Reconstruction of sedimentation rates based on the chronological framework of Lake Pykara, Tamil Nadu, India.

This work presents a piece of initial information about the estimation of the sedimentation rate for Lake Pykara. In this investigation, a chronological sequence of sediment core was set up dependent on Cs and Pb analysis to study sediment accumulation rates in Lake Pykara. Caesium-137 (Cs) is an artificial radionuclide and is regularly utilized in building up the chronology of lake sediments in the Anthropocene period. The unsupported Pb profile shows a non-exponential decline of Pb activity with sediment depth. Sedimentation rates dependent on global atmospheric nuclear weapon maximum fallout of Cs (1963) bolster the utilization of the consistent rate of Pb supply (CRS) model in core sediments. The geochronology studies of the core were performed using the Cs method, to evaluate the model of time changes in the sediment. The Cs radioactivity was resolved directly by gamma spectrometry and fluctuated from 13.11 ± 1.3 Bq kg for top layers to 1.21 ± 0.1 Bq kg for the bottom of the core. Two trademark peaks of Cs radioactivity identified with the global fallouts after atomic weapons testing and the Chernobyl mishap were observed and used to affirm the Pb dating method. Radioactivity of Pb ranged from 8.00 ± 1.0 to 1.40 ± 0.1 Bq kg. The mean sedimentation rate evaluated from both models was 0.71 ± 0.06 cm year, while the estimated age of Lake Pykara was 514.08 years (Cs) and 521.43 years (Pb), respectively.