GEOGRAPHY OF NITRATE AND SULFATE ATMOSPHERIC WET DEPOSITION IN THE SOUTHERN ROCKY MOUNTAINS by IVAN GUILLERMO VALLES B.S., Colorado State University—Pueblo, 2005 A thesis submitted to the Graduate Faculty of the University of Colorado Colorado Springs in partial fulfillment of the requirements for the degree of Master of Arts Department of Geography and Environmental Studies 2018 © 2018 IVAN GUILLERMO VALLES ALL RIGHTS RESERVED ii This thesis for the Master of Arts degree by Ivan Guillermo Valles has been approved for the Department of Geography of Environmental Studies by Curtis D. Holder, Chair Steve Jennings Brandon Vogt Date January 27, 2018 iii Valles, Ivan Guillermo (M.A., Applied Geography) Geography of Nitrate and Sulfate Atmospheric Wet Deposition in the Southern Rocky Mountains Thesis directed by Professor Curtis Holder. ABSTRACT Data from the National Atmospheric Deposition Program’s National Trends Network, the United States Geological Survey’s Rocky Mountain Regional Snowpack Chemistry Program and the United States Environmental Protection Agency’s Air Markets Program were analyzed to identify spatial relationships amongst atmospheric wet deposition concentrations of nitrate and sulfate. The analysis relates atmospheric wet deposition, commonly known as acid rain, to two distinct variables—as a function of elevation and also as a function of proximity to major regional electricity generating stations. This study focuses on the Southern Rocky Mountain region of the United States, and integrates depositional and emissions point-source data from Arizona, Colorado, New Mexico, Utah, and Wyoming. Previous studies have identified wide-ranging adverse effects upon terrestrial and aquatic ecosystems such as nitrogen saturation, changes in plant biodiversity, and soil nutrient cycling where atmospheric wet deposition is the suspected primary means of pollutant transport and delivery. Atmospheric wet deposition then possess the ability to, in a broad sense, impair the United States’ agricultural, economic, and public health sectors; as a result, the iv United States Congress, beginning in the 1970’s had legislated a number of acts and amendments funding research focused on studying and attenuating airborne pollution. However, the spatiotemporal geography of atmospheric wet deposition has been understudied and limited in scope, especially across the Western United States’ high elevation lifezones. As a result, it is currently difficult to assess how the depositions of nitrate and sulfate will respond spatially or temporally as a function of emissions outputs of nitrous and sulfurous oxides from major regional electricity generating facilities. This research builds upon the existing geographic knowledge of atmospheric wet deposition by combining precipitation, snowpack, and emission datasets to analyze specific spatial relationships. The study concludes that levels of atmospheric wet deposition concentrations do in fact show trend changes in relation to elevation; it also finds that atmospheric wet deposition concentrations show relationships that strengthen with increased proximity to regional electricity generating stations. The significance of this research is that the spatial distribution of atmospheric wet deposition is discernible, and with improved application and design, likely capable of forecasting the phenomenon. v To Desede, Emelia, and Senen vi ACKNOWLEDGEMENTS It is with the utmost gratitude that I acknowledge so many who helped make the completion of this thesis possible in some way. I thank Dr. Brandon Vogt, whose enthusiasm for geography, from Columbine Hall to Silverton Mountain, was contagious. To Dr. Steve Jennings, who graciously agreed to join my committee late in the game yet provided invaluable suggestions from proposal through defense that well supported this work, I thank you. I also acknowledge and thank Dr. David Havlick, Dr. Emily Skop, Dr. Tom Huber, Dr. Paddington Hodza, and Dr. John Harner, for having constructively shaped my experience at UCCS in some way. And I especially thank my chair, Dr. Curt Holder, who throughout the journey was a compass in so many ways. And of course I thank my family for their support, especially Felicia, for enduring countless hours of neglect along the way... vii TABLE OF CONTENTS CHAPTER I. INTRODUCTION 1 II. LITERATURE REVIEW 6 Atmospheric Wet Deposition 7 Ecological Scope of the Atmospheric Wet Deposition Problem 9 Emission Source Areas and Deposition 11 Spatiotemporal Trends of Atmospheric Wet Deposition 14 Methodological Problems Associated with AWD Research 19 III. JUSTIFICATION & PURPOSE OF STUDY 25 IV. STUDY AREA 29 V. DATA 34 VI. METHODOLOGY 42 VII. RESULTS & OBSERVATIONS 52 Elevation and deposition—Precipitation 52 Elevation and deposition—Snowpack 58 Results 64 Spatial Relevance and Deposition 67 Results 84 VIII. DISCUSSION & CONCLUSION 87 REFERENCES 92 MAP CREDITS 97 viii DATA APPENDICES 98 EPA Facility-Level Annual Emissions 98 NTN Annual Mean Concentrations of Nitrates and Sulfates 105 RMRSCP Annual Mean Concentrations of Nitrates and Sulfates 111 ix LIST OF TABLES TABLE 1. Networks of the NADP 3 2. NTN Precipitation Chemistry sites 30 3. RMRSCP Snowpack Chemistry sites 32 4. Major electricity generating facilities utilized in study 37 5. National Emission Inventory categories and subcategories 38 6. Subareas of the study 49 x LIST OF FIGURES FIGURE 1. Subregions of the USGS’ RMRSCP 29 2. NTN Precipitation Chemistry sites 31 3. RMRSC Snowpack Chemistry sites 33 4. Map of study area major electricity generating facilities 39 5. Relative influence of generating stations in study period 40 6. Combined map of data point origins 41 7. Arc Polygon—Manitou subarea 45 8. NOAA Wind Rose Diagrams 46 9. Areal extents of arc polygon created subareas 50 10. Annual mean concentrations of nitrates in precipitation 54 11. Annual mean concentrations of sulfates in precipitation 55 12. Combined annual mean concentrations in precipitation 55 13. Long-term mean concentrations of nitrates in precipitation 57 14. Long-term mean concentrations of sulfates in precipitation 57 15. Combined long-term mean concentrations in precipitation 58 16. Annual mean concentrations of nitrates in snowpack 59 17. Annual mean concentrations of sulfates in snowpack 60 18. Combined annual mean concentrations in snowpack 60 19. Long-term mean concentrations of nitrates in snowpack 61 20. Long-term mean concentrations of sulfates in snowpack 62 21. Combined long-term mean concentrations in snowpack 62 22. Long-term concentrations—segregated trends 63 xi 23. Long-term concentrations—combined trends 64 24. NCAR 30-year Normal Precipitation: Annual 68 25. Medicine Bow subarea 69 26. Medicine Bow trends of emissions and concentrations 70 27. Rocky Mountain subarea 71 28. Rocky Mountain trends of emissions and concentrations 72 29. Grand Mesa subarea 73 30. Grand Mesa trends of emissions and concentrations 74 31. Manitou subarea 75 32. Manitou trends of emissions and concentrations 76 33. Arkansas Headwaters subarea 78 34. Ark. Headwaters trends of emissions and concentrations 79 35. San Juans subarea 80 36. San Juans trends of emissions and concentrations 81 37. Rio Grande subarea 82 38. Rio Grande trends of emissions and concentrations 83 1 CHAPTER I INTRODUCTION The Navajos are in a predicament like the one facing Appalachian coal towns and the oil and gas counties of the Dakotas: They're damned if they stick with the status quo, damned if they don't ... But this much is clear: [leaders] have sacrificed their people's air, water, land, and public health—in short, everything—for jobs and money from the coal operations. Eventually, regardless of when the plant and mine close, they'll lose those, too. —Evelyn Nieves, Sierra In the 1960s, media sources in Europe and the United States began introducing the public to a phenomenon termed “acid rain”. At the time, acid rain, the result of processes where airborne particles are captured and later deposited upon the earth’s surface by precipitation mechanisms, was poorly understood by most. However, scientific intrigue on acid rain had been mounting because of early assessments regarding air quality, which exposed abnormalities in precipitation chemistry in some regions of the world. As a result, research attention began to focus on suspected relationships between atmospheric wet deposition (AWD) and environmental health. In the United States, specific policy actions aimed at addressing air pollution were legislated in response to other air quality concerns. In 1955 the United States Congress passed the Air Pollution Control Act, which awarded funding for air pollution research. Later, it also passed the Clean Air Act of 1963 and thereafter the 1967 Air Quality Act out of a continually growing concern about national air quality and its effects upon public health. Prior to 1970, public health was the primary concern of pollution-centered 2 research. By the late 1970s, research attention began to focus on possible relationships between air quality and the degradation of terrestrial and aquatic ecosystems (Menz & Seip, 2004). Research efforts and resulting legislative actions enabled governmental and other agencies to begin establishing better techniques for monitoring air pollution. However, it was not until the 1980s and 1990s that specific amendments to the earlier legislative acts were introduced specifically aimed at monitoring and attenuating acid rain at a national level. The Acid Deposition Act of 1980 authorized the creation of the National