Emission, dispersion and deposition of automotive pollutants

The Science of the Total Enuironment, 33 (1984) 141-145 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

EMISSION,

DISPERSION

AND DEPOSITION

- Preliminary

J.S.

Hooghiemstra,

Agricultural 6700

communication

H.

Harssema

University,

EV

OF AUTOMOTIVE

and

Deparment

Wageningen

(The

141

POLLUTANTS

-

P.

Hofschreuder

of

Air

Pollution,

P.O.

Box

6123,

Netherlands).

SUMMARY The emission of road traffic can be estimated by using a mass-balance technique; this way, an average emission rate, for a given traffic situation, can be found, which is not influenced by the factors that govern emission rates for individual cars. The need for a detailed dataset, which contains dispersion data for both gaseous and particulate pollutants, is pointed out. The instrumental lay-out, which overlaps for both experiments, is described. At present only limited data are available.

EMISSION Estimates tests,

for

traffic

performed

out

by

Bullin

emission into

account

tions,

individual

al

(ref.

which

are

et

rates

emissions

on

factors

are cars,

I),

in

usually in

this

way

representative

like

vehicle

mix,

derived

specified it

from

test is

for

the

state

of

chassis

cycles.

very

difficult

whole

of

dynamometer-

As

is

to the

car

maintenance,

pointed

establish park,

taking

operating

condi-

etc. However,

tion

and

the

emission

road

Using a vertical

individual

principle plane

of are

realistic

of

configuration of

the

upwind sinks

determination

the

of

possible. are

averaged

amount

of

a roadway equal

the

this

-a,

Q

q

minus

material measuring

U

= wind

z,y

= height,

strength

the

amount

emitted

by

occurs),

the

site

during

0 1984

(m/s)

length

Elsevier

(ml

Science

Publishers

a given

situa-

which

influence

factors way. pollutant

(Wms)

velocity

all

a particular

amount

in

a realistic

1

source

traffic

way in

C.u.dydz

-1

”

004%9697/84/$03.00

of

I+"

Q= with

the of

passing

cm

In

is

buffering

cars,

established.

emission

cars,

of

must

or

average

the

downwind roadway

present mix

that

the

B.V.

flowing

flowing the

through

traffic

emission the

through

rate sample

a plane

(provided of time,

no a can

be

142 If

wind

velocities

currents,

wind

and

background

fied

equation

are

higher

directions

are

concentrations can

be

than

low

used

C2.uy;dz

massbalance

an

upwind

At

the

wind

background same

and were

class

between

1500

to

the

same taken

by

Whatman

41

mm/s

lead/km an

large

average

at was

were

1.10,

1.10

m height

one

hour

was

(2)

of

4.50

and the

in

emission as

m and

road-edge. anemometers, vane.

Pasquill

stabili-

a traffic

intensity

obtained

emission

an

and

propeller

mainly and

times

7.50

cup

a Gill

8 m/s

SF6

the

20

highway

10 m from

runs, and

The

85%

car the

sensitive

10 m with

5 m/s

cars/hour.

2.50,

with

at

emitting from

0.70,

measured eight

(2)

a SF6

measured

between

all

emission place

as

mm 0 open

face

47

for

lead f

low

lead same

direction.

content

into

of

thus

based

often

on

far

from

us

DISPERSION

AND DEPOSITION type

pollutant

develop

from

determined

integra-

in

the

physical

processes

emissions,

the

in

physical

any

meaning

as

an must

this

to

Thus,

induced

by

give

et

were and

when the

- experimentally obscure.

type

al set

an

to

1);

their

test

this

description

the

for

itself, - correction

dispersion is,

results,

to

actually

found

results, concept

technique.

estimate

traffic

for

balance

describe

modelling

fuel

itself,

preliminary

mass

9.1 100

potential

roadway

approach

to

of of

sampler

(ref.

own

of

average

the of

lead

sampled

rate

speed

the

up

our the

a fair claim

velocity

36% of

of

evaluate

not

a face

average

this

a statistical

do

was

Assuming is

Bullin

never

to

are

detail.

remain

the

purpose,

program

try

emission

deposition

in

but

g/dm3.

of

which

an

of

aerosol

an emission

of

surprising.

they

0.39

the

not

models

with

with

efficiency

presence

level,

turbulence

expressed

km/h

for

holders

of

concentrations

The

measurements

the

ideal

as

on ground

filter

low

from

samples.

traffic

reported

dispersion

SF6

fuel

100

a field

dispersion,

concentrations

the

measurements

encouraged

Gaussian

to

is are

calculated

the

these

the

and

lead

calculations cases

on km at

3)

was

cruising

account

(ref.

retrieval

From steady

8 dm3/100

Taking

Similar

the

point

the

fitted

particles

models,

0.35,

the

at

deduced

consumption

of

of

velocity

equation

in upward was

emission.

and

10 m downwind

passenger

time

samples

in

driving

during

.dz

2

car.

At

26.5

a simpli-

(C2-C,)uy

by

windspeeds

- 3000

in

the

Z),

according

emission

and

obtained

road

0:

at

-direction

C (ref.

the

concentrations

2

tested

heights

wind

counterto

LX>

located

measuring

heights

velocity

tion

at

induced

perpendicular

downwind

C,.uy,.dz

was tower

tracer

Results ty

concept

the

to

traffic

45"

0:

a measuring

sampling

avoid of

compared

-

0I

past

to

angle

N

Q =

This

an

:

w

hour

1 m/s

within

pollutant occurring of

in factor,

traffic

Gaussian of

type which

mg km/h

143 K-type the

To the

validate

on

this

of

type

pattern

needs

also

as

equation,

processes

models

Gaussian

but

advection-diffusion physical

type

of

road,

the

formulate

concentration the

logical

far

more

models,

for

to

be

a function

in input

data

a given

known,

of

give

are

only

required

than

for

situation

as a function

besides

us

way.

meteorological

not

height,

however,

a mathematical

more

of

distance

extensive

meteoro-

data.

The tion

number of

Most

of

models

notable

in

(ref.

experiments used

very

the

were Long

(SF6),

the

exact

which

allow

evaluation

and

valida-

small.

respect

and

roadways

the

General

Island

from

running

instead

of

the

Sulfate

Dispersion

Experiment

cars

pattern,

knowledge

Motors

Expressway

emitted

a concentration

Of course

of

emission

(re.

along the

5).

the

actual

rate

is

In

road,

both was

traffic

emis-

advantageous

for

put-poses.

It

is

traffic

very

likely

that

emissions some

there

hardly

dispersion a data

particulate

set,

on

particle

deposition

any

studies

and

deposition

and

tracergas

disperses

in

the

dispersion

however

short-term

effects

same

way

will

be

as

the

different

size. on

containing

pollutants

on

used

particulate

dependent

are

establish

the

themselves,

degree,

particulate

data

is this

4)

establish

modelling

As

along

a tracergas

to

sion.

experiments

K-type

Experiment

to

based to

validation

the to

models,

opportunity

the along

roadways,

concentration

patterns

simultaneously

for

meteorological

data.

short

of

the

periods

meteorology

need

was

on

felt

to

of

both

gaseous

and

of

time

- i.e.

1 hour

EXPERIMENTAL The

field

programs

concentration

patterns

programs Site

is : the

site

as

which

is

is

to

road

Instruments:

gas one

Gassamples

are

gaschromatographically. instruments, Fine

aerosol

rod,

is

detail

collected

with

a 50%

cut-off

is

impacted

on

aerosol mounted

in

on

a 12-V

have

with

in

fig.

sequential

1.

of

both

Sampling

in

tower

vertical

B

dispersion,

are

sampled

Vrins

and filter,

diameter

at

Vaseline-coated rotating

multiple-bag

sampling

a Bendix

on a paper

DC motor,

lay-out

estimation.

NO with

by

the

a minimum

4 l/h,

Particulates described

preseparator, Coarse

on

that

complete

one.

presented to

approximately

analysed

establishing

6. is

taken

for

extent, in

emission

are

of

ref.

possible,

a good

samplers

sample

an

and

described

lay-out

as

for

such

be in

the

the

emission

to

will

described

necessary

obtaining hour.

and

lay-out:

close

estimating

overlap

combined

Instrumental is

for

NO/NO, with

(ref. passing at

'Rotorods". at

2400

and

a combination

after pm,

during

monitor,

Hofschreuder

5.5

samplers,

continuously

t/min.

35

on of

the CO,

two

7). through

a cyclone

l/min. A Rotorod

is

a U-shaped

-

144

The

sampling

rate

windtunnel is

6 pm,

while properties

samples.

Sampling atomic

for

instrument,

full

is

days, is

indication

measured

since

particle

been

m3/h.

diameters even

minutes.

the

parts

All

tested The

of

aerosol

extensively

lower

only

50%

in

cut-off

diameter

limitations

insects

can

samples

are

are

be

found

the in

analysed

on

the lead

spectrophotometry. on

level.

the

particle

60

has 7.2

Vaseline;

is

paper

Filters for

The actual

size,

filters

are

shorter

limitative. of

between

the

time

which

approximately

larger

of

on ground

analysis

the

absorption

Deposition placed

this is

for

adhesive

with

of

experiments,

(0

analysed

exposure

deposition on

deposition

the

thus

natural

velocity

mm),

lead.

times date

deposition

135 on

in

small

The

filters

detection

and

surface

windspeed

and

trays, at-e

limit

obtained

surfaces,

flat

give since

of

only the

exposed the

qualitative t-elation

properties

are

extremely

complex. Meteorological temperature with

measurements at

Casella

8 and

include

2 m heigt,

cupanemometers

and

supplemented Young

with

propellor

1.

and

NO from The

information preceeding

program

will

on test be

emission

continued

is

dispersion at 1 and

for

and deposition 20 m (west)

bag sampler), sensor, Y2 C : Casella

and

reported

a period

of

to

fig.

1.

west

rates,dispersion

experiments

10 m height,

measurements

according

road

Instrumental lay-out for emission, ments. Sampling trays for deposition 1, 5, 10, 20 and 50 m (east). Instruments: q : NO + CO (multiple cyclone + Rotorod, T : temperature vane, Y3 : Young propellor bivane,

Limited

at

wind-profile

bivanes,

east IGURE

-direction

and

measureat

o : oarticulates: : Young propellor cupanemometer.

deposition

in

ref.

8.

one

and

a half

of

Years.

lead

145

ACKNOWLEDGEMENTS The

authors

assistance. Dutch

thank The

Ministry

J.

emission of

Housing,

van part

Tongeren of Physical

and the

study Planning

R.

de is

Wit

for

supported and

technical by

a grant

and

analytical from

the

Environment.

REFERENCES 1 2 3 4 5 6 7 8

J.A. Bullin et al, Determination of vehicle emission rates from roadways bv mass balance techniaues. Env. Sci. Technol. 14 (1980) 700-705. F". Pasquill, Atmospheric diffusion. Wiley, New York (1974). Barrett et al, Proceedings VIth World Congress on Air Quality, Vol. 1 (1983) 305-311. S.H. Cadle et al, General Motors Sulfate Dispersion Experiment: experimental procedures and results. JAPCA 27 (1977) 33-38. S.T. Roa et al, Characteristics of turbulence and dispersion of pollutants near major highways. J. Appl. Met. 18 (1979) 283-293. J.S. Hooghiemstra et al, Long term concentrations of nitrogen oxides along a highway - in this volume E. Vrins and P. Hofschreuder, Sampling total suspended particulate matter. Proceedings GAF-Conference, Bologna (1982). Emission, dispersion and deposition of P. Hofschreuder and H. Harssema, automotive pollution. Proc. VIth World Congress on Air Pollution Paris, 4 (1983) 113-119.