The Effect of Particle Phase State on Multiphase Hydroxyl Radical (OH) Oxidation Kinetics and Products of Biomass Burning Aerosol

生物质燃烧气溶胶（BBA）在全球大气中普遍存在。BBA源强度据信与燃烧化石燃料的气溶胶具有相似的量级。生物质燃烧羽流可以在局部到全球尺度上影响大气，而BBAs可以对能见度和由于辐射的直接散射和吸收而产生的辐射强迫产生重大影响。通过改变云的性质，BBA还对辐射平衡产生间接影响。有机气溶胶占亚微米颗粒的主要质量部分，与人类健康影响有关。在大气运输过程中，有机气溶胶颗粒由于与微量氧化物质（如羟基自由基（OH））的反应而发生化学转化，导致化学老化并最终净化大气。反应性微量气体对BBA颗粒的化学老化作用尚不清楚，迄今为止的研究主要局限于室温和干燥条件下，尽管大多数大气在较低温度和相对湿度变化较大的情况下表现出氧化状态。环境参数会改变BBA的粘度甚至相变化，从而改变BBA的化学反应性，进而可能改变许多化学转化的动力学。为了进一步描述天然生物质燃烧气溶胶在形成、扩散和老化过程中发生的化学转化，将在受控条件下使用代理和替代化合物进行一系列基于实验室的研究

Biomass burning aerosols (BBA) are ubiquitous throughout the global atmosphere. BBA source strength is believed to be of similar magnitude to the fossil fuel burning aerosols. Biomass burning plumes can affect the atmosphere on local to global scales, and BBAs can have a significant impact on visibility, and on the radiative forcing due to the direct scattering and absorption of radiation. By altering the properties of clouds, BBA also exert indirect effects on the radiation balance. Organic aerosols, representing a major mass fraction of the submicron size fraction, are implicated in human health effects. During atmospheric transport, organic aerosol particles are chemically transformed due to reactions with trace oxidizing species such as the hydroxyl radical (OH), resulting in chemical aging and ultimately cleansing of the atmosphere. The chemical aging of BBA particles by reactive trace gas species is not well understood, and so far investigations have been limited mostly to room temperature and dry conditions, although most of the atmosphere exhibits oxidizing conditions at lower temperatures and wider variations in relative humidity. Ambient environmental parameters, which induce altered viscosity or even phase changes, are responsible for altered chemical reactivity in BBA, and may in turn be responsible for altering the kinetics of many of these chemical transformations. A series of laboratory based investigations, using proxy and surrogate compounds under controlled conditions, are to be carried out in order to further describe the chemical transformations taking place during the formation, dispersal and aging of natural, biomass burning aerosols