| 摘要: |
| 环境持久性自由基（EPFRs）是一类具有长寿命的污染物，可稳定存在于各种环境介质中。由于大气颗粒物具有较强的环境迁移能力，EPFRs可以随之发生远距离迁移，还可以附着于大气颗粒物上，与典型的气态污染物相互作用参与大气化学反应，影响区域大气环境质量。根据国内外的相关研究现状，总结大气颗粒物中EPFRs的基本特征，概述由过渡金属参与的和不含金属元素的体系中EPFRs的产生机理及其影响因素，另外对EPFRs诱导生成活性氧物种来对生物机体产生氧化损伤的机制进行讨论，并对未来EPFRs的研究方向进行展望。然而，目前对非过渡金属元素参与的EPFRs的形成机理，以及EPFRs与大气污染物之间的相互作用及其对环境空气质量的影响等问题仍不清楚，未来有待进一步研究。 |
| 关键词: 大气颗粒物 环境持久性自由基 生成机理 影响因素 |
| DOI：10.7515/JEE221029 |
| CSTR： |
| 分类号: |
| 基金项目:国家自然科学基金项目（51878644，41573138） |
|
| Characteristics and fate behavior of environmentally persistent free radicals in atmospheric particulate matter |
|
WANG Xueying, CUI Long, XUE Yonggang, HO Kinfai, HUANG Yu
|
1.State Key Laboratory of Loess and Quaternary Geology, Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710061, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China
4. CAS Center for Excellence in Quaternary Science and Global Change, Xi’an 710061, China
|
| Abstract: |
| Background, aim, and scope Environmentally persistent free radicals (EPFRs) have received significant attention due to their longer lifetime and stable existence in various environments. The strong environmental migration ability of particulate matter allows EPFRs to migrate over long-distance transport, thereby impacting the quality of the local atmospheric environment. Additionally, EPFRs can also adhere to atmospheric particles and interact with typical gaseous pollutants to affect atmospheric chemical reactions. EPFRs can produce some reactive organic species, promoting oxidative stress in the human body, damaging biological macromolecules and ultimately affecting the organism health. EPFRs are considered as a novel type of pollutant that affects human health. Despite their significance, there are few literatures available on the characteristics and fate behaviors of EPFRs up to date. Therefore, supplemental reviews are crucial for providing comprehensive understanding of EPFRs. Materials and methods This review summarizes the characteristics of EPFRs in particulate matter, outlines the generation mechanism and influencing factors of EPFRs, and the impacts of EPFRs on environmental quality and organism health. Results The content of EPFRs in particulate matter ranges from 1017 to 1020 spins·g−1. Due to the strong mobility of atmospheric particulate matter, the long-term exposure to high levels of EPFRs may aggravate the impact of particulate matter on human health. The interaction between EPFRs and typical gaseous pollutants can alter their fate and influence atmospheric chemical reactions. EPFRs are mainly produced by transition metal elements and substituted aromatic hydrocarbons through electron transfer. Additionally, the chemical bond rupture of organic substances through heat treatment or ultraviolet radiation can also produce EPFRs, and heterogeneous reactions are capable producing them as well. The production of EPFRs is not only influenced by transition metal elements and precursors, but also by various environmental factors such as oxygen, temperature, light radiation, and relative humidity. Discussion EPFRs in atmospheric particulates matters are usually rich in fine particulates with obvious seasonal and regional variations. They can easily enter the human respiratory tract and lungs with inhalable particulates, thereby increasing the risk of exposure. Additionally, EPFRs in atmospheric particulates can interact with some typical gaseous pollutants, impacting the life and fate of EPFRs in the atmosphere, and alter atmospheric chemical reactions. Traditionally, EPFRs are generated by transition metal elements and substituted aromatic hydrocarbons undergoing electron transfer in the post-flame and cool-zone regions of combustion systems and other thermal processes to remove HCl, H2O or CO groups, ultimately produce semiquinones, phenoxyls, and cyclopentadienyls. Recent studies have indicated that EPFRs can also be generated under the conditions of without transition metal elemental. Organics can also produce EPFRs through chemical bond rupture during heat treatment or light radiation conditions, as well as through some heterogeneous reactions and photochemical secondary generation of EPFRs. The presence or absence of oxygen has different effects on the type and yield of EPFRs. The concentration, type, and crystal type of transition metal elements will affect the type, content, and atmospheric lifetime of EPFRs. It is generally believed that the impact of transition metal element types on EPFRs is related to the oxidation-reduction potential. The combustion temperature or heat treatment process significantly affects the type and amount of EPFRs. Factors such as precursor loading content, pH conditions, light radiation and relative humidity also influence the generation of EPFRs. EPFRs can interact with pollutants in the environment during their migration and transformation process in environmental medium. This process accelerates the degradation of pollutants and plays a crucial role in the migration and transformation of organic pollutants in environmental media. The reaction process of EPFRs may lead to the production of reactive oxygen species (ROS) such as ·OH, which can induce oxidative stress, inflammation and immune response to biological lung cells and tissues, leading to chronic respiratory and cardiopulmonary dysfunction, cardiovascular damage and neurotoxic effects, ultimately impacting the health of organisms. Conclusions The interaction mechanism between EPFRs in particulate matter and gaseous pollutants remains unclear. Furthermore, research on the generation mechanism of EPFRs without the participation of transition metals is not comprehensive, and the detection of EPFRs is limited to simple qualitative categories and lack accurate qualitative analysis. Recommendations and perspectives Further research should be conducted on the generation mechanism, measurement techniques, migration pathways, and transformation process of EPFRs. It is also important to explore the interaction between EPFRs in atmospheric particulate matter and typical gaseous pollutants. |
| Key words: particulate matter (PM) environmentally persistent free radicals (EPFRs) formation mechanism influencing factors |
