Source apportionment of atmospheric ammonia before, during, and after the 2014 APEC summit in Beijing using stable nitrogen isotope signatures
Item
Title (Dublin Core)
Source apportionment of atmospheric ammonia before, during, and after the
2014 APEC summit in Beijing using stable nitrogen isotope signatures
2014 APEC summit in Beijing using stable nitrogen isotope signatures
Description (Dublin Core)
Stable nitrogen isotope composition (<i>δ</i><sup>15</sup>N) offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH<sub>3</sub>), a vital precursor of PM<sub>2.5</sub> (particulate matters with aerodynamic diameter equal or less than 2.5 µm) inorganic components, in the urban atmosphere. In this study, the <i>δ</i><sup>15</sup>N values of NH<sub>3</sub> samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle) to over 6000 (human excreta) µg m<sup>−3</sup>), different NH<sub>3</sub> sources have generally different <i>δ</i><sup>15</sup>N values (ranging from −52.0 to −9.6 ‰). Significantly high <i>δ</i><sup>15</sup>N values are seen as a characteristic feature of all vehicle-derived NH<sub>3</sub> samples (−14.2 ± 2.8 ‰), which can be distinguished from other sources emitted at environmental temperature (−29.1 ± 1.7, −37.8 ± 3.6, and −50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively). <br><br> The isotope <i>δ</i><sup>15</sup>N signatures for a range of NH<sub>3</sub> emission sources were used to evaluate the contributions of the different sources within measured ambient NH<sub>3</sub> in Beijing, using an isotope mixing model (IsoSource). The method was used to quantify the sources of ambient NH<sub>3</sub> before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC) summit, when a set of stringent air quality control measures were implemented. Results show that the average NH<sub>3</sub> concentrations (the overall contributions of traffic, waste, livestock, and fertilizer) during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %), 7.3 (8.8, 24.9, 14.3, and 52.0 %), and 12.7 (29.4, 23.6, 31.7, and 15.4 %) µg m<sup>−3</sup>, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH<sub>3</sub> mass concentrations. During (after) the summit, the contributions of traffic, waste, livestock, and fertilizer decreased (increased) by 56.7 (234.2), 12.0 (−5.0), 39.4 (120.8), and −87.7 % (−70.5 %) when compared with periods before (during) the summit, respectively, signifying that future NH<sub>3</sub> control efforts in megacities like Beijing should prioritize traffic sector as well as livestock breeding. The results show that isotope ratio measurements of NH<sub>3</sub> to be a valuable tool to quantify the atmospheric sources of NH<sub>3</sub> in urban atmospheres.
Creator (Dublin Core)
Chang, Yunhua
Liu, Xuejun
Deng, Congrui
Dore, Anthony J.
Zhuang, Guoshun
Date (Dublin Core)
2018-09-19
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-16-11635-2016
https://acp.copernicus.org/articles/16/11635/2016/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
