Use of environmental magnetic techniques to monitor urban pollution origins in Lanzhou, Northwest China

In this study, samples of dustfall collected monthly or semi-monthly, during 1997–1999, at two representative sites (Kexueguan: KLD and Gaolanxan: GLX) in Lanzhou, a typical industrial city in northwestern China, have been examined using environmental magnetic measurements. A set of magnetic parameters of 50 dustfall samples were analysed. Results demonstrate that Lanzhou City is heavily polluted, with the main pollution sources being anthropogenic activities and natural dust. The former poses a threat to human health all the year, which is different from the general opinion that natural dust is the main source of pollution in summer. This study extended the application of environmental magnetic techniques and can be regarded as a progressive step in exploring urban pollution problems using environmental magnetic techniques. The results from the present study have an important implication on the design of future urban pollution control strategies in Lanzhou, and the method could be applied to other urban cities in the world.