长三角地区城市O3和PM2.5污染特征及影响因素分析

Characteristics of O3 and PM2.5 and its impact factors in Yangtze River Delta

O3和PM2.5是影响长三角地区空气质量的主要污染物。利用2016年33个城市大气环境监测站6项污染物的小时浓度及4个省会城市的气象数据进行统计分析,研究了该地区O3和PM2.5浓度的时空分布特征及其影响因素。结果表明:长三角地区O3年平均浓度为50~73μg·m-3,平均为61μg·m^-3;除芜湖和宣城外,其余31城市均存在不同程度的超标状况,超标率为0.34%~18.86%,平均为5.68%。O3在5月和9月达到浓度高值;四季O3日变化均呈单峰型,峰值出现在15∶00,夏季O3峰值浓度最高值为157μg·m^-3。O3浓度沿海城市整体高于内陆城市;夏季宿迁—淮安—滁州片区O3污染较重。O3与NO2、CO显著负相关,且与NO2相关性较强;O3与气温、日照时数显著正相关,与相对湿度、降水呈负相关。PM2.5年平均浓度在25~62μg·m-3范围内,平均为49μg·m^-3;各城市均出现PM2.5超标,滁州PM2.5超标率最大,为23.91%。PM2.5在3月和12、1月达到浓度峰值;其日变化呈双峰型,09∶00—10∶00和22∶00—23∶00达到峰值。冬季徐州PM2.5浓度最高,为102μg·m^-3。PM2.5与NO2、CO、SO2、PM10显著正相关,与气温、风速、降水负相关。

O3 and PM 2.5 are the main pollutants that affect the air quality in Yangtze River Delta. To investigate the spatial and temporal characteristics of O 3 and PM 2.5 and its impact factors, the hourly concentrations of six pollutants and meteorological data collected at atmospheric environment monitoring stations in 33 cities and the meteorological data of four provincial cities in Yangtze River Delta in 2016 were analyzed. The results are shown as follows. The annual concentration of O 3 ranged from 50 μg·m -3 to 73 μg ·m ^-3 with an average of 61 μg ·m^-3 in Yangtze River Delta. The O 3 concentrations in 31 cites exceeded the standard to different degrees except Wuhu and Xuancheng in the region. The O 3 exceedance rate ranged from 0.34% to 18.86% with an average of 5.68%. The monthly average concentration of O 3 reached high values in May and September. The diurnal variation of O 3 concentration shows a single peak distribution, with the peak value appearing around 15 ∶00 in all the seasons. The highest peak value was 157 μg ·m^-3 in summer. The O 3 concentrations in coastal cities were generally higher than those in inland cities. Suqian-Huai an-Chuzhou region was more severely polluted in summer. O 3 was negatively correlated with NO 2 and CO, and the correlation was strong with NO 2 . O 3 was positively associated with temperature and sunshine duration while it was negatively correlated with relative humidity and rainfall. The annual concentration of PM 2.5 ranged from 25 μg ·m^-3 to 62 μg ·m^-3 with an average of 49 μg ·m^-3 . The concentrations of PM 2.5 in all cites exceeded the standard, with the highest exceedance rate as 23.91% in Chuzhou. The monthly concentration of PM 2.5 peaked in March and December or January. The diurnal variation of PM 2.5 showed two peaks in all the seasons at around 09 ∶00 to 10 ∶00 and 22 ∶00 to 23 ∶00 . In winter, the highest concentration of PM 2.5 was 102 μg ·m ^-3 in Xuzhou. PM 2.5 had a significantly positive correlation with NO 2 , CO, SO 2 and PM 10 , while it was negatively correlated with temperature, wind speed and rainfall.