The vertical variability of ammonia in urban Beijing, China
<p>Weekly vertical profiles of ammonia (NH<sub>3</sub>) were measured at 16 heights on the Beijing 325 m meteorological tower for 1 year from March 2016 to March 2017. The average NH<sub>3</sub> concentrations exceeded 4 µg m<sup&g...
Main Authors: | , , , , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2018-11-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/18/16385/2018/acp-18-16385-2018.pdf |
Summary: | <p>Weekly vertical profiles of ammonia (NH<sub>3</sub>) were measured at
16 heights on the Beijing 325 m meteorological tower for 1 year from
March 2016 to March 2017. The average NH<sub>3</sub> concentrations exceeded
4 µg m<sup>−3</sup> at all heights with an overall
average (±1<i>σ</i>) value of 13.3 (±4.8) µg m<sup>−3</sup>. The
highest NH<sub>3</sub> concentrations along the vertical profiles mostly
occurred from 32 to 63 m, decreasing both towards the surface and at higher
altitudes. Significant decreases in NH<sub>3</sub> concentrations were only
found at the top two heights (280 and 320 m). These results suggest an
NH<sub>3</sub> rich atmosphere during all seasons in urban Beijing, from the
ground to at least 320 m. The highest seasonal NH<sub>3</sub> concentrations
across the profile were observed in summer (18.2 µg m<sup>−3</sup>) with
high temperature, followed by spring (13.4 µg m<sup>−3</sup>), autumn
(12.1 µg m<sup>−3</sup>) and winter (8.3 µg m<sup>−3</sup>).
A significant vertical variation in the NH<sub>3</sub> concentration was only found
in summer. Source region analyses suggest that air masses from intensive
agricultural regions to the south contribute most to the high NH<sub>3</sub>
concentrations in Beijing. Local sources such as traffic emissions also
appear to be important contributors to atmospheric NH<sub>3</sub> in this
urban environment.</p> |
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ISSN: | 1680-7316 1680-7324 |