Table 1.
Descriptions of the five monitoring sites and the corresponding measurements in this study
| Monitoring site | Species | Monitoring period | Measurement height (m) and underlying surface | Population density (persons km−2)b | Surrounding environment and possible emission sources | |||
|---|---|---|---|---|---|---|---|---|
| Gasesa | PM2.5 | Gases | PM2.5 | Surface | ||||
| China Agricultural University (CAU) | NH3, HNO3, NO2, PM2.5 | Jan. 2011–Dec. 2014 | Mar. 12–Nov. 2014 | 2 | 10 | Roof | 7616 | Densely occupied residences, small-scale urban agriculture, and traffic roads |
| Shangzhuang (SZ) | NH3, HNO3, NO2, PM2.5 | Jan. 2011–Dec. 2014 | Apr. 12–Nov. 2014 | 2 | 2.5 | Grass | 519 | Small towns, traffic roads, and farmland |
| Quzhou (QZ) | NH3, HNO3, NO2, PM2.5 | Jan. 2011–Dec. 2014 | Apr. 12–Nov. 2014 | 2 | 2.5 | Grass | 606 | Small villages, a traffic road, and dense farmland |
| Yucheng (YC) | NH3, HNO3, NO2, PM2.5 | Jan. 2013–Dec. 2014 | Apr. 13–Nov. 2014 | 2 | 2.5 | Lawn | 495 | Small villages, a road, and farmland |
| Zhengzhou (ZZ) | NH3, HNO3, NO2 | Jan. 2011–Dec. 2014 | n.d. | 2 | – | Grass | 17,069 | Densely occupied residences and traffic roads |
n.d. not determined
aNH3, HNO3, and NO2
bPopulation density was estimated by dividing population by area of the town/district/county where the monitoring site is located. Population data were sourced from the sixth census of China in 2010 (http://www.stats.gov.cn)