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AMMONIA EMISSIONS AND DRY DEPOSITION FROM BROILER BARNS IN THE
Abstract Ammonia emissions from commercial broiler operations have been noted as one of the potential contributors to the nitrate contamination of the Abbotsford-Sumas aquifer in southwestern British Columbia (BC). The localized dry deposition of this emitted ammonia was of special interest and had not been measured in any comparable climate. Three barns, on two farms, located on the aquifer were assessed from July 2011 to June 2012. Ventilation, emission, and deposition samples were taken weekly throughout the seasons to accurately characterize the impact on the local environment. Ventilation was measured using a Fan Assessment Numeration System and timers that recorded individual fan activity. Acid impinger traps were used to measure the ammonia emitted by the sidewall fans. A methodology for measuring dry deposition by exposing air-dried soil was modified to use small Petri dishes and a 24-hr exposure time. The modified dry deposition method was found to be robust and effective for the requirements of this study. Dishes of soil were placed 2.1 and 3.6 m in front of and between each fan, as well as around the barns and farm properties. Ventilation rates for the barns were significantly and positively correlated with bird age and exterior temperature. Ammonia emissions were correlated with bird age and the emission factors for the three barns ranged from 0.19-0.37 g NH3 bird-1 day-1with annual ammonia emissions for each barn reaching 600 to 815 kg NH3. Dry deposition levels on the two farms exceeded 50 kg NH3 annually although this accounted for less than 10% of the ammonia emitted. The deposition levels were highest near the barns and were concentrated directly under the sidewall fan hoods. These levels of ammonia show significant potential to cause nitrate to leach into the groundwater and further contaminate the aquifer but future work and upscaling of data collection are needed.
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Preface This research project was designed by the author. The field work, sampling, and lab analysis was completed by the author with some assistance from members of the Agriculture and Agri-Food Canada Agassiz Station Forage Lab when multiple people were required. The analysis of the research data was undertaken by the author.
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Table of Contents
Abstract .............................................................................................................................. ii Preface ............................................................................................................................... iii Table of Contents ............................................................................................................. iv
List of Tables ..................................................................................................................... vi List of Figures .................................................................................................................. vii Acknowledgements ........................................................................................................... x
1 INTRODUCTION AND LITERATURE REVIEW ............................................................... 1
1.2 Chemical Processes Involved in the Nitrogen Cycle ........................................... 1 1.2.1 Ammonia Production ........................................................................................ 2
1.2.4 Nitrification of Ammonia .................................................................................. 6
1.3 Industrial Broiler Production ............................................................................... 7 1.3.1 Barn Design and Management .......................................................................... 7
1.4 Geographical Context .......................................................................................... 17 1.4.1 Agricultural Practices in the Lower Fraser Valley .......................................... 17
1.4.2 Air Quality in the Lower Fraser Valley ........................................................... 18
1.4.3 Water Quality in the Abbotsford-Sumas Aquifer ............................................ 19
1.5 Study Objectives ................................................................................................... 20
2 ASSESSMENT OF MODIFIED METHODOLOGY FOR MEASURING DRY AMMONIA
DEPOSITION USING SOIL AS AN AMMONIA SORPTION MEDIUM ......................................... 21
4 GENERAL CONCLUSIONS ......................................................................................... 85
4.2 Conclusions and Recommendations ................................................................... 85 4.2.1 Future Research ............................................................................................... 86
4.2 Evaluation of Study Methods and Recommendations for Future Modifications ............................................................................................................... 87
APPENDIX I: Historic and study period weather data for Abbotsford, BC. ........... 97
APPENDIX II: Description of treatments and samples sizes for each of the methodology trials. .......................................................................................................... 98
APPENDIX III: Fan Assessment Numeration System (FANS) .................................. 99
APPENDIX IV: Gas Impinger Acid Trap System and sidewall fan hoods. ............. 101
APPENDIX VI: Average flow rate for sidewall fans at each ventilation stage. ...... 104
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List of Tables
Table 2.1 NH4-N deposition (μg cm-2) in sample size and rain cover trials .................................32
Table 2. 2 ANOVA table for the soil moisture and soil texture trials ...........................................32
Table 3.1 Summary of multiple linear regressions ........................................................................79
Table 3.2 Summary of emission factors and literature values ......................................................80
Table 3.3 Average flow rate for each fan across all stages ...........................................................81
Table 3.4 Average flow rate for each fan for each ventilation stage and total flow rate for each stage at the Farm No.1 in Chilliwack, BC. ............................................................................82
Table 3.5 Average flow rate for each fan for each ventilation stage and total flow rate for each stage at the Farm No.2 in Aldergrove, BC.............................................................................83
Table 3.6 Total emitted ammonia for each flock for each barn at Farm No.1 in Chilliwack, BC and for Farm No.2 in Aldergrove, BC. ....................................................................................84
Table 3.7 Total deposited ammonia for each flock for each barn at Farm No.1 in Chilliwack, BC and for Farm No.2 in Aldergrove, BC. ................................................................84
Table A.1 Description of treatments and samples sizes for each of the methodology trials. .........98
Table A.2 Average flow rate of fans at each stage for Farm No. 1 .............................................104
Table A.3 Average flow rate of fans at each stage for Farm No. 2 .............................................105
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List of Figures
Figure 2.1 Increase in dry deposited NH4-N over exposure times ranging from 1 to 144 hours. Soil samples were located 1.5 m from poultry barn ventilation fan ...................................33
Figure 3.1 Map of lower Fraser Valley of British Columbia and locations of Farm No.1 in Chilliwack, BC and Farm No. 2 in Aldergrove, BC. .....................................................................59
Figure 3.2 Map of Farm No.1 located in Chilliwack, BC showing locations of dry deposition sampling sites and gas impinger traps ..........................................................................60
Figure 3.3 Map of Farm No.2 in Aldergrove, BC showing locations of dry deposition sampling sites and gas impinger traps ...........................................................................................61
Figure 3.4 An isoconcentration plot of the average high density ammonia deposition samples obtained at Farm No. 1 located in Chilliwack, BC. .........................................................62
Figure 3.5 Changes at Farm No.1 during the four stages of ventilation and at farm No.2 during the seven stages of ventilation in (a) air pressure deficit within the barns and (b) sum total ventilation flow rates ......................................................................................................63
Figure 3.6 Percentage of time that (a) any fans were active in the barns of Farm No.1 and No.2 during sample times and (b) that ventilation stages 3 or higher were active. .......................64
Figure 3.7 Ammonia in ventilated air within the barns on Farm No. 1. Determined during the summer and winter periods. .....................................................................................................65
Figure 3.8 Barn ventilation rates for each flock and weather station air temperature during the year-long period of measurement.............................................................................................66
Figure 3.9 Barn exhaust NH3 concentration for each flock and weather station air temperature during the year-long period of measurement. ............................................................66
Figure 3.10 Barn NH3 emissions for each flock and weather station air temperature during the year-long period of measurement. ................................................................................67
Figure 3.11 Emission factors for each flock and weather station air temperature during the year-long period of measurement.............................................................................................67
Figure 3.12 Total Farm NH3 deposition for each flock and weather station air temperature during the year-long period of measurement. ................................................................................68
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Figure 3.13 Flock A-105 from Farm No.1’s (a) ammonia emission curve in actual units, (b) after being normalized, (c) plotted alongside normalized growth curve (weight vs age), (d) with the estimated harvest date emission using the growth curve’s slope, and (e) the ammonia emission curve converted back into actual units along with the new final point. ..........70
Figure 3.14 High density deposition samples from 1 m to 3.6 m away from the side of the barn at Farm No.1 at positions (a) in front of a 36” fan, (b) halfway between a 36” and a 24” fan (5 m apart), (c) in front of a 24” fan, and (d) halfway between two widely spaced 24” fans (10 m apart) .....................................................................................................................72
Figure 3.15 Average high density ammonia deposition sample points along the corridor (parallel to barn) at 2.1 m and 3.6 m from the barn and fans at Farm No.1. .................................73
Figure 3.16 Comparison of the non-MLR calculated and the MLR NH3 deposited in the corridor between the barns at Farm No.1 for flock A110. .............................................................73
Figure 3.17 Comparison of the non-MLR calculated and the MLR NH3 deposited in the corridor between the barns at Farm No.2 for flock A111. .............................................................74
Figure 3.18 Deposition of ammonia at 2.1 m from each barn and 3.6 m, between the barns, at Farm No.1 averaged for all sample dates with birds over 20 days old. ..........................74
Figure 3.19 Isoconcentration of ammonia deposition on the entire Farm No.1 for flocks (a) A105 (36 days old), (b) A106 (29 days old), (c) A107 (32 days old), (d) A108 (22 days old), (e) A109 (34 days old), and (f) A110 (34 days old). .............................................................75
Figure 3.20 Isoconcentration of ammonia deposition for the field in front of Farm No.2 for flocks (a) A109 (24 days old), (b) A110 (35 days old), and (c) A111 (32 days old). ...............76
Figure 3.21 Deposition of ammonia at 2.1 m and 3.6 m from the fans in line with the barn at Farm No.2 averaged for all sample dates with birds over 20 days old. .....................................77
Figure 3.22 Deposition of ammonia in line with active hooded fans at Farm No.2 averaged for all sample dates with birds over 20 days old. ...........................................................77
Figure 3.23 Isoconcentration of ammonia re-deposition on the entire Farm No.1 between flocks A105 and A106 ....................................................................................................................78
Figure 3.24 Isoconcentration of ammonia re-deposition for the field in front of Farm No.2 after flock A111 ..............................................................................................................................78
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Figure A.1 Comparison of historic monthly data (1981-2010) in comparison with the July 2011 to June 2012 for (a) total precipitation and (b) average temperature for Abbotsford, BC, Canada (Environment Canada 2015). .....................................................................................97
Figure A.2 Fan Assessment Numeration System (FANS) measurements of a 24” ventilation fan at Farm No.2 located in Aldergrove, BC ...............................................................99
Figure A.3 Contour plot of air flow (m s-1) through the FANS while measuring a 36” ventilation fan ..............................................................................................................................100
Figure A.4 Gas Impinger Acid Trap System (with four separate sample streams) outside the barn at Farm No.2 located in Aldergrove, BC .......................................................................101
Figure A.5 Air filters used for the gas impinger traps. Shown is the ambient sampling point. ............................................................................................................................................101
Figure A.6 Dust clogged air filter beneath a fan hood. ................................................................102
Figure A.7 Corridor at Farm No.1 with hooded 24” (0.61 m) sidewall fans and non-hooded 36” (0.91 m) fans.............................................................................................................102
Figure A.8 Rain cover for soil filled Petri dish dry deposition sample on (a) grass and (b) dusty soil beneath a fan hood. ......................................................................................................103
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Acknowledgements
I am eternally grateful to my supervisors Dr. Maja Krzic and Dr. Shabtai Bittman,
without whose guidance I would never have come this far. I also want to thank my
committee members Dr. Andy Black and Dr. Andreas Christen, who provided me with
such helpful advice and encouragement, often exceeding their obligations. The endless
reassurance and editing advice of Dr. Les Lavkulich, statistical aid of Dr. Tony Kozak,
and the technical expertise provided by Zoran Nesic were all critical to my success. A
special thanks to my fellow LFS Soils and “Pro-Soils” Forestry grad students who helped
me through endless classes and assignments. The wonderful soils professors were
contagious with their passion and love for the study of soils.
This research would not have been possible without the wonderful people at the
pH, (6) soil texture, and (7) addition of a rain cover. These modifications were selected as
they reflect various soil conditions found in the study area of the Fraser Valley in BC. The
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exposed surface area of all the samples was kept constant as the same sized Petri dishes
were used.
2.3.1 Sample Mass
Different masses of soil, placed in the same sized Petri dishes, were exposed to
ammonia to determine if there is a significant effect on dry deposition. As mentioned
above, existing methodologies have used soil masses of 5 g and 20 g (McGinn et al. 2003;
Hao et al. 2005). The masses of the exposed samples were 8.0, 12.0, and 16.0 g, which
ranged from approximately 4 mm of soil depth to 8 mm, or 1/3 to 2/3 the capacity of the
small Petri dish. The samples were all placed at a location 20 m away from the barn and
at another location 1.5 m from an active fan for 6 hours. Unexposed samples (double
bagged and left onsite) were used as a control and the average ammonia content of the
controls were subtracted from the exposed samples in order to calculate the net increase
in ammonia (i.e., the true value of deposition).
The mean ammonia depositions on the soil samples of different masses were not
found to be significantly different (Table 2.1). This suggests that an 8.0-g soil sample,
which provided full coverage of the entire surface of the Petri dish had the same reactive
surface as the other samples.
2.3.2 Sample Volume Measurement
Instead of weighing each sample, which is very time consuming, the possibility of
using a volume measurement for preparing soil samples for ammonia dry deposition was
investigated. A short plastic test tube (7 ml) was used to scoop up soil, the soil was then
given a light tap to eliminate any air spaces, soil was then added to overfill the test tube,
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and the soil was leveled off to the top edge.
The resultant soil mass was 7.83 g with a standard deviation of 0.22 g (n = 66).
This variability was smaller than that of the return masses of the rain cover trial samples:
12.39 g 1.86 g (n = 64), all of which started out at 12.0 0.01 g. The dust and moisture
(humidity or precipitation) additions and soil lost as a result of the high air speed created
by the barn ventilation system appeared to cause a greater sample error than the volume
measurements. Lower variability in mass accompanied with shorter sample preparation
time favor the volume measurement method for the soil sample.
2.3.3 Exposure Duration
The potential saturation of the soil sample with ammonia was measured over
various exposure times ranging from 1 to 144 hours (Table A.1). The existing
methodology was exposed for 1-2 weeks downwind from a beer feedlot (McGinn et al.
2003; Hao et al. 2005), but the ammonia outside a poultry barn are much more variable
and so shorter exposure times are required. The length of sample exposure was strongly
correlated with the deposition of ammonia (r2 = 0.98) and was approaching saturation in
the samples with the highest exposure duration (Fig. 2.1).
2.3.4 Soil Water Content
The existing methodology used air dried soil (X. Hao et al. 2005), as in this study,
but water content is an important issue due to the high levels of precipitation at the study
site. Knowing the effect of water content on the samples would possibly allow wet
samples to be used as viable data. Three different volumes of DI water (2, 4 and, 6 ml)
were added to Petri dishes containing 12 g of air dried soil and then laid out in front of an
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active fan for 1.5 hours (Table A.1). This short exposure did not reveal any trends of
increasing deposition with increasing water content. Only the 4 ml treatment was
significantly different from the 2 and 6 ml (Table A.1). When dry samples were compared
with all of the wet samples, no significant difference was found (Table 2.2).
The greatest complication with moist samples was the risk of under-sampling
when weighing out 5 g of damp soil to be extracted and compared with 5 g of the dry
samples. In addition, the added water serves to slightly dilute the extracted ammonia. If
there was enough water to puddle in the dishes, there may be a considerable measurement
error. In light of this, heavily wetted soils should not be analyzed, which emphasizes the
requirement for rain protection. Additionally, subsampling 5 g from the total 12 g appears
to be an overcomplicated lab process and source of sampling error. Extracting the entire
sample would remedy this by allowing analysis of the entire surface of the exposed soil.
2.3.5 Soil pH
The effect of a change in soil sample pH was also of interest as acidic surfaces are
often highly susceptible to ammonia dry deposition and the transformation of ammonia to
ammonium causes a lowering of pH (Van Herk 1999; Wesely and Hicks 2000). All soil
samples received 0 ml, 0.5 ml, 1 ml, or 4 ml of 0.05 M H3PO4 and enough DI water to
make a total of 4 ml (Table A.1). These additions represented an approximate decrease in
the soil pH of 0, 0.2, 0.3, and 1.0, respectively. Only the addition of 4 ml 0.05 M H3PO4
had significantly higher deposition from the control treatment with only 4 ml of DI water
addition (Table A.1).
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2.3.6 Soil Texture
The impact of soil texture on ammonia dry deposition rate was examined by
mixing in various proportions of clean sharp sand with the silt loam soil. The existing
methodology used soil similar to that found on the study site (X. Hao et al. 2005). Since
the soils in the study area range from silt loam into gravelly silt loam, additions of sand
were made to approximate and extend this range of textures. The percentages of the
sample that was sand in this trial were: 0%, 25%, 50%, 75%, and 100%, even though the
range that would be found in the field is between 0% and 50% (Kelley and Spilsbury
1939).
The ammonia deposition levels significantly decreased (P <0.0001) as sand
content in soil samples increased above 50% (Table 2.2) as would be expected since the
reactive surface of the soil is inversely related to sand content. There were no significant
differences in ammonia deposition among 0%, 25%, and 50% of sand (Table A.2),
implying that variability in soil texture found the study area does not affect the dry
deposition of ammonia.
2.3.7 Rain Cover
The effect of the proposed 18 cm rain covers on ammonia deposition was tested at
1.5, 3.0, and 20 m (ambient) distances from an active fan. No detailed information on the
rain covers of the existing methodology was available so small rain covers were a new
variable to test. The presence of the rain cover relative to no cover did not result in a
significantly different dry deposition of ammonia (P = 0.498) (Table 2.1). Any water
content that the soil samples gained during exposure to the humid fan exhaust has been
discussed above and removed as a possible source of variation.
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2.3.8 Proposed Sampling Protocol
In light of these findings, a modified sampling protocol is proposed. In regards to
the soil sample size and the potential error of subsampling 5.0 g from the 12.0 g exposure
samples, it is proposed that an ~8 g sample is used and that the entire sample is extracted.
This relatively small increase from 5.0 g to ~8 g in the soil sample used for the extraction,
is still large enough to effectively cover the entire surface area of the Petri dish, where 5.0
g would be insufficient.
Rather than weighing each sample, which is tedious and time consuming, an
approximate sample mass is to be made by using a simple and quick volume
measurement. The 24-hour soil sample exposure time appears to fall well below the
ammonia saturation level and will also remove potential diurnal variations in the
ammonia deposition rates. The emission rates of poultry barns change rapidly as the birds
age; hence, the improved time resolution of a 24-hour exposure should provide a greater
level of detail over the existing week-long exposure. The lack of effect of low levels of
water content on the deposition of ammonia is reassuring, but rain covers will be
employed to avoid excessive wetting and subsequent dilution effects that could
complicate the extraction procedure. The silt loam soil also is to be used without textural
modification since sand additions did not result in any difference in ammonia dry
deposition. This may not be the case for all soils and should be reexamined if this
methodology was to be used again.
2.4 Conclusions
As part of an investigation of the dry deposition of ammonia resulting from
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poultry barn ventilations systems, a methodology using soil as a sorption medium was
modified and tested. Varying the amount of soil exposed in a standardized container did
not significantly impact the dry deposition of ammonia. Surface area was deemed to be
the important factor, but not the mass of the soil, which implies that depth of soil was not
important. The standard deviation of soil sample mass was compared between the return
mass of 12.0 g of exposed soil and a 7 ml volume measure of soil and the volume
measure appears to be sufficiently accurate. This method worked well for this specific
soil, but should be reassessed if a different texture was used. The dry deposition of
ammonia on soil samples was monitored over 144 hours to determine whether the
proposed exposure time of 24 hours would suffer from any saturation effects, potentially
underestimating the deposition of ammonia. The large capacity for ammonia deposition
in the soil samples was sufficient to quell any concerns with the proposed 24-hour
exposure. Three different volumes of DI water were added to soil samples prior to
ammonia exposure and no significant differences in deposition were observed. Additions
of acid were also investigated to evaluate the effect of differing soil pH on ammonia
deposition. Only the treatment with a decrease of 1.0 in pH had a significantly greater
ammonia deposition relative to the control, but this pH was well beyond what is expected
under the field conditions in this region. Various mixtures of the sample soil and sand
were exposed to ammonia and the deposition levels significantly decreased as sand
content in soil samples increased especially in 75 and 100% sand samples. That range of
sand content, however, is not typically found in the study area and so the dry deposition
sample texture does not need to be modified to better represent the soil in-situ. Even
though the water content trial did not show significant issues with low levels of water
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content in the soil samples, very wet samples are still of a great concern in this region
with high fall and winter precipitation. Consequently, use of rain covers was investigated
at various distances from an ammonia source but was shown not to have any significant
effect on dry ammonia deposition.
These findings support the modification of the sample volume, exposure duration,
soil texture, and rain cover of the existing methodology for use in determining ammonia
dry deposition from poultry barn ventilation systems. These modifications will enhance
the ease of this method allowing for a greater number of samples to be processed in a
relatively short time. In turn, sampling of ammonia deposition on the entire farm could be
undertaken allowing a larger scale assessment of this complex process.
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Table 2.1 NH4-N deposition (μg cm-2) in sample mass and rain cover trials Trial Treatment N Ammonia
deposition (μg cm-2)
Sample Mass
8 g 8 151.4a*
12 g 8 144.8a 16 g 8 174.2a
5% LSD 57.3 Rain Cover Cover 24 266.3a
No Cover 24 228.5a 5% LSD 95.1 * Means followed by the same letter are not significantly different within the same trial (P > 0.05). Table 2.2 ANOVA table for the soil water content and soil texture trials
Trial Source of Variation df Sum of Squares
Mean Square
F-Value Pr > F*
oil Water Content
Model 1 6.17 6.17 1.40 0.2539 Error 16 70.44 4.40 Corrected Total 17 76.60 Soil Texture Model 4 7276.90 1819.23 17.86 <.0001 Error 15 1527.68 101.85
Corrected Total 19 8804.58 Soil Texture** Model 2 362.22 181.11 1.12 0.3681 Error 9 1456.49 161.83 Corrected Total 11 1818.71 * Trials with Pr > 0.05 do not have significant differences between the treatments. ** Limited to 0-50% sand content
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Figure 2.1 Increase in dry deposited NH4-N over exposure times ranging from 1 to 144 hours. Soil samples were located 1.5 m from poultry barn ventilation fan. Error bars represent standard deviation (n = 5). Equation: y = 315.53 + 129.49x – 0.3947x2 (r2 = 0.9988)
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3 ANNUAL AMMONIA EMISSION AND DEPOSITION LEVELS FOR TWO
BROILER FARM VENTILATION SYSTEMS IN THE LOWER FRASER VALLEY OF
BRITISH COLUMBIA
3.1 Introduction
Ammonia emissions from agriculture are a significant contributing factor to air
pollution and imbalances in the global nitrogen cycle. Confined livestock operations such
as poultry barns are important sources of ammonia emissions especially if they are
concentrated spatially, due to the need for access to market, feed and labour (X. Hao et al.
2005). Local nitrogen deposition in areas with a high concentration of confined livestock
operations may contribute to overloading of nitrogen in soils and waterways by
exceeding the area’s loading capacity (Harper et al. 2010).
The Lower Fraser Valley in British Columbia (BC) is an example of an
agricultural area with a large number of confined poultry operations. These are
concentrated in a few areas within the valley, reaching almost 40 barns over a 16 km2
area, with the largest concentration in the municipality of Abbotsford (Bittman, S.
personal communication). Though poultry production, in particular broiler chickens (bred
and raised specifically for meat production), is one of the largest agricultural industries in
the area the extent of its impact on the nitrogen cycle is still poorly understood. The need
for a better understanding of nitrogen fluxes stems from the concern about nitrate
contamination of the shallow surficial Abbotsford-Sumas aquifer, which is located in the
Abbotsford, Sumas, and Lynden areas of BC and Washington State (Almasri and
Kaluarachchi 2004). Intensive dairy and berry farming operations have been investigated
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as potential causes of the aquifer pollution, but broiler barns have not been assessed for
their potential emission of ammonia and subsequent deposition (Almasri and
Kaluarachchi 2004; Zebarth et al. 1998). The Abbotsford-Sumas aquifer has had a
historic problem with nitrate contamination that frequently surpasses the 10 mg N L-1
Canadian water quality health standard (Mitchell et al. 2003). The aquifer supplies
drinking water to 100,000 people in BC, and the water quality is worse in Washington
state where nearly 10,000 people rely on the aquifer for potable water (Chesnaux et al.
2007).
Broiler bird production is a highly regimented process and the management
scenario of the birds is unique to each area. In the lower Fraser Valley the birds are placed
in a freshly cleaned barn with sawdust litter that is replaced between each flock. The
birds are grown indoors for 35-39 days, removed for processing, and the next flock is
placed into the barn one month later. In contrast, some barns in the U.S. are empty for
only 10 days before a new flock is placed in them (Harper et al. 2010). The length of the
growth cycle can also vary substantially with U.S. barns often aiming for a market age of
approximately 50 days (Table 3.2). This range in management scenarios of bird
production cycles requires that local studies be performed to assess the local ammonia
emissions, deposition and their impact.
The deposition of ammonia emitted from broiler barns follows two pathways: wet
deposition and dry deposition. The majority of deposition occurs via wet deposition;
when ammonia or ammonia salts are scavenged from the atmosphere by water particles
in clouds, fog, or rain (Belzer et al. 1997; Fowler et al. 1998; Hao et al. 2006) and
eventually, this ammonia is brought to the ground by rainfall. The location of this wet
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deposition is typically within the weather system of the emission source and thus the
exact source is difficult to determine (Loubet et al. 2009). In this study the weather
system of concern is limited to the Lower Fraser Valley (Fig. 3.1) (Belzer et al. 1997).
Dry deposition can occur due to the simple adsorption of molecular ammonia to
an inert surface as dictated by Fick’s law, but more often can involve the complex
surfaces of soil and plant tissues such as leaves that have complex laminar boundary
layers (Loubet et al. 2009). High air speed and turbulence can increase dry deposition of
ammonia due to amplified impaction velocities (Theobald et al. 2001). Ammonia
deposited on leaves is typically transported to the soil by rain. The ammonia can also be
re-released from the soil into the air. The level of dry deposition, as compared to the total
emission of ammonia is quite low, often less than 5% within 1 km of the source (Xi. Hao
et al. 2006; Loubet et al. 2009). The impact of high concentrations of poultry operations
within a small area and the dry deposition that occurs nearby is not well understood,
especially in the Fraser Valley of BC.
The objectives of this study were to (a) evaluate ammonia emissions of three
broiler barns (two barns were located on the same farm, while the third barn was on a
different farm) typical for the Fraser Valley poultry industry during a period of one year,
(b) calculate ammonia emission factors for each barn, and (c) determine the dry
deposition of emitted ammonia over the entire area of each farm during a period of one
year.
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3.2 Materials and Methods
3.2.1 Study Sites
This study was carried out from July 2011 to June 2012 on two broiler farms
located in the lower Fraser Valley of BC (Fig. 3.1). The area is characterized by a humid
maritime climate with wet winters and short dry summers. The monthly precipitation
during the fall of 2011 was slightly below the historical averages, though the spring of
2012 was slightly above (Fig. A.1a). Total precipitation during the study period was
1,379 mm, which was somewhat lower than the 1981-2010 average (1,538 mm)
(Environment Canada 2015). The average monthly temperatures during the study were
very close to the historic (1981-2010) averages (Fig. A.1b).
Broiler Farm No.1 was located in Chilliwack, BC (4916’N 12191’W). This farm
has two parallel barns with ventilation fans that exhaust into the corridor between the
barns (Fig. 3.2). The stocking rate of the west and east barns are 11,000 and 12,000 birds,
respectively. Prior to the construction of the barns, this low lying parcel of land had been
raised with the addition of a large amount of gravel to provide quick drainage. There is,
as a result, very little topsoil in the area around the barns.
Broiler Farm No.2 was located in Aldergrove, BC (4903’N 12252’W) and has
three barns, with the northern most barn exhausting into a small grass field, away from
the other barns (Fig. 3.1 and 3.3). Only the north barn at Farm No.2 was included in this
study and had a stocking rate of 18,000 birds. The soil in the field adjacent to the farm
ranged in texture from silt loam to sand, was formed on gravelly glacial outwash and is
classified as Orthic Humo-Ferric Podzol.
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The barns of Farm No. 1 and 2 had numerous 24”-52” (0.61-1.32 m) diameter (so-
called sidewall) fans mounted on one side of each barn (Fig. 3.2 and 3.3). All of the fans
had shutters to prevent passive air flow through them and the smaller fans also had hoods
that directed the airflow downwards (Fig. A.6). The fan activity of each barn was
controlled by an automated system that monitored indoor air temperature and relative
humidity and turned sets of fans on or off until the ideal temperature for bird growth and
comfort was achieved (Turnbull and Huffman 1987). The barns were kept at a lower
indoor pressure allowing the incoming air to enter the barn with a rapid turbulent flow,
which led to better mixing. This meant that the thermal shock of cool incoming air was
not felt by the delicate young poultry (Vest and Tyson 1991). Indoor barn temperature has
a large impact on the mortality rates of birds in the first week of growth cycles and can
impact body weight after the third week (May and Lott 2000). Incoming air is controlled
by a louver that runs the length of the barn on the opposite side from the fans. Farm No.1
had a manually adjusted louver that had the same opening for each of the ventilation
stages. Farm No.2 had a static pressure control machine that adjusted the louver opening
for each of the ventilation stages, allowing for constant indoor to outdoor pressure
differential. The fans were activated in a series of ventilation stages and each stage
included a set of 2-4 fans, depending on the size of the fans and their location on the barn.
During this study there were four ventilation stages at Farm No.1 and seven at Farm No.2.
Ambient air temperature, precipitation and wind speed measurements were
obtained at a weather station located in Abbotsford, BC about 28 km and 21 km from the
Farm No.1 and No.2, respectively. Average daily environmental values were calculated
using the day the sampling started and the day the sampling ended.
39
3.2.2 Sampling and Laboratory Analyses
At Farm No.1, both emission and deposition measurements were taken from July
2011 to May 2012, covering six bird production cycles. At Farm No.2, emission and
deposition measurements were taken from February 2012 to June 2012, covering three
bird production cycles. Emission and deposition measurements were made
simultaneously for a 24-hour period each week when the barns were occupied and at least
once when the barns were empty.
Ventilation rates of the barn fans were measured using a Fan Assessment
Numeration System (FANS) (Richard et al. 2004). The FANS consisted of a frame with
five propeller anemometers that transverse the area of the fan, while also measuring the
air pressure difference between the inside and outside of the barn (Fig. A.2). The FANS
software determined the flow rate of each fan using approximately 1,400 sample points
generated by each anemometer (Fig. A.3). Two measurements were taken for each fan
and averaged for each stage of ventilation. In July 2010, all nine of the fans on the west
barn and the ten functioning fans on the east barn were measured at Farm No.1 (Table
3.3). In August 2010, seven of the eleven fans were measured at Farm No.2 (Table 3.4).
Due to the size of the FANS frame and the internal framing of the barn at Farm No.2, the
flow rates of fans 8 and 10 could not be measured. An assumption was made that the
average flow rates of the other fans of the same size (fans 2 and 4) at the same ventilation
stage could be used to estimate fans 8 and 10 (Table 3.5).
The active times of each fan at Farm No.1 were measured using LH2H Panasonic
Hour Meter timers that counted the duration of time that the fan was in operation during
the sampling period. The active times of each fan at Farm No.2 were monitored using
40
CR9321-PNP current switches feeding to a CR1000 Campbell Scientific data logger that
recorded how many minutes each fan was active during a 24-hour period. This data was
stored on a CompactFlash card and downloaded after every bird production cycle.
Concentrations of ammonia emissions were measured using a gas impinger acid
trap system (Fig. A.4) (Ndegwa et al. 2005). Exhausted air from the ventilation fans was
sampled through an automotive air filter to remove particulates and bubbled through a
series of two cylinders with 0.01 M H3PO4 solution to ensure all ammonia was collected
(Fig. A.5). The air exited through a gas meter and a diaphragm pump. Emitted ammonia
measurements were taken for 24 hours and then the acid samples were collected, diluted
to 0.005 M, to correct for any evaporation during sampling, and refrigerated until they
could be analyzed for ammonia on a FIAstar 5000 Analyzer (FOSS, Hillerod, Denmark).
Dry deposition of ammonia was measured using 55-mm plastic Petri dishes filled
with air-dried soil as a sorption medium (McGinn et al. 2003). These collection dishes
were placed in front and between each fan at distance of 2.1 m and 3.6 m perpendicular
from the barn, as well as around the perimeter of the barns and the farm property (Fig.
3.2-3.3). The distances used allowed for sampling at the center of the corridor at Farm
No.1 and just beyond the most wind-blown ground in front of the fan hoods (Fig. A.7).
The same distances were used at Farm No.2 to give comparable data. Four high density
(HD) dry deposition samplings were also carried out at Farm No.1. The same 2.1 m and
3.6 m sampling distances were maintained, but the number of sampling points in a 26 m2
area increased from 8 to 54 (Fig. 3.4). Rain covers were installed 16 cm above collection
dishes used to avoid wet deposition and the confounding effects of wet samples during
analysis (Fig. A.8a, b). The collection dishes were sealed inside two plastic bags, each
41
sealed with twist ties, prior to and after exposure at the barn. After exposure the dishes
were kept in a refrigerator until extraction could be carried out to prevent any potential
transformation of nitrogen species. The collection dishes were extracted with 2 M KCl
and analyzed for NH4-N and NO3-N on a FIAstar 5000 Analyzer (FOSS, Hillerød,
Denmark).
3.2.3 Statistical Analysis
The statistical analysis of environmental, ventilation, emission, and deposition
data was done using a backward selection multiple linear regression (MLR) with an α
value of 0.05 (SAS Institute Inc., 2011). The high density (HD) deposition ratios were
constructed with the same MLR, but used transformations of distance from the barn and
down the corridor to create a series of limited spatial models.
3.2.4 Calculation of Ammonia Emissions
Ammonia emission values (E) were calculated using the barn ventilation rate (Q)
at each ventilation stage, the amount of time each stage was functioning, and ammonia
concentration sampled outside the fans and at the edge of the farm property. The barn
ventilation rate for each stage was calculated as follows:
1-11 Qstage1 = Σ Qfan n (3.1) n=1
where Q is in liters.
The ammonia in the barn exhaust emitted by the birds was calculated using the
following relationship. The concentration of ammonia collected by outside ([NH3]o) of
the intermittently running ventilation fan of the barn over one sample period (24 hrs) is
42
equal to the sum of the ambient ammonia concentration ([NH3]a) when the fan is off (toff)
and the exhausted ammonia concentration ([NH3]e) when the fan is on (ton). The outside
ammonia concentration was measured directly with the impinger acid trap by collecting
air outside a fan, while the ambient ammonia concentration was determined by collecting
air at the edge of the farms away from the barns. The mass of ammonia collected was
divided by the volume of air sampled by the impinger acid trap (μg NH3 L-1).
It was assumed that the concentration of ammonia leaving each of the fans
was the same throughout the 24-hour sampling period as high frequency sampling of the
concentration of ammonia leaving the fans and the fan activity was not feasible. This is
not absolutely accurate as diurnal variability in interior ammonia concentration can be
quite high, but since all sampling periods were 24 hours in duration, this approximation
allows for comparative values for every sampling period (Jacobson et al. 2011). The total
barn emissions of ammonia (g NH3 hr-1) were calculated using the exhausted ammonia
concentration and the total barn ventilation for all of the stages during the 24 hr sampling
period.
1-4 E = (Σ [NH3]e * Qstage n) / 24 hrs (3.3) n=1
3.2.5 Calculation of Ammonia Deposition
Dry deposition totals were calculated by transforming the net increase in ammonia
content for each collection soil dish into an “ammonia deposited over area” value. The
43
assumption of these collection dishes was that they were consistent sinks for ammonia
and were effective representations of the soil in situ (Fowler et al. 1998). Another
assumption was that all ammonia collected was from the barn ventilation and not re-
emitted from the immediate surrounding area (Grunhage et al. 1993). The areas external
to the corridor or beyond 3.6 m from the barns were estimated by using the deposition
value of each point as the center of its own block (Fig. 3.2). These blocks were summed
and added to the corridor total to determine the total deposition on the farm.
The corridor between the barns, or area nearer than 3.6 m from the barns, are
areas of high deposition with large spatial gradients. The HD sampling of deposition was
used to develop a series of Multiple Linear Regression (MLR) models for each standard
measurement point, located in front of and between each of the fans (2.1 m and 3.6 m
away) (Fig. 3.4); thus avoiding a gross underestimate or overestimate that using simple
blocks for each sampling point could result in. The 54 HD sample points were divided
into 8 unequal groups delineated by the thick grid lines as seen in Fig 3.4. These groups
were drawn so that 8 models could be constructed to modify the 8 standard sampling
points (Fig. 3.4).
Each group was made up of multiple small blocks and the total deposited
ammonia was calculated for each block using the average deposition of the 4 corners
applied to the area between them. The blocks in the group were summed to give a total
and it was this deposition value that the MLR model was applied to. Each group
deposition total had a model constructed using a backward selection regression of the
positional coordinates of the standard measurement point (i.e., the distance down the
corridor and away from the fan). The resulting model was used to estimate the total
44
deposition of the group area and this total was divided by the average of the standard
sampling point deposition value to form a coefficient. This resulting coefficient, when
multiplied with a standard sampling point produced an estimate of the deposition of the
entire area of the group (i.e., the ammonia deposited in Group B is estimated by
multiplying this coefficient by the standard sampling point B) (Fig. 3.4). If the ammonia
deposited in Group B was calculated by using it as the center of its own block the
extremely high deposition peak directly below the 24” fan could be missed and result in a
poor estimation. The 8 group coefficients were used to convert the corridor standard
sampling points for every deposition sample set, improving the estimate, while keeping
the sample size manageable.
3.2.6 Estimation of End of Cycle Ammonia Emission and Deposition
The measurement methods used only collected dry ammonia deposition; therefore,
sampling during rainy conditions was avoided. Due to frequent inclement weather and
the variable length of bird production cycles, the entirety of the cycle was rarely captured
in the sample set (i.e., though the last week of the bird cycles were sampled, the harvest
date was often missed). This resulted in measurements that did not span the entire growth
cycle, which was required for the best estimate of the total emission and deposition of
ammonia. Since broiler growth was very consistent, a bird growth curve was used to
estimate the emission and deposition from the last sampling date to the harvest date. The
measured values and the bird growth curve were normalized and then the final emission
(or deposition) value was estimated using the slope of the normalized growth curve
between the last sample age and the age of interest (Fig. 3.13a-d). The measured values
were transformed back into their original form, along with the estimated final value (Fig.
45
3.13e). This estimated value is subject to variability depending on the magnitude of the
last measured value, but since the emission and deposition curves both followed the
growth rate curve shape, an assumption was made that this uncertainty was acceptable in
order to achieve total flock estimation. Once final flock estimations were determined, an
emission factor (EF) was calculated by dividing the total flock emissions (E) by the
number of birds in the barn at the harvest date (B) and divided by the number of days in
that the cycle (D).
EF = E / B / D (3.4)
The resultant emission factor units were g NH3 bird-1 day-1. These emission
factors were combined for each barn and a standard deviation was calculated so that they
could be compared with literature values.
3.3 Results and Discussion
3.3.1 Barn Ventilation Rates
The individual fan ventilation data collected by the FANS were very consistent.
The average flow rates that were calculated for each fan at each stage (n = 2) had a
relative standard deviation of less than 1.3% at Farm No.1 (Table A.2) and 1.6% at Farm
No.2 (Table A.3). When examining the average flow rate of fans of a similar size,
regardless of stage, there was a relative standard deviation of less than 7.2% for Farm
No.1 and 5.3% for Farm No.2 (Table 3.3). This increase in standard deviation was likely
due to the decreasing performance of the fans as the ventilation stages increase, which
results in more fans turning on and struggling against the restricted turbulent inflow. The
west and east barns at Farm No.1 had an average decrease in performance from the
46
lowest active stage to the highest stage of 15±4% and 6±1%, respectively, which is
consistent with the west barn having an increasing pressure differential over the different
ventilation stages, as compared to the east barn (Fig. 3.5a) (Tables 3.4 and 3.5). Further
evidence that the east barn had a more effective ventilation system is that the total
ventilation was greater than in the west barn (Fig. 3.5b). The increasing air pressure
difference at Farm No.1 as the ventilation stages increased was quite different from Farm
No.2, where the air pressure difference remained unchanged across the ventilation stages
due to the static pressure control system that governed the louver opening (Fig. 3.5a). A
common value for required pressure difference allowing minimum adequate mixing of
incoming air is 25 N m-2 (Czarick and Fairchild 2013)(Turnbull and Huffman 1987). It is
apparent that Farm No.1 had difficulty in achieving this level at the lower ventilation
stages, which is common, but Farm No.2 easily exceeded this at all stages.
The accurate characterization of the ventilation rate and fan activity is very
important as it is used in the calculation of the emission data, which influences the
deposition data. A limited subset of fans was used for emissions measurements and had
any of these fans had unusual performance the barn emission estimates would be
inaccurate. The deposition measurements were collected in front of every fan and any
unusual data points may be explained with the fan activity data. There were occasions
when timer data and observations showed that individual fans were under repair and not
function, thereby had to be omitted from the whole barn ventilation and emission
estimates. Notification of this was passed onto the farmers so that repairs could be made.
At Farm No.1, fan 6 was not running for 3 of the 6 flocks and so the emission data from
that fan was not used and the total ventilation for the entire barn had to reflect the actual
47
number of fans functioning (Table 3.4). Of the 35 sampling dates at Farm No.1, there
were 3 instances that a random fan was found to be nonfunctional, but these occurrences
did not impact any emissions testing and total barn ventilation rate was, again, adjusted.
The timer data or fan activity were found to be positively related to bird age (r2 =
0.712) (Fig. 3.6a and Table 3.1). Along with increasing the amount of time that the
ventilation system was on, the time that a ventilation stage 3 or higher was running also
increased with bird age (Fig. 3.6b), which led to the much higher total ventilation rates
just prior to harvest date (Table 3.4-3.5).
The calculated ventilation rates of the barns at Farm No.1 were significantly
correlated (r2 = 0.825) with both exterior daily mean temperature and bird age (Table 3.1).
The summer bird production cycles showed a much larger increase in ventilation rate
than the winter cycles as the birds progressed through 5 weeks of growth (Fig. 3.7). A
comparison of the ventilation levels from each study site over the year showed a striking
trend with exterior daily mean temperature (Fig. 3.8). Farm No.2, had less data than Farm
No.1, but it unexpectedly showed a significant correlation (r2 = 0.925) between
ventilation rates and both exterior mean temperature and bird age (Table 3.1). Although
fan activity is directly controlled by interior temperature, the positive correlation between
ventilation rate and exterior temperature was expected because during the summer, the air
coming into the barn is much warmer than during rest of the year and less effective at
cooling. Bird age also had a substantial impact on interior barn temperature. The
metabolic rate of adult birds is much greater than that of chicks; hence, older birds
require significantly more ventilation to keep cool. In cool weather barn cooling is not
needed and ventilation is used to improve air quality in the barn by exhausting ammonia,
48
but this is minimized to save on heating costs.
3.3.2 Ammonia Emissions from the Barns
The ammonia collected by the gas impinger traps from different fans on the same
barn was not consistent, while the internal replicate impinger traps (paired on a same fan)
were much more reliable. The relative standard deviation of ammonia concentrations for
the fans with replicated impinger traps at Farm No.2 (fan 10) was only 5%, while Farm
No.1 (fan 7) was 6% (data not shown). When looking at all the gas impinger traps
sampling at Farm No.1, the relative standard deviation of ammonia concentration was
24% and 25%, for the west and east barns respectively, while Farm No.2’s was 35%. This
level of consistency is a complication with this methodology, though equipment issues
and environmental sensitivity were also a difficulty, such as dust clogged air filters (Fig.
3.15). A possible explanation of this large relative standard deviation is that when the
birds are small they do not spread out in the barns evenly, and often move around the
barn in large groups, which could give higher ammonia concentrations at apparently
random fans. When the birds are mature, however, there is less free space and they cannot
clump to the same extent. When only the week prior to harvest date is examined, the
relative standard deviation of the ammonia concentrations drops to 14%, 16%, and 26%
for Farm No.1 west barn, east barn, and Farm No.2, respectively. The previously
mentioned assumption that the ammonia leaving each fan would have the same
concentration appears more appropriate as the birds mature and the emissions become
more substantial.
Similar to ventilation rates, the concentration of emitted ammonia followed an
inverse trend with exterior mean temperature, with high concentrations of ammonia in the
49
winter when the temperature was the lowest (Fig. 3.9). The emission of ammonia from
the barns at Farm No.1 showed a significant correlation (r2 = 0.765) with bird age and
exterior temperature (Table 3.1 and Fig 3.10), while at Farm No.2 emission rate was only
correlated (r2 = 0.775) with bird age (Table 3.1). When emission rates for Farm No.1 were
correlated to bird age and exterior temperature individually the resultant P values were
<0.0001 and 0.534, respectively (Table 3.1). This suggests that emission rate, unlike the
ventilation rate, is less impacted by the exterior temperature. The increase of ammonia
emissions with bird age is expected as manure excretion increases substantially with bird
age (Amon et al. 1997). One possible reason that exterior temperature would affect the
emission level is that this is actually an effect of the relative humidity inside the barns,
which has been shown to be higher during the winter months due to the low ventilation
rate that decreases the drying of the litter (Harper et al. 2010). Larger amounts of
ammonia would then volatilize from the wet broiler manure as volatilization is highly
dependent on surface moisture of the source (Sommer et al. 1991).
3.3.3 Emission Factors
Calculating representative emission factors required the use of complete ammonia
emissions for the entire duration of the flock growth, from stocking date to harvest date.
This was only possible if the emissions at harvest date could be estimated as various
circumstances prevented measurements from being taken on all nine of those dates. The
relationship between bird age and ammonia emissions mentioned above made it plausible
to use a broiler growth curve to estimate emissions during periods where no emission
measurements were taken (Amon et al. 1997; Harper et al. 2010). Using this estimated
value, emission factors for the each of the entire growth cycles could be calculated (Fig.
50
3.10). The west and east barns of Farm No.1 had emission factors of 0.30±0.08 and
0.37±0.10 g NH3 bird-1 day-1, respectively, and Farm No.2 was lower at 0.19±0.06 g NH3
bird-1 day-1 (Table 3.2). Without using the estimated final value, the emission factors for
the west and east barns of Farm No.1 and for Farm No.2 were 86%, 82%, and 88%,
respectively, of the above value and caused two of the reported literature emission factors
to fall outside the range of those from this study’s (Table 3.2).
When comparing the study sites, only the emission factor of the east barn of Farm
No.1 was significantly different from Farm No.2 (Table 3.2). Though only three flocks at
Farm No.2 were sampled and they did not span the whole year, the emission factor
measured in Denmark fell within the standard deviation of Farm No.2’s emission factor
(Koerkamp et al. 1998). The standard deviation of the emission factors for Farm No.1
encompassed those in six other studies (Table 3.2). These literature values were mostly
from studies in Europe, but those that were carried out in the U.S. followed a fresh-litter
management scenario more similar to the European and Canadian poultry industry.
Typically in the U.S. the birds are kept longer (market age) and the litter in the barn is de-
caked between flocks and used for an entire year, occasionally top-dressed with fresh
litter (Wheeler et al. 2006). This results in higher emission factors than in Europe and
Canada where new litter is used for every flock (Table 3.2).
The emission factors were not significantly correlated with temperature,
precipitation, or time of year (Fig. 3.11), which agrees with data collected in California
(Harper et al. 2010). The only significant correlation (r2 = 0.324 ) was with stocking
density, which is interesting as the emission factors are scaled to a per bird unit and the
other reported emission factors do not appear to follow a distinct trend with respect to
51
stocking density (Table 3.1).
The usefulness of emission factors are two fold, first they are estimates of annual
ammonia production of a poultry barn, and second they are a commonly reported derived
value that describes how a specific environmental or management scenario determines
the atmospheric impact of a poultry barn. For management scenarios the impact of new
litter versus de-caked litter can be seen in emission factors, as mentioned previously, as
can different ventilation scenarios, market ages, feed regimes, etc. (Wheeler et al. 2006).
As to annual ammonia production, the emission factors can easily be multiplied by the
number of flocks in a year and by the average stocking rates used in a specific facility to
give an informative estimate. For all of the study sites used, the maximum number of
flocks in a year is 6 as usually a 20 day rest period is used between flocks to ensure a
thorough cleaning and sanitation of the barns. This gives an estimated annual ammonia
emission of 639 kg and 815 kg from the west and east barns at Farm No.1, respectively,
and 600 kg for Farm No.2. These values are for barns of different size and population,
which must be addressed for larger-scale estimates. Flock quotas are also typically
reported in units of 20,000 birds; hence, converting the average ammonia emissions per
cycle to this quota would give an annual production of 1,188 kg of NH3 per flock.
Considering the lower emission factors observed at the study sites, this value is
comparable to the annual broiler flock ammonia production of 3,786 kg in Kentucky
where the emission factor is 0.65 g NH3 b-1 d-1, more than twice that of this study (Gates
et al. 2008). Broilers are expected by the quota system in BC to be 2.0-2.2 kg live weight
and by using the 2014 BC Chicken Marketing Board report on Lower Mainland quota
holdings there were nearly 75,000,000 birds produced annually in BC (BC Chicken
52
Marketing Board 2014). The product of the average emission factor (EF) of all the barns,
the average days per cycle (d = 37), and the reported total broilers grown in BC results in
an estimate that 794,000 kg of ammonia is released annually from broiler barn ventilation
systems.
3.3.4 Dry Deposition of Ammonia
The HD deposition measurements made at Farm No.1 were highly informative of
the spatial distribution of ammonia deposition outside of the fan hoods (Fig. 3.4).
Directly in front of a highly active hooded 24” fan the deposition rates decrease rapidly
with distance from the fan (Fig. 3.14c). The samples that fall halfway between the 24”
and 36” fan and the 24” fan and the next 24” fan are much less drastic in slope and
magnitude, but there is still a decrease in deposition of ammonia from over 400 µg cm-2
at 1 m to almost 350 µg cm-2 at 2.1 m to less than 100 µg cm-2 at 3.6 m away from the
barn (Fig. 3.14b, c, d). The larger 36” fan is much less active and so the deposition levels
are relatively low (<150 μg cm-2), but as it does not have a hood it exhibits a slight
increase in deposition as the samples move further from the fan (Fig. 3.14a). These plots
also show the variability between three sample sets, which demonstrates the importance
of replication when measuring dry deposition of ammonia in such a harsh and active
environment. When moving down the corridor (parallel to the barn) the positions directly
in front of the active 24” fan (5 m along corridor distance) show a deposition level much
greater than those only 1.25 m away from the fan (3.75 m and 6.25 m along corridor),
though the standard deviation is quite large (Fig. 3.15). This sample data was very
informative in determining that using the 8 standard sampling points (the filled points at
2.1 m and 3.6 m from the barn) would not be sufficient as the representative deposition
53
value applied to the area centered on that sample point. For example, the 2.1 m and 3.6 m
samples in front of the 24” fan would underestimate the deposition for their respective
areas (0 m to 2.85 m and 2.85 m to 3.6 m from the fan) (Fig. 3.14c). This underestimation
can be seen in a larger scale when the total deposition in the corridor between the barns at
Farm No.1 was determined using the simple block method (non-MLR) and the using
MLR model coefficients , the latter of which had a 50% larger deposition estimate (Fig.
3.16).
The same MLR model system was also used for estimating the deposition out to
3.6 m from the barn at Farm No.2, but with some modifications. The different spacing of
fans resulted in slightly different groups of the HD samples being used to create the new
coefficients. The result of using the MLR models at Farm No.2 was a 25% lower
ammonia deposition total that the simple block method (Fig. 3.17). It is suspected that
this occurred because the larger block size (due to the wider fan spacing) would over
emphasize the high deposition levels found directly in front of the fans.
The highly localized large deposition levels of ammonia were also apparent when
examining the regular data sets for individual sampling dates. The locations of the active
fans at Farm No.1 were readily apparent as the large peaks surrounded by relatively low
deposition levels (Fig. 3.18). There was noticeable deposition directly north of the west
barn, where manure was being stored (Fig. 3.18). This area is also completely paved and
a more uniform deposition pattern was observed compared to the grassy corridor with the
multiple point sources of ammonia. The manure pile deposition points were not included
in further estimates of deposition. Two of the sample periods also showed a dispersed
deposition west of the barns, where a field had been recently fertilized with poultry
54
manure (Fig. 3.19e-f).
The field in front of the barn at Farm No.2 also demonstrated localized ammonia
deposition outside of the fans, especially at the 2.1 and 3.6 m distances from the fans (Fig.
3.20). The peak at 58 m is due to a moderate amount of activity from one of the large 52”
fans that were not hooded (Fig. 3.21). Unlike Farm No.1, the size of the field at Farm
No.2 allowed for a longer transect along the exhaust plume, which again demonstrates
the high spatial dependency of dry deposition. Within the first 8 m, 98.8% of the total
deposition on these transects had occurred (Fig. 3.22). In the field at Farm No.2 there are
two groups of trees that were tested as a wind break to capture dust from the ventilation
systems (Fig. 3.3). Two of the long transects used passed through these and a few sample
dates at in the first two weeks of growth showed a slight, but not significant, increase in
ammonia deposition within these trees (data not shown).
Another interesting process was observed from the deposition samples collected
between two flocks residing in the barns. After the barns were cleaned out and the fans
were turned off, deposition of ammonia was observed at the manure pile, as expected,
and in the corridor (Fig. 3.23). Though the levels of ammonia were quite low the same
pattern of the ventilation system can be seen. Ammonia is known to deposit at high levels
when a highly concentrated source is present, but when that source is removed the
deposition surface can release some of the previously deposited ammonia, becoming a
new source due to the shift in concentration equilibrium (Fowler et al. 1998). As with
Farm No.1, a familiar deposition pattern was observed at Farm No.2 on the ground close
to the fans (Fig. 3.24). The barns were empty and no fan activity was recorded, though
the barns had not yet had the litter cleaned out. Because of this internal concentration
55
some of the deposition may be explained by loosely closing fan shutters, especially in the
case of the large 52” fan located 58 m down the barn. The other traces of deposition at
Farm No.2 were 60 μg NH3 cm-2 or less, only slightly higher than those found at Farm
No.1.
The deposition rates over that year showed some seasonality at Farm No.1 when
plotted alongside ambient air temperature (Fig. 3.12). This is in contrast to the emission
of ammonia, but is very similar to ventilation rates (Fig. 3.8, 3.10). Since ammonia
deposition is known to be highly dependent on impaction velocities, higher levels of
ventilation should result in higher levels of deposition. This importance of air velocity
helps to explain why deposition is so spatially dependent and why less than 10% of the
total deposited ammonia is recorded further than 3.6 m from the ventilation fans, even
though the area beyond 3.6 m makes up 86% and 83% of the total farm area at Farm No.1
and No.2, respectively (Table 3.7).
The dry deposition of ammonia at both Farm No.1 and No.2 were significantly
correlated (r2= 0.885 and 0.903, respectively) with bird age (Table 3.1). This is similar to
the findings of the ammonia emissions. For the barn at Farm No.1 exterior temperature
was also included in a backward selected regression, but the improvement in fit was
minor (r2 = 0.896). Again this strong relationship with deposition and bird age was used
to support using a broiler growth curve to estimate the final deposition value on the
harvest date. The ammonia deposition rates were also significantly correlated with the
calculated ammonia emissions in barns at both Farm No.1 and No.2 (r2= 0.786 and 0.836,
respectively) (Table 3.1). Considering the deposition of ammonia after emission can be
dependent on numerous environmental factors and the difference in measurement
56
techniques, this relationship is quite encouraging.
Similar to emissions, the deposition totals calculated can be scaled to an annual
value by averaging to find a “per flock” deposition and assuming a 6 flock year (BC
Chicken Marketing Board 2014). The total annual deposition of ammonia would be 50.03
kg and 52.52 kg at Farm No.1 and No.2, respectively. The deposition on the farm
property only accounts for 3.4% and 8.8% of the total emission at Farms No.1 and No.2,
respectively. The values cited in the literature often describe ammonia dry deposition
levels around 3-10% of emission within 300 m of the emission source and this study did
not have samples further than 25 m from the emission source (Fowler et al. 1998). The
large difference in deposition percentage of the two study sites is quite different from the
relatively similar emission levels. This is likely due to the different orientation of the
barns and may show that corridor ventilated barns have less deposition than barns that
simply exhaust to a field. Having a more turbulent area in the corridor could result in
more upward flow of emissions and cause a plume effect, drastically decreasing the
localized deposition of the ammonia and increasing the atmospheric impact. Because of
the differences between the barns, a large-scale estimate would have an extremely large
error.
3.4 Conclusions
The ventilation systems at both study sites were effectively characterized with the
combination of fan activity timers and FANS measurement. A significant relationship
between ventilation rate and both bird age and exterior temperature was found at both
sites, though fan activity was only correlated with bird age. The emission methodology,
impinger gas traps, demonstrated some substantial variability between sample points on
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the barns, though the replicate samples on the same fan were promisingly consistent. The
distribution of birds inside the barns were suspected of causing this variability as it
appeared to decrease once the birds were large enough that uneven distribution in the
barn was no longer possible. The emission of ammonia from the barns was significantly
related to bird age (0.765 and 0.775 for Farm No.1 and 2 respectively) and a slight
relationship was seen to exterior temperature at Farm No.1. The emission factors
calculated for each barn were consistent with numerous literature values, especially those
obtained under similar management scenarios. End of cycle estimations using a poultry
growth curve provided larger emission factor estimates than the data not including a
harvest date sampling and appeared to be an appropriate method. Emission factors
appeared to be unaffected by seasonal variability as has been seen in the literature, but a
weakly significant relationship with stocking density was also found. The ammonia
emissions factors calculated for the three broiler barns ranged from 0.19-0.37 g NH3 bird-
1 day-1with total ammonia emissions from 600 to 815 kg annually.
Measurements of ammonia deposition were highly successful in demonstrating the
spatial variability nearby ventilation fans and the high density samplings revealed
extremely high rates. The methodology used proved very effective and inexpensive to use
on a large scale, though there were issues with measuring dry deposition in an area with
large amounts of precipitation. The methodology was sensitive enough to measure re-
volatilization and deposition of ammonia from the ground after the barns were emptied
and the primary source of ammonia was removed. The most significant factor affecting
deposition levels appeared to be bird age and the percentage of emissions deposited
locally supported previous findings in the literature. The annual deposition of ammonia
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calculated for the two study sites (0.56 ha and 0.28 ha for Farm No.1 and 2 respectively)
exceeded 50 kg, though this represented less than 5% of the emissions at Farm No.1 and
less than 10% of the emissions at Farm No.2.
Future sampling of broiler facilities in the Lower Fraser Valley is recommended as
more emission data would lead to a better understanding of nutrient cycling in the region.
A recent trend of changing broiler barns to tunnel ventilation, as opposed to the sidewall
ventilation examined in this study, will also require further study as the flow dynamics
are quite different. The fan hoods used in sidewall barns appear to increase the localized
deposition nearby the barns, which may lead to greater problems with respect to the
groundwater contamination prevalent in the study area.
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Figure 3.1 Map of the Lower Fraser Valley of British Columbia and locations of Farm No.1 in Chilliwack, BC and Farm No. 2 in Aldergrove, BC.
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Figure 3.2 Map of Farm No.1 located in Chilliwack, BC showing locations of dry deposition sampling sites and gas impinger traps. The dry deposition sites are indicated by the red dots and the fans being sampled by gas impinger traps are indicated by the blue boxes. The green box in the corridor indicates where the high density (HD) deposition samples were taken. The light blue boxes on the east side of the barns show the area that the deposition samples were applied to when estimating for the entire property.
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Figure 3.3 Map of Farm No.2 in Aldergrove, BC showing locations of dry deposition sampling sites and gas impinger traps. The dry deposition sites are indicated by the red dots and the fans being sampled by gas impinger traps are indicated by the blue boxes. The hash marked barns were not studied
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Figure 3.4 An isoconcentration plot of the average high density ammonia deposition samples obtained at Farm No. 1 located in Chilliwack, BC. The active 24” fan is located at 5 m down the corridor and the inactive 36” fan is located at 0 m down the corridor. Samples were taken at every intersection of the grid and the standard sampling points are marked with the large grey points. The thick grid lines show the edges of the 8 groups, each with an associated standard sampling point.
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(a)
(b)
Figure 3.5 Changes at Farm No.1 during the four stages of ventilation and at farm No.2 during the seven stages of ventilation in (a) air pressure deficit within the barns and (b) sum total ventilation flow rates
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(a)
(b) Figure 3.6 Percentage of time that (a) any fans were active in the barns of Farm No.1 and No.2 during sample times and (b) ventilation stages 3 or higher were active.
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Figure 3.7 Ammonia in ventilated air within the barns on Farm No. 1. determined during the summer and winter periods.
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Figure 3.8 Barn ventilation rates for each flock and weather station air temperature during the year-long period of measurement.
Figure 3.9 Barn exhaust NH3 concentration for each flock and weather station air temperature during the year-long period of measurement.
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Figure 3.10 Barn NH3 emissions for each flock and weather station air temperature during the year-long period of measurement. Each hollow point represents an estimated point using the growth curve method.
Figure 3.11 Emission factors for each flock and weather station air temperature during the year-long period of measurement.
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Figure 3.12 Total Farm NH3 depositions for each flock and weather station air temperature during the year-long period of measurement. Each hollow point represents an estimated point using the growth curve method.
69
(a) (b)
(c) (d)
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(e) Figure 3.13 Flock A-105 from Farm No.1’s (a) ammonia emission curve in emission factor units, (b) after being normalized, (c) plotted alongside normalized growth curve (weight vs age), (d) with the estimated harvest date emission using the growth curve’s slope, and (e) the ammonia emission curve converted back into actual units along with the new final point.
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(a)
(b)
72
(c)
(d) Figure 3.14 High density deposition samples from 1 m to 3.6 m away from the side of the barn at Farm No.1 at positions (a) in front of a 36” fan, (b) halfway between a 36” and a 24” fan (5 m apart), (c) in front of a 24” fan, and (d) halfway between two widely spaced 24” fans (10 m apart). Filled points represent the standard sampling locations at 2.1 m and 3.6 m from the side of the barn. 51S, 56S, and 57S were the sample set numbers that the high density samples were taken.
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Figure 3.15 Average high density ammonia deposition sample points along the corridor (parallel to barn) at 2.1 m and 3.6 m from the barn and fans at Farm No.1. Filled points represent the standard sampling locations directly in front of fans (0 m and 5 m) and halfway between fans (2.5 m and 10 m).
Figure 3.16 Comparison of the non-MLR calculated and the MLR NH3 deposited in the corridor between the barns at Farm No.1 for flock A110. Flock A110 was the bird cycle that occurred from April to May 2012.
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Figure 3.17 Comparison of the non-MLR calculated and the MLR NH3 deposited in the corridor between the barns at Farm No.2 for flock A111. Flock A111 was the bird cycle that occurred from May to June 2012.
Figure 3.18 Deposition of ammonia at 2.1 m from each barn and 3.6 m, between the barns, at Farm No.1 averaged for all sample dates with birds over 20 days old.
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Figure 3.19 Isoconcentration of ammonia deposition on the entire Farm No.1 for flocks (a) A105 (36 days old), (b) A106 (29 days old), (c) A107 (32 days old), (d) A108 (22 days old), (e) A109 (34 days old), and (f) A110 (34 days old). The west and east barns are represented by the grey boxes and the fans are marked with the black arrows.
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Figure 3.20 Isoconcentration of ammonia deposition for the field in front of Farm No.2 for flocks (a) A109 (24 days old), (b) A110 (35 days old), and (c) A111 (32 days old). The barn is represented by the grey box and the fans are marked with the black arrows.
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Figure 3.21 Deposition of ammonia at 2.1 m and 3.6 m from the fans in line with the barn at Farm No.2 averaged for all sample dates with birds over 20 days old.
Figure 3.22 Deposition of ammonia in line with active hooded fans at Farm No.2 averaged for all sample dates with birds over 20 days old.
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Figure 3.23 Isoconcentration of ammonia re-deposition on the entire Farm No.1 between flocks A105 and A106. The barns were empty, clean and fans turned off. The barns are represented by the grey box and the fans are marked with the black arrows.
Figure 3.24 Isoconcentration of ammonia re-deposition for the field in front of Farm No.2 after flock A111. The barns were empty, clean and fans turned off. The barn is represented by the grey box and the fans are marked with the black arrows.
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Table 3.1 Summary of Multiple Linear Regressions
Factor Variable* r2
Site
Ventilation Farm No.1 BA + ET 0.825 Farm No.2 BA + ET 0.925 Fan Activity
Farm No.1 and No.2 BA 0.712 Emissions Farm No.1 BA + ET 0.765 BA (P <0.0001) ** ET (P = 0.534)** Farm No.2 BA 0.775 Emission Factor Farm No.1 and No.2 SD 0.324 Deposition Farm No.1 BA 0.885 BA + ET 0.896 Farm No.2 BA 0.903 Deposition Farm No.1 BA + E 0.786 Farm No.2 BA + E 0.836 *Variable: BA = bird age, E = emissions, EF = emission factor, ET = exterior temperature, SD = stocking density, V = ventilation **Values of P when individually correlated with emissions
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Table 3.2 Summary of emission factors and literature values
Study Location (Reference) Market Age (days)
Stocking Density (b
m-2)
Litter Management*
Monitoring Method**
Number of
Flocks
Emission Factor (g NH3 b-1 d-1)
BC, Canada (this study) Farm No.1 - West Barn 36.4 12.34 N S-CF 6 0.30 ± 0.08 Farm No.1 - East Barn 36.4 10.97 N S-CF 6 0.37 ± 0.10 Farm No.2 - North Barn 38.7 12.10 N S-CF 3 0.19 ± 0.06 Europe (Koerkamp et al. 1998) England - - N C-CL 4 0.48
Netherlands - - N C-CL 4 0.27 Denmark - - N C-CL 4 0.21 Germany - - N C-CL 4 0.44
U.S. (Harper et al. 2010) CA (summer) 47 10.6 P C-OPL 16 0.34 CA (winter) 47 10.6 P C-OPL 16 0.30 U.S. (Wheeler et al. 2003) PA and KY 42 14.7 N C-EC 10 0.47
PA and KY 42 14.7 D C-EC 12 0.65 PA and KY 49 13.4 D C-EC 24 0.76 PA and KY 63 10.8 D C-EC 20 0.98 U.S. (Lacey et al. 2003) TX 49 13.5 D S-CM 12 0.63 U.K. (Wathes et al. 1997) England 32 9.4 N C-CL 4 0.26 *Litter Management: N = new, P = partial (new every three flocks), D = de-caked **Monitoring method: C = continuous, S = sample (discrete), CF = colorimetric flow injection analysis, CL = chemiluminescence extraction, CM = colorimetric tube, EC = electrochemical extraction, OPL = open-path laser, and PS = photoacoustic extraction
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Table 3.3 Average flow rate for each fan across all stages
7E 6,457.55 6,303.45 6,270.70 6,022.70 7 8E - - - 13,541.85 - 9E - - 6,585.45 6,031.80 8 10E - 6,828.35 6,663.25 6,400.15 6 11E - - - 12,523.10 -
West Barn Total 13,788.05 27,018.90 49,439.40 67,423.65 Mean: 15±4 East Barn Total 20,549.58 33,861.43 47,081.05 96,883.02 Mean: 6±1
*1W is the designation of fan 1 in the west barn. E is for the east barn. The bold text indicates which fan’s emissions were sampled. **Fan 6E was not functioning for 3 of the 6 flocks that were studied and was assumed to have flow rates averaging those of similar sized fans at the same ventilation stage.
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Table 3.5 Average flow rate for each fan for each ventilation stage and total flow rate for each stage at the Farm No.2 in Aldergrove, BC.
Fan # Flow rate (m3 hr-1) Percent loss over stages (%) Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6 Stage 7
Confined livestock operations in the Lower Fraser Valley of BC are known to
produce large amounts of ammonia. Broiler barns in this area have not been well
researched with respect to quantifying the ammonia that the ventilation systems exhausts
and how much of that is locally dry deposited, potentially contributing to groundwater
contamination. As management scenarios greatly impact ammonia emissions and
depositions from barns, a locally focused research project was required to determine the
potential environmental impacts. This chapter will outline the conclusions from the
research and then evaluate the strength and weaknesses of the methods used.
4.2 Conclusions and Recommendations
The ammonia emissions measurements at three broiler barns over the period of
one year allowed for a comparison among the barns typical for this region. Emission
factors reported in the literature were found to be similar to those from this study. This
supported the comparison of Canadian broiler operations with those found in Europe and
the USA with similar management styles, primarily litter management. The relatively
modest emission factors of the local barns are encouraging as the best management
practices appear to be reducing excessive nutrient loss. Though the emission factors are
low, the total ammonia emissions from this industry is substantial as the poultry industry
in this region is quite large. The emissions that are dispersed into the atmosphere are a
concern for non-localized deposition of ammonia and PM2.5, but the highly localized dry
deposition of ammonia above Abbotsford-Sumas aquifer is a probable source of nitrate
contamination. Current air quality measurements in the Lower Fraser Valley have not
86
recorded excessive levels of PM2.5 or ammonia, but the indiscriminate deposition of those
nitrogen species is a potential issue (Metro Vancouver 2015).
The highest levels of deposited ammonia exceeded 400 μg cm-2 over a 24-hour
exposure, which is equivalent to 40 kg ha-1. The area with this level of deposition is
limited to less than 2 m2 directly under the fan hood. Over the entire farm area the
deposition level is under 10% of the ammonia emissions measured and would be
expected to be far below the saturation point of the soil. These high values are only found
when the flock is in its last week of growth before harvest, but there are six flocks every
year and the timing of this deposition is critical to the leaching potential (i.e., when plant
uptake is very low and/or when precipitation is high). This study provides localized and
crucial emission factors and information on spatial distribution of deposition that can in
future studies be used to assess the poultry barns’ contribution to the nitrate pollution of
the Sumas-Abbotsford aquifer.
4.2.1 Future Research
Complete assessment of ammonia emissions and leaching from deposition
requires more research. It is highly probably that nitrogen leaching is taking place
considering the levels of ammonia that are being deposited. What needs to be determined
is how significant these “hot spot” sources of nitrate are compared to the typical culprits
of nitrate leaching (e.g., excessive field fertilization, improper manure storage facilities).
To investigate this localized leaching the research must venture below the surface of the
soil. Analyzing soil cores or suction lysimeter samples of the soil solution will not give a
full picture of the magnitude of this problem, though they can confirm that the suspected
leaching is taking place.
87
Various types of lysimeters have been used extensively on the Abbotsford-Sumas
aquifer to assess leaching from raspberry fields, in the effort to design new best
management practices (Malekani 2012). The installation of this type of equipment is
expensive and difficult, but is likely the only way that quantitative data on the
contaminating nitrate could be obtained. Once the initial set of data is collected the use of
modelling to estimate the total impact on the aquifer will be needed.
Although the conventional sidewall ventilation barns are the norm in the Lower
Fraser Valley there are a few different barn designs, including two-story sidewall barns
and tunnel ventilated barns, which some producers are beginning to use. These different
barn types will have a very different emission and dry deposition pattern and possibly a
lesser impact if dispersion of the ammonia is encouraged. Ammonia collection systems
are also better suited to tunnel style ventilation systems so the emission problem could be
remedied in an entirely different way. These new barn designs will need to have emission
and deposition measurements made in a manner similar to this study so that their impact
may also be assessed.
4.2 Evaluation of Study Methods and Recommendations for Future
Modifications
This study involved numerous measurements and methods of varying complexity.
The characterization of the barn ventilation systems was a critical part of this research as
the emission estimates were highly dependent on this being accurate. Measuring the flow
patterns of fans is a complicated task and using equipment designed for that purpose
made it far easier. The FANS unit is highly recommended since it measures the air flow
88
of the fan in addition to recording the pressure differential that is critical to understanding
the efficacy of the ventilation system as a whole.
The acid impinger system that collected the ammonia in the exhausted air was
another effective, though temperamental system. The numerous Teflon tubes, glass
containers, fragile fritted glass bubblers, and diaphragm pumps create a delicate system
often in need of repair. The sensitivity of the system was comparable to the levels of
ammonia it was required to measure. High-frequency measurements would require a
much more expensive system and investigation of the diurnal emission patterns were not
of concern in this study. In the future, protecting the impinger system from the seasonal
temperature fluctuations would be recommended as they resulted in a great number of
repairs. Another limitation of the ammonia measurements concerned the replication and
number of fans that could be sampled. The impinger system is complex enough that
sampling all of the fans of a barn at once requires a great deal of effort and time.
The dust in the fan exhaust was a variable that has been investigated to a limited
extent in other studies. Consisting mainly of dander and fecal particulate the potential for
it to contaminate both impinger samples and dry deposition samples deserves more
research. The level of dust would make optical ammonia measurements at the barns
unreliable and the contamination of dry deposition measurements would be considerable,
except possibly in the case of measuring deposition with biological systems such as grass.
The dry deposition sampling methodology was very successful in this study. The
modification of the existing method demonstrated the flexibility of using soil as a
collection medium. The extremely low cost of the method was offset by the time
consuming process of extracting and analyzing the large number of samples. Using a
89
naturally occurring medium allowed for a logical transferal of measured deposition in the
sample which would occur in situ. The soil was surprisingly stable in the high air speed
environment below the fan hoods, though some loss of soil was inevitable. The elevated
humidity of the fan exhaust likely dampened the soil and increased its stability. The high
levels and rate of deposition in that environment allowed any newly exposed soil to retain
sufficient ammonia to still yield an appropriate sample.
The high density samples and the MLR model used to modify the standard
deposition measurement points of the other sampling dates is one aspect of this study that
could use expanded complexity. The MLR model was effective in preventing the over-
and under-estimations of deposition in the large sample blocks, but it is rather crude.
Spatial statistical methods could certainly be used to improve this method of estimation
in future studies.
Overall, the methods used in this study effectively characterized and quantified
the emissions and localized dry deposition of ammonia. The calculated emission factors
demonstrated that the broiler operations in the Lower Fraser Valley are similar to those in
Europe and the USA. The dry deposition levels on the three farms included in this study
were similar to those reported in the literature, accounting for less than 10% of the total
emissions. The extremely high levels of ammonia deposition found directly below the fan
hoods is a new information that requires further study to determine the associated nitrate
leaching potential. An assessment of the overall contribution of the broiler industry to the
contamination of the Abbotsford-Sumas aquifer will be made possible by addition of
estimates of nitrogen leaching from individual farms.
90
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APPENDIX I: Historic and study period weather data for Abbotsford, BC.
(a)
(b)
Figure A.1 Comparison of historic monthly data (1981-2010) in comparison with the July 2011 to June 2012 for (a) total precipitation and (b) average temperature for Abbotsford, BC, Canada (Environment Canada 2015). The Abbotsford weather station was located 12 km from the Aldergrove study site and 40 km from the Chilliwack study site.
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APPENDIX II: Description of treatments and samples sizes for each of the methodology trials. Table A.1 Description of treatments and samples sizes for each of the methodology trials.
Trial Treatment n Mass (g)* Location Exposure Time (h)
NH4-N Deposited (mg m-2)**
Sample - 8 8.00 1.5 m & 20 m*** 6.8 1521.15 a****
Mass - 8 12.00 1.5 m & 20 m 6.8 1462.50 a
- 8 16.00 1.5 m & 20 m 6.8 1753.68 a
Saturation - 10 12.00 1.5 m 1.0 365.27 a
- 5 12.00 1.5 m 6.0 1108.14 b
- 5 12.00 1.5 m 9.5 1354.78 b
- 5 12.00 1.5 m 24.1 3488.52 c
- 5 12.00 1.5 m 47.8 5503.49 d
- 5 12.00 1.5 m 72.8 7610.37 e
- 5 12.00 1.5 m 144.8 10804.52 f
Moisture Dry 6 12.00 1.5 m 1.5 390.23 ab
2 ml DI 3 12.00 1.5 m 1.5 296.38 a
4 ml DI 3 12.00 1.5 m 1.5 507.85 b
6 ml DI 3 12.00 1.5 m 1.5 272.63 ab
Dry 6 12.00 1.5 m 1.5 390.23 a
Wet 9 12.00 1.5 m 1.5 390.23 a
pH 0 ml Acid 5 12.00 1.5 m 25.0 3992.34 a
0.5 ml Acid 5 12.00 1.5 m 25.0 4181.23 a
1 ml Acid 5 12.00 1.5 m 25.0 4001.42 a
4 ml Acid 5 12.00 1.5 m 25.0 4681.53 b
Texture 0% sand 4 12.00 1.5 m 23.3 3240.94 a
25% 4 12.00 1.5 m 23.3 2891.11 a
50% 4 12.00 1.5 m 23.3 2561.31 ab
75% 4 12.00 1.5 m 23.3 1909.47 b
100% 4 12.00 1.5 m 23.3 506.68 c
Rain No Cover 4 12.00 1.5 m 7.0 1650.10 a
Cover Cover 4 12.00 1.5 m 7.0 1536.03 a
No Cover 4 12.00 3 m 7.0 685.74 b
Cover 4 12.00 3 m 7.0 669.37 b
No Cover 4 12.00 20 m 7.0 16.08 c
Cover 4 12.00 20 m 7.0 7.35 c * Masses were measured to +/- 0.01 g ** NH4-N deposited is not given in a per hour unit for the Saturation trial (mg m-2) *** Ambient samples were taken at a location 20 m away from the ventilation fan **** Means followed by the same letter are not significantly different (P > 0.05) as determined by LSD mean comparison.
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APPENDIX III: Fan Assessment Numeration System (FANS)
Figure A.2 Fan Assessment Numeration System (FANS) that allowed measurements of a 24” ventilation fan at Farm No.2 located in Aldergrove, BC
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Figure A.3 Contour plot of air flow (m/s) through the Fan Assessment Numeration System while measuring a 36” ventilation fan at Farm No.1
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APPENDIX IV: Gas Impinger Acid Trap System and sidewall fan hoods.
Figure A.4 Gas Impinger Acid Trap System (with four separate sample streams) outside the barn at Farm No.2 located in Aldergrove, BC
Figure A.5 Air filters used for the gas impinger traps. Shown is the ambient sampling point.
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Figure A.6 Dust clogged air filter beneath a fan hood.
Figure A.7 Corridor at Farm No.1 with hooded 24” (0.61 m) sidewall fans and non-hooded 36” (0.91 m) fans.
Total Averages 181.7 1.56 * Averages calculated from two consecutive measurements (n = 2). ** Fan 8 and Fan 10, though functional, were not measured due to the internal framing of the barn not allowing the FANS to fit around the fan. The flow rates were calculated from the averages of the other fans of similar size at the same stage.