Geochemical aspects and contamination evaluation of major and trace elements in the sediments of Kallada river, southern Western Ghats, India

Abstract

The metal concentrations within the sediments of Kallada River Basin (KRB) draining the south-western flanks of Western Ghats in Kerala, India were examined using pollution indices and statistical analysis in order to inspect the level of contamination. This study includes a systematic analysis of sediment contamination by heavy metals and major oxides of the river Kallada draining the south-western flanks of Western Ghats in Kerala, India during pre-monsoon (May 2019), monsoon (September 2019) and post-monsoon (February 2020) seasons. Sediment samples were taken from 20 locations and the major investigations carried out in the sediment samples include geochemical analysis for the determination of major oxides and minor (trace) elements by using X-ray Fluorescence spectrometer (XRF) and textural analysis for the classification of sediment samples into different categories. To understand the pollution loads in the sediments of the area under study, the heavy metal and major element contamination of the samples were assessed based on crustal enrichment factor (EFc), geo accumulation index (Igeo), contamination factor (CF), degree of contamination (Cdeg) and pollution load index (PLI). From the analysis, it is seen that the coastal sediments of KRB were polluted mainly by Zirconium which exhibits high values in the pre-monsoon season. Among the major elements, Titanium is the only one which manifests slightly higher values in the pre-monsoon period. Based on the textural analysis, it is observed that these sediments predominantly come under sandy loam and loamy silt classifications during the three seasons of study. The concentrations of heavy metals and major ions in the surface sediments of Kallada river were studied to determine the extent of anthropogenic inputs in this tropical river system.