Isotopic partitioning of nitrogen in PM2.5 at Beijing and a background site of China
Item
Title (Dublin Core)
Isotopic partitioning of nitrogen in PM2.5 at Beijing and a background site of China
Description (Dublin Core)
Using isotope mixing model (IsoSource) and natural δ<sup>15</sup>N method, this study evaluated contributions of major sources to N of PM<sub>2.5</sub> at Beijing (collected during a severe haze episode of January 22nd–30th, 2013) and a background site (Menyuan, Qinghai province; collected from September to October of 2013) of China. At Beijing, δ<sup>15</sup>N values of PM<sub>2.5</sub> (−4.1 – +13.5 ‰; mean = +2.8 ± 6.4 ‰) distributed within the range reported for major anthropogenic sources (including NH<sub>3</sub> and NO<sub>2</sub> from coal combustion, vehicle exhausts and domestic wastes/sewage). However, δ<sup>15</sup>N values of PM<sub>2.5</sub> at the background site (+8.0 – +27.9 ‰; mean = +18.5 ± 5.8 ‰) were significantly higher than that of potential sources (including NH<sub>3</sub> and NO<sub>2</sub> from biomass burning, animal wastes, soil N cycle, fertilizer application, and organic N of soil dust). Evidences from molecular ratios of NH<sub>4+</sub> to NO<sub>3−</sub> and/or SO<sub>4</sub><sup>2−</sup> in PM<sub>2.5</sub>, NH<sub>3</sub> to NO</sub>2</sub> and/or SO<sub>2</sub> in ambient atmosphere suggested that the equilibrium of NH<sub>3</sub> ↔ NH<sub>4</sub> + caused apparent <sup>15</sup>N enrichment only in NH<sub>4</sub> + of PM<sub>2.5</sub> at the background site due to more abundant NH<sub>3</sub> than SO<sub>2</sub> and NO<sub>2</sub>. Therefore, a net <sup>15</sup>N enrichment (33 ‰) was assumed for NH<sub>3</sub> sources of background PM<sub>2.5</sub> when fractional contributions were estimated by IsoSource model. Results showed that 41 %, 30 % and 14 % of N in PM<sub>2.5</sub> of Beijing originated from coal combustion, vehicle exhausts and domestic wastes/sewage, respectively. Background PM<sub>2.5</sub> derived N mainly from biomass burning (58 %), animal wastes (15 %) and fertilizer application (9 %). These results revealed the regulation of the stoichiometry between ammonia and acidic gases on δ<sup>15</sup>N signals in PM<sub>2.5</sub>. Emissions of NO<sub>2</sub> from coal combustion and NH<sub>3</sub> from urban transportation should be strictly controlled to advert the risk of haze episodes in Beijing.
Creator (Dublin Core)
Wang, Yan-Li
Liu, Xue-Yan
Song, Wei
Yang, Wen
Han, Bin
Dou, Xiao-Yan
Zhao, Xu-Dong
Song, Zhao-Liang
Liu, Cong-Qiang
Bai, Zhi-Peng
Date (Dublin Core)
2018-08-10
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-2016-187
https://acp.copernicus.org/preprints/acp-2016-187/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
