Evaluation of seasonal changes in physicochemical and bacteriological parameters of Gomti River in Bangladesh

This study was undertaken to investigate the current pollution status of the Gomti River in Bangladesh by col-lecting water samples from twenty sites along the 120 km stretch of the Gomti River during the rainy (June 2019) and dry (January 2020) seasons. The collected samples were examined for their physicochemical parameters (pH, EC, TDS, TOC, and turbidity), heavy metals, namely chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn), and bacteriological parameters (aerobic heterotrophic bacteria and total coliforms). All the physicochemical parameters obtained were within the recommended guidelines set by the World Health Orga-nization (WHO, 2011). Among the metals, Fe, Ni, and Zn were found to be higher than the recommended guideline values in the dry season. A significant (p < 0.05) positive correlation was found between Cu and Zn indicating that water pollution by these two metals may have originated from common anthropogenic sources. The present study revealed, for the first time, that the river Gomti was considerably polluted with bacterial populations. Identified in the water samples include Shigella spp., Salmonella spp., Escherichia coli, Bacillus licheniformis, Alcaligenes sp., Bacillus subtilis, Klebsiella sp., Bacillus megaterium, Enterobacter sp., and Staphylococcus sp. The presence of Shigella spp., Salmonella spp., and Escherichia coli in the bacterial isolates is certainly a major water quality concern. Aerobic heterotrophic bacteria and total coliform counts were found to be 0.45 x 102 to 1.84 x 104 CFU/mL and 0.05 x 102 to 7.32 x 103 CFU/mL, respectively, which were above the permissible limits of WHO (2011) and are deemed unfit for drinking and domestic purposes, and fish culture. From this study, the priority pollutants of concern in the Gomti River water are Fe, Ni, Zn, aerobic heterotrophic bacteria, and total coliforms. Considering the importance of the Gomti River in the national economy of Bangladesh, appropriate water management along with the Best Management Practices in terrestrial and aquatic ecosystems should be adopted.