Spatial distribution and geochemical baseline concentration of potentially toxic elements from the north-western...

In light of the pristine but fragile ecosystem of the Himalayas, environmental changes due to rapid urbanization, industrialization in the adjacent Indo-Gangetic plain, and climate change, there is need for focused environmental studies in the Himalayan Region to monitor potential environmental changes caused by anthropogenic activities. The baseline geochemical concentration of Potentially Toxic Elements (PTEs) from the stream sediments in the North-Western (NW) Lesser Himalayan region may have control over their mobility/concentration in Indo-Gangetic plain. The rivers of the Indo-Gangetic plains derive their bulk sediment load from the Himalayan region, in which River Ganges and its tributaries are prominent, originating from the Uttarakhand Himalayas. PTEs in sediments of the Himalayan rivers may thus have an extensive harmful effect on the environment of Himalayas, alluvial plains and delta regions due to their toxicity, bioaccumulation and subsequent biomagnifications in living beings. It is thus important to establish the background values of the PTEs on a regional scale, such that any contamination from such sources may be monitored. Only limited studies have been carried out in the area and moreover, no systematic baseline values are available for PTEs from the NW Lesser Himalayan region. Hence, in this study, stream sediments across parts of four river basins of the NW Lesser Himalayas were studied with objectives: (1) determine and establish baseline geochemical background values of PTEs (Cr, Co, Ni, Cu, Pb, V, Zn, As, Hg, Sb, Cd, Se, Tl and Sn); (2) determine the spatial distributions of the PTEs; (3) evaluate the level of PTEs contamination using Enrichment Factor (EF) index. The present study thus establishes the geochemical background values of 14 PTEs for the first time from the NW Lesser Himalayas, Uttarakhand, India.