Title：Characteristics and Cluster Analysis of Air Pollution in Coastal Areas of China
Journal/Publisher：Research of Environmental Sciences
Year：2018
Authors：Lingbo Long, Qiannan She, Ziqi Meng, Min Liu, Zhu Yue, Yuanyuan Yan
Abstract
To identify the distribution characteristics of air pollution in the coastal areas of China, this paper analyzed the spatial-temporal variation of six criteria air pollutants (PM2.5, PM10, NO2, O3, CO and SO2) based on the observations from 115 cities in the coastal provinces of China during 2015-2016. Cluster analysis coupled with principal component analysis (PCA) and improved Akaike information criterion (AIC) were applied to explore the regional pollution situations. The results showed that the coastal areas of China was seriously polluted by particulate matter (PM), with 70% cities for PM2.5 and 54% cities for PM10 fell below the national secondary standard, according to the National Ambient Air Quality Standard. For ρ(PM2.5), it demonstrated obvious spatial variations between the south and north, with Jinhua City in Zhejiang Province as a demarcation belt. The heavily polluted areas appeared in northern areas in which it showed an increasing trend from east to west. The O3 concentrations around the Bohai Sea and Yangtze River Delta were at relatively high level, while the highest SO2 concentration (71.3 μg/m3) was located in middle Shangdong province. Furthermore, according to the observed six criteria air pollutants, all the 115 cities could be clustered into 3 categories. Cluster I included 21 cities in south Hebei and Shangdong Provinces. The spatial distribution for air pollutants were continuous and relatively centralized with the highest pollutant concentrations and the worst air qualities due to the local emission and diffusion conditions. Cluster II included 42 cities which were mainly distributed in Liaoning province and the Yangtze River Delta. It showed medium air qualities with considerable SO2 and NO2 pollution due to coal burning, plants emission as well as vehicle and shipping emission. The PM2.5 concentration in Cluster II was 34.2% lower that of Cluster I. Cluster III included 52 cities with the best air quality and were mainly distributed in the southeast coastal areas of China with O3 pollution due to monsoon and outside sources. Moreover, the average O3 concentrations among the three clusters were similar but the seasonal variations were different. Specifically, Cluster I and II were characterized with the apparent seasonal variation and the highest values appeared in June. For Cluster III, there was no obvious seasonal variations with the highest values in October. In particular, western Shangdong and northern Jiangsu provinces showed similar pollution characteristics to southern Beijing-Tianjin-Hebei region and Liuzhou was one of the air pollution hot spots in the Guangxi Zhuang Autonomous Region.
Keywords：air pollution, spatial variation, cluster analysis, coastal area
