Heavy Metal and Major Ionic Contamination Level in Effluents, Surface and Groundwater of an Urban Industrialised City: A Case Study of Rangpur City, Bangladesh

Abstract

Industrialisation and unplanned urbanisation in different city areas of Bangladesh have greatly distorted the natural water resources. The present study was undertaken to evaluate ionic contamination level including heavy metals in effluents, surface and groundwater of Rangpur city, Bangladesh. Total 29 samples (24 effluents and surface water and 5 groundwater) were collected from the city area and analysed for various physicochemical parameters at the Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh during January to September 2017. The concentrations of heavy metals (Fe, Mn, Cu, Pb, Cr, and Zn) in water samples were measured by an atomic absorption spectrophotometer (AAS). Major cation chemistry showed their dominance in the order of Na+ > Ca2+ > Mg2+ = K+ and Ca2+ > Na+ > Mg2+ > K+ for effluents and surface and groundwater, respectively. Most of the water samples were rated as unsuitable for irrigation due to a higher concentration of CO32-, HCO3- and Cl-, although SO42- was the dominating anion. In the context of heavy metals, the amounts of Mn, Cu and Pb in effluents and surface water were comparatively higher than the standard limits. Enhanced concentration of Mn made 50% effluents and surface water and 80% of groundwater samples unsuitable for irrigation and drinking, respectively. Similarly, 21 effluents and surface water and all groundwater samples of the study area exceeded the freshwater toxicity reference value for Cu as prescribed by the US EPA. The study results concluded that these metals might release into the water as a consequence of natural weathering of soil, discharges from domestic and industrial effluents, and sewage treatment plants. Finally, the study suggested that one should not discharge and/ or dispose of any waste containing chemical substances without proper treatment which may ultimately contaminate both surface and groundwater.