Abstract.From 3 April to 16 May 2014, a ground-based mobile laboratory was deployed to measure the optical and microphysical properties of tropospheric aerosols near dust source regions in Wuwei, Zhangye, and Dunhuang along the Hexi Corridor over Northwestern China. This study is novel in that we not only captured natural mineral 5 dust near the Taklimakan and Badain Jaran desert regions but also characterized the properties of anthropogenic soil dust produced by agricultural cultivations (e.g., land planning, ploughing, and disking), especially during floating dust episodes. In this dust campaign, the aerosol scattering (absorption) coefficient ( "# and $# ), single scattering albedo ( ), scattering Ångström exponent (Å sp ), mass scattering efficiency 10 (MSE), and aerosol size distribution were observed at 5-min intervals. The results indicate that large differences were found between the optical and microphysical properties of anthropogenic and natural dust because of floating dust episodes and dust storms. The values of "# , $# and of PM 2.5 measured at 550 nm range from ~37-