Institute of Urban Meteorology, China Meteorological Administration, Beijing, 100089, China; Environmental Meteorological Forecast Center of Beijing-Tianjin-Hebei, China Meteorological Administration, Beijing, 100089, China.
Institute of Urban Meteorology, China Meteorological Administration, Beijing, 100089, China; Environmental Meteorological Forecast Center of Beijing-Tianjin-Hebei, China Meteorological Administration, Beijing, 100089, China; Beijing Shangdianzi Regional Atmosphere Watch Station, Beijing, 101507, China.
Environ Pollut. 2020 Oct;265(Pt A):115062. doi: 10.1016/j.envpol.2020.115062. Epub 2020 Jun 20.
Measuring ammonia (NH) is important for understanding the role of NH in secondary aerosol formation and the atmospheric deposition of reactive N. In this study, NH was measured in an urban area, a background region, and a tunnel in Beijing. The average NH concentrations between September 2017 and August 2018 were 24.8 ± 14.8 ppb and 11.6 ± 10.3 ppb in the urban area and background region, respectively. Higher NH concentrations at both the urban and background sites, relative to some earlier measurements indicated a likely increase in the NH concentrations in these regions. The urban NH level in Beijing was much higher than that typically observed at urban and industrial sites in other domestic and foreign cities, suggesting that the Beijing urban area was affected by greater NH emissions than other regions. Based on the relationship among NH, wind direction, and wind speed, the urban area was affected by both local emissions and air transported from North China Plain (NCP). Potential source contribution function analyses suggested that regional transport from the NCP could greatly affect local concentrations of NH in both urban and background areas in spring and autumn; however, in addition to the NCP, urban emissions could also affect NH levels in the background region in summer and winter. The average NH concentration at the Fenshuiling Tunnel was 8.5 ± 7.7 ppb from December 2017 to February 2018. The NH:CO emission ratio measured in the tunnel test was 0.022 ± 0.038 ppb/ppb, which was lower than values in the USA and South Korea. The contribution of traffic to NH in Beijing did not agree well with the available emission inventories, suggesting that vehicular emissions were underestimated and further evaluation is necessary.
测量氨（NH）对于了解 NH 在二次气溶胶形成和活性氮大气沉积中的作用非常重要。本研究在北京的一个城区、一个背景地区和一条隧道中测量了 NH。2017 年 9 月至 2018 年 8 月期间，城区和背景地区的平均 NH 浓度分别为 24.8±14.8 ppb 和 11.6±10.3 ppb。城区和背景地区的 NH 浓度均高于一些早期的测量值，这表明这些地区的 NH 浓度可能有所增加。北京城区的 NH 水平远高于其他国内外城市的城区和工业地区的典型水平，这表明北京城区受到的 NH 排放影响大于其他地区。基于 NH、风向和风速之间的关系，城区既受到本地排放的影响，也受到来自华北平原（NCP）的空气传输的影响。潜在源贡献函数分析表明，来自 NCP 的区域传输可能会极大地影响春、秋两季城区和背景地区的本地 NH 浓度；然而，除了 NCP 之外，城区排放也会影响夏季和冬季背景地区的 NH 水平。2017 年 12 月至 2018 年 2 月，在 Fenshuiling 隧道测量的 NH 浓度平均值为 8.5±7.7 ppb。在隧道测试中测量的 NH:CO 排放比为 0.022±0.038 ppb/ppb，低于美国和韩国的值。北京交通对 NH 的贡献与现有排放清单不一致，这表明机动车排放被低估了，需要进一步评估。
