Air quality improvement in Tokyo and relation with vehicle exhaust purification

Transcription

1 Air quality improvement in Tokyo and relation with vehicle exhaust purification H. MINOURA 1, K. TAKAHASHI, J.C. CHOW 3, J.G. WATSON 3, T. Nakajima, and A. Mizohata 5 1 Toyota Central R&D Labs., Inc., Japan Japan Environmental Sanitation Center, Japan 3 Desert Research Institute, USA. Japan Automobile Research Institute, Japan 5 Frontier Science Innovation Center, Osaka Prefecture University, Japan 1

2 Motivation Understand the PM behavior in downtown area and estimation of vehicle emission contribution Human Health Effects of Diesel Exhaust Particulate (DEP) Regulation effect confirmation in Tokyo for stringent emission control on PM emission since 1997 PM (g/kwh).3..1 JPN LTR (97-99) JPN newstr (3) US () Euro 3() US (7) Euro 5(9?) Euro (5) 6 8 JPN postltr (1) NOx (g/kwh) JPN newltr (5) Euro (97) US (9) US (98) Transaction of emission control value for HDV

3 Inspection by the observation 1.(new model vehicle; whole Japan; from 1997 for each) A severe PM exhaust control.(in-use vehicle; Tokyo and surrounding area; from ) Riding into regulation Low emission zone 3.(in-use vehicle; Tokyo metropolitan area; from 3) Tokyo rule No diesel passage wo DPF or ATS Long run air observation is carried out to inspect atmosphere improvement effect 3

4 Location (Urban background) Observation site is in downtown Tokyo on the roof of 1 th fl. Bldg.(~3m from ground) Ring 8 Yasukuni Shrine Urban background site (Toyota Kudan Bldg) Imperial Palace Tokyo Noge Kudan

5 Summary of ambient measurements PM mass and carbon monitoring at urban background started since June 199 SPM: Suspended Particle Matter Japanese PM standard % transmission for 1µm (~PM7) Sampling Site type site Instrument PM size beta-ray SPM attenuation monitor cyclone (DKK,Japan model cut-off DUB-1) Measured item mass mass Kudan urban background PM.1, Andersen quart PM.1-7, impactor sampling and (Tokyo Dylec PM7model AN-) Impactor carbon ions Noge roadside carbon monitor (R&P model5) PM.5 impactor carbon Measurement method beta-ray attenuation Duration Frequency 1hr flow rate /day = 18 (l/min) gravimetric two-step GM method OC; 1%He at 5 Celsius degree weeks TC; 9%He-1%O at 95 Celsius degree 6/year 6/1/1993/31/6 6/1/1993/31/6 3/31/19973/31/6 ion chromatograph OC; 3 Celsius degree for 78 sec. hr TC; 75 Celsius degree for 8 sec. Measurement period 1/day 1/8/9/5/ 5

6 PM mass concentration trend at Kudan site PM Concentration (µg m -3 ) /6 fine (<.1µm) coarse (.1-7µm) 1995/6 1996/6 1997/6 1998/6 Annual mean (µg m -3 ) 1999/6 3 1 / / coarse 1998 /6 fine 3/6 /6 5/6 from Andersen sampling for weeks 6/ 9 years average y = -.57x PM.1 decrease =.9µg/m 3 /yr Date Mass concentration decrease was confirmed in fine PM 6

7 Emission source placement Incinerator Diesel Fuel Oil % Others K + 5% EC 1% Na + 13% S Cl - Others EC 1% Others OC 1% S 61% EC 75% 7% OC NH + Na + EC NO 3 - SO - Cl - Ca + Al S K + Ti V Mn Fe Zn Pb Others EC is an optimal element to see the contribution of the diesel emission. (Because there are no fuel oil combustion facilities in downtown Tokyo, mobile contribution can be understood by examining the EC in PM) 7

8 EC Concentration (µg m -3 ) OC Concentration (µg m -3 ) Carbon concentration trend at Kudan site /6 1995/6 1996/6 1997/6 1998/6 1999/6 /6 Date EC fine (<.1µm) EC coarse (.1-7µm) OC fine (<.1µm) OC coarse (.1-7µm) 1/6 PM.1 (EC) and PM.1 (OC) started to decrease after 1996 /6 3/6 /6 5/6 from Andersen sampling for weeks 6/ y = -.x+89.7 EC decrease =.8µg/m 3 /yr y = -.55x+.7 OC decrease =.µg/m 3 /yr PM.1 (EC) reduction was due to an improvement in the purification technology of vehicle emission 8

9 Location (Roadside) Observation point is around Ring 8 (Traffic volume=9,/day; HDR=13%). No stationary emission source exists surrounding the area. Ring 8 Ring 8 Tokyo Kudan Daisan- Keihin Highway Noge Roadside Site Noge park Noge Tama river Traffic volume (number hr -1 ) 7, 6, 5,, 3,, 1, Passenger car LDV+HDV Local time (hr) 9

10 Carbon concentration trend at Noge site EC OC from Carbon monitor for hours Concentration (µg/m -3 ) /1 3/ Date / 6 8 EC decrease =.56µg/m 3 /yr y = -.7x Carbon concentration decrease in Pm.5 is remarkable Magnitude of PM.5 (EC) decrease at Noge site (roadside) is about higher than PM.1 (EC) decrease at Kudan site (urban background) 3 times 1

11 Summary of the yearly variations of chemical components in PM Concentration (µg m -3 ) EC OC SO - NO 3 - Cl - NH + Na + K + Ca + Others OC Cl SO EC Year (FY) Average NO NH + 5 Concentrations of all chemical species show decrease tendency except sulfate Ratios of the sulfate relatively increase A decline of the carbon concentration became dull in recent years Why? 11

12 Influence of pyrolysis OC to EC concentration EC concentration (µg m -3 ) Two-step GM method for EC analysis with tree stages Andersen sampling IMPROVE method for EC analysis with 13 stages LPT Year 6 8 Overestimation of EC concentration was confirmed by the conventional method, and the concentration decline was also seen in comparing the past data. However, EC concentration does not change in recent years (around 1µg/m 3 by IMPROVE method). 1

13 Seasonal variation in PM fine (EC) and PM coarse (EC) concentrations Concentration (µg/m 3 ) Apr. EC Jun. Aug. Oct. Dec. Total Fine particle (.1-.1µm) Feb. Apr. Coarse particle (.1-7µm) Month If PM fine (EC) is of diesel car origin, why it shows a seasonal variation? 13

14 Seasonal variation in PM fine (EC/OC) and the percent of Modern Carbon (pmc) PM.1 Conc. (µgm -3 ) PM fine Mass EC OC EC & OC Conc. (µgm -3 ) pmc (%) 5 3 pmc -Aug 16-Aug 3-Aug 13-Sep 7-Sep 11-Oct 5-Oct Date 8-Nov -Nov 6-Dec -Dec 3-Jan A seasonal change in pmc accords with a change in the conc. of EC and the OC. The seasonal change seen in PM fine (EC) depends on a vegetation combustion origin. Approximately % of carbon is of plant origin in the Tokyo downtown area. 1

15 Conclusions SPM (~PM 7 ) concentration have decreased from 199 to 5 in downtown Tokyo, Japan Most of the reductions can be attributed to changes in the carbon fraction of PM fine, especially EC. Magnitude of PM.5 (EC) decrease at roadside is about 3 times higher than PM.1 (EC) decrease at urban background. This followed the introduction of new technology diesel engines in with stringent limits on PM emission rates. The measure of the exhaust control brought an atmosphere improvement successfully The EC had been regarded as the contribution only for diesel cars in Tokyo, but it become clear that % of all carbon components comes from the biomass burning. 15

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17 Yearly trends of Transport in Japan Car ownership number (million vehicles) Passenger car Bus Light car Truck Motorcycle Year Fuel consumption (Giga liter) Gasoline Diesel Year LPG The ownership number of diesel truck deteriorates from the latter half of 9 s, and the fuel consumption also deteriorates from s for all vehicle categories. 17

18 Yearly trends of vehicle usage Car ownership number in Tokyo (million cars) truck light car passenger car bus special car The ratio of the diesel car (%) bus truck All type passenger car Year (FY) Year (FY) In Japan, the diesel passenger car deteriorates from the latter half of 9 s, and there is very little percentage by the present. 18

19 PM mass concentration trend at Kudan site SPM Concentration (µg m -3 ) Roadside This study Urban background '9 '95 '96 '97 '98 '99 ' '1 ' '3 Year (FI) Comparison of SPM concentration trends with other sites operated by the Tokyo metropolitan government SPM Concentration (µg m -3 ) Kudn (this study) Chiyoda Hibiya Date from ß-ray absorption Comparison of short term change in SPM concentration with neighbor sites operated by the Tokyo metropolitan government Measurement result at Kudan site represents urban background of Tokyo 19

20 PM mass concentration trend at Kudan site from ß-ray absorption /6 1995/6 1996/6 1997/6 1998/6 1999/6 /6 1/6 /6 3/6 /6 5/6 6/ SPM Concentration (µg m -3 ) Annual mean (µg m -3 ) Date SPM mass started to decrease in 1998

21 PM mass concentration trend at Kudan site from Andersen sampling for weeks 8 years average Concentration (µg m -3 ) Total Fine (<.1µm) Coarse (.1-7µm) A M J J A S O N D J F M Month Fine Particle Concentration ( µg m -3 ) (Fine) =.77(SPM) r = SPM Concentration (µg m -3 ) High concentration in the winter season was observed due to fine particle contribution Fine particle concentration amounts to about 77% of SPM 1

22 Ion concentration trend at Kudan site (1) 1 1 * fine SO - coarse SO - 6 fine Cl - coarse Cl - Concentration (µg m -3 ) fine NO 3 - coarse NO fine NH + coarse NH Year Year PM.1 (Cl - ) decrease in non-summer months was remarkable

23 Ion concentration trend at Kudan site () Concentration (µg m -3 ) fine Na + coarse Na + 1 Year fine K + coarse K * * * 1 * Year fine Ca + coarse Ca Remarkable change /anthropogenic from Incineration PM fine (Cl - ) & PM fine (K + ) decrease /natural from Volcano PM fine (SO - ) from Dust storm PM coarse (Ca + ) 3

24 Seasonal variations in chemical compositions EC (a) fine NH + 3 fine coarse 1 (f) coarse Concentrations (µg m -3 ) OC SO - NO 3 - Cl (b) (c) (d) (e) fine coarse fine Hot summer evaporation Hot summer evaporation coarse Hot summer evaporation coarse Biomass burning fine coarse fine Na + K + Ca + Mass (g) (h) (i) ( j ) fine coarse Dust storm Typhoon coarse coarse SPM fine Biomass burning Biomass burning coarse fine fine J F M A M J J A S O N D Month J F M A M J J A S O N D Month

25 Seasonal variations in chemical compositions Concentration (µeq-mol m -3 ) PM fine Concentration (µeq-mol m -3 ) PM coarse Temperature (deg) SO - NO 3 - Cl - NH + Temperature (deg) The nitrate in PM fine shows the maximum equivalent concentration just below 1 degrees Celsius, and, in the thereunder, the equivalent concentration of the anion shows about the same concentration 5