The Concentrations, Formations, Relationships and Modeling of Sulfate, Nitrate and Ammonium (SNA) Aerosols over China

Abstract

Sulfate, nitrate and ammonium (SNA) are the dominant composition of secondary aerosols in the atmosphere and have a significant impact on public health, atmospheric chemistry process and climate. In this study, to evaluate SNA pollution in China, a first nationwide investigation derived from almost all published data in the field measurement before 2012 was carried out. The results show that SNA levels in China are about 3-5 times higher than those in USA and Europe. SNA account for 34.2 ± 10.9% in PM 2.5 and 28.2 ± 8.5% in PM 10 . The highest SNA concentrations occur in urban areas of northern China. SNA all have peaks in winter, but the nadirs are in spring for sulfate and ammonium and in summer for nitrate. SOR (sulfur oxidation ratio) and NOR (nitrogen oxidation ratio) values show that the formations of sulfate and nitrate are distinct in different regions and seasons. The low average NO 3 -/SO 4 2-ratio (0.43 ± 0.26) indicates that the stationary emissions from coal combustion remain the main sources. There is a good relationship between (2[SO 42-] + ) and [NH 4 + ] with near 1 slope, signifying that (NH 4 ) 2 SO 4 and NH 4 NO 3 are the predominant forms which SNA exist in particles in China. Based on the comprehensive observational data in China, the simulation for SNA aerosols by GISS in CMIP5 were evaluated.

Correlations between PM2.5 and Ozone over China and Associated Underlying Reasons

“…The total oxidant O x (O x = O 3 + NO 2 ) was used to characterize the atmospheric oxidation capacity, following Wang et al [14], Jia et al [22], and Clapp and Jenkin [54]. The sulfur oxidation ratio, SOR = n-SO 4 2− /(n-SO 4 2− + n-SO 2 ), was a measure of the conversion degree of sulfur; the nitrogen oxidation ratio, which was defined as NOR = n-NO 3 − /(n-NO 3 − + n-NO 2 ), was used to quantitatively express the conversion degree of nitrogen [55][56][57][58]. was used to quantitatively express the conversion degree of nitrogen [55][56][57][58].…”

“…The sulfur oxidation ratio, SOR = n-SO 4 2− /(n-SO 4 2− + n-SO 2 ), was a measure of the conversion degree of sulfur; the nitrogen oxidation ratio, which was defined as NOR = n-NO 3 − /(n-NO 3 − + n-NO 2 ), was used to quantitatively express the conversion degree of nitrogen [55][56][57][58]. was used to quantitatively express the conversion degree of nitrogen [55][56][57][58]. The secondary inorganic particulate was defined as SNA = SO4 2-+ NO3 -+ NH4 + .…”

Numerical analysis of agricultural emissions impacts on PM<sub>2.5</sub> in China using a high-resolution ammonia emission inventory

“…3 , which are formed from SO 2 and NO x (Chang, 1989;McMurry et al, 1983). In addition, NH 3 influences the rate of particle nucleation (Ball et al, 1999;Kulmala et al, 2002) and enhances secondary organic aerosol (SOA) yield (Babar et al, 2017).…”

Dissolved and Suspended Forms of Metals and Metalloids in Snow Cover of Megacity: Partitioning and Deposition Rates in Western Moscow

“…ions was calculated as the difference between the sums of cations and anions equivalents. In aerosol chemistry, the ammonium plays a significant role in chemical processes, including the formation of secondary ammonium sulfate and ammonium nitrate fine inorganic aerosols [57]. However, previous studies on the chemical composition of snow in Moscow showed that the ammonium in urban snow is about 5%-eq.…”