Simultaneous measurements of urban and rural particles in Beijing – Part 2: Case studies of haze events and regional transport
<p>Two parallel field studies were conducted simultaneously at both urban and rural sites in Beijing from 1 to 29 November 2016. An online single-particle chemical composition analysis was used as a tracer system to investigate the impact of heating activities and the formation of haze events....
| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-08-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/20/9249/2020/acp-20-9249-2020.pdf |
| Summary: | <p>Two parallel field studies were conducted simultaneously at both urban and
rural sites in Beijing from 1 to 29 November 2016. An online single-particle
chemical composition analysis was used as a tracer system to investigate the
impact of heating activities and the formation of haze events. Central
heating elevated EC-Nit (elemental carbon-nitrate), EC-Nit-Sul (EC-nitrate-sulfate), and ECOC-Nit (ECOC: internal-mixed elemental carbon and organic carbon) levels by 1.5–2.0 times
due to the increased use of coal in the urban areas. However, in the rural
areas, residential heating, which mainly consumes low-quality coal, and
biomass burning elevated ECOC-Nit-Sul, NaK-Nit, and OC-Sul levels by
1.2–1.5 times. Four severe haze events (hourly PM<span class="inline-formula"><sub>2.5</sub></span> > 200 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span>) occurred at both sites during the studies. In each
event, a pattern of transport and accumulation was found. In the first
stage of the pattern, particles were regionally transported from the south
and southwest and accumulated under air stagnation, creating significant
secondary formation, then PM<span class="inline-formula"><sub>2.5</sub></span> was elevated to 300 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span>.
At both sites, the severe haze occurred due to different patterns of local
emission, transport, and secondary processes. At Pinggu (PG), the sulfate-rich
residential coal burning particles were dominant. The regional transport
between PG and Peking University (PKU) was simulated using the Weather Research and Forecasting HYbrid Single-Particle
Lagrangian Integrated Trajectory (WRF-HYSPLIT) model, confirming
that the transport from PG to PKU was significant, but PKU to PG occurred
occasionally. These cases can explain the serious air pollution in the urban
areas of Beijing and the interaction between urban and rural areas. This
study can provide references for enhancing our understanding of haze
formation in Beijing.</p> |
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| ISSN: | 1680-7316 1680-7324 |