Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Regional Air Pollution Study Alissa Dickerson, M.S. Environmental Specialist Enviroscientists, Inc. Goal of Study Western Regional Air Partnership (WRAP) http://wrapair.org Causes of Haze Assessment (COHA) Goal: provide assessment of Class I areas through integrated approach www.coha.dri.edu 2 Overview Introduction Methodology Analysis Results & Discussion: Case Studies Summary 3 What is Spatial Representativeness? Area within which pollutant concentrations are approximately constant Quantitative and qualitative approach to investigate equivalency of measurements 4 Why is it important? Data assessments can determine dependence and elicit solutions Comprehensive picture of a complex system Tool to assess degree to which measured concentrations can be derived from reference points Optimal network design 5 Why is it Important? (cont.) Evaluation tool to help more efficiently in mediation of environmental problems Understanding regional visibility & reduction 6 Introduction Visibility reduction 1977 CAA USEPA Regional Haze Rule, Final (40 CFR 51, 1999) Interagency Monitoring of Protected Visual Environments = IMPROVE (1985) 5 regional organizations 7 The IMPROVE Network: Objectives Federally mandated Class I areas National parks, monuments, wilderness areas Identify current conditions of visibility Determine aerosol species and sources Document trends Cultivate representative monitoring network 8 The IMPROVE Network 163 sites 1-in-3 day sampling 4 cyclone-based modules Coarse mass & speciated fine aerosols 9 The Improve Network bext visibility Light Extinction Formula bext= 3*f(RH)[Sulfate] + 3*f(RH)[Nitrate] + 4*[Organic Carbon] + 10*[Elemental Carbon] + 1*[ Fine Soil] + 0.6*[Coarse Mass]+ 10 Concentrations [ ] Units=μg/m3 Units= Mm-1, proportional to amount of light lost over distance of 1 million meters Rayleigh Scattering= 10 Mm-1, proportional 0.0 deciviews or 400 km 10 Research Objectives Cascade Range Southern Pacific Rainforests Superior Upland North Central Lowland Plains Northern Great Plains Columbia Plateau Central Rocky Mountains Great Plains Klamath Mountains Great Basin Southern Rocky Mountains Sierra Nevada Range California Central Valleys California Coast Ranges Colorado Plateau Ouachita and Ozark Plateau Central Lowland Plains Southern California Ranges Southwest DesertsMexican Highlands Southern Great Plains West Gulf Coastal and Mississippi Alluvial Plains Determine spatial representativeness of IMPROVE monitorsWRAP WA, OR, CA, NV, ID, ND, SD, CO, AZ, NM, TX 14 Physiographic Regions 11 Considerations What are most dominant chemical species during 20% worst visibility days within a region? What are practical statistical and spatial analysis methods? How do concentrations vary by season? 12 Considerations How can expected average concentrations be determined for a region? What is a method to test validity? 13 Methodology Data 1997-2002, 54 monitors w/most complete data Six aerosol species Sulfates, nitrates, organic carbon (OC), elemental carbon (EC), fine soil, coarse mass (CM) Focus: Upper 20% of calculated visibility impairment values or 20% worst visibility days 14 Assumptions All elemental sulfur is from sulfate -> ammonium sulfate All nitrate -> ammonium nitrate Total organic carbon= C released in four steps (OC1-OC4) + pyrolized organics (OP) Thermal Optical Reflectance (TOR) analysis of quartz filter 15 Assumptions Elemental carbon (light absorbing carbon) = EC fractions (EC1-EC3) – pyrolized organics (OP) TOR analysis of quartz filter Fine soil = sum of Al, Si, K, Ca, Ti particle-induced X-ray emission (PIXE) & Fe X-ray fluorescence (XRF) Coarse mass = total mass - fine mass 16 Analysis Procedures 1) Characterize dynamics of regions Climate & meteorology: wind patterns & back-trajectory analysis (transport) Graphically displays % of time an air mass spent in an area Color coded (shading increases w/ residence) Topography: elevation & intervening terrain Emission sources and population centers 17 Analysis Procedures (cont.) 2) Regional spatial correlation analysis: correlation expected to decrease w/distance Correlation matrix of aerosol measurements Distance matrix (km) Consideration Correlation of site vs. itself = unity [Artificial]= uncertainty * random #+measurement [Artificial] plotted at distance of 0 18 Analysis (cont.) 3) Criteria correlation cut-off = 0.7 Rationalize association between monitoring sites Validation of spatial representativeness 4) Seasons Warm months: April to September Cold months: October to March 19 Analysis (cont.) 5) Expected average concentrations density (like temp.) of atmosphere varies w/ altitude [Estimated] = [aerosol]* site density density @ sea level Put conc. into elevation ranges based on natural breaks, then averaged= regional estimated conc. Uncertainty= standard deviation of average concentrations within elevation range (applicable only with 2 or more sites) 20 Analysis (cont.) 6) Test of representativeness Analyzed sites within each region Calculated seasonal average concentrations Uncertainty= average measurement uncertainty Compared to estimated concentrations 21 3.The Northern Great Plains Region Characteristics (E) Montana, (NE) Wyoming, & (W) portions of North and South Dakota Terrain: mostly prairie & rolling hills, mix of forest and grassland Badlands composed of steep buttes and pinnacles Sparse population centers Several coal-fired power plants, west-central ND 22 The N. Great Plains 6-IMPROVE sites Site Name Abbreviation Elevation (m) Badlands National Park BADL1 736 Lostwood Wilderness Area LOST1 692 Medicine Lake Wilderness Area MELA1 605 Theodore Roosevelt Nat'l Park THRO1 853 UL Bend Wilderness Area ULBE1 893 Wind Cave National Park WICA1 1300 23 Residence Time Analysis WICA1 Warm months Prevailing winds SE Bring in dry air from SW U.S. Moist warm air masses from Gulf of Mexico Few inversions 24 Residence Time Analysis MELA1 Cold months Cold continental air flowing from N/NW from Canada L system typical, flushes atmosphere 25 Aerosol Summary Average Concentration (ug/m3) Average Aerosol Concentration During the 20% Worst Visibility Days 18 16 14 CM 12 Soil 10 8 LAC OMC 6 Nitrate 4 Sulfate 2 0 BADL1 LOST1 MELA1 THRO1 ULBE1 WICA1 26 Aerosol Summary (cont.) Contribution to Bext (1/Mm) Average Contribution to Light Extinction During the 20% Worst Visibility Days 70.0 60.0 CM 50.0 Soil 40.0 LAC 30.0 OMC Nitrate 20.0 Sulfate 10.0 0.0 BADL1 LOST1 MELA1 THRO1 ULBE1 WICA1 27 Estimated Concentration (µg/m3) Elevation 500-1000m UNC 1000-1500m UNC WARM Months 0.31 0.02 0.26 0.03 COLD Months 0.30 0.03 0.22 0.00 WARM Months 0.21 0.06 0.17 0.05 COLD Months 0.71 0.27 0.34 0.10 WARM Months 1.10 0.15 1.13 0.02 COLD Months 0.52 0.07 0.44 0.01 WARM Months 0.16 0.01 0.16 0.01 COLD Months 0.13 0.01 0.11 0.01 WARM Months 0.78 0.10 0.67 0.03 COLD Months 0.37 0.03 0.29 0.06 WARM Months 7.27 0.61 4.67 0.12 COLD Months 3.27 0.19 2.08 0.12 SO4 NO3 OC EC Soil CM 28 Test Sites FOPE1 (2yr) NOCH1 (2 yr) Expected Elevation UNC 500-1000m FOPE1 UNC 638m Expected UNC 1000-1500m NOCH1 UNC 1332m SO4 WARM Months 0.31 0.02 0.32 0.02 0.26 0.03 0.28 0.01 COLD Months 0.30 0.03 0.29 0.01 0.22 0.00 0.17 0.01 WARM Months 0.21 0.06 0.21 0.03 0.17 0.05 0.20 0.02 COLD Months 0.71 0.27 0.90 0.04 0.34 0.10 0.21 0.01 WARM Months 1.10 0.15 1.08 0.29 1.13 0.02 1.51 0.34 COLD Months 0.52 0.07 0.54 0.17 0.44 0.01 0.33 0.14 WARM Months 0.16 0.01 0.14 0.01 0.16 0.01 0.19 0.02 COLD Months 0.13 0.01 0.10 0.01 0.11 0.01 0.07 0.01 WARM Months 0.78 0.10 0.26 0.02 0.67 0.03 0.28 0.02 COLD Months 0.37 0.03 0.11 0.01 0.29 0.06 0.14 0.01 WARM Months 7.27 0.61 6.62 0.20 4.67 0.12 4.79 0.15 COLD Months 3.27 0.19 2.31 0.09 2.08 0.12 1.72 0.08 NO3 OC FOPE1 30m elev. difference MELA1 [NO3]=0.9 µg/m3 EC Soil CM 29 Northern Great Plains Regional Conclusions Relatively flat terrain with good dispersion of air Atypical stagnation alleviates regional haze problems during most days SO4 representative ~ 180km Colder months show good agreement out to 700 km 30 Northern Great Plains Regional Conclusions (cont.) NO3 Rep. Distance ~ 450 km, 200km warm months Factor – chemical nature to volatilize quickly in warmer temperatures or not form at all OC Southerly located IMPROVE samplers recorded higher OC concentrations on worst visibility days Forest fire episodes Rep. distance (Southern region) ~250 km 31 Thank you Questions? 32