Potential Effect of Halogens on Atmospheric Oxidation and Air Quality in China
Potential Effect of Halogens on Atmospheric Oxidation and Air Quality in China
复制标题
卤素对中国大气氧化和空气质量的潜在影响
DOI：
10.1029/2019jd032058
复制
发表时间：
2020-05-16
影响因子：
4.4
通讯作者：
Saiz-Lopez, Alfonso
中科院分区：
文献类型：
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作者：
Li, Qinyi;Badia, Alba;Saiz-Lopez, Alfonso
近几十年来，空气污染在中国一直是一种危害，威胁着5亿人的健康。中国在减轻空气污染方面付出了诸多努力，使得2013年至2017年主要污染物排放大幅减少，但在同一时期，地表臭氧（O - 3，一种二次污染物和温室气体）却呈现持续恶化的趋势。以涉及羟基自由基（OH）的日间反应为主的大气氧化作用是将新排放的化合物转化为二次污染物的关键过程，而在中国当前的空气污染模型中，这一过程被低估了。已知卤素（氯、溴和碘）对海洋环境中的氧化化学有深远影响；然而，它们对中国大气氧化和空气污染的影响尚不清楚。在本研究中，我们首次报道卤素显著提高了中国污染地区的大气总氧化能力，通常提高10% - 20%（冬季可达87%），主要是通过显著提高OH水平实现的。沿海地区氧化能力的增强是由海洋排放驱动的，内陆地区则是由人为排放驱动的。卤素影响的程度和季节性在很大程度上由亚洲季风的动态、卤素排放的位置和强度以及O - 3的形成机制所决定。忽略卤素排放和化学过程可能会导致对污染地区大气氧化演变的历史重新评估和未来预测出现重大误差。
Air pollution has been a hazard in China over recent decades threatening the health of half a billion people. Much effort has been devoted to mitigating air pollution in China leading to a significant reduction in primary pollutants emissions from 2013 to 2017, while a continuously worsening trend of surface ozone (O3, a secondary pollutant and greenhouse gas) was observed over the same period. Atmospheric oxidation, dominated by daytime reactions involving hydroxyl radicals (OH), is the critical process to convert freshly‐emitted compounds into secondary pollutants, and is underestimated in current models of China's air pollution. Halogens (chlorine, bromine, and iodine) are known to profoundly influence oxidation chemistry in the marine environment; however, their impact on atmospheric oxidation and air pollution in China is unknown. In the present study, we report for the first time that halogens substantially enhance the total atmospheric oxidation capacity in polluted areas of China, typically 10% to 20% (up to 87% in winter) and mainly by significantly increasing OH level. The enhanced oxidation along the coast is driven by oceanic emissions, and that over the inland areas by anthropogenic emission. The extent and seasonality of halogen impact are largely explained by the dynamics of Asian monsoon, location and intensity of halogen emissions, and O3 formation regime. The omission of halogen emissions and chemistry may lead to significant errors in historical re‐assessments and future projections of the evolution of atmospheric oxidation in polluted regions.