Observation of Road Salt Aerosol Driving Inland Wintertime Atmospheric Chlorine Chemistry
Observation of Road Salt Aerosol Driving Inland Wintertime Atmospheric Chlorine Chemistry
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DOI：
10.1021/acscentsci.9b00994
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发表时间：
2020-05-27
影响因子：
18.2
通讯作者：
Pratt, Kerri A.
中科院分区：
文献类型：
--
作者：
McNamara, Stephen M.;Kolesar, Katheryn R.;Pratt, Kerri A.
形成大气中硝基氯（ClNO2）的内陆氯颗粒来源仍然未知且无法量化，这阻碍了空气质量评估。每年冬天，在全球范围内，数千万吨道路盐被撒在道路上用于除冰。本研究确定道路盐气溶胶为主要氯化物气溶胶源，占内陆城区冬季ClNO2形成的80-100%。该研究通过产生氮氧化物和氯自由基的重要储存库，为道路盐与空气质量之间的联系提供了实验证据，这些氮氧化物和氯自由基显著影响大气成分和污染物的命运。采用数值模型量化了氯化物源对ClNO2生成的贡献。传统的模拟ClNO2的方法认为氯化物在大气粒子群中均匀分布；然而，我们表明，只有一小部分的颗粒表面积含有氯化物。我们的新单粒子参数化考虑了这种异质性，极大地降低了使用主流方法常规报道的ClNO2水平的高估。将道路盐确定为ClNO2来源将这种常见的除冰做法与城市冬季环境中的大气成分和空气质量联系起来。
Inland sources of particulate chloride for atmospheric nitryl chloride (ClNO2) formation remain unknown and unquantified, hindering air quality assessments. Globally each winter, tens of millions of tons of road salt are spread on roadways for deicing. Here, we identify road salt aerosol as the primary chloride aerosol source, accounting for 80-100% of ClNO2, formation, at an inland urban area in the wintertime. This study provides experimental evidence of the connection between road salt and air quality through the production of this important reservoir for nitrogen oxides and chlorine radicals, which significantly impact atmospheric composition and pollutant fates. A numerical model was employed to quantify the contributions of chloride sources to ClNO2 production. The traditional method for simulating ClNO2 considers chloride to be homogeneously distributed across the atmospheric particle population; yet, we show that only a fraction of the particulate surface area contains chloride. Our new single-particle parametrization considers this heterogeneity, dramatically lowering overestimations of ClNO2 levels that have been routinely reported using the prevailing methods. The identification of road salt as a ClNO2 source links this common deicing practice to atmospheric composition and air quality in the urban wintertime environment.