不同季节工业城市大气颗粒物浓度监测与聚类分析

Monitoring and cluster analysis of particulate matters in an industrial city in different seasons

以2015年4月、8月、12月和2016年1月作为4个季节典型月,在福建省三明市第二中学环境监测站进行了4个时段的颗粒物粒径分布监测,采样粒径段为10~10 000 nm。粒径谱分布显示,质量谱4个季节均为3峰,可能存在煤烟型污染的特征;表面积谱秋季为3峰,其余为双峰。爱根核模态颗粒物对总数浓度贡献最大,积聚模态颗粒物对总表面积浓度贡献最大并且是总质量浓度的重要贡献部分。总质量浓度上,春季污染最重,其余3季相差不大,积聚态颗粒物成分具有明显日差异性。春季更容易发生新粒子形成事件。后向轨迹模型结果表明:在春季,主要观测到来向为我国西南地区靠近华中地区,我国西南方向、东南沿海地区气团颗粒物浓度较高;在夏季,主要观测到来向为我国华中地区,气团存在较高的颗粒物浓度;在秋季,观测到来向为我国西南地区以及我国北方,气团颗粒物浓度较高;在冬季,主要观测到来向为我国西南方向和靠近我国东北地区,气团颗粒物浓度相对较高。全年后向轨迹模型显示,三明市附近地区为气团迁移最频繁方向,但迁移速度较慢,其携带了较多的积聚态颗粒物。此外,我国西南方向来向气团,我国西北地区来向气团,我国东南方向的海上来向气团以及我国中部地区来向气团均观测到了较多的积聚态颗粒物。

Particulate matters（PM） size distributions ranging from 10 to 10 000 nm were observed in April, August, December of 2015 and January of 2016 as the representative for the four seasons. The instrument was installed at the No.2 High school of Sanming city, Fujian province.The mass concentration size distributions were triple peaks for the four seasons,which indicated coal-smoke pollution.The size distributions of surface area concentration were triple peaks for autumn and single peak for the others. Particles in Atiken model accounted for the most in number concentration and particles of accumulation model made the most contribution in the surface area concentration and a significant contribution to the mass concentration.Regarding to the total mass concentration, spring was at the forefront, and the others are much the same.The composition of accumulation model was of some difference by the day.New particle formation events tended to happen in spring.Back trajectory cluster analysis indicated that the rather high PM concentrations were observed in spring when air masses came from the southwest near central of China, the southeast coastal area of China and southwest to China. In summer strong PM pollution occurred under the air mass coming from the central area of China. The air masses coming from north to China and the southwest of China were observed heavy PM pollution in autumn. The air masses coming from southwest to China and from near the northeast of China were observed PM pollution in winter. The whole year cluster analysis suggested that the air mass coming from vicinity of Sanming was the most frequent but rather slow one, which showed a number of accumulation model particles. In addition, the air masses coming from southwest to China, the northwest region of China,southeast maritime area and the central district of China were observed rather high concentration of accumulation model as well.