Physicochemical characterisation of dust sediment collected by MDCO in surrounding regions of Isfahan city

In recent years, drought, industrial and mining activities have increased the amount of dust deposits in the suburbs of Isfahan. The aim of the present study was to investigate the chemical and physical properties of dust particles in the suburbs of Isfahan and to compare it with previous years. In total, 80 dust sediment samples were collected with Marble Dust Collector (MDCO) at 20 stations across the study area during July 2014 to July 2015. The physicochemical characteristics of the collected samples were analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP_MS), Inductively Coupled Plasma-Optical Emission Spectrometry (ICP_OES), X-Ray Diffraction (XRD), and Scanning Electron Microscope (SEM) methods. The results indicated that the main element composition of dust sediment was Ca, Al, Fe, Mg, Na, K, Ti, Sr, Zn, P, Mn, and Ba. The study also found that concentrations of most heavy metals in the study area were up to five times higher than in previous studies. The northeast part of the study area had the highest amount of dust deposits; However, the highest concentrations of chemicals, especially heavy metals, were observed in the southwest. Considering the highest mean concentration of dust sediments across the study area, the index elements are grouped as Mg, Na, Sr, Mo, Cs and U in the north-east, Mn, Cr, Zr, Pb, Cd and V in the south-west, Hg in the north-western, and Ca in the south-east. According to the mineralogy and morphology analysis, dust sediments in north-east part contained Quartz, Calcite and Gypsum, coated with Dolomite and Muscovite. Angular and semi-rounded morphologies of dust sediment indicate their local source contribution.