' ¥ | 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