. Slash fire atmospheric pollution. Air Pollution; Slashburning Environmental aspects Northwest, Pacific. Period III 1630-1830 Figure 13.—Horizontal distribution of CO and C02 during period III of the broadcast fire. Pack Forest, June 25, 1968. (Shown as isopleths.) over a 400-meter segment of the plume. Integra- tion of the sample over this distance should provide detectable quantities of both CO and C02 if present in greater than ambient concentrations. The change in the ratio of CO to C02 during the fire is apparent in figure 14. CO versus C02 concentration at each point in the sample net i
. Slash fire atmospheric pollution. Air Pollution; Slashburning Environmental aspects Northwest, Pacific. Period III 1630-1830 Figure 13.—Horizontal distribution of CO and C02 during period III of the broadcast fire. Pack Forest, June 25, 1968. (Shown as isopleths.) over a 400-meter segment of the plume. Integra- tion of the sample over this distance should provide detectable quantities of both CO and C02 if present in greater than ambient concentrations. The change in the ratio of CO to C02 during the fire is apparent in figure 14. CO versus C02 concentration at each point in the sample net is plotted for each period. The slopes (m) of the CO:C02 ratios obtained from the 500° and 850° flame gases are indicated by the dashed lines. The smoke in period I apparently originated from flames between 500 and 850 C. H owever, in period II, several of the samples taken along line 1 fail very close to the slope of the cooler flame. Ventilation was available for fuels in the interior of the burn because of turbulence associ- ated with the stage I convection column. The gradient wind which predominated in stage II provided less interior ventilation. The better interior ventilation during period I plus the rapid consumption of flash fuels (0-1 cm.) created higher temperatures and more complete com- bustion during stage I. During stage III, almost all of the finer fuels had been consumed. With the exception of smoldering duff, the fire was con- fined to small, well-ventilated, and compact piles of heavier fuels in which flame temperatures were again higher, and combustion more complete than during stage II. The CO:C02 ratio from the 850° flame gases approximately equals the CO:C02 ratio from laboratory combustion of Douglas-fir slash (). This indicates that both the temperatures and the degree of combustion were approximately the same in the field during stage I and under laboratory conditions. The strong convection column of the stage I fire created return eddies whic
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