Magnetic Properties of Daily Sampled Total Suspended Particulates in Shanghai

Samples of total suspended particulates (TSPs) and <10 μm fractions (PM10) collected daily from in and around two industrial districts in Shanghai, China, during November 1998 have been examined using environmental magnetic measurements. Statistical classifications of the data show that the 11 sampling sites can be classified into four categories of magnetic properties, each expressing a different combination of mainly local dust sources. Changes in meteorological conditions, particularly wind direction, cause daily shifts in particulate types and sources. Interpretation of the magnetic parameters suggests roughly constant proportions of high coercivity (“hematite”) and low coercivity (“magnetite”) mineral phases with a predominance of ferrimagnetic grains in superparamagnetic (SP) and multidomain (MD) + pseudo single domain (PSD) sizes. Negative linear correlations between TSP concentrations and ferrimagnetic concentration parameters suggest that the dominant source of TSPs is weakly magnetic. Mass speci...