In addition, some scenarios to reducc pollution levels in general, especially air pollution ííom road traffic in particular show that, if rcduce 50% number o f motorcycles [r]
Trang 1VNU Journal of Sciencc, Earth Sciences 25 (2009) 179-191
M odeling air quality in Hochiminh city an d scenarios for
reduction air pollution levels
Ho Minh Dung*, Dinh X uan T hang
Institute f o r E nvironm ent an d Resources, Vietnam N a tio n a l U niversity H o C hi M inh City
Received 15 September 2009
A bstract Air pollution in general, espccially air pollution from road traffic in particular in
Hochiminh City (HCMC) are at the alarming Using models to simulate air quality is needed to ■ managc and predict the air pollution levels Research results have prepared em ission inventory o f air pollutants from road traffic, industry and domestic sources in HCMC Besides, TAPOM and
FVM models vvere uscd to simulatc ihe meteorological conditions and air quality in HCMC
Emission inventory results from road traffic show that em ission from motorcycles account for a
signiiìcant amount o f total load o f pollutant emissions from thai source Sim ulation results o f air
quality give better results when using emission inventory with traffic em ission íactors were
cstimatcd in HCMC
In addition, some scenarios to reducc pollution levels in general, especially air pollution ííom road
traffic in particular show that, if rcduce 50% number o f motorcycles (private transportation) and
incrcase 10 times numbcr o f bus (public transportation), air quality will m ore improve and can
rcducc trafíìc jam
Keywords: Road ưaíĩic, emission invcntory, models, scenarios.
1 I n tr o d u e tio n
A ir q u ality m odel is an im p o rta n t tool to
m an ag e air p o llu tio n in u rban area s W e c an use
m o dcls to p rc d ic t im p acts in the p ro cess o f
u rb anization, su ch a s d e v e lo p m e n t o f traffic
netw o rk , th e lo catio n o r cx p a n sio n o f
rcsidcn tial a n d in d u strial a r e a s ,
In ou r co u n try in g eneral and H C M C in
particular, the stu dies aim to sim ulate air quality
w as initially im plem ented and ach icvcd som e
initial rcsults T ypically thcre w erc scveral
research prcỹects a t all lev els an d m aster thesis
H ow ever, o n c m a jo r lim itatio n in alm ost studies
o f d a ta o n th e e m issio n íacto rs (EF) o f air
p o llu tan ts fro m ro a d tra ffic w as used from
n e ig h b o u r co u n trics In ad d itio n , due to traffic is
o n e o f th e m ain so ư rc e o f a ir p o llu tio n gcnerated
in H C M C s o th e s im u la tio n resu lts o f air quality
in th a t stu d ies h ad m o re o r less lim ited accuracy
T h e re ío re , in th is stu d y , th e a u th o rs used results
o f th e stu d y e s tim a te d air p o llu tan ts E F in real
co n d itio n s o f tran sp o rla tio n activ ities in H C M C ,
so th e sim u latio n re su lts o f a ir q u ality w ill get
m ore p recisio n
Corrcsponding author Tel.: 84-8-38651132
E-mail: minhdung@hcmier.edu.vn
179
Trang 2180 H M Dung, D x Thang ỉ VNU Ịournaỉ o f Science, Earth Sciences 25 (2009) Ĩ79-Ĩ91
2 E m issio n in v e n to r y f o r a i r p o llu ta n ts
2 1 Em ission in vento ry daía
T h e general m e th o d o lo g y fo r p rep aratio n o f
the cm ission in v e n to ry in clu d es th rce m ain
steps, id e n tiíy thc so u rces, so u rces
classification an d calcu latio n o f em ission s A
tem poral reso lu tio n o f l h is uscd, and
calculation s are do n c for given w o rk in g day
Jan 19, 2006 A s for th e spatial reso lu tion , the
EI is calcu lated in sid c grid u sed for m odeling
35km by 35km vvith 1 k m squ are cells
E m issio n calcu la tio n s are in d iv id u ally d on c by
sourccs and h ad v alu c ch an g e s acco rd in g to the
each cells
Three m ain sources are considered for the
emission calculations include: road traíTic,
industry and d om estic activitíes Emission
T ablel Road traffic emission
estim ations are done for param ctcrs o f air pollutants N O x, c o , V O C s an d S 0 2 In particular, the em issions from road traffic activities using tvvo kind E F s data, EFs from C hina (used before) and EFs determ incd in IIC M C
2.2 M ethodology a n d input data
a R o a d tra ffìc so u rc e
T raffic em issio n s are calcu latcd u sing three
m ain g ro u p s o f acliv ity d ata: the g eorefercnced
S tr e e t n e tw o rk , th e fleet co m p o sitio n , and tem po ral a n d sp atial v aria tio n s o f circu latio n o f this fleet T h e cm issio n s are com p utcd h o u r per hour, u sin g ho urly cm issio n co efficicn ts in day
In this stu d y , w e use E F s o f a ir p o llu tan ts vvas
d ev clo ped in real co n d itio n s in H C M C by
au th o rs (H o M D , 2 0 0 8 ) [1,2]
factors in Hochiminh City
Note: MC (Motorcycle); LDVs (Light duty vehiclcs); HDVs (Heavy duty vehicles)
n : EFs from China (DOSTH, 2001 )[3]
b Ịn d u stry so u rc e
U p to n o w , H C M C has th rec exporl
P r o c e s s i n g z o n e s a n d 12 i n d u s t r i a l a r e a s w i t h a
total area o f 2 ,3 5 4 ha A t p resen t, H C M C has
abo ut 1,000 p la n ts, factories an d m ore than
33,000 sm all-scale p ro d u ctio n íacilities
han dicraíts In H C M C , th e em issio n calculation
o f air pollution load b ased on the em ission
factors and the p ro d u ctio n p ro cess o f industries
that can bc applied:
G in = I K in N jn (g /y ea r) (1)
W hich, Gin is em issio n o f p o llu tan t i for
sector n (g /y ea r); K m is cm issio n íactors o f
pollutant 1 for secto r n (g/ton s o f ravv m atcrials
o r products); Njn is a m o u n t m aterial o r fucl o f
íactory j for s e c to r n (ton s/year)
c D o m e stic so u rc e
E m ission in v en to ry from h um an activ ities
p la y an im p o rtan t ro lc in m o d e lin g a ir quality
S om e m a in activ ities g en era te p o llu tan ts such
as b u m in g fuel (D O , F O , LPG , co al, etc),
b u ild in g h o m e s, o ffic e s (p a in t and o th er o rg an ic
s o lv e n ts , )
2.3 E m ission inventory resuỉts
T ab le 2 is th e cm issio n in v e n to ry results from so u rc e s in IỈC M C , w h ich in road traffic sou rce w e re d iv id cd to tvvo co lu m n s, EI-1 is used em issio n factors in H C M C and E I-2 is uscđ em issio n factors from C h in a R esu lts o f
cm issio n in v c n to ry shovv th at, w hen w e used
E F s from H C M C , cm issio n load o f N O x and
V O C s a re lo w er (8 9 ,2 % and 43,5 % , resp cctiv ely ) b u t em issio n lo ad o f c o is h ig h er (facto r 1.32) v alu e w hen u sin g E F s from C hina
Trang 3H.M Dung, p x Thang / VNU lonrnal o f Science, Enrth Sciences 25 (2009) 179-197
Table 2 Total emission o f a ư pollutants by sources in HCM C
181
No Pollutants Road traíĩic (tons/year) Industry (tons/year)'2’ Domestic (tons/year)'31
Sources: (I)EMISENS; (2'3>INTEX-B (Zhang Q và nnk, 2009) [4]
2.4 Evaỉuaíion o f the EIs over a specific case
study in H CM C
In o rd cr to assess thc tw o resu lts o f the EIs,
an a ir quality m odel (A Q M ) a t m esoscalc is
applicd for tw o d ay s Jan 19& 20, 2006 T he goal
is to com pare th c co n cen tratio ns o f c o , N O x,
V O C s and O zone generatcd by A Q M for both
EIs (EI-1 and E I-2 ) w ith m easu rem en t values
a M odeỉ description
T h e m o dels T A P O M (T ran sp o rl and A ir
P o llu tio n M odcl, M artin i A ct al., 2002 &
20 0 3 ) (5,6] a n d F V M (P in ite V o lu m e M odcl,
C la p p ic r A et al., 1998) [7] d ev elo p cd at
L P A S -E P F L , a re u scd for this stu d y T h cy arc
th rce d im cn sio n al E u lerian m o d els using terrain
fo llow ing grid a n d íìn ite v o lu m e d iscretizatio n
T h e tran sp o rt and p h o to c h em istry m odel
T A P O M in clu d es the R A C M lu m p ed sp ccies
m c ch an ism chem ical so lv e r for gaseo u s phase
(S to ck w ell ct al., 1997) [8] M eteo rolog ical
input d ata for T A P O M is o b tain s from thc
m odel F V M , w h o se b o rd ers can be forccd using
w in d and tc m p eratu re íìeld s fro m large scale
m odcl rcsu lts FV M in clu d es an urban
tu rb u lcn ce m o d el w h ic h sp e c iíic a lly sim ulates the cffccts o f urban areas on th e m eteorology [9-14]
b C om parison o f sim ulated a n d observed concentrations
A íìrst c o m p a riso n w ith p rim ary pollutants
is co n d u cts ([(C|£i-Cob.)/Cob.]%) S im ulation resu lts by EI-1 h av e v alu e is clo see r to the
m casu rem en ts, esp ccially for c o , prcsen ting an avcragc p c rc c n ta g e d iffere n ce o f 20 % , w hcreas for thc sim u latio n resu lts b y E I-2, the
p ercen tag c dilTerence p rc se n ts 35% F or N O x,
th c p crcc n tag c d iffere n ce w ith resp ect to
ob scrv atio n s are sm aller for E I-1, alth ou gh not
so d iffere n t fro m EI-2 resu lts T h is ind icates a cle a r u n d erestim atio n o f c o em issio n s in EI-2,
w h ereas for N O x b o th EI-1 a n d EI-2 generate sim ilar results
1 4 0
12.0
^ 10.0
1» 8.0
J 6.0
ằ 40
2.0
0.0
1 5 9 1 3 17 21 2 5 2 9 3 3 3 7 41 4 5
H o u r ( h )
0.0
1 5 9 13 17 21 2 5 2 9 3 3 3 7 41 4 5
H o u r ( h )
200.0
16 0 0
- 1 120.0 O)
&
6 8 0 0
“ 4 0 0
Fig 1 Comparison c o conc at IIB slarion (Iefi) and NOx conc at BC slation (right) on Jan 19&20, 2006
Trang 4182 H.M D ung, D x Thang / VNU Ịoum al o f Science, Earth Sciences 25 (2009) 179-191
S in ce th ere is no m easu rin g V O C s d ata, so
w e use co m p ariso n O zo n e co n cen tratio n as a
w a y to assess the ind irect to im pact o f the
ch an ge o f V O C s em issio n in p u t data The
averag e con cen tratio n o f O zo n e in the
sim u lation ep iso d e an d th e m e asu re m en t values
at H B statio n sh o w th at for E I-1 , the p ercentage
d iffere n ce is ab o u t 10%, vvhereas for EI-2, the
p erce n tag e d ifferen ce is ab o u t 30% T herefore,
\ve can con clu d e th at th e sim u latio n for EI-1 vvill g et re a so n a b lc lev els o f O zo n e
5-1 B-2
A O b s e r v e d
9 1 3 1 7 21 2 5 2 9 3 3 3 7 41
H o u r (h)
4 5
Fig 2 Comparison 0 3 conc at HB station on January 19&20, 2006
2.5 D iscussion a n d im plicatioỉis o f E I results
a D istribution o f em issio n s b y s o u rc e a n d
regioìi
E m ission in ventory an d d istrib u tio n o f air
p o llutants em ission from p o llu tio n so u rces in
H C M C for spatial an d tem po ral by u sing G IS
m ethod D om ain w ith d im en sio n o f each cell
Ik m 2 and have 35 cell for X an d y d irectio n is
used in this study D istrib u tio n th e em ission for
tem po ral estim ated as equ ation :
Eh = E a * fa * fw * fd /8 7 6 0 (2)
W hich, Eh, Ea are em ission load p er hour and
year, respectively; fa, fw, fd are coefficient o f
em ission distribution for each m onth, hour in day,
respcctively; and 8760 is total hours o f a year
T h e em issio n load in each cell is
gam /km 2.h W h ich, th e co efficien t o f em ission
distribu tion for each m onth, vveek, and hour
w a s estim ated for each d iffere n ce p ollution
sources
T h e m o s t im p o rtan t c o n trib u tio n o f c o , V O C s and N O x in H C M C is attrib u ted from road traffic A sim ilar relativ e so u rce stren gth is found fo r o th er d ev elo p in g co u n tries, esp ecially for C O , V O C s an d NO*
F or S 0 2, N O x> C O an d V O C s, the 63, 30,
94 an d 6 9 % , o f th e total ro ad traffic em ission, resp ectiv ely , co rresp o n d to m o to rcy cles This resu lt is en tirely reaso n ab le th a t 95% o f thc total vo lu m e o f m o to r v e h ic le s in H C M C is
m o to rcy cles T h e m ost im p o rtan t co ntribu tio n
o f C O , V O C s an d NOx in H C M C is attributed from ro a d traffic A sim ila r relativ e source stren g th is fo u n d for o th er d ev elo p in g countries,
e sp e c ia lly fo r c o , V O C s an d N O x
F o r S 0 2, N O x, C O an d V O C s, th e 63, 30,
94 an d 6 9 % , o f the total ro ad traffic em ission, resp ectiv ely , c o rre sp o n d to m o to rcy cles This resu lt is en tirely re a so n a b le th at 95% o f the total v o lu m e o f m o to r v e h ic le s in H C M C is
m o torcy cles
Trang 5II.M D uny, D x Thang / V N U Ịournnl o f Science, Earth Sciences 25 (2009) 179-19Ì 183
1 0 0 %
90%
80%
70%
6 0 % 50%
40%
30%
20%
10%
0 %
■ M ortocycle □ LDVs □ HVDs ■ C ar □ B us
Fig 3 Distribution o f the on-road vehicle emissions in HCMC by typc o f vehicle and by pollutant
b L im ita tio n s o f th e m e tììo d a n d discussion
W e can State t h a t u n c c r t a i n t i e s in o u r EI
co m c from three m ain so u rces: F irst, the q u ality
o f th e in p u t d a ta vve h a v e c o llc c tc d S e c o n d , th e
ex trap o latio n b ased on thc cx istin g in fo m iatio n
to fill in thc rcm ain in g d a ta gaps T hird, som e
a sp c c ts o f the m eth o đ o lo g y its e lf E M IS E N S
p ro cedu re, as it has b een d e v e lo p e d and initially
a p p lied in S o u th A m erican c o u n trie s an d S outh
V ietnam so it has so m e rcstric tio n s to im prove
D csp ite o f lim itatio n s, all rcsu lts ab o ve allovvs
to co n clu d e that EI w ith E F from H C M C h av e
m o re reaso n ab le sim u latio n v alu es than EI w ith
E F from C hina
3 S im u la tio n o f m c tc o ro lo g y a n d a i r q u a lity
3.1 Select sim ulation episode
E pisode selcctcd for sim u latio n b ased on
several criteria:
In the dry seaso n (Jan u ary to A p ril) b ccau se
d u rin g th at tim e clo u d y sky, a p p ro p ria te for
F V M m odel;
C o n cen tratio n o f p rim ary a ir p o llu tan ts are
h ig h and stab le in the m o n ito rin g stations;
O zon e co n ce n tratio n is h ig h in the
m o n ito rin g station s an d o ften ex cccd stand ards
(1 8 0 ppb);
B ased on th c critcria above, th e period
ch o sen ío r sim u lation is Jan 19 & 20, 2006
3.2 Settings in the m odel
T o sim u late a ir q u ality in m esoscale req uires p recisio n and reso lu tio n o f
m cteo ro lo g ical in p u t d ata T o get the req u ircm cn ts, FV M m odel is run b y u sing one
w ay n e stin g m eth o d w ith 5 dom ains
D im cn sio n and reso lu tio n o f d o m ain s are selected to sim u late m eteo ro lo g y co n d itio n s in
th e stud y a re a as follow s:
- D o m a in l ( D l) : D im en sio n o f d o m a in 2 0 X
2 0 c e l l s , s p a t i a l r e s o l u t i o n 1 5 0 k m X 1 5 0 k m
T h is d o m a in co v ers a n area o ĩS o u th e a s t A sia and a parl o f S o u th C h in a Sca;
- D o m ain 2 (D 2 ): D im en sio n o f d om ain 20
X 2 0 c e l l s , s p a t i a l r e s o l u l i o n 7 5 k m X 7 5 k m T h i s
do m ain c o v e rs an arca o f S outh o f V ietnam ,
C am b o d ia, T h ailan d an d a part o f the South
C h ina Sea;
- D o m ain 3 (D 3 ): D im en sio n o f d om ain 33
X 3 3 c e l l s , s p a t i a l r c s o l u t i o n 1 6 k m X 1 6 k m T h i s
do m ain c o v c rs a n arca o f th e Southern
p ro v in ce s and p a rts o f C entral S outhern
p ro v in ce s a n d S o u th C h in a S ca;
- D o m ain 4 (D 4 ): D im en sio n o f do m ain 35
X 3 5 c e l l s , s p a t i a l r e s o l u t i o n 7 k m X 7 k m T h i s
dom ain c o v crs an arca o f S o u th W estem
p ro vinces a n d H C M C
Trang 6184 H.M Dung, D x Thang ỉ V N U Ịournal o f Science, Earth Sciences 25 (2009) 179-191
- D om ain 5 ( 0 5 ) : D im en sio n o f dom ain 38
X 3 8 c e l l s , spatial r e s o l u t i o n l k m X l k m
3.3 Bounclary a n d in itia l co n d itio n s
T h is sim u latio n u scs 6 -h o u rly d ata from the
N C E P /N C A R (2 0 0 6 ) rcan a ly sis dataset for its
initial and b o u n d ary co n d itio n s D ata have 2.5 X
2.5 degree global rcso lu tio n w ith 17 p r c s s u r e
levels at tim es 0 Z , 6 Z , 12Z an d 18Z
3.4 T o p o g ra p h y a n d ỉ a n d use d a ta
Input data fo r F V M m ođel also includes
topography, land use, c h ara cteristics o f the soil,
roughness, h u m id ity an d th crm al A ll d atabases
is to ok from U SG S vvith lk m resolutio n
4 R csu lỉs a n d d is c u s s io n
4.1 M eíeoroỉogical sim uỉations
a B o u n d a ry a n d in iíia l co n d itio n s
T he m odel is first applied to a 3.000km X
3.000km grid, aim in g to g enerate adequate
C entral o f t h i s d o in a in coiiìcidcs vvitlì the center
o f H C M C
boundary and initial conditions for o u r m esocale dom ain A very sim ilar behav ior o f the vvind
p attcrns bctvveen th e tw o days o f the episodc in sim ulated by th e m otlcl (in range N E to SE dircction) From 5h to 12h, the m ainly vvind dircction often betw een SE and N E directions, sim ilar behav io r o f th e sea vvind From 12h to 14h, as influenced by sea-con tinen lal vvind so the
m ain ly vvind d irectio n is SE
b M eso sca le sim u la íio tĩ
D istribu tion o f land use in urban areas in
m eteo ro lo g ical m o d el is q u ite co m p lex because
th e y n c e d m a n y in ío r m a lio n s u c h a s d e n s ity and
h e ig h t b u ild in g , a r e a o f trc c s and m a n y o th c rs info rm atio n H o\vevcr, th e ir classificatio n m ore detailcd vvill g et th e sim u latio n results closer
th e m c asu re m en ts B ecau sc the resolution o f
sm all do m ain is lk m x lk m to sim ulate
m ctco ro lo g ical in m esoscale so they necd somc
co rrcctio n s for s u rfa c e d ata D atab ases for the Fig 4 Domains for meteorological simulation
Trang 7/ / M D ung,D.x 77ww^ / V N U louninl o f Science, Eartỉt Sciences 25 (2009) 179-191 185
co rrectio n is too k fro m U SG S and land u se in
H C M C D om ain D5 is ch o scn for sim ulate
m eteo ro lo g ical as m e so scale in cp iso de o f
study M easu rem en t d ata from T a n S o n N hat
(T S N ) station vvas u scd to co m p are vvith the
sim ulatio n values
c C o m p a re sim ulcttion re su lt a n d ob served
+ W ind direcíion a n d m n d s p e e d :
S im ulation resu lts from F V M shovv w ind
speed depen d on the ty p c o f su ríace O n the sea,
th e vvind v ecto r is sta b lc o n d irectio n and value,
\vind spccd in lo \v er \vhcn com e to the
co n tin en t W ind d ircc tio n an d w in d speed in
co n tin en t is ch an g e a lot and d ep en d on the
d istrib u tio n o f the su ría c e th erm al In urban
area, vvind sp eed is lo w cr b u t n o t clear
C o m pare w ith th e m e asu rc m en ts sh o w w ind
direction co n sisten t relativ ely C om p ariso n
b etw cen th c sim u latio n w ith m easurem ent
values in ep iso d c study havc co ư elatio n
c o e íĩic ie n t R = 0 6 8 and 0.81 fo r \vind direction and w in d sp ecd , respcctively
+ T em p era ỉu re
S im u latio n rcsu lts show th e effects o f sea to
t h e s u r í a c e tem p eratu re d i s t r i b u t i o n , Coastal areas have lo w an av crag e tem peratu re and tem p cratu re v aria tio n s W h cn g o in g into the
co n tin en t, te m p eratu re v aria tio n s an d average tem p eratu re tc n d s to in c re ase T h e highest tem p eratu re in d o m ain D5 a p p e a r in the cen ter
o f H C M C , th c rcg io n h av e trccs an d \vater
su rface area is low T h e m odel p red icts w ell the tim e o f the d ay w hcn tem p eratu re start
in creasing d u e to the su n rise (aro u n d 6h - 7h),
as vvell as th c tim c o f th c m ax im u m value (betw cen 12h - 13h) C o m p a risio n betw een sim ulatio n a n d m e asu re m en t v alu es in episode stu dy h a v e co rrelatio n c o e ffic ic n t R =0.92
■ọ
ị
ị
ề
360.0 300.0
g 240.0 o
2 180.0
€
ị 120.0
ề 60.0
0.0
1 5 9 13 17 21 25 29 33 37 41 45
Fig 5 C om parison vvind speed and w ind d ừ e c lio n b etw een sim ulation a n d obscrv cd on Jan 19& 20, 2006
4.2 A ir quality m odeliỉìg
E m ission in v e n to ry is c a lc u la te d for 24
h o u rs in Jan 19, 2 0 0 6 w ith l h tem poral
r e s o l u t i o n a n d l k m X l k m sp atial rcso lu tio n in
do m ain 3 5km X 3 5 k m B o u n d ary an d initial
co n d itio n s w ere p re p a rc d w ith the sam e
datab ases A p re-ru n o f o n e d ay vvith the sam e
em issio n s and w ind ficlds is c o n d u c te d for all
th e sim ulatio ns, in o rd e r to p ro vide m ore
realistic initial co n ditions
a P r im a r y a ir p o llu ta n ts
T h e p ro c e ss o f tran sp o rta tio n and dispersion
o f p rim ary p o llu ta n ts in the Central o f H C M C
th rou gh h av e ch an g e d isp e rsio n to w ard at tim es
d u rin g the d a y b u t th c trcn d is m o ving tow ard
th e SE d ire c tio n in gcn erally , th c sam e w ith the
m ain ly vvind d irc c tio n in episod e o f
m eteo ro lo g ical sim u latio n D cp cn d on tim es o f day, th e d istrib u tio n o f air pollu tant
Trang 8186 H M Dung, D x Thang / V N U Ịournal o f Science, Earth Sciences 25 (2009) 179-Ĩ9Ĩ
c o n c e n tra tio n s is d iff e re n c e , th e p c a k is in the
m o m in g (7 -9 h ) a n d a t n ig h t (2 0 -2 lh )
B o th s im u la te d a n d m e a s u re d
c o n c e n tra tio n s o f c o a n d N O x s h o w im p o rta n t
m o m in g p c a k T h is p e a k is re la te d to h ig h
e m is s io n s fro m r o a d tra ffìc in th e m o m in g ru sh
h o u r a n d lovv m ix in g h e ig h t T h e in te n s itie s o f
th e p e a k s o f b o th c o a n d N O x a re g o o d
a g re e m c n t w ith o b s e rv a tio n s a t a ir q u a lity
m o n ito rin g s ta tio n H B a n d D O Im p o rta n t
n ie h tly p e a k s o f c o a n d N O x (a ro u n d 2 1 h),
a p p e a r b o th in th e s im u la tio n and
m e a s u r e m e n ts T h is p e a k is a ls o re la te d to the
ro a d tra ffíc a n d it is s o m e tim e s o v e re s tim a te d
b y th e m o d e l
W ith S 0 2 v a lu e , th e c o m p a ris o n betvveen
s im u la tio n a n d m e a s u re m e n t s h o w th e sam e
p a tte m
ỈU.V
60.0
^ 50.0
" I 40.0
o 30.0
c
o 20.0
10.0
0.0
1 5 9 13 17 21 25 29 33 37 41 45
Hour(h)
0.0
1 5 9 13 17 21 25 29 33 37 41 45
H o u r ( h )
Fig 6 C om parison c o conc at D O station (left) and S 0 2 conc (right) at T N station o n Jan 19& 20, 2006
b S eco n d a ry p o llu ta n t - O zơĩie
+ Spa tial distrib u tỉo n
T h e s p a tia l d is trib u tio n o f O z o n e is
g e n c ra te d d c p e n d in g o n th e p rim a ry p o llu ta n t
( N O x & V O C s ) c o n c e n tra tio n s a n d the
m e te o ro lo g ic a l c o n d itio n s F o r th is e p is o d e ,
p o llu ta n ts a re p u s h e d b y w in d c o m in g fro m S E
d ire c tio n , w h ile O z o n e is b e in g fo rm e d w ith
m a x im u m v a lu e s a t m id d a y A f te r m id d a y ,
w in d d ire c tio n m o v e a little to E d ire c tio n A t
16h, th e m a x im u m O z o n e v a lu e s h a v e d ro p p e d
a n d th e p lu m e m o v e to E -S E d ire c tio n T h e
s im u la tio n r e s u lts shovv th a t, th e p lu m e o f a ir
p o llu ta n ts is p u s h c đ to S E d ire c tio n in the
m o m in g W h e n th e th e rm a l vvind i s d e v e lo p e d ,
p o llu ta n ts a re th e n tra n s p o rte d eastvvards,
C ro ssin g a g a in th e C e n t r a l p a rt o f th e c ity T h is
h a p p e n s a t th e s a m e tim e o f m a x im a l so la r
ra d ia tio n s , th u s im p o rta n t p e a k s o f O z o n e are
g e n e ra te d in tovvn
Trang 9/7.M D ung, D x Thang / VNU Ịottrnal o f Science, Earth Sciences 25 (2009) 179-191 187
25
15
5
J a n 1 9 / 2 0 0 6 1 4 0 0 L T , O z o n , p p b
Fig 7 M apo fO zo ne concenlration (ppb) indomain D5 at lOh, 12h, 14h& 16h on Jan 19, 2006
+ C o m p a riso n m t h m ea su re m en t values
T h e O zo n e m e asu re m cn ts c o ư o b o ra te the
p rc sc n c e o f th e plum e o v c r th e c ity , \vith high
co n ce n tratio n in Ja n 19, 2 0 0 6 a t D O & IIB
statio n s (15 2.3 ^ig/rn3, 8 4 8 fig /m \ respectivcly )
an d lo v cr v alu es in Jan 20, 2 00 6 T h is m ight
im p ly th a t th e city p lu m c rem a in s m ain ly in the
city c c n te r on 19 Jan b u t is slig h tly m oved
to\vards S E on 20 Jan T h e sim u latio n shovvs
high O zo n e lev els at th c sam e statio n s as the
m e asu rc m en t v alu es o n 19 Jan u ary , in d icatin g a
goo d rep ro d u ctio n o f th e p lu m e p osition
5 S cen a rio s to r e d u c e a ir p o llu tio n levcls
5.1 Em ission scenarìos
D u e to th e ro a d traffic is p lay im portant sou rcc ro le to air p o llu tio n in H C M C in general,
so the p ro p o sed sc e n a rio s to re d u c e pollution lev cls from th is so u rcc is n ecessary T w o types
o f tran sp o rla tio n m e an s sp ecial interested is
m o to rcy cle an d b u s S cen ario s to rcduce air
po llu tio n lev els is b a sc d on tw o m ạjo r criteria: (a) ch an ge the n u m b e r o f ty p es o f transportation and (b) ch ang e the ty p e o f fuel used
J a n 1 9 / 2 0 0 6 1 0 0 0 L T , O z o n , p p b J a n 1 9 / 2 0 0 6 1 2 0 0 L T , O z o n p p b
J a n 1 9 / 2 0 0 6 1 6 0 0 L T , O z o n , p p b
Trang 10188 H M Dung, D x Thang / V N U lournaỉ o f Science Enrth Sciences 25 (2009) 179-191
H C M C h a s 3.584 strects vvith total road
le n g th ab o u t 3 6 7 0 km , th e area o f p avcm ent is
3 6 m illio n m 2, s o the ratio o f ro ad area đensity
an d c ity area o n ly abo ut 1.8% (k m /k m 2), m uch
l o w c r t h a n t h e c o m m o n S ta n d a r d o f d e v e l o p e d
c o u n trie s 10-20%
A rea for a m o to rc y c le travel is 10 - 12m 2,
w h ile arca o f a se a t on th e bus o n ly 2rn arca o f
ro ad W ith a b o u t 4 m illion m o to rb ik cs will
a c c o u n t for ap p ro x im a te ly 4 0 m illio n m 2 travel
B ut, H C M C o n ly build a n cw o r ad d in g about
1 % o f ro ad s u ría c e e v ery year
In ad d itio n , fuel co n su m p tio n in d icato r for a
p a sse n g e r is 0.015 liters/k m w hcn using
m o to rc y c lc s a n d 0 0 0 4 4 liters/km vvhcn using
th c b u s T h u s , w h en uscd as a m e an s o f
tra n sp o rt, m o to rcy cle s h av e a fucl co n su m ptio n
h ig h e r th an 3.4 tim es o f the bus
T h e re ío re , o n ly increase thc b u s and reduce
th e m o to rc y c le vo lu m es can so lv e traffic
c o n g estio n in th e statu s o f th e cu rren t tig h t line,
savc fuel an d re d u c e po llutio n
a C h a n g e th e n u m b e r o f veh icle types
S o m c sc e n a rio s to red u ce air p ollution
le v e ls fro m ro a d traffic w as p ro p o sed as
follow s:
- S c e n a rio 1 (S c e n l): redu cc 50% o f
m o to rc y c le v o lu m e trav el th ro u g h o u t th e city at
th e sam e tim e s o the load o f p o llu tan ts em issio n
fro m m o to rc y c le s w ill d ecrease 50%
- S c e n a rio 2 (S cen 2): red u ce 50% o f th e
m o to rc y c le v o lu m e, at th at tim e to fill the
d cm an d fo r tra v e l Vĩ re s t o f th e p eo p le to
in c re ase th e v o lu m e o f b u s 10 tim es o f the
c u rre n t n u m b e r B esides, c h an g e sm all size
b u ses (3 5 -4 0 seats: B 3 5 -B 4 0 ) for th e ty p e s are
c o m m o n ly u s e d (55 -80 seats: B 55 -B 80) The
nevv siz e m c an s in acco rd an cc vvith th e existing
ro ad traffic in H C M C w here th e w h o le city has
o n ly 14% o f the ro ad 12 m e te rs vvidth
(c o n v e n ic n t fo r th e b u s B 5 5-B 80 ), 51% o f the
road from 7 -1 2 m w id th an d 35% o f th e road
w idth less than 7m In ad d itio n , efficiency buses m u st be fro m 8 0 -1 0 0 % (cu rren tly 40-
4 5 % for th e larg e bu ses)
- S ccn ario 3 (S cen 3): red u ce 50% o f the
m otorcycle v o lu m e, a t th at tim c to íìll thc
dem an d for trav el Vi rest o f th e peo plc to
increasc the v o lu m e o f b u s 05 tim cs hig h cr than the cu rrcnt n um b er E fficien cy b u ses have at least 80% (cu rren tly 4 0 -4 5 % )
b C hatìge th e ty p e o f fu e l
C h angc u sin g clean fuel (L P G , C N G , ) instcad o f luel b c in g u sed is o n e o f th e solutions
no t o nly gct c co n o m ica l b e n e íit but also
co n trib u te to rc d u c e a ir p o llu tio n from road traffic sourcc
U sing C N G (C o m p re sse d N atu ral G as)
c o s ts o n ly a b o u t 5 0 -6 0 % o f th e tra n s p o rt th a n gasolinc, oi!, b u t rc d u c in g to 3 5 % o f C*Hy, 60%
C O an d 10% N O x, e m ittc d into the environm cnt W ith so m e o th e r b c n e íits such as
an ti-abrasion , in c re a se d en g in e lifc, rcduccd
m ain tcnance costs
C o m p a riso n w ith g aso lin e, m o to rcy cle run
on 4 0 % gas sav in g fuel co sts and cnv iron m cntal
p o llu tio n levels re d u c e d o v er 70%
5.2 Sim uỉation resu lts a ir q u a lity in th e scenarios
W ith 03 scen ario s a s m e n tio n ed ab o v e show
th e em issio n load c a lc u la te d is a different
am o u n t o f em issio n load a t th e íìrs t o f study (b ase casc) D ep en d in g on th e a ir p o llu tan ts and scenarios th at c m issio n s o f air p o llu tan ts are increase o r dccrease
a C o n cen tra tio n s o f p r im a r y p o llu ta n ts
S im u lation rc su lts o f air qu ality in 3 sccnarios ab o v e m c n tio n cd w ith prim ary
po llu tan ts c o n c e n tra tio n s co m m cn ts as follow s:
- N O x co n ce n tratio n : In sc e n a rio 1, lig h t
d ccrcase w ith th e initial co n ce n tratio n (basc