[Spatio-Temporal Characteristics and Potential Source Areas of Seasonal Atmospheric Pollution in Shijiazhuang]

Abstract

In order to systematically study the transmission characteristics of seasonal and typical pollutants in Shijiazhuang, hourly data of ground-level pollutants(PM_2.5, PM₁₀, O₃, NO₂, SO₂, and CO) from 46 state-and provincial-controlled stations, and meteorological(temperature, humidity, and wind speed) data from 17 counties in Shijiazhuang City from December 2018 to November 2019 was analyzed. The interpolation(IDW) and correlation analysis were applied to seasonal and temporal spatial patterns of pollutant concentration. The backward trajectories analysis was performed to explore the seasonal transmission pattern and potential source areas of pollution in Shijiazhuang by combining with the global data assimilation system(GDAS). The results indicate that the different seasons have characteristic pollutants, as follows:spring(PM₁₀, 48.91%), summer(O₃, 81.97%), autumn(PM₁₀ and PM_2.5, 47.54% and 32.79%), and winter(PM_2.5, 74.44%), which are related to the variation of meteorological conditions. Furthermore, the PM₁₀(spring) concentration correlated negatively with the wind speed, presenting a high distribution in the northwest and low in the southeast, with a southerly transmission direction(53.32%). Central and southern Hebei, central and northern Henan, and central Shanxi are the potential sources of pollution(WPCWT_ij ≥ 160 μg·m^-3), impacting western Shandong and northwest Shanxi(WPSCF_ij ≥ 0.3) with PM₁₀. Moreover, the O₃(summer) concentration correlated positively with temperature, and negatively with humidity. The southeast-south(54.24%) is the source direction of the transmission, and the potential source of O₃ pollution is an arc area with Shijiazhuang in the center and Cangzhou and Heze as the double wings. Lastly, the PM_2.5(autumn and winter) concentration correlated positively with humidity, and the winter concentration shows an increasing gradient from west to east. The trajectories of PM_2.5 clustered the source directions:autumn(northeast-southeast, 74.75%), winter(northwest, 55.47%); central and southern Hebei, central and western Shanxi and northern Henan are the concentrated sources of potential pollution(WPCWT_ij ≥ 180 μg·m^-3).

Keywords: Shijiazhuang; atmospheric pollutant; hybrid single particle Lagrangian integrated trajectory(HYSPLIT); potential source areas; seasonal variation; spatio-temporal evolution.