[A-AS09] Atmospheric Chemistry

[AAS09-P10] Morphological Features and Origins of PM₁₀ in the Eastern Himalayan Region of India: A Mineralogical Investigation

*Sakshi Gupta¹, Shobhna Shankar², Abhijeet Chatterjee³, Ranu Gadi², Sudhir Kumar Sharma¹ (1.CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi-110012, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India., 2.Indira Gandhi Delhi Technical University for Women, Kashmere Gate, New Delhi-110006, India., 3.Environmental Sciences Section, Bose Institute, EN Block, Sector-V, Saltlake, Kolkata-700091, India.)

Keywords:PM10, Mineralogy, Morphology, Sources, Himalayan region

This study explores the morphological and mineralogical attributes of coarse mode particulate matter (coarse mode particles are larger than 2.5 and less than 10 microns, by definition) (PM₁₀) over a high-altitude Himalayan station, Darjeeling in eastern Himalayas (27.01°N, 88.15°E, 2200 m above mean sea level). During the course of January to December 2019, a comprehensive analysis was conducted using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) techniques. The XRD and FTIR methodologies were employed to identify crystalline phases, revealing the presence of minerals such as illite, kaolinite, montmorillonite, quartz, dolomite, calcite, magnetite, hematite, gypsum, halite, mascagnite, augite, albite, wollastonite, calcium aluminium silicate hydrate (C-A-S-H), imogolite, and chrysotile in the PM₁₀ samples. SEM-EDX analysis affirmed the major elemental composition, with the relative abundances of Si > Al > Na > K > Ca > Fe > S > Ba > Mg > Zn > Ti in PM₁₀, indicative of diverse mineral formations. Observable variations in elemental composition highlight Si and Al as predominant elements, suggesting geogenic sources, such as rock weathering, for minerals like quartz, dolomite, albite, augite, etc., containing Al, Si, Na, Ca, Mg, K, and Fe. Conversely, minerals like illite, montmorillonite, mascagnite, hematite, calcium aluminium silicate, etc., exhibiting dominance of elements like K, Si, K, Ca, Fe, S, Ba, Zn, and Ti are associated with anthropogenic sources such as demolition, construction, combustion, and vehicular emissions. These findings contribute significantly to an enhanced comprehension of air quality, environmental conditions, and potential health implications in the eastern Himalayan region.