Articles | Volume 16, issue 19
Research article
07 Oct 2016
Research article |  | 07 Oct 2016

Distribution and sources of air pollutants in the North China Plain based on on-road mobile measurements

Yi Zhu, Jiping Zhang, Junxia Wang, Wenyuan Chen, Yiqun Han, Chunxiang Ye, Yingruo Li, Jun Liu, Limin Zeng, Yusheng Wu, Xinfeng Wang, Wenxing Wang, Jianmin Chen, and Tong Zhu

Abstract. The North China Plain (NCP) has been experiencing severe air pollution problems with rapid economic growth and urbanisation. Many field and model studies have examined the distribution of air pollutants in the NCP, but convincing results have not been achieved, mainly due to a lack of direct measurements of pollutants over large areas. Here, we employed a mobile laboratory to observe the main air pollutants in a large part of the NCP from 11 June to 15 July 2013. High median concentrations of sulfur dioxide (SO2) (12 ppb), nitrogen oxides (NOx) (NO + NO2; 452 ppb), carbon monoxide (CO) (956 ppb), black carbon (BC; 5.5 µg m−3) and ultrafine particles (28 350 cm−3) were measured. Most of the high values, i.e. 95 percentile concentrations, were distributed near large cities, suggesting the influence of local emissions. In addition, we analysed the regional transport of SO2 and CO, relatively long-lived pollutants, based on our mobile observations together with wind field and satellite data analyses. Our results suggested that, for border areas of the NCP, wind from outside this area would have a diluting effect on pollutants, while south winds would bring in pollutants that have accumulated during transport through other parts of the NCP. For the central NCP, the concentrations of pollutants were likely to remain at high levels, partly due to the influence of regional transport by prevalent south–north winds over the NCP and partly by local emissions.

Short summary
With five repeated experiments using a mobile laboratory, we obtained the spatial distribution of major air pollutants over the surface of the North China Plain (NCP). All the pollutants were at high levels, with pollutant peak values in nearby major cities and along transport routes. With simulated wind fields, we identified the prevalent transport routes of air pollutants on different parts of the NCP, reflecting the transport of air pollution between megacities and surrounding regions.
Final-revised paper