Status of multielement in water of the river Buriganga, Bangladesh: Aquatic chemistry of metal ions in polluted river water

Abstract

The peripheral rivers of Dhaka city became highly polluted because of industrialization and urbanization to a greater extent in the last few decades. Thus, an attempt has been taken to measure 48 elements in water of the river Buriganga using the ICP-MS method for the first time. Accordingly, it could be the reference values for future research in Bangladesh. Out of the 48 elements, the following metals are given more attention because of their detrimental effects on living organisms and for discussing their aquatic chemistry in polluted water body: Be, Na, Al, Cr, Mn, Fe, Ni, Cu, Zn, Cd, Ba, Hg, Pb, Bi and U. Results revealed that metals’ concentrations in water in the monsoon were less than that of the winter, however, Cr and Fe were found at below detection limits in the winter that is unexpected. Physicochemical parameters of the river water such as pH, dissolved oxygen play vital roles for hydrolysis reactions in the stagnant water body. Hydrolyzed products of metal ions having low values of solubility products ( K sp ), for example, iron(III)hydroxide, chromium(III)hydroxide, phase out through precipitation reactions. This study also detects and quantifies total concentrations of Hg and U in water of the river Buriganga for the first time. PCA and correlation matrix results provided potential sources of the relevant metals. Mechanisms of hydrolysis and precipitation reactions for metal ions in the polluted river water are also discussed.