Abstract
The Dhaleshwari river which flows near Dhaka, the capital of Bangladesh, is currently under threat due to the recent relocation of the Hazaribagh tannery to the Savar area. This study investigated the physicochemical parameters of water quality along with the heavy metal levels in the Dhaleshwari river and performed a comparative analysis among the peripheral rivers around Dhaka City. Surface water quality parameters such as total dissolved solids (TDS), biochemical oxygen demand (BOD5), and chemical oxygen demand (COD) obtained for the Dhaleshwari river deviated by as much as 90% from World Health Organization (WHO) standards in certain instances due to direct discharge from untreated point sources. Concentrations of toxic metals such as chromium (Cr), cadmium (Cd), and nickel (Ni) were above the Food and Agriculture Organization (FAO) standards for heavy metals in surface waters. Strong correlations among the heavy metals indicated significant linear dependences. Based on the physicochemical and toxicity-based characterization, the river system in Dhaka city can be termed as severely polluted with respect to organic and solids discharge, while ecological risk indices (ERI) indicated disastrously high risk in the Dhaleshwari and Buriganga rivers. The study outcomes emphasize the necessity of frequent investigation while controlling the point and nonpoint urban pollution sources discharging into the peripheral rivers of Dhaka city.
Highlights
Life and health depend on freshwater, which is a vital issue to public health and welfare
Significant contamination was observed at every peripheral river concerning identified parameters such as dissolved oxygen (DO), total dissolved solids (TDS), 5-day biochemical oxygen demand (BOD5 ) and chemical oxygen demand (COD)
Heavy metals pollution was further characterized in this study by ecological risk index (ERI )
Summary
Life and health depend on freshwater, which is a vital issue to public health and welfare. The rivers of Bangladesh were its lifeblood, but pollution is a major national problem, mainly owing to the ever-increasing development activities surrounding riverbank areas that lack appropriate environmental protection [1,2]. Such rivers are vast reservoirs for numerous fish and different aquatic species [3]. The Dhaleshwari receives substantial amounts of municipal waste, surface runoff, unregulated industrial waste, and directly or indirectly treated sewage waste from Saver City [14] These contaminants pollute the river water making it unsuitable for use and harming aquatic lifeforms. Heavy metals in the concerned peripheral r around Dhaka city may be a result of human activities, such as mining and the disp of improperly handled or untreated effluent from industries such as tanneries, ba 698 in agr industries, steel plants, and thermal power plants, as well as pesticides used tural fields and compost containing heavy metals [45]
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