Evaluation of Elemental Compositions in Road-dust Sample (Khulna city, Bangladesh) by Instrumental Neutron Activation Analysis: Risks Assessment

This study looked at the concentrations of constituent (major, minor, and trace) elements in dust samples collected from different places of Khulna city. The goal of this study is to provide background data of elemental compositions as well as to forecast future aspects of road dust contamination based on elemental abundances. In carrying out the analysis, TRIGA Mark-II research reactor and Gamma-spectrometry based Instrumental Neutron Activation Analysis (INAA) was adopted due to its versatile applicability and non-destructive nature. A total of 30 elements, i.e., Na, Mg, Al, K, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, As, Br, Sb, Rb, Cs, Ba, La, Ce, Sm, Eu, Tb, Dy, Yb, Lu, Hf, Ta, Th and U were determined from thirty dust samples by INAA. Both geochemical and anthropogenic origins of heavy metals (HMs) are considered during the evaluation of compositional trends by the environmental indices such as contamination factor (CF), pollution load index (PLI), geo-accumulation index (Igeo), enrichment factor (EF), Radiological risk indices (RI), and the inter-element correlation analysis. Enrichment of some heavy metals, such as Zn, Rb, La, Ce, Sm, Ba, Dy, Yb, Ta, and Th, indicates minor modification, whereas enrichment of Sb, Br, and Lu indicates severe modification, all of which are anthropogenic in origin (s). Geo-accumulation index shows that Br and Th are moderately contaminated while Cr Mn, Ba, and Br is moderately to heavily contaminated. According to PLI, the majority of the elements are in a state of progressive deterioration. PLI indicates that the majority of the elements has no contamination level. Other elements with values greater than one, such as K-8, K-9, and K-15, are regarded as equally polluted. Chromium has positive correlation with Mg (r=0.128), Sc (r=0.255), Ti (r=0.066), and V (r=0.246) respectively. Thus, Zn, Al, K, Sc, V, Cr, Co, As, Rb, Sb and Cs seem to have similar mineralogical and (or) anthropogenic source(s) of origin. Arsenic shows correlation with most of the elements. Thorium shows significant positive correlation with Na (r=0.106), Mg (r=0.481), Al (r=0.303), K (r=0.091), Sc (r=0.667), etc. whereas the Th has also significant correlation with the heavy REEs. The data reveals that elemental content in the IAEA-Soil-7 and IAEA-SL-1 is almost very close to the certificate value. So, to reduce the heavy metals pollution or to keep the ambient quality of the environment source of anthropogenic heavy metals showed be minimized as far as possible. 

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