Open AccessEffects of reactive nitrogen gases on the aerosol formation in Beijing from late autumn to early spring
Author(s) -
Zhang Wen,
Wen Xu,
Xingyi Pan,
Mengjuan Han,
Chen Wang,
Katherine B. Benedict,
Aohan Tang,
Jeffrey L. Collett,
Xuejun Liu
Publication year - 2021
Publication title -
environmental research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.37
H-Index - 124
ISSN - 1748-9326
DOI - 10.1088/1748-9326/abd973
Subject(s) - haze , aerosol , ammonium , chemistry , sulfate , relative humidity , environmental chemistry , nitrate , inorganic ions , nitrogen , particulates , reactive nitrogen , nitrous acid , ammonium nitrate , nitrogen dioxide , pollution , ammonium sulfate , inorganic chemistry , ion , meteorology , organic chemistry , ecology , physics , biology
To investigate the formation and evolution mechanism of haze pollution in Beijing cold days, we measured reactive nitrogen gases (e.g. NH 3 and HNO 3 ), SO 2 and major water-soluble inorganic ions of PM 2.5 simultaneously in a two-year (from November to April) study. We found that NH 3 and NO 3 − have the highest concentrations among the gaseous precursors and inorganic components of PM 2.5 , respectively. The total NH x (gaseous NH 3 and particle NH 4 + ) was mostly in excess the need to neutralize acid compounds. During the whole study period, the aerosol pH with an average value of 4.05. From normal period into haze episodes, the aerosol pH tends to decrease and the concentration of all species (gases and particles) increases. Meanwhile, declined gas fractions exhibited that enhanced partitioning from HNO 3 , NH 3 and SO 2 to their corresponding particle phases. Under the heavy haze period, most HNO 3 (79%) has entered into NO 3 − , about 41% NH 3 remaining as free NH 3 , while only about 51% of SO 2 has been oxidized to SO 4 2− , implying the severe Nr pollution in atmosphere of Beijing in winter. Further analysis shows relative humidity (RH) plays an important driving role on the SNA (sulfate (SO 4 2− ), nitrate (NO 3 − ), ammonium (NH 4 + )) formation and particulate NO 3 − formed at a relatively low RH (20%–60%) and SO 4 2− at a high RH (40%–80%). Thus, synchronized abatement of multi-pollutants emissions especially for NH 3 emission reduction at a regional scale is necessary for mitigating megacities ambient PM 2.5 pollution and achieving the UN sustainable development goal through improving N use efficiency in agriculture.