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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,

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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

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Mention of trade names or commercial products in this publication is solely for the purpose of

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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,

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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)

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ABSTRACT Ground-level ozone is formed when volatile organic compounds (VOCs) react with

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hydroxyl radicals and nitrogen oxides in the presence of ultraviolet light. Research has typically

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focused on the release and control of VOCs from hydrocarbon processing, however, agricultural

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activities, such as poultry production, can also be VOC sources and potentially contribute to

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ozone pollution. Therefore, this study examines the emission of C2 - C6 VOCs emitted from

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poultry houses and the use of a vegetative environmental buffer (VEB) as a potential mitigation

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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

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and had the largest ozone formation potential (OFP). A significantly larger decrease in the OFP

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for methanol was observed as a function of distance from the poultry house at the farm with the

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VEB as compared to the farm without the VEB. These results suggest that besides a visual

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barrier and particulate screen, VEBs can provide some control of VOCs emitted from poul try

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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

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smog. Ground-level ozone is a concern because it can cause severe respiratory problems among

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older adults and young children and can negatively affect vegetation including agricultural crops

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and seed production1-5. Ozone concentrations can reach unhealthful levels when the temperature

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is high and few or no clouds are present with little or no wind. Typically in the US, average

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ozone concentration levels are the highest during April to October. In 2015, the US EPA

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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.

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Ground-level ozone is formed in the atmosphere when volatile organic compounds

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(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

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reactive organic gases, while other VOCs (e.g., methane) are virtually non-reactive with

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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

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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

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were identified as manure, waste bedding, fertilizer and crop residues, and feathers15. Although

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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.

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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

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began near the sidewall ventilation fans and extended perpendicularly outward from the poultry

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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,

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methanol, ethanol, acetone, acetonitrile, propanol, hexane, butanol, and butanal. These VOCs

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were previously reported with relatively large concentrations inside the poultry houses,

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especially during warmer and active feeding periods14, and readily react with hydroxyl radicals7.

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MATERIALS AND METHODS

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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

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(35 m apart) were located on the south sidewall, but were not used during any experiments. A

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vegetative environmental buffer (VEB) was located parallel to the first house. This VEB

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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

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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

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portion of the VEB and the tunnel fans was approximately 5 m.

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Farm 2 was located in Delaware and consisted of two poultry houses (122 m length * 21

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m width) with approximately 28,000 boilers per house. This facility is a typical CAFO poultry

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farm, where each flock was raised on used litter for 60 days with a 10-day inactive time between

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flocks. Mechanical ventilation of the poultry house was accomplished by five 1.2-m tunnel fans

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on both sides of the houses at one end of each house. As with Farm 1, the sidewall fans were not

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used in during any experiments.

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Air sampling. Two air sampling campaigns were carried out, one at Farm 1 in August

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2015 and one at Farm 2 in late May 2015. Five daytime and five nighttime field experiments

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were conducted at each farm, and 13 and 12 2-hr-composite air samples were collected at Farm 1

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and Farm 2, respectively. At Farm 1, three 10-m sampling towers with multiple sampling heights

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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

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heights were deployed perpendicularly to the tunnel fans of house one at distances of 2, 23, and

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47 m. The sampling heights above ground level for all towers (T1, T2, and T3) were 2, 4.5, 7.25,

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and 10 m (Fig. 1). There was no elevation change between T1 and T3. A background sampler

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was deployed at approximately 70 m away east of the tunnel fans.

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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

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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

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collected to evaluate the precision of the VOC measurement procedure.

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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

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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).

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Sample analyses. Air samples were analyzed for nine C2 – C6 VOCs (molar mass < 90 g

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mol-1): propene, methanol, acetone, ethanol, acetonitrile, hexane, propanol, butanol, and butanal.

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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

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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,

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Pennsylvania). Instrument settings were as follows: 35 °C hold 5 min, ramp 5 °C /min to 140 °C,

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ramp 25 °C /min to 220 °C, and hold 5 min; inlet temperature was 175°C, and flow (He) was 1.5

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mL/min, splitless. The mass spectrometer was operated under both scan and sim modes with

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electron ionization mode. Calibration gas standards (10 ppm) with a mixture of 8 standard gases

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were custom made (Restek Corporation, Bellefonte, Pennsylvania). Dilution of calibration gases

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was performed by a dynamic dilution system 4600A (Entech Instruments, Inc., Simi Valley,

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California). The detection limit of each VOC was as follow: butanal (6 µg/m3), butanol (6

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µg/m3), hexane (7 µg/m3), propanol (5 µg/m3), acetone (5 µg/m3), acetonitrile (3 µg/m3), ethanol

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(4 µg/m3), methanol (3 µg/m3), and propene (3 µg/m3). The replicate precision values for the

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most abundant VOCs (methanol, ethanol, and acetone) met or exceeded the US EPA TO-15

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method21.

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Gradient figures and statistical analyses. Plume figures were constructed using

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pollutant concentrations and plotted as a function of distance and/or height from the tunnel fans.

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Figures were created in MATLAB R2016a using the griddata function (The Math Works, Inc.,

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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

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concentrations was very large between experiments. Relative concentrations (  .)

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were obtained by normalizing all VOC concentrations to the concentrations observed at the 2-m

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height of Tower 1 in the same experiment; these samples are referred to as the reference sample.

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Normalization allowed for comparison of the two campaigns. For VOC concentrations below the

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limit of detection, 0.5 of the value of the limit of detection was used for statistical analyses and

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figure construction. VOC levels from background samples varied significantly and were likely

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influenced by additional sources. These values were not used to correct the sample

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concentrations observed at T1, T2, and T3.

.

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RESULTS AND DISCUSSION Composite air samples were collected at multiple heights and distances on three sampling

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towers during five daytime and five nighttime field experiments at both poultry farms (Fig. 1.).

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Samples were analyzed for nine C2 – C6 VOCs (molar mass < 90 g mol-1): propene, methanol,

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acetone, ethanol, acetonitrile, hexane, propanol, butanol, and butanal.

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During the ten sampling time periods at Farm 1, the daytime and nighttime (mean ±

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standard deviation) temperatures were 27.2 ± 1.5 °C and 22.0 ± 2.1 °C; atmospheric pressures

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were 0.89 ± 0.01 atm and 0.94 ± 0.01 atm; relative humidity was 49% ± 4% and 67% ± 3%, calm

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percentages (wind speed < 0.5 m s-1) were 52% ± 30% and 100% ± 0%, respectively. (SI, Table

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S1). At Farm 2, daytime and nighttime (mean ± standard deviation) temperatures were 20.2 ± 4.4

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°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

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temperatures during the campaign at Farm 1 compared to temperatures during the campaign

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conducted at Farm 2 presumably contributed to the larger VOC concentrations observed, even

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though the total ventilation rates were significantly higher at Farm 2 (SI, Tables S3, S4, t-test, p

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< 0.05).

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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

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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

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Farm 1 at the 2-m height, the average methanol concentrations (ranges) were 182 µg m-3 (128 -

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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

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(21 m). At Farm 2 (2-m height), the average methanol concentrations were 116 µg m-3 (96 - 138

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µg m-3) and 56 µg m-3 (17 - 127 µg m-3) at T1 and T2 during the day, respectively, and were 106

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µg m-3 (69 - 137 µg m-3) and 83 µg m-3 (37 - 124 µg m-3) for nighttime. The difference in

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average methanol concentrations between the two poultry houses may be due to the different

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house managements and temperatures.

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To compare the VOC emissions between experiments, relative concentration was used

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due to the wide range of concentration levels. Relative concentrations were plotted as a function

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of distance to the primary ventilation fan and the height for each experiment at both farms (Fig.

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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

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likely due to the presence of the VEB (Fig. 2a; SI, Fig. S3). This is consistent with previous

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studies22,23. Fig. 2c shows an extended plume of more than 40 m observed at Farm 2. Thus, the

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VEB prevented the VOC plume from moving far beyond the poultry house.

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A typical methanol emission pattern during the nighttime at Farm 1 is shown in Fig. 2b.

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It is somewhat similar to the emission plume that emanated from the ventilation fan during the

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day, however, the plume height was much lower and reached further into the VEB. This is not

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unexpected as much calmer wind conditions and lower temperatures during the nighttime can

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create a nocturnal radiation inversion. The ground-level methanol plumes were trapped under the

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warmer air giving rise to the suppressed and extended plume shape. Similar to Fig. 2b, the

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nighttime plume of Farm 2 shown in Fig. 2d is suppressed and somewhat extended.

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For each campaign at ground-level (2-m height), the day and nighttime relative methanol

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concentration reductions were not significantly different (t-test, p > 0.1). The relative methanol

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concentrations at Farm 1 decreased by 69% ± 13% over the span of 18 m (T1 to T3) for all ten

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experiments, whereas, at Farm 2, the decrease in the relative methanol concentrations from T1 to

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T2 (38% ± 36% over 21 m) for all ten experiments were significantly lower (t-test, p < 0.05).

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The reduction of methanol concentrations at Farm 2 represents the effect of dispersion as a

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function of distance only, whereas the methanol concentration decrease at Farm 1 is the result of

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both dispersion due to distance and interaction the VEB. Furthermore, the relative concentrations

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at the highest points were not significantly different between both farms (t-test, p > 0.1). Thus,

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the VEB did not simply push the plume to higher levels above the ground. Although we have no

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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

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acetone were very similar at both farms. The relative ethanol concentrations were plotted as a

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function of distance from the primary ventilation fan and height for each experiment (Fig. 3, SI

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Figs. S5 - S8). Results showed that ethanol was emitted from the poultry house (Fig. 3a). The

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relative concentration gradients for acetone and for ethanol were not significantly different (t-

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test, p > 0.05). Again, the nocturnal ethanol emission plumes at both farms (Figs. 3b, 3d) was

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suppressed which is consistent with the inversion pattern observed with methanol. However,

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high background acetone and ethanol levels observed in some of experiments at both farms

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suggested that additional sources were present. Dairy and swine facilities have also been reported

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as significant contributors for both ethanol and acetone emissions24,25, and these types of

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facilities are within visual distance at both farms.

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Other VOCs. Acetonitrile, propanol, butanol, hexane, and propene were detected in 40%

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of the samples collected at Farm 1 (4 experiments), but in less than 5% of the samples from Farm

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2; thus, the following discussion is for Farm 1 only. For these five VOCs, the ground-level (2-m

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height) VOC concentrations in front of the ventilation fan were significantly lower (t-test, p
0.1),

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therefore, all the experiments were used for the following calculations.

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The ozone formation potential (OFP) of a VOC is a function of its concentration and its

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maximum incremental reactivity (MIR). MIR, which is used by California Air Resources Board

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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

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of reactive organic gases. The MIR coefficient is in units of grams O3 per gram VOC27-29 (Eqn.

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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

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well as their respective ozone formation potential (OFP) values and MIR coefficients using the

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daytime ground-level (2-m height) VOC concentrations from both farms. The largest potential

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contributor to ozone formation is methanol followed by ethanol and acetone. Direct comparison

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of the Prop-Equiv and OFP values between the two farms is not appropriate, since data were

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collected under different environmental conditions, and Prop-Equiv and OFP values are

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calculated using actual not relative concentrations. However, comparison of the changes in the

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Prop-Equiv and the OFP values is valid. The changes in the Prop-Equiv and the OFP values for

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methanol at each farm as a function of distance (2 m and 20 m) are significantly different (t-test,

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p < 0.05). For methanol, the OFP values decreased 69% ± 13% at Farm 1 and 34% ± 39% at

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Farm 2. These calculations suggest that using VEBs will reduce VOC concentrations, and

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furthermore, if VOCs are the limiting factor in ozone formation in this region, VEBs will reduce

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the potential for ozone formation. Finally, the increases in OFP for ethanol and acetone as a

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function of increasing distance from the source at Farm 1 again indicate that additional sources

310

for these compounds exist.

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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

319

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

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staff, students, growers, and volunteers. Funding for this project was provided by USDA-NRCS

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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

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measured in all experiments.

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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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from https://www.epa.gov/chesapeake-bay-tmdl/air-pollution-chesapeake-bay-watershed

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2. Iriti, M.; Maro, A. D.; Bernasconi, S.; Burlini, N.; Simonetti, P.; Picchi, V.; Panigada, C.;

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Gerosa, G.; Parente, A.; Franco Faoro F.; Nutritional Traits of Bean (Phaseolus vulgaris)

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8. Carter, W. Development of ozone reactivity scales for volatile organic compounds. J. Air Waste Manage. Assoc. 1994, 44, 881–899. 9. US EPA. (2015). 2015 Ozone Standards. Retrieved April 9, 2018 from https://ozoneairqualitystandards.epa.gov/OAR_OAQPS/OzoneSliderApp/index.html#

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10. Howard, C. J.; Kumar, A.; Mitloehner, F.; Stackhouse, K.; Green, P. G.; Flocchini, R. G.;

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11. USDA National Agricultural Statistics Service. (2017). United States Department of

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14. Trabue, S.; Scoggin, K.; Li, H.; Burns, R.; Xin, H.; Hatfield, J. Speciation of volatile organic compounds from poultry production. Atmos. Environ. 2010, 44, 3538–3546.

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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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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

429

http://www.cert.ucr.edu/~carter/SAPRC/MIR10.pdf

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Journal of Agricultural and Food Chemistry

FIGURE CAPTIONS

431 432

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

453 454

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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Journal of Agricultural and Food Chemistry

459

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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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Journal of Agricultural and Food Chemistry

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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