Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China.
Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki 00014, Finland.
Environ Sci Technol. 2024 Aug 13;58(32):14361-14371. doi: 10.1021/acs.est.4c06061. Epub 2024 Aug 1.
The photolysis of particulate nitrate (pNO) has been suggested to be an important source of nitrous acid (HONO) in the troposphere. However, determining the photolysis rate constant of pNO () suffers from high uncertainty. Prior laboratory measurements of using aerosol filters have been complicated by the "shadow effect"─a phenomenon of light extinction within aerosol layers that potentially skews these measurements. We developed a method to correct the shadow effect on the photolysis rate constant of pNO for HONO production () using aerosol filters with identical chemical compositions but different aerosol loadings. We applied the method to quantify over the North China Plain (NCP) during the winter haze period. After correcting for the shadow effect, the normalized average at 5 °C increased from 5.89 × 10 s to 1.72 × 10 s. The decreased with increasing pH and nitrate proportions in PM and had no correlation with nitrate concentrations. A parametrization for was developed for model simulation of HONO production in NCP and similar environments.
颗粒物硝酸盐（pNO）的光解被认为是对流层亚硝酸（HONO）的一个重要来源。然而，pNO 的光解速率常数（）的确定存在很大的不确定性。先前使用气溶胶滤器进行的实验室测量受到“阴影效应”的影响——气溶胶层内的光衰减现象，这可能会使这些测量产生偏差。我们开发了一种方法，使用具有相同化学成分但气溶胶负载不同的气溶胶滤器，来校正 HONO 生成（）的 pNO 光解速率常数的阴影效应。我们将该方法应用于量化冬季雾霾期间华北平原（NCP）上空的。校正阴影效应后，5°C 时归一化平均光解速率常数从 5.89×10s 增加到 1.72×10s。光解速率常数随着 PM 中 pH 值和硝酸盐比例的增加而降低，与硝酸盐浓度无关。为了在 NCP 和类似环境中模拟 HONO 的生成，开发了一个用于的参数化。
