Identification of Carbonaceous Species and FTIR Profiling of PM2.5 Aerosols for Source Estimation in Old Delhi Region of India

Identification of sources of coarse mode aerosol particles (PM10) using ATR-FTIR and SEM-EDX spectroscopy over the Himalayan Region of India

This study attempts to examine the morphological, elemental and physical characteristics of PM10 over the Indian Himalayan Region (IHR) using FTIR and scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis. The study aimed at source identification of PM10 by exploring the inorganic ions, organic functional groups, morphology and elemental characteristics. The pollution load of PM10 was estimated as 63 ± 22 μg m-3; 53 ± 16 μg m-3; 67 ± 26 μg m-3 and 55 ± 11 μg m-3 over Mohal-Kullu, Almora, Nainital and Darjeeling, respectively. ATR-FTIR spectrum analysis revealed the existence of inorganic ions (SiO44-, TiO2, SO42-, SO3-, NO3-, NO2-, CO32-, HCO3-, NH4+) and organic functional groups (C-C, C-H, C=C, C≡C, C=O, N-H, C≡N, C=N, O-H, cyclic rings, aromatic compounds and some heterogeneous groups) in PM10 which may arise from geogenic, biogenic and anthropogenic sources. The morphological and elemental characterization was performed by SEM-EDX, inferring for geogenic origin (Al, Na, K, Ca, Mg and Fe) due to the presence of different morphologies (irregular, spherical, cluster, sheet-like solid deposition and columnar). In contrast, particles having biogenic and anthropogenic origins (K, S and Ba) have primarily spherical with few irregular particles at all the study sites. Also, the statistical analysis ANOVA depicts that among all the detected elements, Na, Al, Si, S and K are site-specific in nature as their mean of aw% significantly varied for all the sites. The trajectory analysis revealed that the Uttarakhand, Jammu and Kashmir, the Thar Desert, Himachal Pradesh, Pakistan, Afghanistan, Nepal, Sikkim, the Indo-Gangetic Plain (IGP) and the Bay of Bengal (BoB) contribute to the increased loading of atmospheric pollutants in various locations within the IHR.

Insights into seasonal-variability of SVOCs, morpho-elemental and spectral characteristics of PM2.5 collected at a dense industrial site: Faridabad, Haryana, India

The development-oriented anthropogenic activities have led to intensive increase in emission of various organic pollutants, which contribute considerably to human health risk. In the present study, chemical, physical and spectral characterisation of fine particulate matter (PM_2.5), collected at Faridabad city, in northern India, were examined. Seasonal variation of organic compounds [n-alkanes, polyaromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs)], and potential health risk of Polyaromatic hydrocarbons (PAHs) exposure using toxic equivalency potential (TEQ) approach had been assessed. These showed seasonal average values ranging from 156.4 ± 57.0 ng/m³ to 217.6 ± 72.9 ng/m³, 98.0 ± 21.4 ng/m³ to 177.8 ± 72.8 ng/m³, and 30.9 ± 11.9 ng/m³ to 82.5 ± 29.2 ng/m³, respectively, with the highest value for winter. It is noteworthy that unlike, n-alkanes and PAEs, PAHs were least during spring. The high molecular weight PAHs (BaP, BkF, DahA and IcdP) were found to exhibit higher TEQ values (ranging from 0.7 to 9.7) despite of their lower concentrations. The PAH diagnostic ratio, carbon preference index and total index revealed the enhanced impact of biogenic sources of emissions in comparison to diesel emission sources during winter.

Short-Term Effects: Elemental and Morphological Assessment of Aerosols Over Old Delhi Region, India

This study presents morphological and elemental characteristics of aerosols for the duration January-June, 2021, using Scanning Electron Microscope coupled with Energy Dispersive X-Ray (SEM–EDX). The results revealed that there were numerous spherical particles (D α ≤ 2.5 µm) but did not produced the expected EDX-spectra for elemental constituents. Limited deposited particles were observed which showed definite elemental constitutions. The results show that Cl, S, Al, Ca, K, Fe, Zn, Na, Mg, N, Tb, Ti, Ni, F, Cd, Cu, Mn, P and Cr were the overall determined elements, out of which Cl, S, Al, Ca, K, Fe, Zn, Na and Mg were the major constituents. Variation in particles’ shapes whether definite or irregular, columnar or spherical, flaky or aggregate or crystal-accumulation were attained on the basis of the major constituting element, majorly Ca-rich, S-rich, Cl-rich and Fe-rich. Interestingly, the physical characteristics of the particles varied with variation in elemental composition. All these indicate that there were specific sources contributing toward distinct particle-morphs. Ti, Tb and Cd need more analytical studies for their percent contribution. S, Cl and K contributed the most to the elemental composition as revealed by elemental relative proportion. Atomic weight percent curves for elements were slightly scattered during May. These probably played important role in defining the diversity indices, which was highest for April (2.17 ± 0.12). Particles containing six (P 6) to nine (P 9) elements dominated in this study, and particles containing seven elements (P 7) were generally observed.