中国南北方大气污染物的时空分布特征

Temporal and Spatial Distribution of Atmospheric Pollutants Between Northern China and Southern China

利用中国环境监测总站2014年12月-2015年11月171个城市的逐小时大气污染资料,对比分析了南北方大气颗粒物和气体污染物的时空分布特征。结果表明:(1)全国出现PM_(2.5)和PM_(10)污染日的频率分别为17.23%和10.33%,PM_(2.5)、PM_(10)具有较好的线性相关性,PM_(2.5)浓度约占PM_(10)浓度的47%,颗粒物和气体污染物的重污染区主要分布在环渤海地区、长三角地区、西北地区、四川盆地和两湖地区。(2)南北方大气颗粒物和气体污染物浓度具有明显的月季变化,从12月到次年3月和6、11月差距大,其他月份小(O3除外),PM_(2.5)/PM_(10)比值在秋末冬初大,其他季节小。(3)北方PM_(2.5)年均浓度为62.28μg/m3,比南方高12.62μg/m3,北方PM_(10)年均浓度为115.98μg/m3,比南方高36.34μg/m^3,虽然北方颗粒物浓度比南方大,但除2015年11月外,PM_(2.5)/PM_(10)北方都小于南方;北方SO_2、NO_2、CO年均浓度分别为38.16、42.28、1 256.67μg/m^3,比南方高18.43、3.56、315.83μg/m3,南北O3年均浓度相当。(4)从日变化看,污染物平均浓度(O3和SO_2除外)白天低于夜间,下降速率白天大于夜间;南北PM_(2.5)、PM_(10)、CO、NO_2平均浓度日变化呈"双峰双谷"型,O3呈"单峰单谷"型;日变化曲线还表明,日间和夜间北方PM_(2.5)、PM_(10)、CO、NO_2平均浓度都高于南方,下降速率也是北方大于南方。

By using hourly air pollution data of 171 cities in China from December 2014 to November 2015, the spatial and temporal distribution characteristics of atmospheric particulate matter and gaseous pollutants between northern and southern China were compared and analyzed. The results showed that PM2.5 and PM10 episode days were 17.23% and 10.33% in China, respectively. PM2.5 and PM10 concentration had a good linear correlation. PM2.5 accounted for about 47% of PM10 mass concentrations. The heavily polluted cities were mainly located in Bohai Rim, Yangtze River Delta, northwest China, Sichuan Basin, Hubei and Hunan Provinces. There were obviously seasonal variations of particulate matter and gaseous pollutants in both northern and southern China. A large gap of the pollutants concentration existed between the north and the south from December 2014 to March 2015, June and November 2015, and the gap was small in the other months（except O3）. The ratios of PM2.5 and PM10 were large in later autumn and early winter, but small in the other seasons. The annual average of PM2.5 concentrations was 62.28 μg/m3 in northern China, which was 12.62 μg/m3 higher than that in the south, as well as PM10 annual average 115.98 μg/m3 in the north, 36.34 μg/m3 higher than that in the south. Although the particulate matter concentration in northern China is larger than that in the south, PM2.5/PM10（except November 2015） was reversed between the North and the South. The concentrations of SO2（38.16 μg/m3）, NO2（42.28 μg/m3）, CO（1 256.67 μg/m3） in the North were 18.43 μg/m3,3.56 μg/m3, 315.83 μg/m3 higher than the values of the south, respectively. However, the annual average concentration of O3 in the north was fairly close to the south. The daily mean concentrations of pollutants（except O3 and SO2） were higher in nighttime than that in daytime. The diurnal variation of PM2.5, PM10, CO, NO2 concentration in northern and southern China both showed a＂double peak and double valley＂variation, and O3 as ＂single-peak single-valley＂ type. The daytime average pollutant concentrations as well as nighttime in the north were much higher than that in the south. The diurnal curves also shows thatthe descending rates of PM2.5, PM10, CO, NO2 concentrations had the similar comparison as pollutant concentrations between the north and the south.