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Air pollution

・Economy of Vietnam is drastically developing

Reason...◆Rapid growth (economics and populations)◆Major development of industries

Especially problems in urban area

◆Air pollutants : emitted from motor bikes, cars etc.(NOx, pm2.5 etc.)

However...Air pollutants increase in Vietnam

2Background

Purpose

Air monitoring in Ho Chi Minh city.→ make a pollution mapCompare with previous results of the same experiment.→ discuss about the change of the pollution

in Ho Chi Minh citySurvey with Vietnamese students→ join the exchange program (OPU – VNUHCM)

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Materials & Methods 4

47 sampling pointsTo measure NO2 , NH3

1. Passive Sampler (PS)

4 sampling pointsto measure PM2.5, HNO3, HONO, NO2 and NH3

2. Filter pack (FP)

Sampling points

Passive samples

PS & FP (AC1-4)5

5

Ho Chi Minh

2km

PS : 6 daysFP : each 2 days

What is passive sampler?

Sampler : low Atmosphere : high

Trapping filter

Diffusion of gaseous particles resulted from difference of the gaseous concentration

Principle of passive sampler

○Advantage・ Not use power source・ Small and light・ Low cost・ Easy to set and collect

×Disadvantage・ Variation is over 10 % 

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Passive sampler (PS)Air height : 19 mm

diameter : 30 mmφpore size:1.0 m

remove particles and water drop

Teflon filter

To catchNH3 → H3PO4NO2 → N(CH2CH2OH)3

Filter include chemical

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Filter pack (FP)

○Advantage・ Small and light・ Low variation

×Disadvantage・ Need power source

Analysis

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8

Filter pack

pump

F7: Guaiacol (NO2)F8: Guaiacol (NO2)

0.3 L/min

3.7 L/min

CalculationHONO conc. : F4−F5NO2 conc. : F5×2+F7+F8

MFC

4.0 L/minAir MFC

F1: Donut filter (particle >2.5 µm)F2: Teflon filter (PM2.5)F3: NaF (HNO3 all)F4: Na2CO3 (HONO all、NO2 about 2 %)F5: Na2CO3 (Compensate for NO2 of F4)F6: H3PO4 (NH3 all)

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10Extra experiment 10

NaCl coated (HNO3)

H3PO4 coated (NH3)

Na2CO3 coated (HONO)

Na2CO3 coated (HONO)

Na2CO3 impregnated (HONO)NaCl impregnated (HNO3)

Na2CO3 impregnated (HONO)

Teflon filter (PM2.5)

NH3 impregnated (NH3)

FP on denuder

Denuder

TargetsDenuder : airFP : air from volatile of particle

Sampling point : Roof of university

Passive sampler(47 places)

Material Analytical methodNH3 ICNO2 UV-vis

Analytical methodFilter pack sampler

and denuder(4 places)

Material Analytical method

PM2.5 Weight measurement

HONO ICHNO3 ICNH3 ICNO2 UV-vis

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Analyzed in VNU-HCM

Analytical method of NO2 12

[1] N-1-naphtylethylenediaminesulfanilic acid,phosphorus acid

[2] Standard solution of NO2-

…for make calibration line Add solution[1](1 mL)

Diluted water(10 mL)

Filter absorbed NO2

20 min

ReactionMeasure absorbance

(545 nm)

Calculate NO2 of air using by ratio of FP and PS

Program schedulePassive sampler Filter pack Activity

22/8 Group meeting23 set set Welcome party24 Mekong Delta25 Change filter

Mui Ne beach26

27 Change filter City tour & Cultureexchange program

28 Bamboo village29 Collect sample Collect samples Water park30 Analyzing Water Puppet Show31 Presentation Ben Tanh market

Keep

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1３

NO2 Comparison 2017 and 20192017 2019

Compare 2019 with 2017 (Osaka city in 2016: 29 ppb)• NO2 concentration is lower than that of 2017.• It had rained much in the measurement period.2NO2 + H2O → HONO + HNO3 14

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15~10 to 155 to 100 to 5

NO2 ppbNO2 ppb30 ~20 to 3010 to 20

0 to 10

NH3 Comparison 2017-19

2017

2018

Saigon River

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15

75~50 to 7525 to 500 to 25

2018

2019 NH3 ppb

Location trend is almost same

Comparison of FP sampling points

Compare the density of air pollutants for each point• For all pollutants, AC3 is the highest point.

→ near the airport, heavy traffic jam usually occurs

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0

5

10

15

20

25

30

35

40

HNO3 HONO NO2 NH3 PM2.5

AC1 AC2 AC3 AC4

0

0.5

1

1.5

2

HNO3 HONO

(ppbv) (µg/m3)

Comparison VN data vs. OPU dataHNO3, HONO, NO2

HNO3 HONO NO2HNO3 HONO NO2

VN in 2019 OPU in 2017

NH3

05

10152025

VN 2019 OPU 2015

NH3

 (ppb

v)

>

>HNO3, HONO, NO2

・ Almost same ratio・ VN < OPUNH3

・VN >>>OPU same as other reports

unit : ppbv

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Comparison day vs. night

0

5

10

15

HNO3 HONO NO2 NH3

23‐24day 23‐24night

0.00

4.00

8.00

12.00

HNO3 HONO NO2 NH325‐26day 25‐26night

0.00

2.00

4.00

6.00

HNO3 HONO NO2 NH3

27‐28day 27‐28night

AC1 system

Air SV

5:45 ‐ 18:09

18:10 ‐ 5:44

FP for day

FP for night

NO2 : day >> night         HONO, NH3 : day < night

SV : solenoid valve

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Air

Result of extra experiment 19

Air

Teflon filter

PM2.5

Denuderʼs value was different from FP ➞ leaked?FP on denuderʻs was high ➞ some gas volatile from PM2.5

Conclusion

Air pollution map of Ho Chi Minh city produced.

The conc. of NO2 is lower than 2017.

NH3ʼs conc. and location trend was not changed

Nitrogen oxide conc. was lower than OPU, but NH3 was much higher

Differences in atmospheric composition between day and night was seen

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