Status of heavy metals in water and bed sediments of river Gomti - A tributary of the Ganga River, India

The concentrations of cadmium, chromium, copper, iron, lead, manganese, nickel, and zinc in water and bed sediments of river Gomti have been studied in a fairly long stretch of 500 km from Neemsar to Jaunpur. Grab samples of water ( October 2002 - March 2003) and bed sediments ( December 2002 and March 2003) were collected from 10 different locations following the standard methods. The river water and sediment samples were processed and analyzed for heavy metals viz., Cd, Cr, Cu, Fe, Pb, Mn, Ni, and Zn, and using ICP-AES. The heavy metals found in the river water were in the range: Cd (0.0001 - 0.0005 mg/L); Cr (0.0015 - 0.0688 mg/L); Cu ( 0.0013 - 0.0.0043 mg/L); Fe ( 0.0791 - 0.3190 mg/L); Mn(0.0038 - 0.0.0973 mg/L); Ni (0.0066 - 0.011 mg/L); Pb (0.0158 0.0276 mg/L); and Zn (0.0144 - 0.0298 mg/L) respectively. In the sediments the same were found in the range: Cd (0.70 - 7.90 mu g/g); Cr (6.105 - 20.595 mu g/g); Cu (3.735 - 35.68 mu g/g); Fe (5051.485 - 8291.485 mu g/g); Mn (134.915 - 320.45 mu g/g); Ni (13.905 - 37.370 mu g/g); Pb (21.25 - 92.15 mu g/g); and Zn (15.72 - 99.35 mu g/g) of dry weight respectively. Some physico-chemical parameters viz., pH, total solids, total dissolved solids, total suspended solids, dissolved oxygen, biological oxygen demand, chemical oxygen demand, hardness etc. were estimated as these have direct or indirect influence on the incidence, transport and speciation of the heavy metals. Based on the geoaccumulation indices, the Gomti river sediments from Neemsar to Jaunpur are considered to be unpolluted with respect to Cr, Cu, Fe, Mn, and Zn. It is unpolluted to moderately polluted with Pb. In case of Cd it varies from moderately polluted to highly polluted. As far as Ni is concerned the sediment is very highly polluted at Barabanki and Jaunpur D/s. No correlation was found between enrichment factor and geoaccumulation index.