Seasonal variation in nitryl chloride and its relation to gas-phase precursors during the JULIAC campaign in Germany-猫眼课题宝

DOI：

10.5194/acp-22-13137-2022

发表时间：

2022-10

期刊：

Atmospheric Chemistry and Physics

影响因子：

6.3

通讯作者：

中科院分区：

地球科学1区

文献类型：

作者：

Z. Tan;H. Fuchs;A. Hofzumahaus;W. Bloss;B. Bohn;C. Cho;T. Hohaus;F. Holland;Chandrakiran Lakshmisha;Lü-gang Liu;P. Monks;A. Novelli;Doreen Niether;F. Rohrer;R. Tillmann;Thalassa S E Valkenburg;Vaishali Vardhan;A. Kiendler‐Scharr;A. Wahner;R. Sommariva

抽象。在德国的一个农村地点进行了硝酰氯（ClNO 2）的环境测量，涵盖2019年冬季，夏季和秋季的三个时期，作为JULIAC活动（Jülich大气化学项目）的一部分，旨在了解中西部欧洲典型气团中的光化学过程。测量进行了50米以上的地面，这主要是位于夜间边界层，从而解耦当地的表面排放。ClNO 2在夜间通过五氧化二氮（N2 O 5）与含有气溶胶的氯化物（Cl−）的非均相反应产生。它在白天的光解引起了普遍的兴趣，因为它产生氯（Cl）原子，与不同的大气痕量气体反应形成自由基。在9月20日晚上，观测到的最高ClNO 2混合比为1.6 ppbv（十亿分之一体积; 15分钟平均值）。到达测量地点的气团要么来自西南方向的远距离输送，并受到海洋的影响，要么在附近区域循环，并受到人类活动的影响。夜间最大的ClNO 2混合比约为0.2 ppbv，如果起源于远程运输，在几乎所有的季节，而值较高，范围从0.4至0.6 ppbv的区域影响的空气。长距离输送空气的化学成分是相似的，在所有调查的季节，而区域空气表现出较大的季节差异。ClNO 2形成所需的N2 O 5来自硝酸根（NO3）与二氧化氮（NO2）的反应，其中NO3本身是由NO2与臭氧（O3）反应形成的。ClNO 2、NO2和O3的测量浓度用于量化ClNO 2生产效率，即，每个NO3自由基形成的ClNO 2生成量，以及一个箱模型被用来检查ClNO 2对所观察到的夜间O3和NO2浓度的理想化依赖性。结果表明，ClNO 2的生产效率是最敏感的NO2的有效性，而不是O3的，并随着温度的降低而增加。2月和9月的平均ClNO 2生产效率最高，为18%，12月最低，为3%。从8月到11月，对于来自远程运输的气团，平均ClNO 2生产效率在3%和6%之间。这些数字是在文献中报道的值的高端，表明ClNO 2化学在中西部欧洲农村环境中的重要性。

Abstract. Ambient measurements of nitryl chloride (ClNO2) were performed at a rural site in Germany, covering three periods in winter, summer, and autumn 2019, as part of the JULIAC campaign (Jülich Atmospheric Chemistry Project) that aimed to understand the photochemical processes in air masses typical of midwestern Europe. Measurements were conducted at 50 m aboveground, which was mainly located in the nocturnal boundary layer and thus uncoupled from local surface emissions. ClNO2 is produced at night by the heterogeneous reaction of dinitrogen pentoxide (N2O5) on chloride (Cl−) that contains aerosol. Its photolysis during the day is of general interest, as it produces chlorine (Cl) atoms that react with different atmospheric trace gases to form radicals. The highest-observed ClNO2 mixing ratio was 1.6 ppbv (parts per billion by volume; 15 min average) during the night of 20 September. Air masses reaching the measurement site either originated from long-range transport from the southwest and had an oceanic influence or circulated in the nearby region and were influenced by anthropogenic activities. Nocturnal maximum ClNO2 mixing ratios were around 0.2 ppbv if originating from long-range transport in nearly all seasons, while the values were higher, ranging from 0.4 to 0.6 ppbv for regionally influenced air. The chemical composition of long-range transported air was similar in all investigated seasons, while the regional air exhibited larger differences between the seasons. The N2O5 necessary for ClNO2 formation comes from the reaction of nitrate radicals (NO3) with nitrogen dioxide (NO2), where NO3 itself is formed by a reaction of NO2 with ozone (O3). Measured concentrations of ClNO2, NO2, and O3 were used to quantify ClNO2 production efficiencies, i.e., the yield of ClNO2 formation per NO3 radical formed, and a box model was used to examine the idealized dependence of ClNO2 on the observed nocturnal O3 and NO2 concentrations. Results indicate that ClNO2 production efficiency was most sensitive to the availability of NO2 rather than that of O3 and increased with decreasing temperature. The average ClNO2 production efficiency was highest in February and September, with values of 18 %, and was lowest in December, with values of 3 %. The average ClNO2 production efficiencies were in the range of 3 % and 6 % from August to November for air masses originating from long-range transportation. These numbers are at the high end of values reported in the literature, indicating the importance of ClNO2 chemistry in rural environments in midwestern Europe.

Seasonal variation in nitryl chloride and its relation to gas-phase precursors during the JULIAC campaign in Germany

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