清洁大气背景下贵阳空气质量变化及气象作用

摘要

利用贵阳市2013~2016年空气质量监测及气象观测资料进行分析,研究云贵高原城市空气变化及气象影响作用.结果表明:近4a贵阳区域SO2、NO2、O3_8h、PM10、PM2.5和CO年平均浓度分别为(20.78±19.71),(28.32±9.59),(107.59±27.54),(67.56±34.32),(42.53±24.52)μg/m3和(0.74±0.22)mg/m3,除SO2浓度接近或超出我国中东部城市之外,其它污染物均表现为相对清洁水平;地面O3浓度逐年明显上升,但其它大气污染物水平均呈逐年下降趋势,且呈现与我国中东部一致的空气质量年际、月际和日变化特征.各功能区污染物区域差异明显,颗粒物和SO2、NO2、CO浓度水平表现为工业区>居民区>郊区,O3浓度呈现为郊区>居民区>工业区的特征,表明人为活动对空气质量的影响.近4a O3与PM2.5夏季白天呈显著正相关,冬季显著负相关,反映了云贵高原城市空气质量的复合污染特性.大气污染物浓度与温度、边界层高度、太阳直接辐射和气压的相关性显著,而与相对湿度和风速相关性较弱,这不同于中东部地区风速主导大气污染物水平变化的特征.云贵高原夏季作为主要雨季,小雨和中雨量级降水对PM2.5吸湿增长较弱,中雨以上降水对PM2.5具有清除作用;而在PM2.5浓度较高和干冷的冬季,小雨的PM2.5吸湿增长明显,中雨以上降水对PM2.5清除显著.%Regional changes of urban air quality and meteorological effects were statistically analyzed based on environmental monitoring and meteorological observation data from 2013 to 2016 in the paper. In the recent 4years, annual average concentrations of SO2, NO2, O3_8h, PM10, PM2.5 and CO were respectively (20.78±19.71), (28.32±9.59), (107.59±27.54), (67.56±34.32), (42.53±24.52)μg/m3 and (0.74±0.22) mg/m3 in Guiyang. Except for concentrations of SO2 close or exceeding central and eastern China, other air compositions kept in low levels. Ambient O3 concentrations significantly increased, while other air pollutant level declined with the similar patterns of inter-annual, monthly and diurnal variations with central and eastern China. The significant differences of air pollutants existed among industrial, residential and suburban areas with industrial area> residential area > suburb for particulate matter, SO2, NO2 and CO as well as suburb > residential area > Industrial area for surface O3 concentrations, reflecting impact of human activities on air quality. Air compound pollutants O3 and PM2.5 presented positive correlation in summer and but negative correlation in winter. Air temperature, boundary layer height, solar radiation and air pressure had significant impacts on pollutant concentrations, while relative humidity and wind speed had the weak influences, differently from wind speed dominating changes of air quality in central and eastern China. In summer, rainy season in Guiyang, PM2.5 hygroscopic growth was weak in light or moderate precipitation intensity with the obvious aerosol wash-out by large and heavy rainfall; both PM2.5 hygroscopic growth and removal of precipitation were more remarkable in the dry and cold winter.