Study on Mongla and Rupsha River Sediments for Potential Heavy Elemental Contamination by Instrumental Neutron Activation Analysis

Abstract

This study has been carried out on the concentrations of constituent major, minor and trace like elements present in sediment samples collected from different parts of Mongla River and Rupsha River during the month of September to October, 2016. The objective of this study is to provide the base-line data for the elemental contents of sediments for environmental monitoring. In carrying out the analysis, TRIGA Mark-II research reactor based Instrumental Neutron Activation Analysis (INAA) was adopted due to its versatile applicability and non-destructive nature. A total of 28 elements, i.e., Na, Mg, Al, K, Ca, Sc, Cr, Mn, Fe, Co, Zn, Ga, As, Br, Sb, Cs, Ba, Ce, Nd, Eu, Tb, Dy, Ho, Tm, Yb, Lu, Ta, and W have been determined from eleven sediment samples collected from Mongla and Rupsha Rivers. In this experiment, NIST-1633b (coal fly ash) has used as the standard and the analytical accuracy and precisions have been ensured by the repeated (n = 4) analysis of IAEA-Soil-7. 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) and enrichment factors (EF). Along with the environmental characterization, experimental data are also compared to those of coal fly ash (NIST-1633b), which will be one of the major by product of the coal based power plant in Bangladesh. The data reveals that elemental contents in the coal-fly-ash are almost double (reflected by the NIST- 1633b/mean soil abundances) than those of the elemental abundances in sediments of this study. The industrial effluents and municipal waste discharging into the Mongla and Rupsha Rivers are the main possible sources of the elemental pollution of the river. The results of this study suggest for future monitoring of the elemental pollution as well as possible threat to the biota of the river. Moreover, this study will be helpful to set a picture of contamination of the Mongla and Rupsha Rivers and the nearby Sundarban Mangrove forest area.