Observation of NO₃ radicals over Shanghai, China

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• 作者：Shanshan Wang ; Chanzhen Shi ; Bin Zhou ; ^{binzhou@fudan.edu.cn} ; Heng Zhao ; Zhuoru Wang ; Suna Yang ; Limin Chen
• 关键词：NO3 radical ; DOAS ; Shanghai
• 刊名：Atmospheric Environment
• 出版年：2013
• 出版时间：May, 2013
• 年：2013
• 卷：70
• 期：Complete
• 页码：401-409
• 全文大小：1622 K

文摘

Observation of NO₃ radicals was performed in an urban area of Shanghai using differential optical absorption spectroscopy from August 15 to October 7, 2011. With the exception of the data below detection limit (0.008?ppb), the observed mean NO₃ mixing ratios were 0.016?¡À?0.009?ppb with a range of 0.008-0.095?ppb. Under the assumption of steady state, the NO₃ production rates were calculated ranging from 0.08?ppb?h^?1 to 12.85?ppb?h^?1 throughout the observation, and averaged at 1.10?¡À?1.09?ppb?h^?1. The calculated NO₃ lifetime was determined from several seconds to a maximum value of about 900?s with an average of 102?¡À?93?s. The correlation of NO₃ production rates to the NO₂ mixing ratio is about 0.76, which is larger than the correlation between NO₃ production rates and O₃. Hence, the variability of NO₃ production mainly results from the ambient NO₂ levels present. The positive correlation between the NO₃ mixing ratio and its production rates indicates that direct sinks cannot be neglected for the nitrate radical's chemistry in Shanghai, especially under polluted conditions. However, the slope of the logarithmic correlation between NO₃ lifetime and NO₂ mixing ratio is very close to ?1, which means that the NO₃ removal strongly depends on the indirect loss process. Moreover, the atmospheric suspended particles have an important impact on NO₃ lifetime because the NO₃ removal was accelerated by the high PM₁₀ concentration, e.g. all NO₃ lifetime are below 30?s when the PM₁₀ concentration was larger than 0.05?mg?m^?3 during the severe pollution episode in October.