Studies of Toxic and Heavy Metals Pollution of Karnafuli River and Its Impacts on Environment of Chittagong, Bangladesh

The present study was conducted to assess the toxic and heavy metals concentrations in water at different locations of the Karnafuli River. The assessment was carried out for various toxic and heavy metals concentrations in three seasons during pre-monsoon, monsoon and post-monsoon seasons for various continuous monitoring during the hydrological year 2014-2016. The statistical methods of sampling were used for collecting samples from different points of Karnafuli River. The samples were collected in high and low tide conditions. Since the water quality is expected to vary with season, multiple samples were collected at an interval of 2 to 3 weeks. The work has been carried out by traveling to the sampling sites for collection required water samples and the estimation of water discharge and determination of basic parameters of the sites. Samples were preserved with suitable preservation and transported to the laboratory. Standard methods were followed to determine the toxic and heavy metals concentrations. In the present study, seasonal variation hydrochemical character of Karnafuli River water has been evaluated and assessed the suitability of water for human & animal′s consumption, irrigation and industrial purposes. The study stress to access various essential heavy metals concentrations including  arsenic, cadmium, cobalt, chromium, copper, iron, lead, manganese, nickel and zinc. Toxic and heavy metals concentrations were studied such as As, Cd, Co, Cr, Cu, Fe, Pb, Mn, Ni and Zn were found in variation from (0.01 - 0.05)-mgL-1, (0.12 - 0.75)-mgL-1, (0.01 - 0.013)-mgL-1, (0.051 -0.063)-mgL-1, (0.012 - 0.25)-mgL-1,(0.006 - 4.844)-mgL-1, (0.036 - 0.07)-mgL-1, (0.015 - 0.845)-mgL-1, (0.02 - 0.097)-mgL-1, (0.013 - 0.8)-mgL-1 respectively. The average of maximum heavy metals concentrations studied was found higher than those of the World Health Organization (WHO), Department of Environment (DoE) and BSTI drinking water guidelines. The laboratory finding of water quality parameters were also compared with the recommended values set by DoE and BSTI. From Pearson correlation program, significant positive and negative correlations were found in different parameters. These assessment data indicated that the water quality of Karnafuli River are highly polluted which are continuously polluting the coastal zone, sea and the Halda river of Chittagong. The environmental impact of water quality of Karnafuli River has been discussed. A strategic water quality management plan has been proposed.