本文以汾河平原6城市为研究对象，结合监测数据，分析了汾河平原近年来大气中各主要污染物的时间分布特征，并选取太原市和运城市进行加强观测，研究汾河平原大气重污染的成因。

结果表明汾河平原六城市气象条件变化特征整体较为相似，湿度都呈现出春冬低，夏秋高的特征。风速上具有区域的差异性，呈现出南部风速高，北部风速低的特征。汾河平原各城市各污染物的季节变化特征十分一致。各种污染物浓度存在明显的季节变化。汾河平原6城市的PM_2.5、PM₁₀、NOx、CO等浓度日变化呈现出一定的“双峰”特征，同时在不同污染过程中，南部城市和北部城市污染物变化特征有显著不同。

通过对重污染成因的分析，发现汾河平原各城市PM_2.5主要来源包括燃煤源、扬尘源、机动车源、二次硝酸盐、二次硫酸盐、SOA、工艺过程源、其他以及生物质燃烧源。对比太原和运城市的重污染过程期间，发现二次来源对太原市颗粒物污染具有重要贡献，发现随着污染越严重，二次污染占比越高；对于运城市，燃煤和机动车源是PM_2.5的主要来源。而在传输上太原市的PM_2.5主要受省内南部、西部、东部地区影响，省外源区主要在甘肃、宁夏、内蒙古、河南、山东等地。而对于运城市在重污染时段易受周边区域京津冀城市群输送影响。

汾河平原在把不同污染水平下本地排放和区域传输对PM_2.5的贡献分析，发现随着污染水平升高，本地排放贡献减少，区域输送的贡献增加。太原、吕梁、晋中、临汾、运城和三门峡的本地排放的贡献分别从清洁条件下的82.5%、75.0%、46.0%、85.0%、73.0%和30.6%降到79.7%、68.9%、40.0%、79.0%、66.5%和25.2%。

本文选取汾河平原PM_2.5和O₃为研究对象，首先搭建了曲面响应模型，构建了PM_2.5、O₃和NOx、VOCs削减的响应关系，并以此为基础对费效进行了评估。得出了最终污染控制措施费效比为0.93，污染控制措施效果显著。

In recent years, with the rapid development of the economy and the acceleration of urbanization, the problem of air pollution has become increasingly severe. This article takes six cities in the Fenhe Plain as the research object, analyzes the temporal distribution characteristics of major pollutants in the atmosphere of the Fenhe Plain in recent years, and selects Taiyuan and Yuncheng cities for strengthened observation to establish a case database of heavy pollution causes.

The results indicate that the overall characteristics of meteorological conditions in the six cities of the Fenhe Plain are relatively similar, with low humidity in spring and winter and high humidity in summer and autumn. There are regional differences in wind speed, characterized by high wind speeds in the south and low wind speeds in the north. The seasonal variation characteristics of pollutants in various cities of the Fenhe Plain are very consistent. There are significant seasonal variations in the concentrations of various pollutants. The daily variation of PM_2.5, PM₁₀, NOx, CO and other concentrations in six cities on the Fenhe Plain shows a certain "double peak" characteristic.

Through the analysis of the causes of heavy pollution, it was found that the main sources of PM_2.5 in various cities of the Fenhe Plain include coal-fired sources, dust sources, motor vehicle sources, secondary nitrate, secondary sulfate, SOA, process sources, others, and biomass combustion sources. And comparing the heavy pollution processes in Taiyuan and Yuncheng cities, it was found that secondary sources have an important contribution to particulate matter pollution in Taiyuan city, and it was found that as the pollution becomes more severe, the proportion of secondary pollution increases; For Yuncheng City, coal burning and motor vehicle emissions are the main sources of PM_2.5. In terms of transmission, PM_2.5 in Taiyuan City is mainly affected by the southern, western, and eastern regions of the province, while the external regions of the province are mainly in Xinjiang, Gansu, Ningxia, Inner Mongolia, Henan, Shandong, and other places. For Yuncheng City, during heavy pollution periods, it is susceptible to transportation impacts from surrounding areas such as the Xi’an and the Beijing Tianjin Hebei urban agglomeration.

Analysis of the contribution of local emissions and regional transport to PM2.5 in the Fenhe Plain under clean and relative pollution levels reveals that as pollution levels increase, the contribution of local emissions decreases, while the contribution of regional transport increases. The contribution of local emissions in Taiyuan, Lvliang, Jinzhong, Linfen, Yuncheng, and Sanmenxia decreased from 82.5%, 75.0%, 46.0%, 85.0%, 73.0%, and 30.6% under clean conditions to 79.7%, 68.9%, 40.0%, 79.0%, 66.5%, and 25.2%, respectively.

This article selects PM_2.5 and O₃ in the Fenhe Plain as the research objects. Firstly, a surface response model was built, and the response relationship between PM2.5, O3, NOx, and VOCs reduction was constructed. Based on this, the cost-effectiveness was evaluated. The cost-effectiveness ratio of the final pollution control measures was 0.93, indicating that the pollution control measures have achieved significant environmental benefits.