Abstract：
The frequency and intensity of forest fires are amplified by climate change. Substantial quantities of PM1 emitted from forest fires can undergo gradual atmospheric dispersion and long-range transport, thus impacting air quality far from the source. However, the chemical composition and physical properties of PM emitted from forest fires and its changes during atmospheric transport remain uncertain. In this study, the evolution of organic carbon (OC), elemental carbon (EC), water-soluble ions, and water-soluble metals in the particulate phase of smoke emitted from the typical forest vegetation combustion in Southwest China before and after photo-oxidation was investigated in the laboratory. Two aging periods of 5 and 9 days were selected. The OC and TC mass concentrations tended to decrease after 9-days aged compared to fresh emissions. OP, OC2, and OC3 in PM1 are expected to be potential indicators of fresh smoke, while OC3 and OC4 may serve as suitable markers for identifying aged carbon sources from the typical forest vegetation combustion in Southwest China. K+ exhibited the highest abundant water-soluble ion in fresh PM1, whereas NO3- became the most abundant water-soluble ion in aged PM1. NH4NO3 emerged as the primary secondary inorganic aerosol emitted from typical forest vegetation combustion in Southwest China. Notably, a 5-day aging period proved insufficient for the complete formation of the secondary inorganic aerosols NH4NO3 and (NH4)2SO4. After aging, the mass concentration of the water-soluble metal Ni in PM1 from typical forest vegetation combustion in Southwest China decreased, while the mean mass concentrations of all other water-soluble metals increased in varying degrees. These findings provide valuable data support and theoretical guidance for studying the atmospheric evolution of forest fire aerosols, as well as contribute to policy formulation and management of atmospheric environment safety and human health.
摘要：
气候变化放大了森林火灾的频率和强度。森林火灾排放的大量PM1可以经历逐渐的大气扩散和远距离迁移，从而从源头上影响空气质量。然而,森林火灾排放的PM的化学成分和物理性质及其在大气传输过程中的变化仍不确定。在这项研究中,有机碳(OC)的演化，元素碳(EC)，水溶性离子，在实验室研究了光氧化前后西南地区典型森林植被燃烧产生的烟气颗粒相中的水溶性金属。选择5天和9天的两个老化期。与新鲜排放相比，老化9天后，OC和TC质量浓度趋于降低。OP,预计PM1中的OC2和OC3将是新鲜烟雾的潜在指标，而OC3和OC4可以作为识别西南地区典型森林植被燃烧老化碳源的合适标记。K在新鲜PM1中表现出最高的水溶性离子，而NO3-成为老化PM1中最丰富的水溶性离子。NH4NO3是西南地区典型森林植被燃烧排放的主要次生无机气溶胶。值得注意的是,5天的老化期不足以完全形成二次无机气溶胶NH4NO3和（NH4）2SO4。老化后,西南地区典型森林植被燃烧PM1中水溶性金属Ni的质量浓度降低,而所有其他水溶性金属的平均质量浓度都有不同程度的增加。这些发现为研究森林火灾气溶胶的大气演变提供了有价值的数据支持和理论指导。以及有助于制定和管理大气环境安全和人类健康的政策。
