Western Air Quality Modeling Workshop Air quality impacts of oil and gas development in the Bakken formation region J. L. Collett, Jr. 1 , A. Evanoski ‐ Cole 1 , A. Prenni 2 , D. Day 2 , A. Sullivan 1 , Y. Li 1 , B. Sive 2 , Y. Zhou 1 , A. Hecobian 1 , J. Hand 2 , K. May 2015 Gebhart 2 , M. Schurman 1 , W. Malm 2 , and B. Schichtel 2 1. Atmospheric Science Department, Colorado State University, Ft. Collins, CO 2. NPS Air Resources Division/CIRA, Lakewood and Fort Collins, CO 1
Study Motivation • NO x emissions reductions substantially reduced PM 2.5 Western Air Quality Modeling Workshop nitrate in much of U.S. • Increasing winter nitrate, however, in some regions May 2015 • Increases in U.S. oil and gas production 2 may be relevant
Source: EPA Clean Air Markets Database Regional Power Plant Emissions Western Air Quality Modeling Workshop May 2015 Large decreases achieved in regional power plant emissions, but NO x emissions estimates for the basin suggest these are more than offset by 3 growth in oil and gas emissions. Measured NO 2 concentrations in recent years have been flat or increasing.
Bakken winter 2012/13 and 2013/14 study Western Air Quality Modeling Workshop • Particle mass May 2015 and speciation • NO x , O 3 , NH 3 , HNO 3 , SO 2 , CH 4 • Speciated VOCs 4
Summary of Pilot Study Results • Good news: O 3 concentrations were low, typical of rural sites • Bad news: High particle concentrations Western Air Quality Modeling Workshop • Multi ‐ day episodes occur across study region • Worst episodes in March during stagnant/recirculating air periods • Primarily ammonium nitrate and ammonium sulfate Calcium Ammonium Nitrate Sulfate 20 Concentration (µg m ‐ 3 ) Theodore Roosevelt North Unit (THRO ‐ N) 15 10 5 May 2015 0 20 Fort Union (FOUN) 15 10 5 5 0 2/14/13 2/21/13 2/28/13 3/7/13 3/14/13 3/21/13 3/28/13 4/4/13
Did ammonia limit NH 4 NO 3 formation? 1 FOUS THRO ‐ N Western Air Quality Modeling Workshop + + NH 3 ) 0.8 2 1 NH 3 / (NH 4 0.6 0.4 0.2 0 2/14/13 2/21/13 2/28/13 3/7/13 3/14/13 3/21/13 3/28/13 4/4/13 May 2015 • Ammonia nearly depleted in Theodore Roosevelt National Park during episode 1, but not episode 2 6 • Excess ammonia available both periods at Fort Union
Spatial patterns of methane and ethane Western Air Quality Modeling Workshop May 2015 7 Methane elevated in oil and gas production and some other regions; ethane tied more directly to oil and gas
Light alkanes at all stationary sampling sites: Markers for oil and gas Western Air Quality Modeling Workshop May 2015 8 Concentrations elevated by ~an order of magnitude. Oil and gas impacts seen at all sites.
Bakken VOC North Dakota Bakken Formation (this study) 1 NE Colorado, Denver-Julesburg Basin 2 Southwest Pennsylvania concentrations in 3 Houston shipping channel, TX 4 Mexico City, upper=in city, lower=downwind 5 SW U.S., upper=Sept. mean, lower=Apr. mean context 6 28 U.S. Cities range of means Western Air Quality Modeling Workshop 1) Swarthout et al., 2013; 2) Swarthout et al., 2014, submitted; 3) Gilman et al., 2009; 4) Apel et al., 2010; 5) Katzenstein et al., 2003; 6) Baker et al., 2008 100 Mixing Ratio (ppbv) 10 1 May 2015 0.1 0.01 Ethane Propane i-Butane n-Butane i-Pentane n-Pentane Ethyne Benzene Toluene
Pentane isomer 14 2.33 1.50 1.00 0.76 ratio as a Rural/Urban 12 1.11 Oil and Gas 10 source marker i-pentane (ppbv) 8 Western Air Quality Modeling Workshop 6 Constant i ‐ pentane 4 to n ‐ pentane ratio 2 R 2 = 1.00 suggests all sites Slope = 0.74 0 are impacted by 0 5 10 15 20 same source n-pentane (ppbv) May 2015 region during NE Colorado, Denver-Julesburg Basin Thompson Farm, Durham, NH (Oct.-May) periods of high Thompson Farm, Durham, NH (June-Sept.) Hickory, PA, Marcellus Shale concentrations. Pittsburgh, PA Detroit, MI Natural Gas (Weld County, CO) 10 Typical Urban Ratio THRO-NU FOUS MELA
Aerosol Composition, THRO‐N Western Air Quality Modeling Workshop May 2015 11 High particle concentrations in December, February, & March. Dominated by ammonium sulfate and ammonium nitrate.
Aerosol Composition at all Sites Western Air Quality Modeling Workshop May 2015 Increases in particle concentrations seen at all sites. 12
2‐Day Back Trajectories from Low Concentration Days at Main Site 2/17/13 3/9/13 12/16/13 Western Air Quality Modeling Workshop May 2015 13
2‐Day Back Trajectories from High Concentration Days at Main Site 3/6/14 12/22/13 2/15/14 Western Air Quality Modeling Workshop 2/13/14 May 2015 14
Bakken VOC reactivity Alkanes dominate . OH reactivity, due Western Air Quality Modeling Workshop to their abundance, despite their intrinsically low reactivity Nitration rates of alkanes provide a May 2015 chemical “clock” for aging 15 Bakken VOCs
Highest PM 2.5 Concentrations Correspond with Short VOC Lifetimes Western Air Quality Modeling Workshop May 2015 16
Conclusions • Decreases in NO x emissions from traditional sources have been offset by oil and gas development in the Bakken oil patch. • Oil & gas production is a major regional source of light alkanes. Western Air Quality Modeling Workshop • During air stagnation, SO 2 and NO x accumulate and are oxidized to sulfuric and nitric acids. VOC “clock” suggests that PM episodes are associated with local emissions. • Cold winter temperatures and available ammonia permit substantial NH 4 NO 3 formation. Sufficient ammonia is available to support additional PM formation if NO x emissions continue to grow. May 2015 17
Fort Union ammonia supply + NH 4 NH 3 Concentration (µg / m 2.0 1.5 1.0 0.5 0.0 3 ) NH 3 / N(-III) 1.0 0.8 0.6 0.4 0.2 0.0 11/29/13 12/6/13 12/13/13 12/20/13 12/27/13 1/3/14 1/10/14 1/17/14 1/24/14 1/31/14 2/7/14 2/14/14 2/21/14 2/28/14 3/7/14 3/14/14 3/21/14 Median Sample Time
Bakken winter 2012/13 particle composition Nitrite Chloride Sodium Potassium Magnesium Calcium Ammonium Nitrate Sulfate 20 Theodore Roosevelt North Unit (THRO ‐ N) 15 Episode 1 Episode 2 10 Concentration (µg m ‐ 3 ) 5 0 20 Fort Union (FOUN) 15 10 5 0 20 Knife River (KNRI) 15 10 5 0 20 Medicine Lake (MELA) 15 10 5 0 Sampling Date
2013/14 study shows regional haze episodes, but lower peak concentrations Ammonium 5 5 Aerosol Concentration (µg m Main Site Nitrate 4 4 3 3 Sulfate 2 2 1 1 0 0 Fort Union 5 5 4 4 3 3 2 2 1 1 0 0 Medicine 2 2 Lake 1 1 0 0 -3 ) 11/29/13 12/6/13 12/13/13 12/20/13 12/27/13 1/3/14 1/10/14 1/17/14 1/24/14 1/31/14 2/7/14 2/14/14 2/21/14 2/28/14 3/7/14 3/14/14 3/21/14 Sample Time
Main Study Aerosol at Theodore Roosevelt NP MARGA – Hourly Inorganic PM 2.5 AMS – 5 Minute Organic PM 1 Aethalometer – Black Carbon
Initial Motivation for the Study: Trends from IMPROVE data Western Air Quality Modeling Workshop May 2015 22 PM 2.5 and haze have increased since 2000, counter to national trends.
2013/14 • Fort Union (weekly in January) Measurements • Particle scattering (15 min) • Aerosol composition • Inorganic (24 hr) • Theodore Roosevelt NP Western Air Quality Modeling Workshop • Trace gases: • PM 2.5 mass (15 min; 24 hr) • SO 2 , NH 3, HNO 3 (24 hr) • Particle scattering (15 min) • VOCs (grab samples 4 days/wk) • Aerosol composition • Medicine Lake • Inorganic (24 hr, 1 hr PM 2.5 ; 15 • Particle scattering (15 min) min PM 1 ) • Aerosol composition • Organic (24 hr; 1 min PM 1 ) • Inorganic (weekly) • Black carbon (15 min, 24 hr) May 2015 • Trace gases: • Trace gases: • SO 2 , NH 3, HNO 3 (weekly) • NO x , NO y , NH 3 , CO, O 3 (15 min) • VOCs (grab samples weekly) • SO 2 , NH 3, HNO 3 (1 hr, 24 hr) • VOCs (grab samples • Mobile Measurements 23 throughout; limited PTR ‐ MS) • CH 4 (continuous) and VOCs
Pentane isomers as a source marker (Simpson et al., 2010) Western Air Quality Modeling Workshop May 2015 24 At low concentrations, greater contribution from background air or potentially Alberta oil sands.
2 day back trajectories 24 hr samples Elevated NO x , BC, and SO 2 Western Air Quality Modeling Workshop May 2015 25
2 day back trajectories 24 hr samples Low concentrations. Western Air Quality Modeling Workshop Trajectories suggest little time in Bakken region. May 2015 26
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