Andreae, Meinrat — Page 4 | Engineering Papers

True Emission Factors for Forest Fires and the Role of Non-Fire NOx Robert B. Chatfield and Meinrat Andreae The standard way to estimate biomass burning emissions factors from airborne, surface, or laboratory data is to relate the emitted pollutant concentration to the carbon burned, C(sub tot), and liberated to the air, mostly CO2. We approximate total emitted carbon C(sub tot) ~ (CO2 + CO). Emission ratios that are based on CO, describing burning effects, delta-parameter delta-CO, are often used to quantify fire emissions. These are not as useful as emission factors, for they often complicate analyses, since delta-CO delta-CO2 may vary by unto tenfold, and can have bias artifacts of similar magnitude. We present a methodology that estimates both emission factors and a reasonable description of background C(sub tot). High O3 values require a history of the balanced interaction of two pollutant types, nitrogen oxides (NOx) and a radical source, VOCs. However, high VOC NOx ratios seen in many plumes, especially from smoldering-dominated fires, make substantial O3 formation less likely. One particularly intense fire we analyzed, the notorious Rim Fire of 2013, near Yosemite, California. It produced notable quantities of free NOx and (both gas- and particle-phase) Cl species. Consequently, we also outline a quantitative way to assess the effects of anthropogenic or lightning NOx. We provide the example of California burning emissions using measurements of HCHO, NO, and the photolysis rate j(sub HCHO).

Chatfield, Robert B.↗