The heavy metal contamination history during ca 1839–2003 AD from Renuka Lake of Lesser Himalaya, Himachal Pradesh, India

The Himalayan lakes are facing an acute problem of survival due to increased concentration of toxic elements in water and sediments. In the present study, the heavy metal contamination history of Renuka Lake during the calendar year (ca) 1839–2003 AD has been performed using 137Cs and 210Pb radionuclide-dated core sediment sample and Inductively-Coupled Plasma Mass Spectrometry (ICP-MS). The concentration of heavy metals (Mn, Cr, Cu, Zn, Ni, Pb and Co) during the said time period is found to have significant variations and suggested a contribution of both natural and anthropogenic factors like surrounding rocks, burning of fossil fuels, sewage and agro-chemicals. The highest concentration of Mn is observed during ca 1847, which is 4–5 times more than ca 2003. The Cr is found to be highest during ca 1962; whereas Cu, Zn, Ni and Pb are observed highest during 1883. Similarly, Co is determined highest during ca 1939. The contamination factor (Cf) indicated low to the considerable level of contamination, whereas the degree of contamination (Cd) revealed a low level of contamination in the lake. However, the geo-accumulation index (Igeo) marked the lake uncontaminated to moderately contaminated and on the other hand, the pollution load index (PLI) showed some signs of contamination in the Renuka Lake. The present study has been compared with other lakes and the background concentration of average shale, upper crust, crustal average and carbonate rocks. Although, keeping in view historical contamination, there is a need of stringent steps for the preservation of the Renuka Lake.