Impact of Changes in Oil and Gas Production ... - ACS Publications

Subscriber access provided by UNIV OF DURHAM

Article

Impact of Changes in Oil and Gas Production Activities on Air Quality in Northeastern Oklahoma – Ambient Air Studies in 2015, 2016, and 2017 Buddhadeb Ghosh Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.7b05726 • Publication Date (Web): 13 Feb 2018 Downloaded from http://pubs.acs.org on February 18, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 31

Environmental Science & Technology

1

Impact of Changes in Oil and Gas Production

2

Activities on Air Quality in Northeastern Oklahoma

3

– Ambient Air Studies in 2015, 2016, and 2017

4

Buddhadeb Ghosh*

5

Phillips 66 Research Center, Phillips 66, Highway 60 and 123, Bartlesville, Oklahoma 74003,

6

United States (Email: [email protected]; [email protected])

7

ABSTRACT: Three ground-based ambient air studies were conducted in February through

8

March of 2015, 2016, and 2017 at the Phillips 66 Research Center in Northeastern Oklahoma.

9

C2-C12 non-methane hydrocarbons (NMHCs) were measured using whole air sampling/gas

10

chromatography-mass spectrometry. In 2016 and 2017, online methane and ethane

11

measurements were also conducted. Strong methane-ethane correlation identified oil & gas

12

(O&G) upstream/midstream operations to be the primary methane source. C2-C5 alkanes were

13

the dominant NMHCs whose average mixing ratio peaked in 2016 before dropping in 2017. This

14

observation is attributed to regional O&G upstream operations, which peaked in 2015. Mean

15

mixing ratios of C2-C5 alkanes ranged from 0.99-16.99 ppb. Measured ratios of i-C5/n-C5 were

16

0.97±0.03, 1.18±0.04, and 1.06±0.02 in 2015, 2016, and 2017, respectively indicating O&G

17

upstream/midstream operations to be their primary source. Photochemical age was estimated

18

using hexane/propane ratio. Emission ratios of NMHCs at zero photochemical age were

ACS Paragon Plus Environment

1


Page 2 of 31

19

calculated, which resembled the composition reported in the literature for natural gas field

20

condensate tank flashing. Back-trajectory analysis showed that hydrocarbon-rich plumes came

21

from south/west directions where O&G upstream/midstream operations are abundant. High OH

22

reactivity values were calculated from C2-C6 alkanes mixing ratios with average reactivity for the

23

three years being 1.55, 1.88, and 1.16 s-1. This indicates that VOC emissions from O&G

24

operations may contribute to ozone production.

25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41


2

Page 3 of 31


42 43

INTRODUCTION: Volatile organic compounds (VOCs) can be emitted into the atmosphere

44

from different sources. In an urban environment, vehicle exhaust can be a major source of VOCs,

45

along with industrial and oil and gas (O&G) sources.1 Elevated levels of C2-C5 alkanes typically

46

indicate emissions from O&G upstream/midstream operations, which include oil and gas

47

production and natural gas/natural gas liquids (NGL) processing but exclude downstream

48

processes such as refining, hereafter referred to as O&G operations.2-6 Alkenes and aromatics

49

usually originate from vehicle emissions in urban areas.1,

50

propene have also been found to be emitted from petrochemical facilities in places like Houston.7

51

Among aromatic compounds, benzene is usually emitted from vehicle exhaust.1 However, other

52

fossil fuel sources may also contribute to benzene emissions.4,

53

tracers of different emission sources can be used to identify these sources. Ethane and propane

54

are emitted from O&G operations and are well known tracers for such sources,2,

55

unsaturated compounds such as ethyne and ethene as well as carbon monoxide, are produced

56

during combustion processes and are tracers for vehicle exhaust.1, 4

57

Certain VOCs such as benzene and 1,3-butadiene are hazardous to human health .12, 13All non-

58

methane hydrocarbons (NMHCs) can undergo photochemical oxidation in the presence of NOx

59

to produce ozone.14 Photochemical ozone has traditionally been an urban issue relevant for cities

60

like Los Angeles and Houston where vehicular and industrial emissions are the primary sources

61

of VOCs.7, 14 In recent years, however, high levels of wintertime ozone have been observed in

62

rural areas in Wyoming, Utah, and Colorado where the primary VOC sources are O&G

63

operations.15-17 Given the health hazards and air quality impact of VOC emissions, it is important

6

Certain alkenes like ethene and

8-10

Correlation with chemical

4, 6, 11

while


3


Page 4 of 31

64

to identify VOC emission sources and their role in regional air quality, which can be useful in

65

creating sound environmental regulations.

66

Unlike many NMHCs, over 50% of methane emissions in the US originate from a variety of

67

biogenic sources such as animal agriculture, landfills, and wetlands,18 while natural gas and

68

petroleum systems account for 31% of methane emission as methane is the primary component

69

of natural gas.18 Because methane is an important greenhouse gas, distinguishing its biogenic

70

emission sources from O&G sources can be useful in environmental policymaking. Methane

71

emissions from O&G sources are accompanied by other light alkanes such as ethane and propane

72

while biogenic emissions of methane contain little additional light alkanes. This can be exploited

73

to identify methane emissions from O&G sources.19-21

74

An air research program was developed at the Phillips 66 Research Center (PRC) in 2014 to

75

study regional air quality. To that end, three ground-based field studies were conducted during

76

February-March of 2015, 2016, and 2017 at PRC (36.74oN, 96.00oW) in Bartlesville in

77

Northeastern Oklahoma. NMHCs in ambient air were analyzed using whole air sampling

78

followed by offline analysis. During the 2016 and 2017 studies, methane and ethane were also

79

measured using online instrumentation. Oklahoma has a high concentration of O&G wells;

80

however, there has been only a handful of air quality studies conducted in this region.1,

81

Importantly, the two studies conducted in this region by Baker et al.1 and Katzenstein et al.3 took

82

place prior to the significant increase in O&G operations over the last decade. The current study

83

aims to bridge the gap. The goals of the current study were (1) measure VOCs observed in

84

ambient air and identify their primary emission source and (2) understand the air quality impact

85

of VOC emissions. The results from 2015, 2016, and 2017 campaigns are reported here.

3


4

Page 5 of 31


86

METHODS:

87

PRC is located northeast of Anadarko Basin, north/northwest of Arkoma Basin, and near the

88

center of Cherokee Platform Basin. Given the proximity to O&G fields, there is a high

89

abundance of oil and gas wells west and south of this site (Figure 1).

90

Ambient Air Sampling:

91

Ambient air was sampled at the ground level using evacuated 6-L canisters (Entech Instruments)

92

equipped with flow controllers (Entech Instruments) for time-integrated sampling. The canisters

93

were also equipped with timers containing solenoid valves (Nutech) for automated sampling at

94

predetermined times. During the 2015 campaign, a combination of two-hour and six-hour flow

95

controllers was used for whole air sampling to collect a total of 238 samples during the study

96

period between February 23 and April 5, 2015. During the 2016 and 2017 campaigns, only two-

97

hour time integrated sampling was conducted throughout the study period stretching from

98

February 25 to April 1 in 2016 and February 2 to March 11 in 2017. A total of 375 and 388

99

canisters, respectively, were collected during these time periods.

100

Offline Analysis of Whole Air Samples using GC-MS

101

A preconcentrator (7200, Entech Instruments) was used for sample preparation prior to analysis

102

by gas chromatography-mass spectrometry (GC-MS). Air samples were prepared using three

103

stages of trapping in the preconcentrator and subsequently injected directly into the GC column

104

inside an Agilent 7890 GC interfaced with an Agilent 5975 MS. A 100% dimethylpolysiloxane

105

DB-1 column of 60 m x 0.32 mm O.D., 1-µm film thickness (Agilent J&W) was used in the GC.

106

The instrument parameters were optimized for analysis of C2-C12 hydrocarbons. Electron impact


5


Page 6 of 31

107

(EI) ionization mass spectra of the eluted compounds were recorded by the mass spectrometer.

108

Identification of major constituents was performed via manual interpretation of the

109

corresponding mass spectra, facilitated by comparison with NIST standard reference spectra.22

110

The instruments were calibrated using a commercially available PAMS calibration mix (Restek).

111

The details of sample preconcentration and analysis are discussed in the Supporting Information.

112

Online Analysis of Ambient Air

113

In 2016 and 2017, methane, ethane, CO, CO2, N2O, and H2O were measured in real time using a

114

dual quantum cascade laser (QCL) trace gas analyzer (Aerodyne) operating at 1 Hz. The

115

instrument works on the principle of tunable infrared laser differential absorption spectroscopy

116

(TILDAS), which has been described in detail elsewhere.21, 23-25 Only the salient features relevant

117

to the current study are described here. The instrument employed two tunable QCLs in the mid-

118

IR region. The first laser operated at a wavelength range near 2230 cm-1 and detected CO, CO2,

119

N2O, and H2O while the second laser, operating near 3000 cm-1, detected methane and ethane.

120

The instrument was zeroed every 30 min by flowing ultra-zero air (Airgas) through the cell. The

121

ultra-zero air contained a trace level of CO, which was removed with a sorbent prepared in

122

house.

123

Meteorological Data

124

Meteorological data were collected using a meteorological station (Davis) installed on top of a

125

building onsite (12 m AGL).

126

RESULTS AND DISCUSSION:


6

Page 7 of 31


127

Use of Ethane to Identify Methane Emission Sources. As discussed earlier, a strong

128

correlation between ethane and methane mixing ratios would imply that methane has originated

129

from O&G sources while a lack of correlation would indicate the presence of biogenic methane.

130

Methane and ethane mixing ratios were measured during the 2016 and 2017 campaigns at 1 Hz

131

resolution and later averaged to 10 s for convenience of data handling. The scatter plot of ethane

132

and methane (Figure 2) demonstrates strong correlation with an r2 of 0.87 in 2016 and 0.73 in

133

2017 for the complete dataset representing the entire study periods. This indicates that methane

134

plumes were emitted from O&G sources. As methane mixing ratios are typically two orders of

135

magnitude higher than ethane mixing ratios in the ambient air, the enhancement ratio of ethane to

136

methane is represented in percentage. The enhancement ratios obtained from their scatter plot

137

were 5.1±0.007% and 3.93±0.009% for 2016 and 2017 (error bars represent 2 standard

138

deviations of the linear fit). The average ethane content was 4.9% and 3.8% of methane in 2016

139

and 2017. The datasets have been color coded with the corresponding date and time. The total

140

dataset is comprised of individual plumes with strong correlations (r2>0.95) but widely varying

141

ethane content ranging between a few percent to over 20%. High ethane content indicates “wet”

142

emission sources (i.e. a methane source containing condensable higher alkanes, C2, C3, C4, etc.)

143

whereas low ethane content signifies “dry” sources. An order of magnitude variation in ethane

144

content indicates that methane plumes originated from a wide variety of O&G sources. A small

145

segment of data shows negligible ethane content of 2.41 Baker et al conducted a similar study between 1999 and 2005 in 28 US cities

224

and obtained an average i-C5/n-C5 ratio of 2.27.1 A comparison with these literature values

225

strongly indicates that the NMHC encountered in this study originated from O&G operations.

226

Wind Directions and Mixing Ratios

227

Southern wind predominated during the campaigns in all three years. The second most

228

predominant wind contribution came from northeast in 2015 and 2017 and from northwest in

229

2016. Several clean air masses as well as plumes with high abundance of NMHC were

230

encountered during the studies. Time series of C1-C5 alkanes are provided in Supporting

231

Information (Figure S3, S4, and S5). In all three years, elevated NMHC levels were observed

232

almost exclusively in the southern/western wind (Figure 5). A more detailed understanding of

233

regional air transport was obtained by calculating 72 hour back trajectories for the PRC at 1 m

234

AGL using NOAA Air Resources Laboratory Hybrid Single Particle Lagrangian Integrated

235

Trajectory Model (HYSPLIT).42,

236

agreement with the local meteorological data showing hydrocarbon-rich plumes traveled through

237

south and west directions of PRC. Wind coming from south and west would travel through

238

regions with a high density of O&G operations (Figure 1) and consequently will be enriched in

239

light alkanes. This is consistent with observations in this study.

240

Estimation of Emission Ratios using Photochemical Age Calculation

43

The results (Figure S6, Supporting Information) are in


11


Page 12 of 31

241

The atmospheric decay of a VOC can be attributed to its chemical conversion and dilution. The

242

ratios of any two VOCs emitted from the same source, however, will primarily be controlled by

243

their atmospheric reactivities as they will be similarly affected by dilution.44 Their ratios will

244

change during transport as more reactive species will decay faster than less reactive species. The

245

measured ratio of two VOCs in the atmosphere, therefore, will depend on their residence time in

246

the atmosphere, which is called their photochemical age. Photochemical age can be estimated

247

using a simple model provided the following assumptions are true:44-46

248

I.

249

VOCs are emitted from sources with the same composition upwind of the measurement location

250

II.

Background air has a negligible concentration of VOCs

251

III.

VOCs react exclusively with OH radicals

252

These assumptions have reasonable validity for the dataset used in this study. Within the

253

uncertainties of measurement, VOCs appear to share a common source, O&G operations, as

254

demonstrated by the strong correlation among C2-C5 VOCs, pentane ratios, and wind patterns.

255

Background air has negligible contribution to the VOC levels, as shown in the time-series data in

256

Figures S3, S4, and S5 in Supporting Information. Reactions with OH would be the dominant

257

loss mechanism for the VOCs under consideration; i.e., alkanes and cycloalkanes.

258

Considering the above assumptions, atmospheric decay of the ratio of two VOCs, A and B, can

259

be described as:

260

݈݊ ቀ

[஺] | ቁ [஻] ௧ୀ௧

[஺]

= ݈݊ ቀ[஻] |௧ୀ଴ ቁ − ሺ݇஺ − ݇஻ ሻ[ܱ‫ݐ∆]ܪ‬

(1)

261 262

kA and kB = Rate coefficients for reaction of OH radical with A and B

263

[A]t and [B]t = Ambient mixing ratios of A and B at the measurement location at time t


12

Page 13 of 31


264

[A]0 and [B]0 = Mixing ratios of A and B at the emission source at time zero

265

∆t = Photochemical age

266

Light alkanes were the dominant class of compounds encountered during this study. Therefore,

267

the ratio of hexane and propane were used to estimate photochemical age. The above equation

268

can be re-written as:

269

∆‫= ݐ‬

ଵ

[ைு]ሺ௞ಹ೐ೣೌ೙೐ ି௞ುೝ೚೛ೌ೙೐ ሻ

[ு௘௫௔௡௘]

[ு௘௫௔௡௘]

× ቂ݈݊ ቀ[௉௥௢௣௔௡௘] |௧ୀ଴ ቁ − ݈݊ ቀ[௉௥௢௣௔௡௘] |௧ୀ௧ ቁቃ

(2)

270 271

As shown in equation 2, photochemical age can be determined using the observed ratio of

272

hexane and propane, ([Hexane]/[Propane])t=t, and the ratio at which they were emitted from the

273

source at time zero, ([Hexane]/[Propane])t=0, i.e. their emission ratio. The emission ratio can be

274

approximated to equal the observed ratio for a fresh plume with a low photochemical age.45, 46 As

275

the OH reaction rate coefficient for hexane (kHexane=5.2ᵡ10-12 cm3 molecule-1 s-1) is

276

approximately five times higher than that of propane (kPropane=1.1ᵡ10-12 cm3 molecule-1 s-1),47

277

their ratio decays with aging. In the absence of any prior knowledge on emission ratio of hexane

278

and propane, their highest observed ratio was approximated as the emission ratio. Error

279

associated with choosing the hexane/propane emission ratio in this way would introduce an error

280

in analysis, which is discussed in detail in the supporting information (Figure S7, Supporting

281

Information).

282

Once the photochemical age is calculated for each sample, the ratio of a VOC with propane can

283

be plotted against the photochemical age. Such plots for butane and 2-methylpentane for 2015,

284

2016, and 2017 are shown in Figure 6 (a.1, b.1, and c.1). The reactivity of butane (kOH=2.4ᵡ10-12

285

cm3 molecule-1 s-1) is similar to propane. Therefore, the ratio of butane and propane decays


13


Page 14 of 31

286

slowly, as explained by equation 1. In contrast, 2-methylpentane (kOH=5.2ᵡ10-12 cm3 molecule-1 s-

287

1

288

Effect of photochemical aging on VOCs is also found in their scatter plots, color-coded with

289

corresponding photochemical age (Figure 6). The scatter plots of butane with propane (a.2, b.2,

290

and c.2) demonstrate strong linearity as butane and propane decay similarly with photochemical

291

aging. Other compounds with reactivities similar to butane (i.e., ≤C5 alkanes) also exhibit tight

292

correlations with propane. However, scatter plots for 2-methylpentane with propane (a.3, b.3,

293

and c.3) display some non-linearity. Data points at higher photochemical age exhibit a lower

294

ratio of 2-methylpentane and propane as 2-methylpropane has a much shorter atmospheric

295

lifetime than propane and gets preferentially removed over time. Other compounds with high

296

reactivity similar to 2-methylpentane (i.e., cycloalkanes and ≥C6 alkanes) also demonstrate

297

similar behavior.

298

The intercept of a linear fit to a plot of VOC/propane ratio against photochemical age (Figure 6;

299

a.1, b.1, and c.1) corresponds to the ratio at zero photochemical age; i.e., at the emission source.

300

The emission ratios for selected alkanes from the study were calculated and are provided in

301

Figure 7 and Table S1 (Supporting Information). Emission ratios reported for Uintah Basin by

302

Western Regional Air Partnership (WRAP)48 and measured by Warneke et al.49 are also provided

303

for comparison. The emission ratios estimated in this work qualitatively match with the

304

composition of natural gas field condensate tank flashing. As Utah/Colorado and Oklahoma

305

regions are parts of different basins, the crude/natural gas composition of Uintah Basin is not

306

expected to be identical to those found in the Oklahoma basins (Figure S8, Supporting

307

Information). Acknowledging this difference, the resemblance of the composition calculated in

308

this work to that reported by WRAP is noteworthy. Therefore, this analysis predicts that a

) is considerably more reactive than propane and its ratio with propane has a much faster decay.


14

Page 15 of 31


309

significant portion of emissions encountered in this study originated from natural gas field

310

condensate tank flashing, with other sources like oil tank flashing and conventional gas/gas well

311

pad possibly playing a small role.

312 313

OH Reactivity

314

OH-radical-initiated oxidation of VOCs leads to the formation of tropospheric ozone. While the

315

extent of ozone formation depends on multiple factors including NOx concentration, the potential

316

of a VOC to form ozone can be estimated by calculating its OH reactivity.

317

The OH reactivity of a VOC “A” (ROH-A) is obtained from its mixing ratio ([A]) and OH reaction

318

rate coefficient (kOH-A):

319

R ୓ୌି୅ = ݇ைுା஺ [A]

(3)

320

Using mixing ratios measured in this work and rate coefficients reported in the literature,26 OH

321

reactivity was calculated for C2-C6 alkanes (Table S2, Supporting Information). As these alkanes

322

are primarily emitted from O&G operations, their OH reactivity helps in understanding the

323

potential impact of O&G operations on ozone production. The minimum OH reactivity values

324

from C2-C6 alkanes in 2015, 2016, and 2017 were 0.32, 0.43, and 0.44 s-1, which signify

325

relatively cleaner background conditions. Average OH reactivity values from this class of

326

compounds were 1.55, 1.88, and 1.16 s-1 in these years while the maximum values were 14.8,

327

18.9, and 6.48 s-1. These values are similar to the OH reactivity of 1.81 s-1 reported for total

328

alkane at BAO.6 This is also comparable to the total OH reactivity of 7.25 s-1 reported for total

329

VOCs in Houston and Galveston Bay.47 Results from this work indicate that alkane emissions


15


Page 16 of 31

330

from O&G activity can potentially contribute to ozone production in the region. Given the longer

331

atmospheric lifetimes of alkanes, they will likely contribute to ozone production downwind.

332 333 334

ASSOCIATED CONTENT

335

Supporting Information

336

A description of measurement location, a detailed discussion of the analysis of sampled air, a

337

graph showing diurnal profiles of propane during the study, a graph of mean C2-C4 alkane

338

mixing ratios measured in this work and reported in literature along with O&G production

339

metrics, a graph of C2-C5 alkane time series in 2015, a graph of C1-C5 alkane time series in 2016,

340

a graph of C1-C5 alkane time series in 2017, a description of back-trajectory analysis, a figure of

341

back-trajectories calculated for representative polluted plumes in 2015,2016, and 2017, a detailed

342

discussion on the effect of uncertainties in input parameters in photochemical age estimation, a

343

graph of butane/propane and 2-methylpentane/propane plotted against photochemical age

344

calculated with different values of ([hexane]/[propane])0, a table of calculated emission ratios of

345

selected alkanes and propane at zero photochemical age in 2015, 2016, and 2017, a graph

346

showing composition of crude oil from Colorado and Oklahoma regions, and a table of

347

calculated OH reactivity for C2-C6 alkanes in 2015, 2016, and 2017. This information is available

348

free of charge on the ACS Publications website at http://pubs.acs.org/.

349

AUTHOR INFORMATION


16

Page 17 of 31


350

Corresponding Author

351

Buddhadeb Ghosh. Telephone: 001-918-977-4632. Email: [email protected],

352

[email protected]

353 354

Notes

355

The author declares no competing financial interest.

356

ACKNOWLEDGMENTS

357

The author thanks Joost A. de Gouw and Jessica Gilman (NOAA) for helpful discussions. The

358

author thanks Ryan Fitzpatrick, Dan Nielsen, and Jeff Bean (Phillips 66) for help with writing

359

macros for data analysis. The author thanks Neal McDaniel (Phillips 66) for synthesizing a

360

sorbent for removal of CO from ultra-zero air needed for zeroing instrument. The author thanks

361

Rebecca McFarland, Jennifer Murphy, and Irby Bailey (Phillips 66) for help with the field work.

362

The author gratefully acknowledges the NOAA Air Resources Laboratory (ARL) for the

363

provision of the HYSPLIT transport and dispersion model and READY website

364

(http://www.ready.noaa.gov) used in this publication.


17


Page 18 of 31

TOC/Abstract Art


18

Page 19 of 31


FIGURES

Figure 1. Location of the study site, Phillips 66 Research Center, in northeast Oklahoma is shown using a black star. The site is located northeast of Anadarko basin, north/northwest of Arkoma basin, and near the center of Cherokee Platform basin. The site is located at the eastern edge of a large area with high concentration of oil and gas wells (drilling data and underlying map courtesy of Energy Information Administration, EIA).


19


Page 20 of 31

Figure 2. Scatter plots of ethane (a tracer for O&G operations) and methane mixing ratios in 2017 (a) and 2016 (b) showing strong overall correlation with r2 values of 0.73 and 0.87, respectively. The average ethane/methane enhancement ratios (ER) in 2017 and 2016 are 3.93±0.009% and 5.1±0.007% (error bars represent 2σ standard deviation of the linear fit). The datasets consist of segments of data with varying ethane content while small segments of data show no ethane to methane correlation signifying biogenic contribution.


20

Page 21 of 31


Figure 3. Box plots displaying maximum, 75th, 50th, 25th, and minimum mixing ratios for major VOCs from 2015 (a.1), 2016 (b.1), and 2017 (c.1). Mean mixing ratios for this work as well as Southwestern United States (2003),3 Oklahoma City (2007),1 Houston (2009),47 and BAO (2013)2 are provided for comparison. Scatter plots of ethane, butane, and pentane with propane are also shown for 2015 (a.2), 2016 (b.2) and 2017 (c.2). High r2 values for these scatter plots indicate strong correlation among C2-C5 alkanes and consequently a common source for them.


21


Page 22 of 31

Figure 4. Scatter plots of 2-methylbutane and pentane measured during this study in 2015, 2016, and 2017 that resulted in enhancement ratios (ER) of 0.97±0.03, 1.18±0.04, and 1.06±0.02, where the error bars represent 2σ uncertainty. These results are similar to results reported from studies of O&G emission sources (ER = 0.885 from Gilman et al.2 and ER = 1.21 from Simpson et al.37) and are significantly different from urban emission sources (ER = 2.27, Baker et al.1).


22

Page 23 of 31


Figure 5. Wind rose plots depicting the relationship of mixing ratios for propane, a marker for O&G operations, and wind directions for campaigns in 2015, 2016, and 2017. High propane mixing ratios were primarily observed in wind coming from the directions of O&G operations in south and west.


23


Page 24 of 31

Figure 6. Ratio of butane and 2-methylpentane with propane plotted against photochemical age (a.1, b.1, and c.1) demonstrate the effect of their reactivities on the evolution of their ratios. The intercept of a linear fit to the plots provide the emission ratio at zero photochemical age. The color-coded scatter plots of butane (a.2, b.2, and c.2) and 2-methylpentane (a.3, b.3, and c.3) against propane demonstrates how photochemical aging affects the linearity of these plots.


24

Page 25 of 31


Figure 7. Emission ratios of VOCs with propane estimated at zero photochemical age from data collected during 2015, 2016, and 2017. For comparison, emission ratios reported in WRAP inventory and by Warneke et al. (2014) are also provided.49


25


Page 26 of 31

Table 1. Summary of Mixing Ratios (in ppb) for Major VOCs from 2015, 2016, and 2017 of this Work and Literature.

2015 (n=237) Compound

2016 (n=375)

2017 (n=388)

OK*

SWUS†

Mean

Median

Max

Mean

Median

Max

Mean

Median

Max

Mean

Mean

-

-

-

2136

2014

4073

2148

2049

4160

1810

1850

Ethane

16.04

7.75

163.4

16.47

8.02

164.1

13.42

9.16

97.04

4.42

3.4

Propane

11.48

6.03

125.1

16.99

6.71

245.1

6.90

5.41

49.07

3.17

1.6

2-methylpropane

4.23

1.43

64.76

3.91

1.42

81.89

1.94

1.21

15.67

1.7

0.29

Butane

4.06

2.13

38.57

5.55

2.29

79.48

3.20

2.46

31.73

0.6

0.59

C2-C4 Alkanes‡

33.45

15.39

352.9

41.37

19.29

516.8

24.57

17.91

134.9

9.89

5.88

2-methylbutane

1.82

0.91

17.81

2.18

1.19

21.73

1.15

0.92

9.98

1.22

Pentane

1.53

0.65

18.44

1.89

1.16

16.45

0.95

0.71

9.37

0.7

Cyclopentane

0.31

0.27

1.35

0.46

0.41

1.53

0.36

0.35

0.70

-

2-methylpentane

0.47

0.27

5.07

0.47

0.32

3.41

0.41

0.37

2.18

-

Hexane

0.55

0.31

6.51

0.62

0.43

3.96

0.45

0.40

2.59

0.26

Methylcyclopentane

0.47

0.30

4.64

0.36

0.24

2.56

0.42

0.39

1.91

-

Benzene

0.39

0.29

3.75

0.35

0.32

1.33

0.36

0.34

1.37

0.19

Methane

n = Number of ambient air samples collected. Total mixing ratio of C2-C4 alkanes, i.e. ethane, propane, 2-methylpropane, and butane. * Oklahoma City, Oklahoma- Baker et al.1 † Southwestern United States (Texas, Oklahoma, and Kansas)- Katzenstein et al.3 ‡


26

Page 27 of 31


REFERENCES 1. Baker, A. K.; Beyersdorf, A. J.; Doezema, L. A.; Katzenstein, A.; Meinardi, S.; Simpson, I. J.; Blake, D. R.; Sherwood Rowland, F., Measurements of Nonmethane Hydrocarbons in 28 United States Cities. Atmos. Environ. 2008, 42, (1), 170-182. 2. Gilman, J. B.; Lerner, B. M.; Kuster, W. C.; de Gouw, J. A., Source Signature of Volatile Organic Compounds from Oil and Natural Gas Operations in Northeastern Colorado. Environ. Sci. Technol. 2013, 47, (3), 1297-1305. 3. Katzenstein, A. S.; Doezema, L. A.; Simpson, I. J.; Blake, D. R.; Rowland, F. S., Extensive regional atmospheric hydrocarbon pollution in the southwestern United States. Proc Natl Acad Sci U S A. 2003, 100, (21), 11975-11979. 4. Pétron, G.; Frost, G.; Miller, B. R.; Hirsch, A. I.; Montzka, S. A.; Karion, A.; Trainer, M.; Sweeney, C.; Andrews, A. E.; Miller, L.; Kofler, J.; Bar-Ilan, A.; Dlugokencky, E. J.; Patrick, L.; Moore, C. T.; Ryerson, T. B.; Siso, C.; Kolodzey, W.; Lang, P. M.; Conway, T.; Novelli, P.; Masarie, K.; Hall, B.; Guenther, D.; Kitzis, D.; Miller, J.; Welsh, D.; Wolfe, D.; Neff, W.; Tans, P., Hydrocarbon emissions characterization in the Colorado Front Range: A pilot study. J Geophys Res-Atmos 2012, 117, (D4), D04304. 5. Pétron, G.; Karion, A.; Sweeney, C.; Miller, B. R.; Montzka, S. A.; Frost, G. J.; Trainer, M.; Tans, P.; Andrews, A.; Kofler, J.; Helmig, D.; Guenther, D.; Dlugokencky, E.; Lang, P.; Newberger, T.; Wolter, S.; Hall, B.; Novelli, P.; Brewer, A.; Conley, S.; Hardesty, M.; Banta, R.; White, A.; Noone, D.; Wolfe, D.; Schnell, R., A new look at methane and nonmethane hydrocarbon emissions from oil and natural gas operations in the Colorado Denver-Julesburg Basin. J Geophys Res-Atmos 2014, 119, (11), 6836-6852. 6. Swarthout, R. F.; Russo, R. S.; Zhou, Y.; Hart, A. H.; Sive, B. C., Volatile organic compound distributions during the NACHTT campaign at the Boulder Atmospheric Observatory: Influence of urban and natural gas sources. J Geophys Res-Atmos 2013, 118, (18), 10,614-10,637. 7. Ryerson, T. B.; Trainer, M.; Angevine, W. M.; Brock, C. A.; Dissly, R. W.; Fehsenfeld, F. C.; Frost, G. J.; Goldan, P. D.; Holloway, J. S.; Hübler, G.; Jakoubek, R. O.; Kuster, W. C.; Neuman, J. A.; Nicks, D. K.; Parrish, D. D.; Roberts, J. M.; Sueper, D. T.; Atlas, E. L.; Donnelly, S. G.; Flocke, F.; Fried, A.; Potter, W. T.; Schauffler, S.; Stroud, V.; Weinheimer, A. J.; Wert, B. P.; Wiedinmyer, C.; Alvarez, R. J.; Banta, R. M.; Darby, L. S.; Senff, C. J., Effect of petrochemical industrial emissions of reactive alkenes and NOx on tropospheric ozone formation in Houston, Texas. J Geophys Res-Atmos 2003, 108, (D8), 4249. 8. Chambers, A. K.; Strosher, M.; Wootton, T.; Moncrieff, J.; McCready, P., Direct Measurement of Fugitive Emissions of Hydrocarbons from a Refinery. J. Air Waste Manage. Assoc. 2008, 58, (8), 1047-1056. 9. Halliday, H. S.; Thompson, A. M.; Wisthaler, A.; Blake, D. R.; Hornbrook, R. S.; Mikoviny, T.; Müller, M.; Eichler, P.; Apel, E. C.; Hills, A. J., Atmospheric benzene observations from oil and gas production in the Denver-Julesburg Basin in July and August 2014. J Geophys Res-Atmos 2016, 121, (18), 2016JD025327. 10. Howard, T.; Lamb, B. K.; Bamesberger, W. L.; Zimmerman, P. R., Measurement of Hydrocarbon Emissions Fluxes from Refinery Wastewater Impoundments Using Atmospheric Tracer Techniques. J. Air Waste Manage. Assoc. 1992, 42, (10), 1336-1344.


27


Page 28 of 31

11. Helmig, D.; Thompson, C. R.; Evans, J.; Boylan, P.; Hueber, J.; Park, J. H., Highly Elevated Atmospheric Levels of Volatile Organic Compounds in the Uintah Basin, Utah. Environ. Sci. Technol. 2014, 48, (9), 4707-4715. 12. Health Assessment of 1,3-Butadiene, Office of Research and Development, United States Environmental Protection Agency, Washington, DC, 2002, EPA/600/P-98/001F, https://cfpub.epa.gov/ncea/iris/iris_documents/documents/supdocs/butasup.pdf (accessed July 5, 2017). 13. Toxicological Profile for Benzene, United States Public Health Service, United States Department of Health and Human Services, Atlanta, GA, 2007, https://www.atsdr.cdc.gov/toxprofiles/tp3.pdf (accessed July 5, 2017). 14. Calvert, J. G., Hydrocarbon involvement in photochemical smog formation in Los Angeles atmosphere. Environ. Sci. Technol. 1976, 10, (3), 256-262. 15. Edwards, P. M.; Brown, S. S.; Roberts, J. M.; Ahmadov, R.; Banta, R. M.; deGouw, J. A.; Dube, W. P.; Field, R. A.; Flynn, J. H.; Gilman, J. B.; Graus, M.; Helmig, D.; Koss, A.; Langford, A. O.; Lefer, B. L.; Lerner, B. M.; Li, R.; Li, S.-M.; McKeen, S. A.; Murphy, S. M.; Parrish, D. D.; Senff, C. J.; Soltis, J.; Stutz, J.; Sweeney, C.; Thompson, C. R.; Trainer, M. K.; Tsai, C.; Veres, P. R.; Washenfelder, R. A.; Warneke, C.; Wild, R. J.; Young, C. J.; Yuan, B.; Zamora, R., High winter ozone pollution from carbonyl photolysis in an oil and gas basin. Nature 2014, 514, (7522), 351-354. 16. McDuffie, E. E.; Edwards, P. M.; Gilman, J. B.; Lerner, B. M.; Dubé, W. P.; Trainer, M.; Wolfe, D. E.; Angevine, W. M.; deGouw, J.; Williams, E. J.; Tevlin, A. G.; Murphy, J. G.; Fischer, E. V.; McKeen, S.; Ryerson, T. B.; Peischl, J.; Holloway, J. S.; Aikin, K.; Langford, A. O.; Senff, C. J.; Alvarez, R. J.; Hall, S. R.; Ullmann, K.; Lantz, K. O.; Brown, S. S., Influence of oil and gas emissions on summertime ozone in the Colorado Northern Front Range. J Geophys Res-Atmos 2016, 121, (14), 8712-8729. 17. Schnell, R. C.; Oltmans, S. J.; Neely, R. R.; Endres, M. S.; Molenar, J. V.; White, A. B., Rapid photochemical production of ozone at high concentrations in a rural site during winter. Nature Geosci 2009, 2, (2), 120-122. 18. Overview of Greenhouse Gases, United States Environmental Protection Agency, https://www.epa.gov/ghgemissions/overview-greenhouse-gases (accessed June 29, 2017). 19. Miller, S. M.; Wofsy, S. C.; Michalak, A. M.; Kort, E. A.; Andrews, A. E.; Biraud, S. C.; Dlugokencky, E. J.; Eluszkiewicz, J.; Fischer, M. L.; Janssens-Maenhout, G.; Miller, B. R.; Miller, J. B.; Montzka, S. A.; Nehrkorn, T.; Sweeney, C., Anthropogenic emissions of methane in the United States. Proc Natl Acad Sci U S A. 2013, 110, (50), 20018-20022. 20. Peischl, J.; Ryerson, T. B.; Brioude, J.; Aikin, K. C.; Andrews, A. E.; Atlas, E.; Blake, D.; Daube, B. C.; de Gouw, J. A.; Dlugokencky, E.; Frost, G. J.; Gentner, D. R.; Gilman, J. B.; Goldstein, A. H.; Harley, R. A.; Holloway, J. S.; Kofler, J.; Kuster, W. C.; Lang, P. M.; Novelli, P. C.; Santoni, G. W.; Trainer, M.; Wofsy, S. C.; Parrish, D. D., Quantifying sources of methane using light alkanes in the Los Angeles basin, California. J Geophys Res-Atmos 2013, 118, (10), 4974-4990. 21. Yacovitch, T. I.; Herndon, S. C.; Roscioli, J. R.; Floerchinger, C.; McGovern, R. M.; Agnese, M.; Pétron, G.; Kofler, J.; Sweeney, C.; Karion, A.; Conley, S. A.; Kort, E. A.; Nähle, L.; Fischer, M.; Hildebrandt, L.; Koeth, J.; McManus, J. B.; Nelson, D. D.; Zahniser, M. S.; Kolb, C. E., Demonstration of an Ethane Spectrometer for Methane Source Identification. Environ. Sci. Technol. 2014, 48, (14), 8028-8034.


28

Page 29 of 31


22. NIST Chemistry WebBook, NIST Standard Reference Database Number 69, United States Department of Commerce, National Institute of Standards and Technology, (accessed 23. Fried, A.; Henry, B.; Wert, B.; Sewell, S.; Drummond, J. R., Laboratory, ground-based, and airborne tunable diode laser systems: performance characteristics and applications in atmospheric studies. Appl. Phys. B 1998, 67, (3), 317-330. 24. Güllük, T.; Wagner, H. E.; Slemr, F., A high-frequency modulated tunable diode laser absorption spectrometer for measurements of CO2, CH4, N2O, and CO in air samples of a few cm3. Rev. Sci. Instrum. 1997, 68, (1), 230-239. 25. Zahniser, M. S.; Nelson, D. D.; McManus, J. B.; Kebabian, P. L.; Lloyd, D., Measurement of Trace Gas Fluxes Using Tunable Diode Laser Spectroscopy [and Discussion]. Philosophical Transactions of the Royal Society of London. Series A: Physical and Engineering Sciences 1995, 351, (1696), 371-382. 26. Atkinson, R.; Arey, J., Atmospheric Degradation of Volatile Organic Compounds. Chem. Rev. 2003, 103, (12), 4605-4638. 27. Natural Gas Gross Withdrawals and Production United States Energy Information Administration, https://www.eia.gov/dnav/ng/ng_prod_sum_a_EPG0_FGW_mmcf_m.htm (accessed July 28, 2017). 28. Vinciguerra, T.; Yao, S.; Dadzie, J.; Chittams, A.; Deskins, T.; Ehrman, S.; Dickerson, R. R., Regional air quality impacts of hydraulic fracturing and shale natural gas activity: Evidence from ambient VOC observations. Atmos. Environ. 2015, 110, 144-150. 29. Franco, B.; Mahieu, E.; Emmons, L. K.; Tzompa-Sosa, Z. A.; Fischer, E. V.; Sudo, K.; Bovy, B.; Conway, S.; Griffin, D.; Hannigan, J. W.; Strong, K.; Walker, K. A., Evaluating ethane and methane emissions associated with the development of oil and natural gas extraction in North America. Environmental Research Letters 2016, 11, (4), 044010. 30. Crude Oil Production, United States Energy Information Administration, https://www.eia.gov/dnav/pet/pet_crd_crpdn_adc_mbblpd_a.htm (accessed July 28, 2017). 31. Spot Prices, United States Energy Information Administration, https://www.eia.gov/dnav/pet/PET_PRI_SPT_S1_M.htm (accessed August 1, 2017). 32. Parrish, D. D.; Stohl, A.; Forster, C.; Atlas, E. L.; Blake, D. R.; Goldan, P. D.; Kuster, W. C.; de Gouw, J. A., Effects of mixing on evolution of hydrocarbon ratios in the troposphere. J Geophys Res-Atmos 2007, 112, (D10), D10S34. 33. Composition of Crude Oil and Natural Gas Produced from 14 Wells in the Lower Silurian "Clinton" Sandstone and Medina Group, Northeastern Ohio and Northwestern Pennsylvania, United States Geological Survey, United States Department of Interior, 2003, Open-File Report 2003-409, https://pubs.usgs.gov/of/2003/of03-409/of03-409.pdf (accessed August 18, 2017). 34. Greater Wattenberg Area Baseline Study Greater Wattenberg Area, Colorado Colorado Oil and Gas Conservation Commission, 2007, http://cogcc.state.co.us/documents/library/AreaReports/DenverBasin/GWA/Greater_Wattenberg _Baseline_Study_Report_062007.pdf (accessed August 18, 2017). 35. Gentner, D. R.; Harley, R. A.; Miller, A. M.; Goldstein, A. H., Diurnal and Seasonal Variability of Gasoline-Related Volatile Organic Compound Emissions in Riverside, California. Environ. Sci. Technol. 2009, 43, (12), 4247-4252. 36. McGaughey, G. R.; Desai, N. R.; Allen, D. T.; Seila, R. L.; Lonneman, W. A.; Fraser, M. P.; Harley, R. A.; Pollack, A. K.; Ivy, J. M.; Price, J. H., Analysis of motor vehicle emissions in


29


Page 30 of 31

a Houston tunnel during the Texas Air Quality Study 2000. Atmos. Environ. 2004, 38, (20), 3363-3372. 37. Simpson, I. J.; Blake, N. J.; Barletta, B.; Diskin, G. S.; Fuelberg, H. E.; Gorham, K.; Huey, L. G.; Meinardi, S.; Rowland, F. S.; Vay, S. A.; Weinheimer, A. J.; Yang, M.; Blake, D. R., Characterization of Trace Gases Measured over Alberta Oil Sands Mining Operations: 76 Speciated C2–C10 Volatile Organic Compounds (VOCs), CO2, CH4, CO, NO, NO2, NOy, O3 and SO2. Atmos. Chem. Phys. 2010, 10, (23), 11931-11954. 38. Thompson, C. R.; Hueber, J.; Helmig, D., Influence of oil and gas emissions on ambient atmospheric non-methane hydrocarbons in residential areas of Northeastern Colorado. Elementa: Science of the Anthropocene 2014, 2, 000035. 39. Borbon, A.; Gilman, J. B.; Kuster, W. C.; Grand, N.; Chevaillier, S.; Colomb, A.; Dolgorouky, C.; Gros, V.; Lopez, M.; Sarda-Esteve, R.; Holloway, J.; Stutz, J.; Petetin, H.; McKeen, S.; Beekmann, M.; Warneke, C.; Parrish, D. D.; de Gouw, J. A., Emission ratios of anthropogenic volatile organic compounds in northern mid-latitude megacities: Observations versus emission inventories in Los Angeles and Paris. J Geophys Res-Atmos 2013, 118, (4), 2041-2057. 40. Russo, R. S.; Zhou, Y.; White, M. L.; Mao, H.; Talbot, R.; Sive, B. C., Multi-year (2004– 2008) record of nonmethane hydrocarbons and halocarbons in New England: seasonal variations and regional sources. Atmos. Chem. Phys. 2010, 10, (10), 4909-4929. 41. Determination of C2 to C12 Ambient Air Hydrocarbons in 39 U.S. Cities, from 1984 Through 1986, Atmospheric Research and Exposure Assessment Laboratory, United states Environmental Protection Agency, 1989, EP A/600/SJ-89/058, https://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryId=36296 (accessed August 18, 2017). 42. Rolph, G.; Stein, A.; Stunder, B., Real-time Environmental Applications and Display sYstem: READY. Environmental Modelling & Software 2017, 95, 210-228. 43. Stein, A. F.; Draxler, R. R.; Rolph, G. D.; Stunder, B. J. B.; Cohen, M. D.; Ngan, F., NOAA’s HYSPLIT Atmospheric Transport and Dispersion Modeling System. Bull. Amer. Meteor. Soc. 2015, 96, (12), 2059-2077. 44. Roberts, J. M.; Fehsenfeld, F. C.; Liu, S. C.; Bollinger, M. J.; Hahn, C.; Albritton, D. L.; Sievers, R. E., Measurements of aromatic hydrocarbon ratios and NOx concentrations in the rural troposphere: Observation of air mass photochemical aging and NOx removal. Atmospheric Environment (1967) 1984, 18, (11), 2421-2432. 45. de Gouw, J. A.; Middlebrook, A. M.; Warneke, C.; Goldan, P. D.; Kuster, W. C.; Roberts, J. M.; Fehsenfeld, F. C.; Worsnop, D. R.; Canagaratna, M. R.; Pszenny, A. A. P.; Keene, W. C.; Marchewka, M.; Bertman, S. B.; Bates, T. S., Budget of organic carbon in a polluted atmosphere: Results from the New England Air Quality Study in 2002. J Geophys ResAtmos 2005, 110, (D16), D16305. 46. Warneke, C.; McKeen, S. A.; de Gouw, J. A.; Goldan, P. D.; Kuster, W. C.; Holloway, J. S.; Williams, E. J.; Lerner, B. M.; Parrish, D. D.; Trainer, M.; Fehsenfeld, F. C.; Kato, S.; Atlas, E. L.; Baker, A.; Blake, D. R., Determination of urban volatile organic compound emission ratios and comparison with an emissions database. J Geophys Res-Atmos 2007, 112, (D10), D10S47. 47. Gilman, J. B.; Kuster, W. C.; Goldan, P. D.; Herndon, S. C.; Zahniser, M. S.; Tucker, S. C.; Brewer, W. A.; Lerner, B. M.; Williams, E. J.; Harley, R. A.; Fehsenfeld, F. C.; Warneke, C.; de Gouw, J. A., Measurements of volatile organic compounds during the 2006


30

Page 31 of 31


TexAQS/GoMACCS campaign: Industrial influences, regional characteristics, and diurnal dependencies of the OH reactivity. J Geophys Res-Atmos 2009, 114, (D7), D00F06. 48. Western Regional Air Partnership (WRAP), 2006, http://www.wrapair.org/forums/ogwg/PhaseIII_Inventory.html (accessed August 29, 2017). 49. Warneke, C.; Geiger, F.; Edwards, P. M.; Dube, W.; Pétron, G.; Kofler, J.; Zahn, A.; Brown, S. S.; Graus, M.; Gilman, J. B.; Lerner, B. M.; Peischl, J.; Ryerson, T. B.; de Gouw, J. A.; Roberts, J. M., Volatile organic compound emissions from the oil and natural gas industry in the Uintah Basin, Utah: oil and gas well pad emissions compared to ambient air composition. Atmos. Chem. Phys. 2014, 14, (20), 10977-10988.


31

Impact of Changes in Oil and Gas Production ... - ACS Publications

Recommend Documents