Due to complicated interactions in the atmospheric environment, quantifying the influence of individual meteorological factors on local PM2.5 concentration remains challenging. The Beijing-Tianjin-Hebei (short for Jing-Jin-Ji) region is infamous for its serious air pollution. To improve regional air quality, characteristics and meteorological driving forces for PM2.5 concentration should be better understood. This research examined seasonal variations of PM2.5 concentration within the Jing-Jin-Ji region and extracted meteorological factors strongly correlated with local PM2.5 concentration. Following this, a convergent cross mapping (CCM) method was employed to quantify the causality influence of individual meteorological factors on PM2.5 concentration. The results proved that the CCM method was more likely to detect mirage correlations and reveal quantitative influences of individual meteorological factors on PM2.5 concentration. For the Jing-Jin-Ji region, the higher PM2.5 concentration, the stronger influences meteorological factors exert on PM2.5 concentration. Furthermore, this research suggests that individual meteorological factors can influence local PM2.5 concentration indirectly by interacting with other meteorological factors. Due to the significant influence of local meteorology on PM2.5 concentration, more emphasis should be given on employing meteorological means for improving local air quality.

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To begin with, the gravity model is used to study the spatial distribution and centers of gravity for energy-related CO 2 emission at regional level and to determine how they have changed over the period 1995-2010 in this paper. Furthermore, the occurrence of a decoupling of each province region between economic activity and CO 2 emission from energy consumption is examined based on decoupling index method. The main results are as follows: (1) In 1995, there were only seven provinces, each province of which emitted more than 150 Mt CO 2 . However, there were 25 provinces and each province's CO 2 emission was more than 150 Mt in 2010. (2) In terms of the annual growth speed of CO 2 emission, Neimenggu was the fastest. (3) During the study period, the centers of gravity for CO 2 emission are an overall movement toward southwest. (4) During the study period, the decoupling index for 23 provincial regions firstly increased and then decreased; there were six provincial regions whose decoupling index increased continuously; however, the decoupling index for Tianjin firstly decreased and then increased.