【摘要】 根据2013—2023年湖南省14市（州）大气污染物监测数据，综合采用空气质量模型，评估了多年来湖南地区PM_2.5质量浓度变化成因及区域输送影响。结果表明：2015—2023年湖南省空气质量呈持续改善趋势，除益阳市、娄底市外，其余城市PM_2.5年均质量浓度均显著降低（通过Daniel显著性检验，α<0.05）。PM_2.5质量浓度下降速率较大的是长沙市、湘西州、张家界市，年下降速率均在2.5μg·m^-3·a^-1以上。2015—2023年10个城市重污染天数波动较大，特别是益阳市重污染天数有反弹趋势；与2015年相比，2023年湖南省气象条件整体偏差，仅4个城市气象条件起到促进PM_2.5质量浓度降低的作用，常德市、益阳市PM_2.5质量浓度降幅低与气象条件同比偏差密切相关，污染源减排措施对2015—2023年湖南省主要城市PM_2.5质量浓度的降低起着主导作用；2023年，长沙市、永州市和湘西州PM_2.5区域传输贡献率分别为56.0%、49.7%和44.6%,区域重污染过程中，3个城市外来源贡献在50%～70%左右。更多还原

【Abstract】 Based on air pollutant monitoring data collected from 14 cities in Hunan Province between 2013 and 2023, air quality modeling was comprehensively employed to evaluate the drivers behind long-term PM_2.5 mass concentration changes and the impact of regional transport in the region. The following results were obtained: a continuous improvement in air quality was observed in Hunan Province from 2015 to 2023. With the exception of Yiyang and Loudi, a significant reduction in annual average PM_2.5 mass concentrations was recorded in all other cities（as confirmed by the Daniel test for significance with α<0.05）. Higher reduction rates were observed in Changsha, Xiangxi Autonomous Prefecture, and Zhangjiajie, where the annual decline rate exceeded 2.5 μg·m^-3·a^-1. Considerable fluctuations in heavy pollution days were noted across ten cities during this period, with a rebound trend particularly observed in Yiyang. Meteorological conditions in 2023 were found to be generally less favorable compared to those in 2015. Favorable weather conditions for PM_2.5 reduction were identified in only four cities. The slower improvement in PM_2.5 mass concentrations in Changde and Yiyang was closely associated with comparatively unfavorable meteorological conditions. Emission reduction measures were identified as the dominant factor responsible for the decrease in PM_2.5 mass concentrations in major cities of Hunan between 2015 and 2023. In 2023, the contribution rates of regional transport to PM_2.5 were calculated to be 56.0% in Changsha, 49.7% in Yongzhou, and 44.6% in Xiangxi Autonomous Prefecture. During regional heavy pollution episodes, external sources were estimated to account for approximately 50%～70% of PM_2.5 in these three cities.更多还原