The Vertical Distribution and Stratification of VOC in the Atmosphere at Kaohsiung Area

2012 International Conference on Environmental Quality

Concern, Control and Conservation (EQC 2012)

National Kaohsiung Marine University Department of

Marine Environmental Engineering

Chia-Chun Cheng1*, Ying-Hui Kao1, Chitsan Lin2, Chung-Hsin

Yuan3, Chung-Hsuan Hung41Graduate Student of the Department of Marine Environmental Engineering, National Kaohsiung Marine

University, Kaohsiung 81157, Taiwan.2Professor of the Department of Marine Environmental Engineering, National Kaohsiung Marine University,

Kaohsiung 81157, Taiwan.3Professor of the Institute of Environmental Engineering, National Sun Yat-sen University, Kaohsiung 80424,

Taiwan.4Assistant Professor of the Department of Safety Health and Environmental Engineering, Kaohsiung First

University of Science and Technology, Kaohsiung 81164, Taiwan.

May, 25-26 2011 1

Outline

Introduction

Material and method

Results and discussions

Conclusions

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Many factories were crowded in Kaohsiung, such as refinery, industrial zones and export processing zones...etc. Moreover, many chimneys and burning towers result in serious VOCs emissions and might harmful for nearby residential area. The VOCs is not easy to proliferate. This cause air pollutants to accumulate in specific weather conditions.

The VOCs will harm the human health. When it release to the atmosphere by photochemical reactions, which produce highly toxic secondary pollutants, for example ozone, peroxyacetylnitrate (PAN) and photochemical smog.

Introduction

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Currently, all ozone air quality improvement strategies always take air quality model (AQM) as standard, the atmosphere of VOCs was assumed by the AQM which in the vertical height is uniformly mixed. But in recently, some researchers have shows layered distribution of VOCs in the atmosphere.

The VOCs concentration distribution and stratification in the atmosphere will be affected by weather conditions (such as mixing layer height variation or inversion layer form), season, time, space, vertical height...etc.

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　　 In this study, we would investigate vertical distribution of volatile organic compounds to Kaohsiung area.

To prove the stratification of VOC exists and exploration the stratification period and height.

To prove the VOCs species of photochemical reacts in different high level, Maximum Incremental Reactivity (MIR).

Purpose

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Sampling Location

NKMU

WFES

Sampling time： August, 2010 (summer) and February, 2011 (winter)

12:00, 18:00, 00:00, 06:00

Material and method

Sampling Site

Sampling height： Ground, 100, 200, 300, 400, 500, 600, 700 and 800m.

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The tethered balloon collected the VOCs samples from the atmosphere. A pump was connected to a 10 L sampling bag.

The samples were immediately transferred into a stainless canister to ensure the accuracy of the data.

Sampling Method

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Analysis Method

Auto samplerEntech 7016

Pre-concentratedEntech 7100

Mass Spectrometry Detector (MSD) HP 5973

Gas-chromatography(GC) HP 6890

Urban Air Toxics (UAT)and Photochemical Assessment Monitoring System(PAMS)Taiwan EPA

NIEA A715.13B

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Can be analysis 101 kinds of compounds.

Standard gas patterns

UAT PAMS

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Results and discussions

Relationship between vertical VOCs and stratification

Occurrence periods of stratification

Ozone Formation Potential

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The definition of stratification

stratification non- stratification

The definition of stratification

The stratification means concentration of pollutants increase or decrease suddenly in high altitude. However the concentration of pollutants with stable change is non-stratification.

Conc.

Hei

ght

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Summer Winter

In summer, the pollutants are accumulating in 100m, 400m and 700m.

Especially, ground with high conc. at 18:00. With increasing height and decreasing, but there are lower conc. at 300m and 800m.

In winter, the pollutants are accumulating between 400m to 600m.

There are lowest conc. at 300 and 700m, but it was increased over 800m.

Relationship between vertical VOCs and stratification

Hei

ght (

m)

Hei

ght (

m)

Conc. (ppbv) Conc. (ppbv)

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In NKMU station, pollutants almost accumulate at 400m to 500m, and it was decrease at 600m.

Ground conc. is higher than other time in 18:00.

In WFES station, there is not observable stratification at 12:00.

Almost conc. are decrease at 700m, but it was increased over 800m.

NKMU WFES

Hei

ght (

m)

Hei

ght (

m)

Conc. (ppbv) Conc. (ppbv)

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The probability of stratification is 87.5% in summer.The occur time in summer is 12:00 and height at 700m.

Occurrence periods of stratification

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NKMUGround 100 200 300 400 500 600 700 800

12:00 1 2.13 1.20 4.52 7.65 1.26 1.13 1.08 1.1518:00 1 <1 <1 <1 <1 <1 <1 <1 <100:00 1 <1 <1 <1 2.54 1.32 <1 5.39 <106:00 1 <1 1.81 <1 2.73 <1 <1 <1 <1

Note : " <1 " is no stratification

The probability of stratification

WFES Ground 100 200 300 400 500 600 700 800

12:00 1 5.44 3.82 5.13 3.10 2.58 2.06 3.51 4.1418:00 1 <1 <1 <1 <1 1.43 1.04 1.78 <100:00 1 4.89 3.65 2.69 2.86 2.29 1.33 1.41 6.7506:00 1 2.88 <1 <1 <1 <1 <1 1.13 <1

Note : " <1 " is no stratification

The probability of stratification

Summer 87.5%

Winter

The probability of stratification is 75% in winter.The occur time in winter is 00:00 and height at 400m.

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NKMUGround 100 200 300 400 500 600 700 800

12:00 1 1.26 <1 <1 4.43 6.80 5.38 4.81 <118:00 1 1.28 1.31 <1 <1 1.13 1.18 <1 <100:00 1 <1 2.56 2.29 1.30 3.31 <1 <1 <106:00 1 1.62 <1 <1 1.38 2.02 <1 <1 <1

Note : " <1 " is no stratification

The probability of stratification

WFES Ground 100 200 300 400 500 600 700 800

12:00 1 <1 <1 <1 <1 <1 <1 <1 <118:00 1 <1 <1 <1 <1 <1 <1 <1 <100:00 1 1.94 2.98 1.55 1.30 <1 5.80 <1 <106:00 1 1.60 1.98 <1 1.83 <1 <1 <1 2.48

Note : " <1 " is no stratification

The probability of stratification

75%

NKMU

WFES

75%

From different stations, NKMU probability of occur stratification around 75% at 400-500m, occurrence time are 12:00 and 00:00.

WFES probability of occur stratification around 50% under 200m, occurrence time is 00:00.

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50%

Ozone Formation Potential

This study follow as the Carter (1994) MIR photochemical reactivity index, and select a higher detection rate of compounds to estimate the ozone formation potential in various periods.

Alkanes： Hexane, Isopentane, Undecane, Dodecane

Alkene： Propene, 1-Butene, Styrene

Aromatic hydrocarbon ： Benzene, Toluene, Ethylbenzene, m/p-Xylene, 1,3,5-Trimethylbenzene, 1,2,4-Trimethylbenzene

Aldehydes and ketones： Acetone

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Thus, we going to discussing if stratification occurs will cause ozone formation.

Summer with highest ozone formation potential at 18:00, and main compounds are 1,3,5-Trimethylbenzene and m/p-Xylene.

Winter with highest ozone formation potential at 12:00, and main compounds are Toluene and m/p-Xylene.

Compounds MIR scaleTime 12:00 18:00 00:00 06:00 12:00 18:00 00:00 06:00

Benzene 0.42 1.50 19.4 4.82 9.40 48.8 19.8 14.0 32.8Toluene 2.70 816 999 565 318 1914 834 1316 1313Ethylbenzene 2.70 92.6 169 125 86.0 337 121 96.3 137m / p-Xylene 7.40 612 1166 787 626 1565 1049 804 1032o-Xylene 6.50 228 340 282 197 602 382 279 420Propene 9.40 315 344 606 721 430 417 377 6391-Butene 8.90 279 312 361 324 250 119 198 226Hexane 0.98 65.1 144 156 59.7 51.0 38.5 42.5 135Isopentane 1.38 88.4 81.9 126 50.3 40.4 55.7 136 1301,3,5-Trimethylbenzene 10.1 1441 1694 1338 979 692 716 278 4661,2,4-Trimethylbenzene 8.80 91.6 352 211 176 257 133 90.2 144Styrene 2.20 45.6 91.4 80.0 69.5 109 66.4 76.6 104Undecane 0.42 22.1 11.4 8.84 114 531 23.5 536 57.1Dodecane 0.38 22.0 25.7 14.9 55.5 1049 209 807 843Acetone 0.56 740 583 838 398 209 165 350 252Total 4861 6333 5504 4185 8085 4348 5401 5930Note: Carter (1994)

Ozone Formation PotentialSummer Winter

Ozone Formation Potential of different season and time.

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Compounds MIR scaleHeight Ground 100 200 300 400 500 600 700 800 Ground 100 200 300 400 500 600 700 800

Benzene 0.42 3.29 1.17 4.10 3.29 5.89 15.6 0.00 0.00 3.29 65.0 5.08 16.4 11.9 2.60 3.25 4.10 0.00 7.09Toluene 2.70 324 479 298 206 346 364 161 454 255 1229 757 608 400 514 728 590 258 294Ethylbenzene 2.70 62.9 45.8 55.7 32.1 79.1 87.4 38.8 73.1 36.1 281 66.6 62.8 46.4 53.8 52.7 62.4 25.2 41.4m / p-Xylene 7.40 430 301 360 272 426 403 518 495 228 1131 530 470 353 343 484 535 204 399o-Xylene 6.50 142 111 118 81.1 154 109 137 186 84.5 391 213 190 112 155 187 210 77.7 146Propene 9.40 182 248 513 254 302 178 101 230 169 177 255 286 142 244 281 248 69.2 1591-Butene 8.90 180 157 148 142 220 163 84.7 148 144 117 96.9 82.3 31.7 77.3 127 158 49.5 52.8Hexane 0.98 114 53.2 48.4 48.1 83.3 47.5 23.5 69.8 19.6 49.8 34.5 58.3 32.3 17.3 13.7 23.7 3.29 34.1Isopentane 1.38 34.1 39.7 32.5 33.9 57.2 32.0 17.2 101 56.6 29.1 84.5 59.2 13.4 12.1 65.9 56.0 6.54 35.31,3,5-Trimethylbenzene 10.1 671 668 1171 629 1107 718 244 490 424 547 301 230 74.4 165 230 327 97.1 1811,2,4-Trimethylbenzene 8.80 110 73.2 106 35.2 91.5 42.2 141 141 91.5 67.9 110 73.3 39.5 64.8 124 78.9 45.1 19.7Styrene 2.20 37.5 34.8 39.9 19.5 35.5 18.9 38.3 57.9 19.8 41.7 42.9 47.8 29.1 39.6 57.2 39.8 23.0 34.5Undecane 0.42 4.13 9.53 7.93 6.68 9.79 1.24 2.70 114 2.01 7.73 44.2 129 159 202 344 118 134 11.1Dodecane 0.38 1.15 9.07 8.53 7.92 8.64 5.40 4.39 71.5 1.62 81.3 172 366 339 502 565 329 297 255Acetone 0.56 294 299 210 299 373 292 152 632 368 116 154 144 61.7 72.9 147 127 44.4 108Total 2591 2529 3121 2071 3299 2477 1663 3262 1903 4332 2868 2824 1847 2464 3410 2908 1334 1778Note: Carter (1994)

Summer WinterOzone Formation Potential Ozone Formation Potential

Summer with highest ozone formation potential at 400m and 700m, the main compounds are 1,3,5-Trimethylbenzene and m/p-Xylene.

Winter with highest ozone formation potential at ground and 500m, the main compounds are Toluene and m/p-Xylene.

Ozone Formation Potential of different season and height.

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Conclusions

From the vertical variation of VOCs conc. shows there exist stratification in atmosphere certainly.

In summer, most pollutants were accumulate about 100m and 700m.And accumulate from 400m to 600m in winter.

From different stations, NKMU probability of occur stratification around 75% at 400-500m, occurrence time are 12:00 and 00:00.

WFES probability of occur stratification around 50% under 200m, occurrence time is 00:00.

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The probabilities of stratification are 87.5% in summer and 70% in winter.

The occur time is 12:00 at the height of 700m in summer, and in winter is 00:00 at the height of 400m.

With photochemical reactivates, the highest ozone formation potential in 18:00 at summer and in 12:00 at winter, the main compound is 1,3,5-Trimethylbenzene.

The highest ozone formation potential at 400m and 700m in summer with ground and 500m in winter, the main compound is m/p-Xylene.

Our study indicates the occurrence of stratification at lower height in summer and at 500m in winter with highest ozone formation potential.

Therefore, we suspect occurrence of stratification usually accompany the ozone formation. But we need further research to confirm.

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2012 International Conference on Environmental Quality

Concern, Control and Conservation (EQC 2012)

National Kaohsiung Marine University Department of

Marine Environmental Engineering