2014-2016年北京市PM_(2.5)污染时空分布特征

Temporal and Spatial Distribution Characteristics of PM_(2.5) Pollution in Beijing from 2014 to 2016

分析2014-2016年北京市35个大气PM_(2.5)监测站点数据,对比采暖期与非采暖期PM_(2.5)污染时间变化差异,并对全市PM_(2.5)污染的空间分布特征进行分析,探究近3年北京市大气PM_(2.5)污染的时空分布规律,揭示采暖期与非采暖期PM_(2.5)污染的异同性,为全市大气环境污染治理与改善提供合理性建议。结果表明,2014-2016年北京市PM_(2.5)年均质量浓度分别为90.279、82.261、78.672μg·m^(-3),污染水平逐年下降。其中,非采暖期小时均值分别于12:00与21:00左右达到峰值,污染波谷分别出现在7:00与18:00,采暖期白天浓度低夜间浓度高,从7:00下降至17:00升高,23:00至次日1:00为稳定持续的高污染时段;非采暖期PM_(2.5)月均浓度值均呈"W"形波动,每年5月与8月中旬污染浓度值最低,7月污染相对较高;采暖期污染水平整体高于非采暖期,其中1月、2月污染较为严重。全市PM_(2.5)均值浓度表现出南部>北部的空间分布特征。非采暖期东南部PM_(2.5)污染普遍高于西北部,采暖期西南部的房山区、大兴区与通州区为主要污染区域,包含主城区在内的北部地区PM_(2.5)污染浓度相对较低;非采暖期的主城区在涵盖城市交通要道的区域PM_(2.5)浓度值较高,采暖期污染分布特征为西北与东南较高,中部以植物园监测点为中心的周边污染浓度始终保持全域最低;六环区域内,非采暖期北部新区、植物园与古城周边污染水平低,万柳、云岗以东污染较重,采暖期重污染区域范围缩小,向东、南边缘区域集聚,2015年与2016年主要污染区域分布在以房山为中心的南部地区。整体而言,北京市采暖期大气污染主要来源于冬季取暖燃煤排放,非采暖期起决定性影响的污染源为汽车尾气排放,人为活动是大气中细颗粒物的主要来源。

The data of 35 atmospheric PM 2.5 monitoring stations in Beijing from 2014 to 2016 were analyzed to compare the differences in the characteristics of PM 2.5 pollution time and the differences in spatial distribution characteristics during heating and non-heating periods.By studying the temporal and spatial distribution of atmospheric PM 2.5 pollution in Beijing,it can provide reasonable suggestions for the treatment and improvement of atmospheric pollution in the city.The results showed that the average annual concentrations of PM 2.5 in Beijing from 2014 to 2016 were 90.279μg·m^-3,82.261μg·m3 and 78.672μg·m^-3,respectively.The average hourly value of non-heating period reached the highest value at 12:00 and 21:00 respectively,and the concentration value reached the lowest value at 7:00 and 18:00.During the heating period,PM 2.5 had a low concentration in the daytime and a high concentration in the nighttime.During the non-heating period,the average monthly concentration of PM 2.5 showed a"W"-shaped fluctuation.The pollution concentration was the lowest in May and mid-August,and the pollution was relatively high in July.The pollution level in the heating period was higher than that in the non-heating period,and the pollution in January and February was more serious.The overall concentration of PM 2.5 in the city showed the spatial distribution characteristics of the south side higher than the north side.The air pollution in the southeastern part of Beijing during the non-heating period was significantly higher than that in the northwest.During the heating period,Fangshan District,Daxing District and Tongzhou District in the southwest were the main polluted areas,and the concentration of PM 2.5 in the northern part including the main urban area was relatively low.In the non-heating period,the concentration of PM 2.5 in the main urban area was relatively high.The spatial distribution characteristics of air pollution during heating period were higher in the northwest and southeast.In the middle,the pollution concentration in the adjacent area centered on the monitoring point of the botanical garden always kept the lowest value in the whole region.In the six-ring area,the level of air pollution near the three monitoring points in the northern new area,the botanical garden and the ancient city during the non-heating period was low,and the pollution was heavy in the east of Wanliu and Yungang.During the heating period,the area of the city's heavily polluted areas had been significantly reduced,showing a concentration in the eastern and southern margins.Among them,in 2015 and 2016,the main polluted areas were concentrated in the southern part with Fangshan as the center.Overall,the main source of fine particulate matter pollution in Beijing's atmosphere is mainly from human activities.Among them,the main source of air pollution during the heating period is the large amount of exhaust gas emitted from coal burning in winter for heating,and the pollution source that is decisively affected during the non-heating period is automobile exhaust.