野火导致的持久性有机污染物的生成和暴露风险

Formation and human exposure of persistent organic pollutants due to wildfires

关键词:  野火  持久性有机污染物  持久性自由基  全球排放

Key words:  wildfire  persistent organic pollutants  environmental persistent free radicals  global emission

摘要:

21世纪全球变暖引起区域持续高温，不可控的极端野火事件在全球生物圈内频发，文章总结了 2000—2022年全球野火事件变化的趋势，讨论了野火烟雾中的持久性有机污染物（POPs）和环境持久性自由基（EPFRs）两类新污染物的生成和污染特征，阐述了污染物在不同环境体系中的迁移途径和机理， 初步评估了由于野火事件导致的人体室外和室内的暴露风险。结果表明，随着野火事件频发，燃烧面积在全球的覆盖率会迅速扩大，火灾季节也将向秋冬季延续。火灾的变异性增强了POPs和EPFRs的全球循环和极地迁移，生物质燃烧引起的区域效应可能会相互藕合而成为全球效应。因此，为了积极应对气候变化，需要对野火的生成进行更细致的追踪探究，以更好地了解野火事件产生的POPs和EPFRs等新污染物的环境行为及健康效应。

Abstract:

Background, aim, and scope In the 21st century, global warming has caused sustained regional high temperatures and extreme wildfire events. The growing frequency of wildfires poses significant threats to both human society and the ecological environment, making it crucial to understand wildfire patterns, mitigate their hazards, and establish effective prevention mechanisms. However, quantitative studies on pollutant emissions from wildfires remain relatively limited, and there are considerable challenges in detecting and tracking these events. This review summarizes the global trends of wildfire events from 2000 to 2022, with a particular focus on the formation and human exposure to two new types of pollutants: persistent organic pollutants (POPs) and environmental persistent free radicals (EPFRs) in wildfire smoke. Materials and methods This paper analyzes future changes in wildfire regimes, highlighting the transport pathways and impact mechanisms of increased and complex emissions across different environmental matrices. Additionally, it examines the risks of both outdoor and indoor exposure to POPs and EPFRs resulting from wildfires. Results The results indicate that the risk of wildfires continues to rise, with global fire areas expanding rapidly and fire seasons extending into autumn and winter. Moreover, fire variability enhances the global circulation and polar transport of POPs and EPFRs, leading to increased migration speed and distance of these pollutants. Additionally, as a major source of free radicals and persistent pollutants, wildfires may significantly increase their share of emissions across all sources, thereby exacerbating atmospheric pollution and disrupting the radiation balance. Moreover, poorly ventilated indoor air can also be impacted by wildfire smoke, leading to the accumulation of pollutants indoors and the formation of new emission sources, which pose increased health risks to humans. Discussion In the context of global warming, wildfires are expected to become an increasingly significant source of pollutant emissions, presenting substantial challenges to efforts aimed at mitigating climate change. Studies have demonstrated that the pollutants emitted by wildfires exhibit heightened toxicity compared to those from other sources, which is compounded by their widespread dispersal through atmospheric circulation. As a result, these pollutants can affect both regional and global air quality, with particular consequences for vulnerable populations. In the future, environmental health concerns related to wildfire emissions will intensify, necessitating frequent and comprehensive assessments of the health risks associated with these pollutants. These risks, which include respiratory illnesses and cardiovascular diseases, are expected to grow, especially in areas where wildfire seasons become longer and more severe. Furthermore, the impact of these emissions on ecosystem health and biodiversity is equally concerning, as the release of particulate matter and toxic gases can disrupt local ecosystems and alter the dynamics of plant and animal populations. To address these challenges, it is essential to develop effective strategies for monitoring, mitigating, and adapting to the evolving environmental and health risks posed by wildfires. Conclusions Increased fuel availability, higher temperatures, and human activities have heightened the likelihood of wildfires, resulting in a significant expansion of burn areas and an extended wildfire season. The emissions from wildfires further intensify global circulation and the polar transport of pollutants. In addition to the emissions from wildfires, high temperatures also cause the volatilization of organic compounds trapped in the soil. Furthermore, driven by global atmospheric circulation, this likely leads to changes in POPs and EPFRs in the Antarctic and Arctic regions. Recommendations and perspectives As the climate continues to warm, increasingly frequent, larger, and more intense wildfires may become a significant source of organic pollutant emissions. Additionally, regional effects from biomass burning could amplify global impacts, highlighting the need for more in-depth research into the factors driving wildfire occurrence, in order to better understand the environmental behavior of POPs and EPFRs from wildfires.