Investigation of severe water problem in urban are

Authors: Mst Shamsun Nahar Jing Zhang Akira Ueda Fujishiro Yoshihisa

Publish Date: 2014/04/19

Volume: 36, Issue: 6, Pages: 1079-1094

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Abstract

The present study evaluated water supply geochemistry in Dhaka City Bangladesh to provide detailed trace level subppb water quality data that include major ions low dissolved oxygen DO and toxic trace metals for sustainable development Dhaka Groundwater which almost uniformly meets the World Health Organization guideline has become the preferred source Due to groundwater depletion and an everincreasing need to meet water demands by city residents Dhaka water supply and sewerage authority has initiated the treatment of river water despite the fact that very little is known about the geochemical structure and trace metal content in the Dhaka water supply Major ion composition of water samples was determined and the results used to generate Stiff diagrams The diagrams served to visually compare water from different sources based on units of mass/volume Hydrochemical facies analysis showed supply ground and surface waters are comprised predominately of Ca–Na–Mg–HCO3 and Ca–Na–Mg–HCO3–Cl types Spatial distribution of ions and Na/Cl and Na/SiO2 molar ratio indicated that silicate weathering is the dominant geochemical process Chemical data revealed that toxic Cr metal mobilization is associated with chemical hazards from the leather industry The vulnerability of deep wells to contamination by As is governed by the geometry of induced groundwater flow paths and the geochemical conditions encountered between the shallow and deep regions of the aquifer Quantifying total arsenic As and As from interlocking geochemical cycles Fe Mn may assist in interpreting As dynamics in Dhaka well water The surface source water was hypoxic to anoxic low DO associated with very high concentrations of biological oxygen demands and electrical conductivity compared to industrial and nonindustrial urban processes and standard activity guidelines The results of this study should be applied to future research focused on the potential to improve water quality in urban and surrounding areasThe research was financially supported by a grantinaid for Scientific Research No 19310007 from the Ministry of Education Science Sports and Culture of Japan and by funds from Toyama City Project November 2012–March 2013 Support for Ground Water Evaluation

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