Abstract:

Air pollution is now the most serious environmental problem in China, especially for Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration. Under the background of Jing-Jin-Ji integrated development, it is of great importance to study the spatio-temporal distribution and its influencing factors. This paper firstly analyzed the spatio-temporal characteristics of PM_2.5 concentration in 202 counties of Jing-Jin-Ji urban agglomeration using spatial analysis and visualization. Then we quantified the effect degree of different natural and human factors and the spatial spillover effect of these factors using Spatial Durbin Model (SDM). The results are as follows: (1) The PM_2.5 concentration was on the rise as a whole from 2000-2014, and it was high in autumn and winter, while low in spring and summer. Seen from spatial distribution, the PM_2.5 concentration was high in the southeast, while low in the northwest of the study area, and the concentration in urban built-up area was 10-20 μg/m³ higher than that of its surrounding suburban and rural areas. (2) The counties, whose PM_2.5 concentration was below 35 μg/m³, only accounted for 13.9% in 2014. There were significant spatial agglomeration and diffusivity of PM_2.5, and the mean distance interacting among the cities was 200 km. The PM_2.5 of a city increased by more than 0.5% for every 1% increase in the average PM_2.5 of neighboring cities. (3) Socio-economic factors have positive impact on PM_2.5, and most of natural factors have negative impact. (4) Among the influencing factors, contributions to local atmospheric pollution with direct effect are: mean wind speed > annual mean temperature > population density > relief amplitude > the secondary industry share of GDP > energy consumption > vegetation coverage; however, per capita GDP, annual precipitation, and relative humidity have no significant effect on local pollution. (5) Contributions to neighborhood atmospheric pollution with spatial spillover effect are: vegetation coverage > relief amplitude > population density. The findings suggest that we should adopt the adaptation strategies for natural factors and control strategies for human factors. A coordinated and strengthened cooperation between local governments should be established for air pollution control, and environmental planning and legislation should be strengthened in a new round of urban agglomeration planning in China.

Key words: air pollution, haze, PM_2.5, spatial-temporal evolution, pollution control, Spatial Durbin Model (SDM), Beijing-Tianjin-Hebei (Jing-Jin-Ji) urban agglomeration