Mineral magnetic and geochemical characterization of the dust and soils around Mejia Thermal Power Plant, West Bengal: Implications to source apportionment.

Characterization of magnetic, morphological, chemical properties and source apportionment of environmental transporters (dust and soil) around Mejia Thermal Power Station (MTPS), West Bengal, India were performed. Rock magnetic measurements combined with scanning electron microscopy (SEM) and X-ray fluorescence (XRF) study distinguish the mineral magnetic phases and identify their environmental implications concerning anthropogenic and natural factors. Findings of this study strengthen detection of anthropogenic magnetite, contributed by traffic and MTPS emission in dust and soil, respectively. However, presence of antiferromagnetic minerals in residential areas confirms their lithogenic and/or pedogenic origin. Existence of a low amount of anthropogenic magnetite in residential areas indicates their onset from fly ash emission due to prevailing north-easterly wind direction. Both soil and dust samples are categorized into three types of ferrimagnetic particles (spherules, irregular, and aggregate) with diverse morphologies and enriched iron concentration. Soil and dust were influenced by quartz, while the average concentrations of potentially toxic elements (PTEs) occurred in decreasing order of Ba>Zr>Cr>V>Sr>Zn>Y>Nb>Pb>Co>Sc>Ga>Ni. Sampling sites near ash pond with higher concentrations of PTEs than those situated at distance suggest that PTEs association with fly ash happened during coal combustion. This explains the observed correlation between magnetite particles and proxies for multiple pollution sources (like MTPS and traffic). It also reveals the necessity for attention when detecting abundance of anthropogenic magnetite using environmental magnetic methods. Thus, the identification of magnetite using environmental magnetic measurements can be used as a tracer for natural loading within anthropogenic background. [ABSTRACT FROM AUTHOR]