2018~2020年北京市大气PM_(2.5)污染特征及改善原因  

Pollution Characteristics and Factors Influencing the Reduction in Ambient PM_(2.5)in Beijing from 2018 to 2020

作　　者：刘保献 李倩 孙瑞雯 董瑞 王书肖[1] 郝吉明[1] LIU Bao-xian;LI Qian;SUN Rui-wen;DONG Rui;WANG Shu-xiao;HAO Ji-ming(School of Environment,Tsinghua University,Beijing 100084,China;Beijing Municipal Ecological and Environmental Monitoring Center,Beijing 100048,China;Beijing Key Laboratory of Airborne Particulate Matter Monitoring Technology,Beijing 100048,China)

机构地区：[1]清华大学环境学院,北京100084 [2]北京市生态环境监测中心,北京100048 [3]大气颗粒物监测技术北京市重点实验室,北京100048

出　　处：《环境科学》2023年第5期2409-2420,共12页Environmental Science

基　　金：北京市科技计划项目(Z191100009119004)。

摘　　要：利用2018~2020年北京市33个环境评价站和5个区域评价站的空气质量数据,以及气象数据和北京市城区PM_(2.5)组分数据,研究了3年间北京PM_(2.5)的浓度演变、时空变化和重污染发生情况,并对PM_(2.5)组分和气象条件变化进行比较分析.结果发现,3年间北京市ρ(PM_(2.5))分别为51、42和38μg·m^(-3),2020年的PM_(2.5)相比2017年下降30.9%,但仍超过国际标准8.6%;北京市PM_(2.5)空间分布依旧维持南高北低的特征,但南北差异逐年减小,区域浓度趋于均一化;1~3月PM_(2.5)浓度相对较高,8~9月PM_(2.5)浓度相对较低,采暖季各污染物浓度均显著高于非采暖季,NOx和CO分别偏高58.4%和52.9%,PM_(2.5)偏高27.5%;采暖季和非采暖季PM_(2.5)日变化出现反向特征,采暖季夜间PM_(2.5)明显高于白天,而非采暖季PM_(2.5)峰值出现在中午前后;2018~2020年北京市发生重污染过程16次,重污染天共25 d,主要集中在秋冬季,区域性重污染特征显著;经分析,近年来大气扩散条件有好有差,持续的污染减排仍是PM_(2.5)逐年降低最重要的原因;2020年北京市PM_(2.5)组分中有机物、元素碳和地壳物质浓度较2017年分别下降43.3%、53.2%和51.5%,硝酸盐、硫酸盐和铵盐浓度降幅分别为34.5%、52.2%和43.7%,结果显示北京市PM_(2.5)各主要来源均取得明显控制效果.Air quality data from 33 environment sites and five regional sites from 2018 to 2020,as well as meteorological data,were used to research PM_(2.5)variation,spatial and temporal change,diurnal variation,and heavy pollutions in Beijing.The annual average mass concentrations of PM_(2.5)in Beijing were 51,42,and 38μg·m^(-3),which showed great progress in air quality improvement.However,the PM_(2.5)concentration in 2020 was still 8.6%above the national limit value despite a 30.9%decline since 2017.The PM_(2.5)south-north gradient in Beijing remained throughout the three years,but this pattern showed a less significant trend.The highest monthly mean PM_(2.5)concentrations in Beijing tended to occur in January-March,with the lowest in August-September.NOx,CO,and PM_(2.5)concentrations were significantly higher in the heating season than in the non-heating season by 58.4%,52.9%,and 27.5%,respectively.Diurnal variation showed that greater PM_(2.5)concentrations were observed at nighttime during the heating season and,conversely,at noontime during the non-heating season.Sixteen pollution episodes occurred in Beijing over the last three years,resulting in 25 heavy pollution days distributed in autumn-winter of 2018-2020.The regional heavy pollution characteristics of PM_(2.5)in Beijing were significant.Through analysis,a continuous pollution reduction was still the most important reason for the yearly decrease in PM_(2.5).The concentrations of organic matter,elemental carbon,and crustal matter in the PM_(2.5)in Beijing decreased by 43.3%,53.2%,and 51.5%since 2017,respectively,and nitrate,sulfate,and ammonium decreased by 34.2%,52.2%,and 43.7%.The results showed that the control effect of PM_(2.5)in Beijing was obvious.

关 键 词：北京 污染特征 采暖季 PM_(2.5)组分 空气质量改善 

分 类 号：X513[环境科学与工程—环境工程]