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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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7
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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9
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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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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