A Thesis Presented to The Faculty of Alfred University
Nitrate and Sulfate Atmospheric Deposition and Visitation in United States National Parks
by
Jenevieve Keaveney Huta
In partial fulfillment of The requirements for
The Alfred University Honors Program April 29, 2022
Under the Supervision of:
Chair: Dr. Frederic Beaudry, Professor of Environemntal Studies and Geology Committee Members:
Justin Grigg, Assistant Dean of Graduate and Continuing Studies, Certified GIS Professional Dr. Michele Hluchy, Professor of Environmental Studies and Geology
Table of Contents
FOREWORD ... 1
ABSTRACT ... 7
INTRODUCTION ... 8
METHODS ... 11
RESULTS ... 17
DISCUSSION ... 22
LITERATURE CITED ... 26
1 FOREWORD
In April 2014, I took my longest flight to date across the country to Las Vegas, Nevada. It was the start of a weeklong trip with my family to Zion, Bryce, and Grand Canyon National Parks. My family was not new to traveling, however most trips took us up and down the east coast. At the age of fourteen, I was amazed when the rock beneath my feet was red, and the landscape was bare of trees like I saw every day. I was filled with questions and wonder. My world had just opened much wider than I previously understood. When asked what my favorite place was, I always told people Zion National Park after that. I could close my eyes and envision what I saw and felt standing inside that canyon. I frequently told people about the time I hiked Angel’s Landing. The National Parks felt distant and far away up until this point, and in many ways, they continued to. Due to this fascination, each time when planning a summer vacation, I asked my parents if we could go to the National Parks instead of a beach.
Being six hours away from the closest National Park, it would be seven years before I found myself in one again. I frequented the state parks during high school and loved the time I spent hiking in the Adirondacks. In college, the majority of my free time was spent with WILD About Alfred and the Forest People club exploring local parks and engaging in outdoor
education programs. I became president of the Forest People later that year. I researched and planned adventures to local parks for weekend trips and became responsible for organizing our larger trips on school breaks. During my sophomore year, I was no longer inspired by the work I was doing in my engineering classes. I realized that no amount of money could make me love that work or feel accepted as in that environment.
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Switching my major to environmental studies helped bring the passion I felt for the outdoors into the classroom. More and more I talked about the places I wanted to hike and the locations I wanted to visit. As my independence grew, so did my dreams. My knowledge grew along with my comfort in planning through preparation of weekly outings. Later that year, I was diagnosed with mono, which proved to be very severe. My plans of going to North Carolina with Forest People, a trip I had meticulously planned, slipped away from me. I hoped to do the trip on my own, someday down the line when my health improved. Shortly after, a remote pivot and the pandemic would push me outside even more than I previously had been. I felt safety in the outdoors because I was not trapped with a viral enemy I could not see. My dreams of traveling were squashed though my passion for the outdoors was not. Chronic illness prevented me from completing larger hikes, but I found peace in short walks outside and afternoons laying in my hammock. I was able to complete a six-mile hike for the first time seven months after being diagnosed with mono, through my recovery was not close to over.
My best friend and I had previously dreamed of a road trip across the country, though plans never went through due to the events of 2020. I continued to think about and dream of an opportunity like this. In my junior year, I floated the idea of traveling across the country to my partner. I longed for the exploration of traveling after being so locked down. I mourned the opportunity I had to travel and hike before my illness and the pandemic. I sought the peace I felt as a kid in Zion looking up at the canyon walls towering around me. When we found out our jobs at the vaccination center in Monroe County would end mid-summer, two free months and no plans felt like an open opportunity.
On June 28, 2021, we began a road trip that would change the course of my thesis, career path, and personal goals. Thirty-seven days later, I had been to twenty states, fifteen National
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Parks and more state parks, National Forests, and National Monuments than I could count (Figure 1). As time passed, we traveled to more and more National Parks and the desire to see as many places as we possibly could grew. I walked on snow in July in Rocky Mountain National Park and watched a heard of buffalo running along the road in Theodore Roosevelt National Park. I sat in awe at the mirror image of the mountains at Lake Taggart in Grand Teton and the sun hitting the Delicate Arch in Arches for the first time that day. There was not a place that did not amaze me.
Figure 1. Estimate route for summer 2021 road trip starting and ending in Rochester, New York made in Google Maps. Letters denote major visited locations.
However, not everything was easy and simple. Prior to visiting Rocky Mountain National Park, we had to reserve an entry ticket or else we would not be permitted to drive Bear Road. In Yellowstone National Park, we drove around in bumper-to-bumper traffic trying to find a parking spot after 9am. In Zion National Park, we got in line at 6:30am where we waited nearly two hours to board a shuttle which would take us to our trailhead. In Arches National Park, we hiked to the Delicate Arch in the dark to experience the view before every park visitor showed
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up on that exact trail. For two days, we sat on our phones at exactly 10am waiting to reserve entry tickers to Glacier National Park with no luck until the second day. Much of my serenity was dampened by people climbing over “Do Not Touch” signs protecting alpine vegetation or walking towards bison, ignoring all signs, pamphlets, and warnings by every park ranger. I felt the weight of being a member of the group responsible for the destruction of our public lands when all I wanted was to appreciate and protect them. After summer, I promised myself I would always strive for the same happiness, spontaneity, and freedom I felt during that time. I also felt a sense of responsibility to protect the lands I had fallen in love with.
During my junior seminar class, I wrote a thesis proposal about land management and land cover in Allegany County. I had hoped to classify the current land cover and propose future opportunities for conservation. The idea of completing a thesis, regardless of topic was terrifying in many ways. After multiple years as a student during the COVID-19 pandemic, I felt like my skills were lacking. While students before had an entire laboratory class on a machine, my class may have only had fifteen minutes to adhere to social distancing mandates. Our professors did all they could to give us the same experience, but I was left feeling like I had enough experience to understand the concepts in the moment, but not to apply them within the context of a thesis. I also recognize the mental toll of the pandemic. I know I was not nearly as focused on my schoolwork as I was previously due to the fatigue of the “new world” we were living in. Due to this, I felt ill-equipped to complete an extensive and independent project.
After my trip over the summer, I was feeling less inspired in regard to my proposed thesis topic. I began conversations around changing my thesis topic to reflect my new passion for the National Parks. Though switching topics felt incredibly overwhelming, it was important to me to work on something I was enthusiastic about and inspired by. When deciding on a new topic, I
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thought about the experiences that impacted me the most and that I became most passionate about. I originally considered a project on the pika, after they piqued my interest when I saw one in Yellowstone National Park. Much research had already been done on the species, especially concerning the impact of climate change on the population so I disqualify this as an idea. During a conversation with Dr. Fred Beaudry surrounding atmospheric deposition, which describes the process by which precipitation, particles, aerosols, and gases collect on the Earth’s surface, it was suggested I consider deposition in relation to vehicular impact of visitors within the National Parks. I thought about all the moments in which I fought through crowds for a view or searched for a parking spot. In my opinion, the most special experiences in the parks were the hikes just before sunset when no one was around or on a lesser-known trail. This was a topic I was already passionate about as visitor numbers contributed so heavily to my experience within the parks, and I was so interested to see how the results played out. I was relatively comfortable using ArcGIS Pro, which is a software used to create, analyze, manage, and visualize geospatial data.
The opportunity to use GIS and incorporate statistics was especially encouraging given my minor in mathematics.
Originally, I was not optimistic the results would show any type of correlation, simply due to the information I read about the National Atmospheric Deposition Program and the site locations. I was worried that vehicles, since they are a non-stationary source, would not impact the deposition enough to create a statistically significant relationship. When I set to begin my thesis, I struggled to obtain the necessary data and convert it to a format able to be uploaded into GIS. Though I knew what I wanted to do, I did not know exactly what steps to take to get there.
Dr. Fred Beaudry and I discussed a three-step process for thesis completion which included obtaining the necessary data and uploading it to GIS, using GIS tools to determine the mean
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deposition value within each park boundary, and preforming a regression analysis in Minitab. I originally intended to include all sixty-three parks in my analysis but was limited due to the constraint of National Atmospheric Deposition Program data to the continental United States and the time required to run the tools in GIS.
I learned a lot about myself as a student through this process and was pushed in many ways. First of all, I did not have a great understanding of atmospheric deposition or the National Atmospheric Deposition Program. This required research to have a base understanding of the data that would be central to my project. Secondly, I finished my environmental statistics course online due to the COVID-19 pandemic which prevented me from learning to use Minitab within a course setting. Though the software itself is not challenging, there is a learning curve to use any program for the first time. I also learned about new tools in GIS I had not previously used.
There was a significant amount of trial and error involved in finding the correct tool to perform the function to provide a deposition average. It was a proud moment to discover the significance of visitation numbers on both chosen parameters of atmospheric deposition. I recognize the importance of and encourage future research of this topic to attempt to further solidify the unintended impact of rising visitors in the National Parks.
7 ABSTRACT
The National Atmospheric Deposition Program oversees the sampling and analysis of
atmospheric deposition, including of chemicals associated with automobile emissions, such as NOx and sulfur oxides. Visitation to National Park Services sites has increased 16% in the decade prior to 2018, to 318 million visitors total in 2018. The goal of this analysis was to determine whether rising visitor populations within the United States National Parks lead to increased nitrate and sulfatedeposition, which would have a negative effect on the lands parks are intended to protect. Parks were only considered for analysis if they were within the
continental United States, accessible by vehicle, and in remote locations. Using average visitors from 2000-2015, parks were classified as high or low visitation. Five parks from each category were randomly chosen as representatives of the subset. Using ArcGIS Pro, average deposition values were obtained in each park boundary for the years 2000, 2005, 2010, and 2015. Two regression analyses were performed for both emission types using visitation data from each of the four years and the mean deposition within the park boundaries. Results show that there is a significant effect of visitation on both nitrate (p=0.005) and sulfate (p=0.002) atmospheric deposition within National Park boundaries. This indicates an increased effect of vehicle emissions within parks of higher visitation, suggesting that the increased visitor use of public lands may negatively affect soil and water health in that area.
8 INTRODUCTION
The National Park Service system contains a diverse collection of public lands including national parks, monuments, preserves, memorials, recreation areas, battlefields, historical parks, trails, parkways, rivers, seashores, and lakeshores (Schuett et al. 2010). Of all these
classifications, most visitations come from national parks, followed by national recreation areas.
As of 2022, the United States has designated sixty-three national parks. Visitation data from many of the national parks is available from the 1920s (Schuett et al. 2010). During the 20th century, visitation increased to record high of 287.2 million visitors in 1987 and plateaued until about 2000 (Schuett et al. 2010). In 2000, park visitations began to decline, bottoming at 266 million visitors in 2003 (Schuett et al. 2010). Since 2003, recreation visits have fluctuated at around 275 million (Schuett et al. 2010). There is a lot of debate over the reasons for these fluctuations, but some of the given reasons include less exposure of children to nature, personal, social, and economic constraints, and more leisure time spent with technology and media
(Schuett et al. 2010). In 2021, The National Park Service experienced a 25.3% increase in visits from 2020, largely due to the changing COVID-19 protocols ("NPS Visitation 2021”, 2022).
Though National Park Service visitation numbers have not yet recovered to pre-pandemic levels overall, visitations are expected to continue to rise. Many parks have experienced recent record breaking visitation, including the forty-six parks that set a visitor record in 2021 ("NPS
Visitation 2021", 2022). With increased number of visits, parks experience a number of issues, including elevated vehicle traffic.
Vehicles emit a variety of pollutants that effect human, atmospheric, and ecological health (Bhandarkar 2013). These pollutants include CO, NOx, sulfur oxides, (SO), HC, lead (Pb) and suspended particulate matter (Bhandarkar 2013). Corridors of increased air pollution arise
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from NOx emitted from vehicles on highways (Redling et al. 2012). Air pollution causes significant environmental hazards including, but not limited to, acid rain, climate change, depletion of the ozone layer, soil pollution, and water pollution (Bhandarkar 2013). Vehicles are responsible for air pollution due to the discharge of pollutants as well as soil pollution. They emit potentially toxic elements that can accumulate in roadside soils, such as As, Co, Cr, Cu Mn, Mo, Ni, Pb, Pd, Pt, Rh, Sr, Sb, Sn, Sr, Ti and Zn (De Silva et al. 2020).
The National Atmospheric Deposition Program (NADP) oversees the long-term sampling and analysis of precipitation in the United States, Puerto Rico and the Virgin Islands (Lamb and Bowersox 2000). Routine data is collected at about 280 sites (Lamb and Bowersox 2000). The goal of this program is to help scientists and agencies concerned with environmental effects to develop a chemical climatology of atmospheric deposition (Lamb and Bowersox 2000). Both emission source areas and wind pattern are reflected in patterns of concentration and deposition (Lovett, 1994). Deposition describes the amount of a chemical that is moved to the ground, most often through precipitation ("Educational Resources", 2022). There are three main mechanisms of atmospheric deposition: wet, dry, and cloud deposition (Ollinger et al., 1993). Wet deposition, which this study will focus on, reflects both concentration and amount of precipitation
("Educational Resources", 2022). For example, the western United States experiences a higher chemical concentration in limited rainfall compared to the East. The East will have more deposition even though the concentration is lower due to the higher precipitation ("Educational Resources", 2022).
In the Eastern United States, 50% of emissions come from vehicles (Butler et al. 2005).
Many of the national pollution monitoring facilities in the United States, including the National Atmospheric Deposition Program, are located in rural areas (Redling et al. 2015). These facilities
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are intentionally located far from major source pollution and transportation corridors because regional air pollution trends are the focus (Redling et al. 2005). Long term, this provides an assessment of the background deposition levels, but due to the remote location of the sites, the total deposition is likely underestimated (Redling et al. 2005).
Of the pollutants emitted from vehicles, the National Atmospheric Deposition Program monitors sulfate and nitrate. Natural sources are responsible for measurable levels of nitrogen and sulfur deposition, even at remote sites (Lovett, 1994). About 90% of nitrogen oxides and more than 95% of sulfur oxides emitted into the air come from anthropogenic sources (Lovett, 1994). Much of the dry nitrogen deposition from automobiles is deposited locally, so the wet and dry nitrogen deposition monitored at the NADP sites may not take the effect of automobile pollution into account (Redling et al. 2005). Many of the National Parks are located away from stationary sources, so this analysis will seek to determine if there are fluctuations that cannot be attributed to stationary sources. These would then potentially be linked to vehicular emissions from park visitors as the anthropogenic origin. My analysis will focus on whether a statistically significant relationship exists between National Park visitation and the National Atmospheric Deposition Program’s deposition data, specifically for nitrate and sulfate.
11 METHODS
This analysis was conducted using data obtained from the National Park Service as well as the National Atmospheric Deposition Program. The data from the National Park Service detailed visitation numbers per park per year as well as the traffic counts in each park in a variety of locations (https://irma.nps.gov/STATS/). The National Park Services manages over 400 park units with sixty-three having National Park Status. For this analysis, only parks within the continental United States were considered. Four additional parks were eliminated due to being inaccessible by vehicle. This left forty-seven parks remaining to be considered. Using average visitation numbers per year from 2000-2015, parks were ordered from highest visitation to lowest. To ensure representation, the sample was stratified into low visitation (23,252 – 934,833 average visitors per year, n=23) and high visitation (990,824 – 9,743,136 average visitors per year, n=23).
Using United States Census Bureau population density data from 2010, all forty-seven parks were sorted by urban or remote status. Parks within two hours of high populations were qualified as urban, which totaled seventeen parks. These parks were eliminated from further research due to the need to isolate the effect of national park visitation from urban traffic. Only the thirty parks with remote status were considered further. Remote status was identified for parks outside of a two-hour drive from a high population area, designated with darker colors on the US. Census GIS population density map. Of the thirty parks, 18 had low visitation and 12 has high visitation. Using a random number generator, five parks from each category were chosen.
The remote parks with high visitation included Hot Springs, Acadia, Olympic, Arches and Yellowstone (Figure 2). The remote parks with low visitation include Black Canyon of the Gunnison, Redwood, Great Sand Dunes, Capitol Reef, and Canyonlands (Figure 2).
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Figure 2. Locations of ten chosen National Parks made in ESRI ArcGIS Pro. Park size not to scale.
The National Park boundaries shapefile was obtained from the National Park Service website and uploaded into ESRI ArcGIS Pro. This was clipped to include just the ten chosen National Park sites. Next, the Project tool was used to transform the coordinate system from the provided into UTM NAD 1983. There were then five different files with each of the UTM zones from the parks. GRID files were obtained from the National Atmospheric Deposition Program (https://nadp.slh.wisc.edu/maps-data/ntn-gradient-maps/) for each emission type, sulfate and nitrate, in each of the five chosen years, 2000, 2005, 2010, and 2015. Sulfate and nitrate were chosen after research about the pollutants emitted from vehicles which include sulfur oxides and NOx. The GRID files were uploaded to ArcGIS as raster files (Figure 3). For each file, the tool
“Extract by Mask” was used by selecting the desired park from the zone file (Figure 3; Figure 4;
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Figure 5). Extract by mask pulls the cells of a raster, for example the NADP raster deposition values, that correspond to the areas defined by a mask, in this case the National Park boundary.
An example is shown using the nitrate wet deposition in Yellowstone National Park in 2000 in figures 3-5. After running the tool, I recorded the maximum, minimum, mean, and standard deviation deposition value in the park. This process was repeated with each combination of year, emission type and park boundary. The tool was run a total of eighty times to obtain mean
deposition values of each emission type in each of the four years.
Figure 3. Example map of the raster format shown in ESRI ArcGIS Pro for a chosen example year and pollutant, nitrate in 2000. The raster file covers all areas of the continental United States and ranges in value from 0.0821268 kg/ha (pictured in the darkest color) to 33.1143 kg/ha
(pictured in the lightest color).
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Figure 4. Example of step prior to using “Extract by Mask” tool for nitrate wet deposition
(kg/ha) in 2000 in Yellowstone. This is an enlarged clip of Figure 3 centered around Yellowstone National Park, which is shown in blue. The raster file containing the National Atmospheric Deposition program values is shown around the park in greyscale with darker values being lower deposition values.
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Figure 5. Result after “Extract by Mask” tool is used in ESRI ArcGIS Pro for example of nitrate wet deposition (kg/ha) in 2000 in Yellowstone National Park. Deposition values within the park boundary range from 1.30282 kg/ha (depicted in darkest color) to 9.93638 kg/ha (depicted in lightest color).
I used Minitab 21.1 to perform multivariate regression analyses, one for nitrate and one for sulfate. This type of analysis was chosen because it shows the strength of the relationship between multiple independent variables and dependent variable. I looked for a significant positive relationship meaning that when one variable increases, the other does as well. For both analyses, the response variable (dependent) was the mean deposition value. Continuous
predictors (independent) included visitation, year, and National Park. After variables were
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assigned, numerical values were assigned to each national park and were used as a dummy variable rather than alphabetical inputs.
17 RESULTS
Visitation in the ten chosen National Parks ranged from over four million visitors annually in Yellowstone National Park to less than 200,000 in Black Canyon of the Gunnison National Park (Figure 6). Total visitations to the ten parks were at a high in 2015 at 15,601,522 visitors and a low in 2005 with 11,949,922 visitors. The most visitations occurred in 2015, followed by 2010, 2000, and 2005. Every park, apart from one, had their highest annual
visitation in 2015. Olympic National Park experienced its highest visitation in 2000, higher than the 2015 annual visitors by just over six thousand people. Half of the parks experienced their lowest visitation numbers in 2005.
The highest average nitrate wet deposition over the four years was in Hot Springs (9.54 kg/ha) followed closely by Acadia (9.51 kg/ha). Both parks were classified as high visitation and had the third and fourth highest average visitation numbers of the course of the four years. The third highest wet deposition was found in Redwood, a low visitation park with the third lowest annual average visitation of the ten parks. Great Sand Dunes had the lowest average deposition at 1.95 kg/ha and had the third lowest average annual visitation. Olympic experienced the highest standard deviation within the park boundary, especially in the years 2000 and 2010 (Figure 8).
The highest nitrate wet deposition value was 12.12 kg/ha in Acadia in 2000 (Figure 10). In 2000, Acadia had nearly 2.5 million visitors. Yellowstone experienced the highest visitation of any park in 2015 with over 4 million visitors but had a wet deposition of 3.25 kg/ha (Figure 10).
The highest average sulfate wet deposition values were found in Hot Springs National Park at 11.08 kg/ha annually. Hot Springs had the fourth highest average annual visitation with 1.35 million average annual visitors. Acadia (10.73 kg/ha) and Olympic (7.79 kg/ha) had the second and third highest average nitrate wet deposition and the second and third highest average
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annual visitation. Of the three lowest visitation parks and lowest deposition parks, the only overlap was Great Sand Dunes with second lowest deposition (1.27 kg/ha) and visitation (280,794 visitors). Canyonlands had the lowest average deposition (1.25 kg/ha) and the fourth lowest visitation (466,364 visitors). Redwood was considered a low visitation park with 430,840 average visitors but had the fourth highest atmospheric deposition (3.41 kg/ha). Like with nitrate, the highest standard deviation of the wet deposition mean values was found in Olympic National Park (Figure 7).
The sulfate wet deposition values followed a similar trend to that of nitrate. The highest deposition was 15.86 kg/ha at Acadia in 2000 (Figure 9). The highest wet deposition for both nitrate and sulfate occurred in Acadia in 2000. There are two outlying values where the visitation is very high (over 3.5 million) but the annual wet deposition is under 2 kg/ha (Figure 9). This occurs at Yellowstone in 2010 and 2015.
There was a significant effect of visitation on nitrate deposition ((p=0.005; Figure 10).
Neither year (p=0.069) nor National Park (p=0.769) had a significant effect on nitrate deposition.
The r2 was 24.96% indicating that this percentage of variation within sulfate can be described by visitation. There was a significant effect (p=0.002) of visitation on sulfate deposition (Figure 9).
There was not a significant effect of either year (p=0.113) nor National Park (p=0.254) on sulfate deposition. The r2 was 25.56% indicating that this percentage of variation within nitrate can be described by visitation.
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Figure 6. Visitors per year in ten United States National Parks in 2000, 2005, 2010 and 2015.
Figure 7. Mean sulfate ion wet deposition values (kg/ha) within ten United States National Parks in 2000, 2005, 2010, and 2015. Error bars show the standard deviation within the park boundary.
0 500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 4500000
Visitors Per Year
National Park
2000 2005 2010 2015
0 2 4 6 8 10 12 14 16 18
Wet Deposition (kg/ha)
National Park
2000 2005 2010 2015
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Figure 8. Mean nitrate ion wet deposition values (kg/ha) within ten United States National Parks in 2000, 2005, 2010, and 2015. Error bars show the standard deviation within the park boundary.
Figure 9. Association between annual visitation and mean sulfate wet deposition (kg/ha) in ten United States National Parks.
0 2 4 6 8 10 12 14
Wet Depsoition (kg/ha)
National Park 2000 2005 2010 2015
0 2 4 6 8 10 12 14 16 18
0 500 1000 1500 2000 2500 3000 3500 4000 4500
Mean Yearly Wet Deposition (kg/ka)
Visitors Per Year in Thousands 2000
2005 2010 2015
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Figure 10. Association between annual visitation and mean nitrate wet deposition (kg/ha) in ten United States National Parks.
0 2 4 6 8 10 12 14
0 500 1000 1500 2000 2500 3000 3500 4000 4500
Mean Yearly Wet Deposition (kg/ha)
Visitors Per Year in Thousands 2000
2005 2010 2015
22 DISCUSSION
There are significant relationships between both sulfate and nitrate atmospheric deposition and visitation in United States National Parks. As more visitors enter the National Parks, vehicles release sulfate and nitrate emissions, increasing the deposition of these chemicals. Year was a nearly significant factor in nitrate deposition (p =0.069), suggesting measurable annual variations.
The r2 value demonstrated that 25.56% of the variation for nitrate and 24.96% of the variation for sulfate was explained by visitation numbers, however there are many other possible contributing factors. Of the five high visitation parks, two (Olympic and Acadia) are near the ocean. The ocean has a high sulfate concentration which could influence the areas in close proximity depending on the amount of precipitation (Canfield & Farquhar, 2009). Acadia is the furthest east of all ten parks, followed by Hot Springs, both high visitation parks. The eastern United States tends to have higher deposition values for both nitrate and sulfate due to higher precipitation than in the West ("Educational Resources", 2022). This could alter the results by boosting deposition within the park, though the cause is not high local traffic. Since deposition is influenced by rainfall, many of the parks in the eastern United States have higher deposition, regardless of visitation numbers. Adding longitude as a factor to be tested could yield insight on the effect of geographical location.
Olympic National Park experienced the highest standard deviation within the park boundary of the ten parks for both sulfate and nitrate. There are a few potential reasons for this.
First is the size of the park. It is the second largest of the ten parks which could contribute to higher variability of deposition. Additionally, it is the closest of the parks to a metropolitan area
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being just over a two-hour drive from Seattle, WA. Periods of easterly winds, in addition to the proximity of the ocean, could contribute to higher deviation.
For additional research, I would suggest doing this analysis on a larger scale to include more parks. Further analysis would help to further confirm the initial finding that there is
significant impact of visitation on sulfate and nitrate atmospheric deposition. More National Park sites would allow for greater diversity in the location and geography of the sites which would eliminate any potential of the data being influenced by the trends of an individual park. This could potentially increase the r2 value and better represent sources of variation. I would also potentially add an analysis of dry deposition in addition to wet. There is data to suggest that ratios of wet and dry deposition will increase with distance from the emission source (Lovett, 1994). Incorporating this as part of the analysis would help to isolate vehicle traffic within the parks as the emission source given the distance atmospheric pollutants can sometimes travel.
Nitrate is harmful to the environment as well as human health. Air pollution is a major factor contributing to the decline of forests in heavily polluted areas of Europe and North America (Gheorghe and Ion, 2011). Nitrogen oxides, such as nitrate, react with other air pollutants present in air (Gheorghe and Ion, 2011). These gases contribute to the formation of ozone in the lower atmosphere and in acidification and eutrophication processes (Gheorghe and Ion, 2011). In addition to air quality, nitrogen oxides can harm vegetation by entering the leaves through stoma, dissolving in cells and case increase in nitrate ions which are toxic in high concentrations (Gheorghe and Ion, 2011). Exposure to these gases from wet deposition, such as in this analysis, contributes to soil acidity. Nitrogen oxides can also be incredibly harmful to humans in addition to the environment. They can penetrate deep into the lungs and damage function (Gheorghe and Ion, 2011).
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Sulfates are responsible for a variety of negative effects as well. Like nitrate, sulfates contribute to acidification of surface water and soil which can be harmful for vegetation
("Sulfate & Health | California Air Resources Board", 2022). For humans, sulfate particles have health effects similar to those from exposure to PM2.5, including reduced lung function,
aggravated asthmatic symptoms and increased risk of hospitalizations and death for people with chronic heart or lung disease ("Sulfate & Health | California Air Resources Board", 2022).
Besides the relationship to sulfate and nitrate deposition, vehicles pose other problems in National Parks, especially with wildlife. As of 2007, public roads have direct and indirect ecological effects on one fifth of the United States area with the “road zone effect” which extends one hundred meters from the road (Ament, Clevenger, Yu & Hardy, 2008). Some of these effects include habitat loss, degradation and fragmentation, wildlife mortality, and
changing behaviors to avoid roads (Ament, Clevenger, Yu & Hardy, 2008). Effects are increased with larger road size, higher speed limits, and greater traffic volumes (Ament, Clevenger, Yu &
Hardy, 2008). One-fourth of the endangered and threatened species are found in the United States National Parks (Ament, Clevenger, Yu & Hardy, 2008). Endangered and threatened species, as well as migrating species are more vulnerable to road mortality (Ament, Clevenger, Yu & Hardy, 2008). Habitat can become less favorable due to the increased noise and air pollution (Ament, Clevenger, Yu & Hardy, 2008).
Some solutions to the problems associated vehicle traffic in National Parks include reservation systems, ridesharing services, bicycle rentals, and no-car access options (National Park Service U.S. Department of the Interior, 2022). Reservation systems are a relatively new tool for traffic management and have increased in popularity due to the COVID-19 pandemic.
The goal of the reservation system is to manage increasing demand while maintaining visitor
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experience and have been implemented during peak season in parks such as Acadia, Glacier, Rocky Mountain, Arches, Shenandoah, Haleakala, and Zion National Parks. Ridesharing and bicycle rentals would decrease the volume of cars within the park and reduce vehicle congestion, ultimately decreasing the amount of time people spend in their running vehicles. As of 2007, The National Park Service had 115 alternative transportation systems in 99 different park sites
including shuttles or buses, with 34 of these being water based (Ament, Clevenger, Yu & Hardy, 2008). Continued promotion and expansion of these alternatives would encourage less vehicle usage within the parks. No car access options, such as in Zion and Denali National Parks, limit the visitors to bus systems as a means of reducing the cars driving on a specific road or area.
The mission of the National Park Service is to “preserve unimpaired the natural and cultural resources and values of the national park system for the enjoyment, education, and inspiration of future generations” ("About the National Park Service", 2022). This analysis demonstrates that though this mission symbolizes an ideal, there are many unintended
consequences to preserving and protecting public lands. Vehicles and visitors within the parks do leave our resources impaired. This analysis seeks to answer one question in a much greater fabric of conservation and land use planning issues. Education of visitors and future research is needed to provide solutions that both maintain visitor experience and prioritize the diverse resources found within National Parks.
26 LITERATURE CITED
About the National Park Service. (2022). Retrieved 28 April 2022, from https://www.nps.gov/aboutus/aboutus.htm
Adeyanju, A. A., K. Manohar. Effects of Vehicular Emission on Environmental Pollution in Lagos. 2017. Sci-Afric Journal of Scientific Issues, Research and Essays: 33-51.
Ament, R., Clevenger, A., Yu, O., & Hardy, A. (2008). An Assessment of Road Impacts on Wildlife Populations in U.S. National Parks. Environmental Management, 42(3), 480- 496. doi: 10.1007/s00267-008-9112-8
Bhandarkar, S. Vehicular Pollution, Their Effect on Human Health and Mitigation Measures.
2013. Vehicle Engineering Volume 1 Issue 2: 33- 40.
Buckley, L. B., M. S. Foushee. Footprints of climate change in US national park visitation. 2011.
Int J Brimeteorol.
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