• 关键词：PM_2.5  重污染  太原  区域输送

• 基金项目：环保公益性行业科研专项(No.201309071);国家科技支撑计划(No.2014BAC06B05);国家自然科学基金(No.41401222)

• 程兵芬
• 山西省环境规划院, 太原 030002

• 韩丽
• 山西省环境规划院, 太原 030002

• 程念亮
• 北京市环境保护监测中心, 北京 100048

• 罗锦洪
• 山西省环境规划院, 太原 030002

• 韩锋
• 太原理工大学, 太原 030024

• 摘要：采用数值模拟(CAM_x)与污染物、气象观测资料相结合的方式,对太原市及周边区域2014年10月6-12日一次典型空气重污染过程的大气环境背景、气象条件和形成原因进行了分析.结果表明:2014年10月8-10日太原ρ(PM_2.5)日均值平均为175μg·m^-3,太原城区约1460 km²的国土面积处于重度污染(ρ(PM_2.5)>150μg·m^-3)之下,而京津冀约20×10⁴ km²的国土面积达到重度污染水平;区域稳定的气象条件是形成重污染的主要原因,重污染过程中大气层结稳定,逆温明显(2.14℃/100m)、风速小(1.91 m·s^-1)、湿度大(68.13%)、负变压(-0.74 hPa)、正变温(0.92℃).模拟结果显示,8-10日重污染期间区域输送对太原PM_2.5的贡献率在17%~24%之间,太原市PM_2.5浓度以本地贡献为主;估算的2014年太原城区PM_2.5排放量是其大气环境容量的1.4倍,重污染期间大气环境容量的大幅降低又加剧了空气污染的程度.

• Abstract：In this paper, atmospheric environmental background, weather conditions and formation mechanism of one typical air pollution episode in Taiyuan and the surrounding areas in October 2014 were all investigated by combining pollutants, meteorological observation data and numerical model of CAM_x. Results showed that air pollution episode on October 8~10th was the most serious with daily average PM_2.5 concentration of 175μg·m^-3 in Taiyuan with heavily polluted land area (PM_2.5 >150μg·m^-3) of about 1460 km². Same episode led to about 20×10⁴ km² pollution area in Beijing, Tianjin, and Hebei.The situation was mainly related to the regional meteorological conditions. Stable atmospheric circulation provided favorable environmental field for this heavy air pollution which was characterized by a stagnant atmospheric structure with average wind speed of 1.91 m·s^-1, high relative humidity of 68.13%, large temperature inversion of 2.14℃/100m, negative pressure (-0.74 hPa), and positive temperature (0.92℃) that were unfavorable to the dispersion of air pollutants. Modeling results showed that regional transport contributions to the receptor sites were between 17%~24% during 8~10th October 2014 and the local emission was the dominated source of the surface PM_2.5 in Taiyuan. The estimated PM_2.5 emission was 1.4 times the capacity of the atmospheric environment in Taiyuan city in 2014. Sharply decreased atmospheric environmental capacity intensified the degree of air pollution on October 8~10 th episode.

• Key words：PM_2.5  heavy pollution  Taiyuan  regional transportation

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