摘要
大气氧化能力(AOC)通常是指大气通过氧化过程去除大气中微量气体成分的速率总和。在对流层和近地层大气中,AOC主要表观为对污染气体的清除能力或净化能力,亦称大气氧化性。AOC是地球大气自洁净的核心能力,但一直缺乏对其内涵的深入认知和对其指标的量化描述。本文作者通过承担国家重点研发计划“区域大气氧化能力与空气质量的定量关系及调控原理”研究等项目,从大气化学基本理论入手,对AOC开展了系列研究,并在其量化表达方面取得了突破性进展。本文将围绕“大气氧化能力量化研究”这一科学问题,对这些进展进行简要的描述。首先在深入认知AOC内涵的基础上,分别从大气化学的热力学和动力学基本原理出发,构建了大气氧化能力表观指数(AOIe)和潜势指数(AOIp),并通过二者归一化指数日变化闭合研究,发现了非均相化学过程对AOC的贡献不容忽视。随着PM2.5污染的加重,无论夏季还是冬季,AOIe亦随之增加,但在冬季AOIp则出现了相反的情景,表现出AOIp的变化受气象条件的影响更大。AOC闭合研究思路用于大气OH自由基的储库分子HONO“未知源”研究,发现了北京大气HONO的重要非均相来源,阐释了MCM(Master Chemical Mechanism)机制对冬季AOC低估的重要原因。AOIp用于预测我国大气臭氧污染潜势格局,发现臭氧光化学生成表观潜势(AOIp_O_(3))与NO_(2)的光解系数[J(NO_(2))]直接相关,全国J(NO_(2))的年均值为4.39×10^(-3)s^(-1),高值区主要分布在四川、贵州、重庆和湖南等地。与其他化学反应氧化性指数对比,AOIe与AOIp组合指数更具准确性、普适性和实用性,可评价已发生的污染过程AOC的变化,亦可预测城市或区域重污染发生的可能性及其变化和格局。
Atmospheric oxidation capacity(AOC)is usually defined as the sum of the rates at which the atmosphere removes trace gaseous constituents through oxidative processes.In the troposphere and near-surface atmosphere,AOC is mainly characterized by the removal or purification of pollutant gases,also known as atmospheric oxidizability.AOC is the essential driving force of tropospheric chemistry,but its quantitative representation remains limited.For researching the“Quantitative Relationship between Regional Atmospheric Oxidizing Capacity and Air Quality and the Principles of Regulation”,supported by the National Key R&D Program of China and other projects,the authors have conducted a series of studies on AOC using the basic theories of atmospheric chemistry and have advanced the quantitative expression of AOC.In this paper,the authors briefly describe these advances,focusing on the“quantitative study of atmospheric oxidation capacity”.First,based on the in-depth knowledge of AOC,the authors constructed the evaluation index of AOC(AOIe)and potential index of AOC(AOIp)using the fundamentals of the thermodynamic and kinetic atmospheric chemistry,respectively,and found that contributions of heterogeneous chemical processes to the AOC should not be neglected when studying the daily variation of the normalized AOIe and AOIp.Moreover,with increasing PM2.5 pollution,AOIe increased in summer and winter campaigns while AOIp decreased in winter,showing that meteorological conditions had more influence on AOIp variations.Second,the AOC closure research idea was used to explore the“unknown source”of HONO,which is the reservoir molecule of atmospheric OH radicals,and an important heterogeneous source of atmospheric HONO was found in Beijing,explaining the underestimation of the winter AOC by the MCM(Master Chemical Mechanism)mechanism.The AOIp was used to predict the potential pattern of atmospheric ozone pollution in China,showing that the annual mean J(NO_(2))value of AOIp_O_(3) directly correlates with J(NO_(2)).Furthermore,O_(3) directly correlates with J(NO_(2)),and the nationwide annual average value of J(NO_(2))is 4.39×10^(−3) s^(−1),with mainly Sichuan,Guizhou,Chongqing,and Hunan exhibiting high values.The combined AOIe and AOIp indices are more accurate,generalizable,and useful than other chemical reaction oxidizability indices.They can evaluate AOC variations during the pollution process and predict the likelihood of urban or regional heavy pollution occurrence as well as its variations and patterns.
作者
王跃思
刘子锐
胡波
王润玉
WANG Yuesi;LIU Zirui;HU BoWANG Runyu(Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029;University of Chinese Academy of Sciences,Beijing 100049)
出处
《大气科学》
CSCD
北大核心
2024年第1期34-50,共17页
Chinese Journal of Atmospheric Sciences
基金
国家重点研发计划项目2017YFC0210000
国家大气重污染成因与治理攻关项目DQGG0101。
