Weekend/Weekday Ozone Observations in the South Coast Air Basin

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VOC mix. Sonoma Technology, Inc. conducted concurrent traffic and emission source surveys during the field study Supplemental measurements by DRI at the monitoring stations included hourly C 2 to C 11 VOC by automated gas chromatography with ion-trap mass spectrometry at Azusa, continuous black carbon by light absorption with an aethalometer at Azusa and Pico Rivera, and 3-hour composite Tenax samples for C8 to C18 hydrocarbons. The California Air Resources Board collected canister samples at Los Angeles – N. Main for speciated hydrocarbons on the same schedule, and SCAQMD measured 3-hour average speciated VOC with an automated gas chromatograph at Pico Rivera. 4.1 Field Measurement Program Desert Research Institute (DRI) conducted a 9-day field study in the Los Angeles area from September 30, 2000 to October 8, 2000 as part of Phase II of this Weekend Ozone Study. The study was conducted in accordance with the study plan in Chapter 4 of the August 23, 2000 draft report for Phase I (Fujita et al., 2000a). The plan presented in the draft report was modified in response to comments from the National Renewable Energy Laboratory (NREL), Coordinating Research Council (CRC), and the California Air Resources Board (ARB). This section describes the experimental approach and methods used in field study. The field study focused on detailed time-resolved measurements to test the hypothesized relationship between emissions sources and the diurnal and day-of-the-week variations in VOC and NOx, and VOC/NOx ratios. The field measurements involved two approaches: supplemental measurements at existing SCAQMD monitoring sites and mobile sampling during periods that coincide with overnight carryover, ozone inhibition, and ozone accumulation. Supplemental measurements made by DRI at the monitoring stations included hourly C 2 to C 11 volatile organic compounds by automated gas chromatography with ion-trap mass spectrometry at Azusa, continuous black carbon by light absorption with an aethalometer (approximately 5-minute averages) at Azusa and Pico Rivera, and 3-hour composite Tenax samples for C 8 to C 18 hydrocarbons beginning at 2, 6, and 9 a.m. PDT on September 30, October 1,2,4,6,7, and 8. ARB also collected canister samples at Los Angeles – N. Main for speciated hydrocarbons on the same schedule, and SCAQMD measured 3-hour average speciated VOC with an automated gas chromatograph at Pico Rivera. Figure 4.1-1 shows the locations of District monitoring stations along with the locations of freeway loops and regional/background sites used during the mobile sampling. Primary pollutants (CO, NO, black carbon [BC] and speciated hydrocarbons) were measured simultaneously in a mobile van along several freeway loops in different areas of the Basin. Carbon monoxide, NO/NOy and black carbon estimated from light absorption were measured continuously with averaging times of 1, 1, and 5 minutes, respectively. Canister and Tenax cartridge samples were integrated over a period of approximately 50 minutes for each freeway loop and fixed locations. Sonoma Technology, Inc. conducted concurrent traffic and emission source surveys during the field study. Mobile sampling was conducted during the carryover period between 2-5 a.m. (PDT), the ozone inhibition period between 6 to 9 a.m., and during the ozone accumulation period between 4-2
9 a.m. andnoon. Sampling was conducted on Saturday, September 30, 2000, Sunday, October 1, Monday, October 2, Wednesday, October 4, Friday, October 6, Saturday, October 7, and Sunday, October 8 along the following loops and fixed locations. • 0200 to 0245 – (IH1) Industry Hills Conference Center (overflow parking lot on the south end of the conference center) on all days. • 0300 to 0345 – (CV1) Covina Loop (east on S-60 from Azusa Blvd on-ramp, north on S-57, west on I-10 to I-5) on all days. • 0415 to 0500 – (DS1) Dodger Stadium (four loops around the perimeter of the Stadium) on all days. • 0515 to 0600 – (CO1) Compton Loop (south on S-110 from Stadium Way onramp, east on I- 405, north on I-710 to I-10) on all days. • 0630 to 0715 – (HF1) Source-dominated samples for the spark ignition vehicle exhaust profile (fixed location sampling on southbound S-110 just south of Stadium Way onramp) on October 2, 4, 6, 7, and 8. This section of the 110 (Harbor Freeway) is restricted to automotive traffic only. • 0730 to 0815 – (DS2) Dodger Stadium onall days. • 0830 to 0915 – (CO2) Compton Loop on all days. • 0930 to 1015 – (CV2) Covina Loop (east on I-10 at I-710, south on S-57, west on S-60 to Azusa Blvd off-ramp) on all days. • 1030 to 1115 – (IH2) Industry Hills Conference Center on all days. • 1130 to 1215 – (PO1) Pomona Loop (east on S-60 at Azusa Blvd onramp, north I-15, west of I-10 north on 210 to Azusa Blvd off-ramp on October 2, 4, 6, 7, and 8. Five sets of canister and Tenax samples and continuous CO, NO, NOy and black carbon measurements were taken at a truck stop near I-10 and I-15. Measurements were made during the early morning hours from 0100 to 0500, and consisted of three sets of samples at the truck stop and upwind samples before and after the truck stop samples. Additionally, ten gasoline and two diesel fuel samples were collected for analysis of speciated VOCs. 4.2 Measurement Methods The concentrations of black carbon were determined using an Anderson RTAA-1000 Aethalometer. The instrument continuously collects aerosol on a quartz-fiber filter tape. During the deposition process, the light attenuation through the aerosol collection spot and an unloaded reference spot are monitored. Their difference yields the absorption due to the integral of all light-absorbing materials collected on a particular spot. The time derivative of this quantity is a measure of the current aerosol light absorption. The Aethalometer converts the result of its filter 4-3
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WEEKEND/WEEKDAY OZONE OBSERVATIONS
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obtained by DRI from the Phase II f
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TABLE OF CONTENTS Preface..........
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Table No. Table 1.4-1 Table 1.4-2 T
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periods by day-of-week at Los Angel
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Figure 1.4-13. Hourly average nitro
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Figure 3.1-2 Mean day-of-the-week v
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Figure 4.4-1b. Mean estimated sourc
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1. STUDY PERSPECTIVE AND SUMMARY Th
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40 percent. Consequently, the contr
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dioxide (NO 2 ) 4 , and carbon mono
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and upwind samples before and after
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where J 1 is the photolysis frequen
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transported from an urban center to
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of the week on Friday and Saturday.
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VOC reactivity, photochemical aging
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corresponding source attributions a
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multiplicative constant. This const
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Table 1.4-1 Trends in Duration and
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Table 1.4-3 Regression Statistics f
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O 3 Ozone Formation Chemistry NO 2
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200 1981-84 200 1995-98 160 160 120
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100 NO 1000 NMHC (estimated from CO
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5 Sunday - Wednesday (1981-84) 10 T
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10.0 8.0 NMHC/NOx 6.0 4.0 2.0 0.0 S
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Ratio of Peak Ozone to Potential Oz
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Nitrogen Oxides at Azusa, 9/30/00 t
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Ambient NOx Associated with CO and
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Source Contribution Estimate (ug/m3
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2.8 2.6 Ozone (ppb) 2.4 log NOx (pp
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2. EVOLUTION OF THE OZONE EFFECT IN
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the SoCAB has dropped sharply as sh
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the duration of ozone accumulation,
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• NO 2 concentrations and NO 2 /N
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Table 2-1 Air Quality Parameters fo
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0.18 Azusa, Summer 1995 12.0 0.15 1
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250 200 150 100 50 0 1976 1977 1978
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80 1981-84 60 40 20 0 80 Sun Mon Tu
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1.00 1981-84 0.80 0.60 0.40 0.20 0.
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160 1981-84 120 80 40 0 160 Sun Mon
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5.0 1981-84 4.0 3.0 2.0 1.0 0.0 5.0
Page 83 and 84: 12.00 1981-84 11.00 10.00 9.00 8.00
Page 85 and 86: NMHC (ppbC) 1000 800 600 400 200 4-
Page 87 and 88: 10.00 1981-84 8.00 6.00 4.00 2.00 0
Page 89 and 90: Sunday 1981-84 Time (PDT) 16 15 14
Page 91 and 92: 16 Sunday 1990-94 35 Time (PDT) 15
Page 93 and 94: 40 Sunday O3 Accumulation Rate (ppb
Page 95 and 96: 15.0 1981-84 12.0 9.0 6.0 3.0 0.0 1
Page 97 and 98: 3. CHARACTERIZATION OF THE CURRENT
Page 99 and 100: 3.2 Weekday Differences in Diurnal
Page 101 and 102: timing hypothesis, which requires a
Page 103 and 104: through the conversion of NO to NO
Page 105 and 106: Weekday Differences in Diurnal Vari
Page 107 and 108: activity including [HNO 3 ]/[H 2 O
Page 109 and 110: Table 3.2-1 Day-of-the-Week Variati
Page 115 and 116: Table 3.3-1b Day-of-the-Week Differ
Page 117 and 118: 120 Los Angeles - N. Main - Saturda
Page 119 and 120: 160 140 Upland - Saturdays mean Ozo
Page 121 and 122: maximum 1hour ozone (ppb) 100 90 80
Page 123 and 124: NMHC/NOx ratio 14 12 10 8 6 4 2 0 S
Page 125 and 126: Los Angeles - N. Main Azusa 140 140
Page 127 and 128: Los Angeles - N. Main Azusa 140 140
Page 129 and 130: 2.8 2.6 PAN (ppb) 2.8 2.6 HCHO (ppb
Page 131 and 132: NO2 Photolysis Rate Parameter 0.35
Page 133: 4. WEEKDAY VARIATIONS IN THE SOURCE
Page 137 and 138: interfaced to an Entech model 7100
Page 139 and 140: values measured at the regional sit
Page 141 and 142: into a category named "UNID." The s
Page 143 and 144: more than a few percent of the tota
Page 145 and 146: period, the amount of NOx associate
Page 147 and 148: weekend/weekday differences during
Page 149 and 150: • Day-of-the-week changes in the
Page 151 and 152: Table 4.4-1 Default Source Composit
Page 153 and 154: Table 4.4-1a Number of observations
Page 155 and 156: Table 4.4-1c Number of observations
Page 157 and 158: Table 4.4-2a Number of observations
Page 159 and 160: Table 4.4-2c Number of observations
Page 161 and 162: Table 4.4-3a CMB Performance Parame
Page 163 and 164: Table 4.4-3c Source Contribution Es
Page 165 and 166: Table 4.5-2 Weekend/Weekday Differe
Page 167 and 168: 800 700 600 Wednesday NO and NOy (p
Page 169 and 170: Estimated NOx Estimated NOx (ppb) 5
Page 171 and 172: VOC/NOx Ratios 6.0 5.0 4.0 Mon, 10/
Page 173 and 174: Nitrogen Oxides at Azusa 80 60 02-0
Page 175 and 176: Nitrogen Oxides at Pico Rivera 180
Page 177 and 178: Nonmethane Organic Gas at Azusa 500
Page 179 and 180: Nonmethane Organic Gas at Pico Rive
Page 181 and 182: NMOG/NOx Ratios at Azusa 20 15 02-0
Page 183 and 184: estimated contribution by source (u
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500 Nonmethane Hydrocarbons 400 NMH
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5 Azusa, Weekdays 6-9 a.m (10/2/00-
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2.0 Azusa, Weekdays 6-9 a.m (10/2/0
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Pico Rivera 150 120 BC-Associated C
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Nitrogen Oxides 800.00 700.00 600.0
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5. REFERENCES Altshuler, S.L., T.D.
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Fujita, E.M., J.G. Watson, J.C. Cho
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Roberts, J.M. (1983) Measurements o
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Weekend/Weekday Ozone Observations in the South Coast Air Basin

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