Characteristics of surface fire emission of PM2.5 and its water-soluble carbon in red pine plantation
[Objective]The effects of fire disturbance on the mass concentration of PM2.5 emitted from wildfires were studied,and the potential ability of PM2.5 emitted from wildfires to participate in the atmospheric carbon cycle was understood.The effects of fire environmental conditions and fire behavior factors on the mass concentration of PM2.5 emitted from wildfires and its water-soluble carbon were explored.It can provide a scientific basis for revealing the multi-process mutual feedback relationship between wildfire disturbance-wildfire emission particles-atmospheric environment,and is of great significance for further quantifying the impact of wildfires on the atmospheric environment.[Method]In this study,the surface combustible materials of red pine plantation were used as experimental materials.Simulated combustion experiments with different load,moisture content and slope preconditions were carried out to quantify the effects of flame height,flame length,flame width,combustion efficiency and other fire behavior and fire environment factors on PM2.5 and water-soluble carbon.The effects of fire environment on fire behavior,fire environment and fire behavior on PM2.5 and water-soluble carbon mass concentration were analyzed by one-way ANOVA,multi-factor ANOVA,correlation analysis and random forest regression importance ranking methods.[Result]The fuel load significantly affected the mass concentration of PM2.5 and water-soluble carbon(P＜0.01).The fuel moisture content significantly affected the mass concentration of water-soluble carbon(P＜0.05),but had no significant effect on the mass concentration of PM2.5(P＞0.05).The slope had no significant effect on the mass concentration of PM2.5 and water-soluble carbon(P＞0.05).There was a significant positive correlation between fuel loading and fire behavior(P＜0.05).There was a significant negative correlation between fuel moisture content and fire behavior(P＜0.05).Slope only significantly affected flame depth(P＜0.05).Through random forest regression analysis,the flame height(39.12),bed thickness(36.27),flame depth(35.01)and flame length(30.76)had a higher impact on PM2.5 mass concentration,and the bed thickness(40.05),flame height(31.98)and flame length(31.06)had a higher impact on water-soluble carbon mass concentration.[Conclusion]The mass concentration characteristics of PM2.5 and water-soluble carbon emitted by surface combustible combustion in red pine plantation were significantly affected by fire behavior directly and fire environment indirectly.The fire environment can indirectly affect the mass concentration of PM2.5 and water soluble carbon emitted by wildfire.Fire disturbance can have a lasting impact on the ecological environment of the wildfire area and its surrounding areas by affecting the mass concentration of PM2.5 and water-soluble carbon emitted by wildfire.
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