Abstract: With the development of economy globalization, rapid urbanization has led to serious effects on ecological environment, which has become a global research hotspot. To analyze aerosol number concentration under different background in mountainous areas of Fujian and the impact of urbanization, particle samples were collected in Gutian (county) of Ningde, Yushan of Nanping (clean region) and Qixingping of Fuzhou (city suburb) during June 2017 by fine dust measuring device Fidas Frog. Consequently, the results show that there were different characteristics of particle number concentrations at different observation points during the observation period: The size of particles in Gutian was mainly less than 400 nm, and the average particle number concentration was 434.37 cm^-3; The average particle number concentration of Yushan as a clean region was the lowest, and the number concentration of accumulation mode (0.18-1.00 μm) particles were equivalent to coarse mode's (>1.00-20.00 μm). The average particle particle number concentration of Qixingping was the highest, and the dominant size of the particle number concentration at Qixingping was located at less than 500 nm; The particle number concentration of Gutian and Yushan were bimodal distribution, and the number concentration spectrum of Qixingping showed a single peak distribution. Through the backward trajectory clustering and the analysis of potential source weight of aerosol number concentration, it is concluded that the south area of the observation point in Gutian is the potential strong source area which is greatly affected by human activities in Gutian County; Potential source regions were located in the southwest of both Yushan and Qixingping; and the accumulation mode aerosols of Qixingping were mainly from coastal cities such as Xiamen, Quanzhou, Putian and Fuzhou.

Key words: aerosol, number concentration, size distribution, HYSPLIT, potential source region