Author(s)

Mst Shamsun Nahar^1*, Md. Nurunnabi Mondal², Mohammad Ferdous Hasan³, Jannatun Shahin⁴, Md. Ariful Haque⁵, Atsushi Nishii¹

¹Department of Environmental Analysis, Earth Consultant Co. Ltd., Toyama, Japan.
²Department of Fisheries Management, Faculty of Fisheries, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh.
³Department of Computer Science and Engineering, Tokyo University of Technology, Tokyo, Japan.
⁴Department of Fisheries, Ministry of Fisheries and Livestock, Dhaka, Bangladesh.
⁵Department of Oceanography, University of Dhaka, Dhaka, Bangladesh.

This research investigated the water qualities and distribution of heavy metals concentration in rain, river, ground and supply waters, providing a baseline in Dhaka Urban, Bangladesh, against which future changes can be assessed. The water sample was collected in the Dhaka central zone, from a site located in the center of the Bengal Delta plain between 23°40'N - 23°54'N latitude and 90°20'E - 90°31'E longitude which is affected by environmental pollution for high traffic, industrialization and because of its rapid urbanization. The water samples were analyzed for heavy metals by Inductively Coupled Plasma Mass-Spectrometry (ICP-MS), major ions by Ion-Chromatography (IC), water tracer (δ¹⁸O and δD) by Mass-Spectrometry (MS), following the standard techniques. Elevated EC and chloride (Cl^-) are the markers of wastewater, providing an indication of impacts in the Buriganga River water. The relative concentrations of major ions were presented in the form of Piper and Stiff Diagram. The color maps were constructed to present ions distribution over the areas. The stream reaches directly in Buriganga River from leather industries which may reflect the naturally low dissolved oxygen (DO) 0.3 - 3.5 (mg/L), where aquatic life can’t survive. Uranium contents U²³⁸ (0.1 - 2.7 μg/L) are not exceeding the WHO guideline level of 30 μg·L^-1. Significant portion of Cs¹³³ (0.05 - 0.32 μg/L), Se (0.03 - 0.12 μg/L), B (50 - 2986 μg/L) and Cr (0.55 - 18.59 μg/L), could be increased in Buriganga River areas by the effect of local sources like leather industry. Zn (10 - 1466 μg/L) in the Dhaka Rain and Pb (4 - 6 μg/L) in Dhaka Water occur mainly in industrial and the high traffic areas, respectively. The isotopic (δ¹⁸O/δD) distributions have been evaluated for understanding of contaminant sources in groundwater and wastewater recharge from Buriganga River to adjacent depleted groundwater system. The results indicate that the magnitude of pollution problem depends on the size of the area affected, rapid groundwater depletion, polluted river water recharge and the type of the pollutant involved and finally that makes the complex in Dhaka Geochemical pattern.

Uranium-238, Dhaka Urban, δ18O, Geochemistry, Buriganga River, Cesium

Nahar, M. , Mondal, M. , Hasan, M. , Shahin, J. , Haque, M. and Nishii, A. (2017) Geochemical Color Maps of the Dhaka Water, Bangladesh—New Map Presentations for Toxic Metals and Isotopes. Journal of Geoscience and Environment Protection, 5, 134-151. doi: 10.4236/gep.2017.53010.