Assessment of toxic heavy metals contamination in water collected from different selected sites of the Karnaphuli River, Chattogram, Bangladesh

Abstract

Heavy metal pollution of water arising from anthropogenic sources continue to become a great challenge to human and aquatic population. In Chattogram, conflicts arising from industrials wastages, a growing population without proper sewerage facilities, increase in the number of aging automobiles, fertilizers and pesticides from the agricultural farms in the highlands of Chattogram are the biggest contributors of heavy metals in the water. Since the heavy metals in the environment have continued to increase, there is need to determine their levels in the environment for efficient environment management and hence the need to determine the levels of heavy metals in the water of the Karnaphuli River, Chattogram. In the present study, the heavy metals that were analyzed included Pb, Cr and Ni. There are 10 water samples were collected from different industrial, non-industrial, residential and commercial sites of the Karnaphuli River at dry seasonal period. The collected water samples were immediately preserved at 3º to 4ºC and digested using nitric acid and hydrochloric acid. The digested water samples were analyzed for heavy metals using Atomic Absorption Spectrophotometer (AAS). The data was analyzed using ANOVA with the level of significance (≤ 0.05). From the findings, means of Pb were found below detection limit (BDL) in several points like Patenga sea beach, Shipping Corporation, Chaktai New Bridge, Lamburhat and Rangunai sadar. Within the detection limit the mean concentration of Pb 0.0455±0.00015, 0.131±0.0014, 0.0152±0.00015, 0.0172±0.00014, 0.072±0.0014 mg/L were found in the 15 no. ghat (opposite of KAFCO), Sadarghat jetty, Banglabazar ghat, Firingibazar ghat, Kalurghat industrial areas respectively. The mean levels of Cr were found BDL in the Patenga sea beach, Lamburhat and Rangunai sadar. Within the detection level, concentration of Cr 0.0264±0.00015, 0.0123±0.00015, 0.115±0.00212, 0.0091±0.0003, 0.024±0.0015, 0.0186±0.00014, 0.092±0.0014 mg/L were found in the 15 no. ghat, Sadarghat jetty, Banglabazar ghat, Firingibazar ghat, Kalurghat industrial areas respectively. The means of Ni were found BDL in Patenga sea beach, the 15 no. ghat, Shipping Corporation, Lamburhat and Rangunai sadar. While the mean levels of Ni 0.012±0.003, 0.0072±0.00015, 0.012±0.0015, 0.016±0.0015, 0.050±0.0014 mg/L were found in Sadarghat jetty, Banglabazar ghat, Firingibazar ghat, Kalurghat industrial areas respectively. Ni was found below the permissible limit of WHO standard of drinking water (0.07 mg/L) in all stations during the analysis. However, the highest content of Pb and Cr were found in Sadarghat jetty are 0.131±0.0014 and 0.115±0.00212 mg/L respectively which exceeds the permissible limits of WHO standards (WHO, 1993, 2004 and 2011). This study will convey a strong message for the government body, policy maker and local authority to establish rules and regulation for frequent monitoring of heavy metals in this environment and hence providing a guideline to curb heavy metal pollution in water of the Karnaphuli River including other important rivers in Bangladesh.