'
¥
|
Liiis
a
-
5
—-
.
s
%
=
z
42
< Q
=
‘
a
8
w
Ee
-=
=
=
S
4
4
4
SB mw
C—
x
r
eve
7
oOo z
Fre
4
=
=oga
i
4
i
-—
SFeLo
5
.
a
a
oO
Fr
J
wo
J
1
Lia
2
J
L
i
i
Lo
j
i
a
W ‘LHOI3SH SNITMWYS YIV
Another resuspension stress is the release of radioactive particles by burning contaminated vegetation (Sehmel and Orgill, 1975, 1976}. To determine
an indication of this release, smoke from a forest fire was sampled with an
aircraft-mounted air filter. Air activity concentrations measured on the
smoke filter were compared to concentrations measured with a similar filter
in background air uncontaminated with smoke. A comparison of the radioactivity in the smoke sample versus the background sample indicated that
radioactivity was released by the forest fire. Results are shown in Table 1
for 8 radionuclides.
The airborne concentration ratio (smoke/background)
for equal volumes of smoke and background air ranged from 1.2 to 22.2. All
of these concentration ratios indicate the release of deposited fallout by
the forest fire.
However, release rates are unknown.
Calculations of
release rates would require knowledge of the smoke plume's total volume and
average smoke concentration as well as the contamination level in the burning forest.
TABLE 1.
Radionuclide Air Concentration:
Isotope
Function of Wind Speed
an
.
—
Total Airborne 239Py Concentration at AB Site as a
=~
=
q
4
FIGURE 4.
w
(FROM TOTAL IMPACTOR SAMPLE)
=
AIRBORNE Pu CONCENTRATION, aCi/m?
w
“4
os
10
C
C
10
T
ep
ere'y
T
ry} try
Fatlout Resuspension from Burning Vegetation
"he
1.2
54Mn
97,
Ts
3.8
1.9
1.8
106pu
2.9
W254
Va2e,
M44,
Smoke/Background
Concentration
Ratio
4.6
22.2
2.9
TRACERS
Tracer particles placed on selected surfaces were used to measure resuspension rates caused by both mechanical and wind resuspension,
Mechanical
resuspension was measured for vehicular traffic on asphalt and cheat grass
areas and pedestrian traffic on an asphalt area. Wind resuspension was
l
—_
S
measured as a function of wind speed and also as a function of respirable
and nonrespirable particle diameters.
Mechanical Resuspension Rates
Mechanical resuspension includes both vehicular resuspension and pedestrian
resuspension,
190