2013—2015年中国PM2.5污染状况时空变化

自2013年我国首次开展全国范围PM_2.5近地面监测以来，少有研究从全国空间尺度分析近3年全国PM_2.5污染状况时空变化的总体特征，识别PM_2.5污染加剧或缓解的空间范围，更缺乏直接对比评估国家大气污染重点防控区内外PM_2.5污染特征变化的差异.基于2013—2015年PM_2.5监测数据，综合运用时空统计分析与空间插值制图手段，揭示近3年ρ(PM_2.5)及不同等级污染天数的时空变化格局，并着重对比分析“三区十群”区域内外ρ(PM_2.5)的变化差异.结果表明，2013—2015年，全国持续监测的413个站点中有335个监测站点ρ(PM_2.5)年均值下降，其中218个站点实现连续两年年均浓度降低，74个站点ρ(PM_2.5)年均值降至符合国家二级标准；全国大部分地区ρ(PM_2.5)年超标率由50%以上降至30%以下，重度污染站点占比由88.38%降至73.77%，严重污染站点占比由65.86%降至36.35%；长三角城市群、长株潭城市群、武汉及周边城市群、陕西关中城市群PM_2.5污染呈现明显好转趋势；西藏、云贵高原以及海峡西岸城市群、珠三角城市群等沿海地区ρ(PM_2.5)一直较低，空气质量相对优良；但与此同时，京津冀城市群、山东半岛城市群及河南中部和北部地区仍是中国PM_2.5重污染区域，新疆西南部、合肥、南昌等地区逐渐形成新的PM_2.5重污染格局. 

Pollution Status and Spatial-Temporal Variations of PM2.5 in China during 2013-2015

PM_2.5 pollution in China has attracted serious concern worldwide since the release of observational data at stationary monitoring sites in 2013. However, few studies have focused on national scale analysis of pollution status and associated spatial-temporal variations of PM_2.5 in the recent three years, let alone the identification of spatial extensions with aggravated or mitigated PM_2.5 pollution and comparative assessment of the characteristic differences of PM_2.5 pollution of the 'Key Prevention and Control Regions'. Based on the nationwide PM_2.5 concentrations regularly observed at the monitoring sites from 2013 to 2015, this study revealed the spatial-temporal variations of PM_2.5 concentrations and pollution days at various grades in China. The entire process was implemented by using the methods of spatial statistical analysis and spatial interpolation, while including the comparison of the variation difference of areas inside or outside the 'Key Prevention and Control Regions'. The results showed that, for all the annual PM_2.5 concentrations at 335 monitoring sites, the annual PM_2.5 concentrations at 218 monitoring sites continuously decreased in the years 2014 and 2015, while those concentrations at 74 sites declined to the class Ⅱ China National Air Quality Standard. The exceeding-standard rates of annual PM_2.5 concentration in most areas of China were reduced from 50% to 30%. The situation also existed for the monitoring sites with heavily and seriously polluted PM_2.5, at which the exceeding-standard rates simultaneously dropped from 88.38% to 73.77% and from 65.86% to 36.35%, respectively. As a result, the PM_2.5 pollution in Yangtze River Delta, urban agglomerations of Wuhan, Changsha-Zhuzhou-Xiangtan and Shanxi Guanzhong was clearly improved. Air quality in Tibet, Yunnan-Guizhou Plateau and coastal regions such as Fujian Straits urban agglomeration and Pearl River Delta were always good. However, the eastern and southern Beijing-Tianjin-Hebei region, Shandong urban agglomeration, as well as the central and northern Henan remained severe PM_2.5 pollution, while the newly heavy pollution pattern was gradually emerging in areas such as southwestern Xinjiang, Hefei and Nanchang.