Characteristics and Source Identification of Air Pollution in Shahe, a Typical Industrial City in Beijing-Tianjin-Hebei Region

In the autumn and winter, severe air pollution events occur frequently in Beijing-Tianjin-Hebei region. As is known, industrial emissions and residential coal burning are the major reasons for atmospheric pollution. As a typical industrial city focusing on glass manufacturing and processing, Shahe city is selected as the research object. An air diffusion model and potential source analysis are employed to study spatiotemporal characteristics and sources of major pollutants based on the atmospheric monitoring data in Shahe city from January to December, 2017. Major results are as follows. (1) There are obvious seasonal characteristics of primary pollutants in Shahe. The primary pollutant is PM₁₀ in the spring, O₃ in the winter, and PM_2.5 in the autumn and winter. Their seasonal contribution rates are 43.3%, 72.3% and 61.5% respectively. (2) Affected by changes in urban atmospheric boundary layer and pollution emissions, the concentrations of PM₁₀, PM_2.5, SO₂, NO₂ and CO have strong seasonal-diurnal changes. (3) When northeasterly winds prevail in the winter, correlation coefficients between PM_2.5, NO₂, SO₂ and their concentrations are high, which may be attributed to emissions from glass factories to the northeast of the city. Meanwhile, the observational site may also be affected by coal burning in surrounding villages. (4) The mean concentration of PM_2.5 in Shahe is 143 μg m^-3 in the winter. The analysis of a severe pollution case shows that the max values of SOR (sulfur oxidation ratio), NOR (nitrogen oxidation ratio) are 0.67 and 0.39, respectively. This indicates that the conversion from primary gaseous pollutants to secondary pollutants is severe. It also proves that high humidity does favor the formation of air-borne particulates. The mean value of C(NO₃^-)/C(SO₄^2-) is 1.89. It is concluded that NO₂ in Shahe mainly comes from emissions of heavy transport vehicles and factories. (5) Local area is a strong potential source for Shahe’s PM_2.5. The surrounding industrial cities also make some contributions. Not only local emission reduction, but also regional management regimes are needed to control the PM_2.5 pollution.