2015—2020年川南地区大气PM_(2.5)和O_(3)质量浓度变化特征、影响因素及输送特征

Concentration,influencing factors,and transport characteristics of PM_(2.5)and O_(3)in southern Sichuan from 2015 to 2020

随着川南地区的经济发展,地面臭氧(O_(3))、细颗粒物(PM_(2.5))成为危害人体健康的主要污染物。本文分析了2015—2020年间川南地区(自贡、内江、泸州、宜宾)PM_(2.5)和O_(3)质量浓度的时间变化特征。以污染严重的自贡市为例,研究当地PM_(2.5)和O_(3)浓度与常见影响因素的相关性,并通过潜在源分析方法,探究污染物区域输送对自贡市的影响。结果表明:1)2015—2020年,川南地区年均PM_(2.5)质量浓度呈下降趋势,年均O_(3)质量浓度呈略上升趋势。月均PM_(2.5)质量浓度呈“U”型分布,7—8月质量浓度低,12—2月质量浓度高;月均O_(3)质量浓度呈“M”型分布,7、8月出现峰值,4、5月出现次峰值。2)自贡市PM_(2.5)质量浓度与CO、NO_(2)、SO_(2)质量浓度呈显著正相关,O_(3)质量浓度与气温、相对湿度分别呈显著正相关和负相关。3)自贡市PM_(2.5)和O_(3)的区域输送主要以局地气团为主,辐射和人为源排放强度影响气流轨迹中的PM_(2.5)和O_(3)质量浓度。PM_(2.5)和O_(3)的主要潜在源区位于四川盆地和贵州部分地区。

With the economic development of southern Sichuan,ground-level ozone(O_(3))and particulate matter less than 2.5μm in aerodynamic diameter(PM_(2.5))have emerged as major pollutants detrimental to human health.In response to air pollution challenges,the Chinese Government implemented the“Air Pollution Prevention and Control Action Plan”in 2013 and the“Three-Year Action Plan to Win the Blue Sky Defense War”in 2018.This study evaluates the effectiveness of control measures for PM_(2.5)and O_(3)in southern Sichuan post-implementation and aims to provide a theoretical and scientific basis for the coordinated management of these pollutants.We analyze the temporal variations in PM_(2.5)and O_(3)concentrations in four cities in southern Sichuan(Zigong,Neijiang,Luzhou,and Yibin)from 2015 to 2020.Zigong,identified as the most polluted among the cities,serves as a case study to investigate the correlations between PM_(2.5)and O_(3)concentrations and various influencing factors.The study utilizes backward trajectory clustering,source emission intensity analysis,and potential source analysis to assess the impact of regional pollutant transport on Zigong.The results indicate that:1)From 2015 to 2020,the annual average concentration of PM_(2.5)in southern Sichuan showed a declining trend with a 38.9%reduction,while the annual average concentration of O_(3)showed a slight increasing trend,rising by 8.2%.These trends suggest that current control strategies are effective for PM_(2.5)but may be insufficient for O_(3),highlighting the need for enhanced O_(3)management strategies.2)The monthly average PM_(2.5)concentration exhibits a“U”shape,with the lowest values in July and August and the highest from December to February.In contrast,the monthly average O_(3)concentration exhibits an“M”shape,peaking in July and August with secondary peaks in April and May.These patterns suggest that PM_(2.5)control should be prioritized in winter,while O_(3)control should be emphasized in spring and summer.3)In Zigong,PM_(2.5)concentration shows significant positive correlations with CO,NO_(2),and SO_(2) concentrations,while O_(3)concentration is significantly positively correlated with temperature and negatively correlated with relative humidity.4)The regional transport of PM_(2.5)and O_(3)in Zigong is predominantly influenced by local air masses.Radiation levels and anthropogenic emission intensities along air trajectories significantly affect PM_(2.5)and O_(3)concentrations.The primary potential source areas for these pollutants are located within the Sichuan Basin and parts of Guizhou.Given the regional transport influnece,there is a need for strengthened regional collaborative governance,joint prevention and control efforts,enhanced source control,accelerated replacement of VOC-containing materials,and increased utilization of clean energy soucres.The study employs Pearson correlation analysis to preliminarily identify relationships between PM_(2.5)and O_(3),and various influencing factors.Future research will include a more quantitative analysis of these relationships,including the impact of temperature on photochemical reactions,the role of relative humidity in PM_(2.5)wet deposition,and the effects of atmospheric diffusion conditions on pollutant concentrations.These analyses will provide precise quantification of the specific impacts of each influencing factor on PM_(2.5)and O_(3)pollution,thereby enhancing the objectivity and reliability of the research findings.