Assessment of influence of heavy metal, organochlorine pesticide, and bacterial presence on water quality of Gomti river, India

Sustainable ecosystem is of essence to the river for its survival and maintenance of ecological balance. Gomti river, a groundwater-fed tributary of the Holy Ganges, is the lifeline of the middle Indo-Gangetic Plains. Screening of river pollutants for river cleanup is a challenging task. To this end, 20 km Lucknow stretch of Gomti was sampled at 5 locations for physicochemical–bacteriological analysis. Collected samples were analyzed for pH, TA, turbidity, DO, BOD, TH, COD, TDS, fecal coliform, and E. coli. Analytical instruments AAS and GC-ECD were used for heavy metal and organochlorine pesticide analysis. DO was 3.2 ± 0.3 to 7.4 ± 0.4 (avg 5 ± 1.8) mg/l, BOD was 10.6 ± 0.5 to 41 ± 1.7 (avg 22.9 ± 13.3) mg/l, while COD was 26.6 ± 4.6 to 93.5 ± 4.6 (avg 56 ± 31.3) mg/l. WQI values gradually increased from S1 (56.7) to S5 (181.8) which denotes a significant deterioration of water quality downstream of the river. Cd, Mn, Fe, Pb, and Cr had increment of 64, 18, 12, 6, and 2 fold, respectively, as compared to individual BIS:10500 standards. Among the OCPs, concentrations were in the order: aldrin > pp-DDT > β-HCH > γ-HCH > α-endosulfan > pp-DDE > α-HCH. Statistically strong positive correlation (r > 0.95 at 0.01) was observed among physicochemical parameters. Furthermore, bacterial species Aeromonas salmonicida subsp. Achromogenes, Aeromonas salmonicida strain A527, Aeromonas encheleia strain NCTC12917, and Aeromonas salmonicida strain ATCC33658 were identified by 16S rRNA gene amplification and molecular phylogenetic analysis. The study indicated heavy contamination of the river with organic and inorganic pollutants owing to mixing of untreated sewage, industrial effluents, and associated toxicants along with pathogenic bacteria which are a barrier to the harmony of aquatic life. Graphical abstract