Spatial and temporal variation in magnetic properties of street dust in Lanzhou City, China

Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in Northwest China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain (PSD) magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentrations associated with heavy industry, concentrated residential development, and vehicular traffic suggest mixed contributions of magnetic material from both anthropogenic and natural sources. chi(If) and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic properties in street dust, convenient and economical methods for monitoring street dust pollution.