Changing environmental conditions in recent past: Reading through the study of geochemical characteristics, magnetic parameters and sedimentation rate of mudflats, central west coast of India

Abstract

Geochemical (sediment components, major and trace metals), magnetic related parameters (concentration, mineralogy and grain size) and radionuclide (210Pb) analyses were carried out on sediment cores collected from mudflat regions of central west coast of India viz, Kolamb creek (Malvan), Mandovi estuary (Panaji) and Tadri creek (Gokarn), in order to study the variations in sediment characteristics with time. The changes in spatial and temporal (depth) distributions of sediment composition were observed to be mainly controlled by the catchment area geology, geomorphology and anthropogenic activities. The sedimentation rate in the study area varied from 0.13 to 2 cm/yr. The rate was extremely low at the lower half of the cores (0.13-0.31 cm/yr, before approx 1980) as compared to the near surface (1.21-2 cm/yr, after approx 1980) with two clear phases of sedimentation rates. The higher sedimentation rate in the upper portions of the cores was found to correspond to increased deposition of finer sediment components, metals and magnetic minerals which in turn were found to be mainly controlled by geology and/or human activities. The results of the present study reveal variations in sediment properties with time and support the use of geochemical in addition to magnetic susceptibility parameters on mudflats to understand changing environmental conditions of recent past.