Source Apportionment of Urban Ammonia and its Contribution to Secondary Particle Formation in a Mid-size European City
Source Apportionment of Urban Ammonia and its Contribution to Secondary Particle Formation in a Mid-size European City
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DOI：
10.4209/aaqr.2020.07.0404
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发表时间：
2021-05-01
影响因子：
4
通讯作者：
Klemm, Otto
中科院分区：
文献类型：
--
作者：
Ehrnsperger, Laura;Klemm, Otto
细颗粒物（PM）和微量气体造成的环境空气污染是一个紧迫的问题，因为它影响到世界上绝大多数人口，在人口密集的城市环境中影响尤其严重。除了氮氧化物（NOx）和PM，氨（NH3）也是一种相关的空气污染物，因为它是颗粒铵的前体。本文研究了德国西北部明斯特（Munster）城市NH3浓度的短期时间动态、道路交通和农业作为NH3来源的作用以及氨对二次颗粒形成（SPF）的重要性。与其他城市地区相比，NH3混合比相当高（平均为17 ppb），并且在上午10点左右和晚上9点表现出明显的日最大值。在明斯特，氨的主要来源是农业，但道路交通也通过当地车辆催化剂的排放产生影响。来自周边农业区的NH3在夜间边界层积累，对市中心的SPF有贡献。《排放因子手册》结合交通流量估算的NH3模型排放量在同一量级。PM10中无机离子的化学组成以NH4+ (8.66 μ g m(-3))为主，其次是NO3- (3.89 μ g m(-3))、SO42- (1.58 μ g m(-3))和Cl - (1.33 μ g m(-3))。颗粒在粒径0.1 ~ 1 μ m的积累范围内无机离子浓度最高。铵中和指数J（111%）表明过量的NH4+导致PM以碱性为主。周围农业区的高氨排放加上道路交通产生的大量一氧化氮对明斯特的SPF起着至关重要的作用。
Ambient air pollution caused by fine particulate matter (PM) and trace gases is a pressing topic as it affects the vast majority of the world's population, with a particularly heavy influence in densely populated urban environments. Alongside nitrogen oxides (NOx) and PM, ammonia (NH3) is also a relevant air pollutant due to its role as a precursor of particulate ammonium. This is a study about the short-term temporal dynamics of urban NH3 concentrations in Munster, northwest Germany, the role of road traffic and agriculture as NH3 sources and about the importance of ammonia for secondary particle formation (SPF). The NH3 mixing ratio was rather high (mean: 17 ppb) compared to other urban areas and showed distinct diurnal maxima around 10 a.m. and during the night at 9 p.m. The main source for ammonia in Munster was agriculture, but road traffic also contributed through local emissions from vehicle catalysts. NH3 from surrounding agricultural areas accumulated in the nocturnal boundary layer and contributed to SPF in the city center. Modeled emissions of NH3 as estimated by the Handbook for Emission Factors in combination with traffic counts were in the same magnitude for NH3. The size-resolved chemical composition of inorganic ions in PM10 was dominated by NH4+ (8.66 mu g m(-3)), followed by NO3- (3.89 mu g m(-3)), SO42- (1.58 mu g m(-3)) and Cl - (1.33 mu g m(-3)). Particles in the accumulation range (diameter: 0.1-1 mu m) showed the highest inorganic ion concentrations. The ammonium neutralization index J (111%) indicated an excess of NH4+ leading to mostly alkaline PM. High ammonia emissions from surrounding agricultural areas combined with large amounts of NOR from road traffic play a crucial role for SPF in Munster.