spatial changes as butanol (SI Fig. S15, S16), suggesting that other emission
278
sources other than poultry farms are dominant.
279
Ozone formation potential. VOCs have a wide range of hydroxyl radical reactivity
280
which is a function of their chemical properties. Propylene-equivalent concentration (Prop-
281
Equiv) is one approach26 to measure the relative VOC reactivity based on a scale normalized to
282
propene reactivity,
283
Prop-Equiv (j) = Conc (j) × kOH (j)/kOH (propene)
(Equation 1)
284
where Conc (j) is the averaged concentration of the VOC (j), and kOH (j) and kOH (propene) are
285
the rate constants at 298 K for the gas-phase reactions of VOC and the hydroxyl radical7 (Eqn.
286
1). Although sunlight is required for ozone formation, in this study as discussed above, the
287
nighttime and daytime concentration profiles were not significantly different (t-test, p > 0.1),
288
therefore, all the experiments were used for the following calculations.
289
The ozone formation potential (OFP) of a VOC is a function of its concentration and its
290
maximum incremental reactivity (MIR). MIR, which is used by California Air Resources Board
291
for regulation applications of VOCs associated with ground-level ozone formation, assumes a
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modeled scenario in which the NOx level yields the highest incremental reactivity of the mixture
293
of reactive organic gases. The MIR coefficient is in units of grams O3 per gram VOC27-29 (Eqn.
294
2).
295 296
OFP (j) = Conc (j) × MIR coefficient (j)
(Equation 2)
Table 1 shows the VOC reactivity (Prop-Equiv) of methanol, ethanol, and acetone as
297
well as their respective ozone formation potential (OFP) values and MIR coefficients using the
298
daytime ground-level (2-m height) VOC concentrations from both farms. The largest potential
299
contributor to ozone formation is methanol followed by ethanol and acetone. Direct comparison
300
of the Prop-Equiv and OFP values between the two farms is not appropriate, since data were
301
collected under different environmental conditions, and Prop-Equiv and OFP values are
302
calculated using actual not relative concentrations. However, comparison of the changes in the
303
Prop-Equiv and the OFP values is valid. The changes in the Prop-Equiv and the OFP values for
304
methanol at each farm as a function of distance (2 m and 20 m) are significantly different (t-test,
305
p < 0.05). For methanol, the OFP values decreased 69% ± 13% at Farm 1 and 34% ± 39% at
306
Farm 2. These calculations suggest that using VEBs will reduce VOC concentrations, and
307
furthermore, if VOCs are the limiting factor in ozone formation in this region, VEBs will reduce
308
the potential for ozone formation. Finally, the increases in OFP for ethanol and acetone as a
309
function of increasing distance from the source at Farm 1 again indicate that additional sources
310
for these compounds exist.
311 312
ABBREVIATIONS USED
313 314
ARS – Agricultural Research Service
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CAFO – concentrated animal feeding operations
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Conc – concentration
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GC – gas chromatography
318
MIR – maximum incremental reactivity
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NAAQS – National Ambient Air Quality Standards
320
NRCS – Natural Resources Conservation Service
321
OFP – ozone formation potential
322
Prop-Equiv – propene equivalent
323
T1, T2, T3 – Tower 1, Tower 2, Tower 3, respectively
324
USDA – United States Department of Agriculture
325
US EPA – United States Environmental Protection Agency
326
VEB – vegetative environmental buffer
327
VOC – volatile organic compound
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ACKNOWLEDGEMENTS
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The authors wish to acknowledge the dedicated contributions from numerous field and technical
330
staff, students, growers, and volunteers. Funding for this project was provided by USDA-NRCS
331
Conservation Innovation Grant Program (Award 69-3A75-12-244), University of Delaware,
332
University of Maryland, Oklahoma State University, Pennsylvania State University, and USDA-
333
ARS. This work was also supported financially by USDA-ARS intramural projects in National
334
Program 212, Soil and Air.
335 336
SUPPORTING INFORMATION DESCRIPTION
337 338
Supporting information includes: aerial views of Farm 1 and Farm 2 noting deployment positions
339
of samplers, the meteorological conditions (temperature, relative humidity, pressure, wind speed,
340
and wind direction), tunnel fan data, and the relative concentration profiles of all VOCs
341
measured in all experiments.
342
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REFERENCES
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1. US EPA. (2017). Air Pollution in the Chesapeake Bay Watershed. Retrieved January 2, 2018
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Gerosa, G.; Parente, A.; Franco Faoro F.; Nutritional Traits of Bean (Phaseolus vulgaris)
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Seeds from Plants Chronically Exposed to Ozone Pollution. J. Agric. Food Chem. 2009, 57,
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10. Howard, C. J.; Kumar, A.; Mitloehner, F.; Stackhouse, K.; Green, P. G.; Flocchini, R. G.;
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Kleeman, M. J. Direct measurements of the ozone formation potential from livestock and
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18. Copeland, N.; Cape, J. N.; Heal, M. R. Volatile organic compound emissions from
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Hatfield, J. L.; Wanjura, J. D.; Holt, G. A., Torrents, A.; Plenner, S. J.; Clarida, W, Brown, S.
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buffer surrounding an animal feeding operation. Agric. Ecosys. Environ. 2017, 240, 101–108.
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24. Filipy, J.; Rumburg, B.; Mount, G.; Westberg, H.; Lamb, B. Identification and quantification
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of volatile organic compounds from a dairy. Atmos. Environ. 2006, 40, 1480–1494.
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25. Ni, J. Q.; Robarge, W. P.; Xiao, C.; Heber, A. J. Volatile organic compounds at swine
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facilities: A critical review. Chemosphere 2012, 89, 769–788. 26. Chameides, W. L.; Fehsenfeld, F.; Rodgers, M. O.; Cardelino, C.; Martinez, J. Parrish, D.;
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Lonneman, W.; Lawson, D. R.; Rasmussen, R. A.; Zimmerman, P.; Greenberg, J.;
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Middleton, P.; Wang, T. Ozone precursor relationships in the ambient atmosphere. J.
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Geophy. Res. 1992, 97 (D5), 6037 – 6055.
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27. California Air Resources Board. (2010). Final statement of reasons for rulemaking: public
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hearing to consider proposed amendments to the tables of maximum incremental reactivity
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(MIR) values. Retrieved January 2, 2018 from
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https://www.arb.ca.gov/regact/2009/mir2009/mir2009.htm
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28. Carter, W. (1998). Development and application of an updated photochemical mechanism for
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VOC reactivity assessment. Retrieved January 2, 2018 from
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https://www.arb.ca.gov/research/apr/past/a932-094a.pdf
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29. Carter, W. P. L. (2010). Updated maximum incremental reactivity scale and hydrocarbon bin
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reactivities for regulatory application. Retrieved January 2, 2018 from
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http://www.cert.ucr.edu/~carter/SAPRC/MIR10.pdf
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FIGURE CAPTIONS
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Figure 1. Experimental set up for the two farms with sampling points (purple dots). Farm 1 was
433
equipped with three sampling towers (T1, T2, and T3) deployed at distances of 2, 6, and
434
20 m to the primary fan. The sampling heights on the towers were: T1 (1, 2, 4.5, 7.25,
435
and 10 m); T2 (1, 2, 4.5, and 7.25 m); and T3 (2, 4.5, 7.25, and 10 m). A 3-m change in
436
elevation existed between T1 and T3. Farm 2 was equipped with three sampling towers
437
(T1, T2, and T3) deployed at distances of 2, 23, 47 m to the primary fan. The sampling
438
heights on three towers were the same: 2 m, 4.5 m, 7.25 m, and 10 m.
439
Figure 2. Examples of the methanol relative concentration gradient a) daytime at Farm 1; b)
440
nighttime at Farm 1; c) daytime at Farm 2; d) nighttime at Farm 2. All concentrations
441
were normalized using the concentration of the 2-m height sampler on Tower 1 (T1-2 for
442
Farm 1 and T1-1 for Farm 2) from the same experiment.
443
Figure 3. Examples of the ethanol relative concentration gradient: a) daytime at Farm 1; b)
444
nighttime at Farm 1; c) daytime at Farm 2; d) nighttime Farm 2. All concentrations were
445
normalized using the concentration of the 2-m height sampler on Tower 1 (T1-2 for Farm
446
1 and T1-1 for Farm 2) from the same experiment.
447
Figure 4. Example of the butanol relative concentration gradient at Farm 1. Concentrations at
448
Farm 2 were only observed at less than 5% of the samplers and are not shown. All
449
concentrations were normalized using the concentration of the 2-m height sampler on
450
Tower 1 (T1-2) from the same experiment.
451
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TABLE
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Table 1. Photochemical properties of poultry emitted VOCs at a height of 2 m.
455 VOCs
Methanol
Ethanol
Acetone
Distance
Avg. Conc.
10-12 * kOH b
(m)
(µg/m3)
(cm3mol-1s-1)
Farm 1
Farm 2
2
194 ± 37
111 ± 23
~ 20 a
62 ± 34
47± 23
2
27 ± 10
47 ± 12
~ 20 a
24 ± 25
17 ± 11
2
24 ± 110
40 ± 12
~ 20 a
31 ± 41
MIR c
1.06
3.74
0.63
0.67
1.53
0.56
26 ± 18
Prop-Equiv
OFP
(µg/m3)
(µg/m3)
Farm 1
Farm 2
Farm 1
Farm 2
7.9 ± 1.5
4.5± 0.9
130 ± 25
75± 16
2.5 ± 1.4
3.0 ± 1.7
41 ± 23
49 ± 27
3.9 ± 1.5
6.7 ± 1.7
41 ± 16
71 ± 18
3.5 ± 3.6
3.8 ± 1.9
37 ± 38
40 ± 20
0.6 ± 0.2
1.0 ± 0.3
13 ± 6
22 ± 7
0.7 ± 1.0
0.7 ± 0.4
17 ± 23
17 ± 19
456
a
Farm 1: 20-m distance to the primary fan; Farm 2: 23-m distance to the primary fan
457
b
OH radical rate constant at 298 K [6]
458
c
Maximum incremental reactivity [(g O3 formed) (g VOC)-1] [7]
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Figure 1. Experimental set up for the two farms with sampling points (purple dots). Farm 1 was equipped with three sampling towers (T1, T2, and T3) deployed at distances of 2, 6, and 20 m to the primary fan. The sampling heights on the towers were: T1 (1, 2, 4.5, 7.25, and 10 m); T2 (1, 2, 4.5, and 7.25 m); and T3 (2, 4.5, 7.25, and 10 m). A 3-m change in elevation existed between T1 and T3. Farm 2 was equipped with three sampling towers (T1, T2, and T3) deployed at distances of 2, 23, 47 m to the primary fan. The sampling heights on three towers were the same: 2 m, 4.5 m, 7.25 m, and 10 m.
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Figure 2. Relative methanol concentration gradient a) daytime at Farm 1; b) nighttime at Farm 1; c) daytime at Farm 2; d) nighttime at Farm 2. All concentrations were normalized using the concentration of the 2-m height sampler on Tower 1 (T1-2 for Farm 1 and T1-1 for Farm 2) from the same experiment.
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Figure 3. Ethanol relative concentration gradient: a) daytime at Farm 1; b) nighttime at Farm 1; c) daytime at Farm 2; d) nighttime Farm 2. All concentrations were normalized using the concentration of the 2-m height sampler on Tower 1 (T1-2 for Farm 1 and T1-1 for Farm 2) from the same experiment.
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Figure 4. Typical butanol relative concentration gradient at Farm 1. All concentrations were normalized using the concentration of the 2-m height sampler on Tower 1 (T1-2) from the same experiment.
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