CAREER: Bridging the gap from biomass burning and wildfires to atmospheric pollutants

近年来，野火的发生率和强度在世界某些地区有所增加，并且由于气候变暖，未来将继续增加。野火排放，这可能会有重大的有害健康影响，同样会增加。此外，一些野火排放物吸收和散射紫外线和可见光，这使得这些排放物在地球的辐射平衡中特别重要。识别、量化和模拟这些排放物的形成将有许多好处，例如有助于有关野火的管理决策，并为野火健康影响的研究提供信息。然而，人们对燃烧生物质最初排放的化合物以及它们如何在大气中演变形成野火附近测量的老化排放物类型缺乏了解。因此，预测这些排放的形成及其影响具有挑战性。本研究将弥合实验室测量的新鲜排放物和现场测量的大气老化的排放物之间的差距，从生物质燃烧。本研究将开发一个预测模型的木质生物质燃烧排放物的辐射强迫相关的木质纤维素生物质的三个主要成分的基础上的层次的方法：半纤维素，纤维素和木质素。实验将被用来开发这个模型的形成的初级和老化的排放量的生物质及其成分的条件下有关的露天燃烧。这些条件包括由于大的燃料尺寸和木材的低导热性而导致的显著的热量和质量传输限制，以及与单独的火焰燃烧相反的长时间阴燃燃烧。将测量生物质热解和氧化产生的排放量，重点是评估已被确定为高度吸收和散射的物种的产生率，以建立动力学模型。这些排放物的组成和光学性质的变化将在光化学老化过程中进行研究，以产生一个连续的大气测量化合物的理解，从前体形成通过光化学transition.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Wildfire incidence and intensity have increased in some parts of the world in recent years and are poised to continue increasing in the future due to the warming climate. Wildfire emissions, which can have significant detrimental health impacts, will likewise increase. Additionally, some wildfire emissions absorb and scatter ultraviolet and visible light, which makes these emissions particularly important in the radiative balance of the earth. The ability to identify, quantify and model the formation of these emissions would have many benefits, such as aiding in management decisions regarding wildfires and informing studies of wildfire health effects. Yet, there is a significant lack of understanding of what chemical compounds are initially emitted from burning biomass, and how they evolve in the atmosphere to form the types of aged emissions that are measured near wildfires. Thus, it is challenging to predict the formation of these emissions and their impacts. This research will bridge the gap between laboratory measurements of freshly emitted emissions and field measurements of atmospherically aged emissions from biomass burning.This research will develop a predictive model of woody biomass burning emissions which are pertinent to radiative forcing using a hierarchical approach based upon the three major constituents of lignocellulosic biomass: hemicellulose, cellulose and lignin. Experiments will be utilized to develop this model for formation of primary and aged emissions from biomass and its constituents under conditions relevant to open burning. These conditions include significant heat and mass transport limitations due to large fuel sizes and low thermal conductivity of wood, and prolonged smoldering combustion as opposed to solely flaming combustion. Emissions from biomass pyrolysis and oxidation will be measured, with an emphasis on evaluating the rates of production of species that have been identified as highly absorbing and scattering, for the development of kinetic models. Changes in the composition and optical properties of those emissions will be studied during photochemical aging to generate a continuum in understanding of atmospherically measured compounds from precursor formation through photochemical transformation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.