Abstract

Suspended sediments samples were collected from ten different locations through the Subansiri River to assess heavy metals contamination such as Fe, Al, Ti, Pb, Zn, Cu, Ni, Co, Mn and Cr. The enrichment factor (EF), contamination factor (CF), geo-accumulation index (I_geo) and pollution load index (PLI) were investigated for evaluate metal contamination in the sediments. The relative distribution of major minerals such as quartz, feldspar (orthoclase and microcline) and kaolinite are determined by calculating extinction co-efficient. The mean concentration exhibits positive correlations among Fe, Al, Ti, Mn, Zn, Pb, Ni, and Co. The relative distributions of the contamination are: Al > Ti > Fe > Mn > Cu > Cr > Zn > Pb > Ni > Co. The investigating factors suggest the significant contamination for Subansiri river sediments are Cu and Pb. The mean concentrations of heavy metals in the sediments were found to be below the geochemical background level of world surface rock average. The elemental correlation is indicative to the metamorphosed pyrophanite (MnTiO₃) deposition. The infrared analysis indicates presence of micro-crystalline quartz particles and weathered metamorphous silicate minerals.

Key words: Heavy metals, suspended sediments, pollution.