Unraveling Various Sources of Particulates Matter in Air-Dust Samples Collected from North India Through Elemental Mapping and Concentration Correlation Using Micro-Particle-Induced X-Ray Emission Spectroscopy

Abstract

Particulate matter (PM) found in the air is one of the major sources of pollution and air-borne diseases. Therefore, it is imperative to examine the elemental concentration distribution of the PM to identify the pollutant sources. In this study, it has demonstrated the capabilities of micro-particle-induced X-ray emission (micro-PIXE) spectroscopy in quantitative analysis of air samples collected from the Old Delhi outdoor market and indoor locations in the Panjab University hostel in the winter months. A 2-million electronvolts energetic scanning proton micro-beam (diameter ≈1 µm²) is used in micro-PIXE experiments generating high-resolution elemental maps of different regions of interest (ROI). Micro-PIXE along with the GeoPIXE analysis provides a non-destructive, standard-less, and ng/mg level-sensitive tool for the investigation of elemental distributions and highlighting pixels, which correlates to specific concentration ratios between elements at ROIs, thereby enabling a comprehensive understanding of the source of each elemental particulate. Si, Ca, and K detected in indoor PM suggest the source to soil erosion and crop burning, while high S levels in outdoor PM are primarily associated with coal power plants. Additionally, Sc, Ti, Cr, Mn, and Zn are found in outdoor samples, while indoor locations also contained trace amounts of V, Co, and Cu.