Light Rare Earth Elements in Freshly Deposited River Sediments of Ganga Alluvial Plain, Northern India: Geogenic Variability and Anthropogenic Influences

Abstract

ABSTRACT Rare Earth Elements (REE) are the industrial “Vitamins” because of the high-technology based modern uses and their anthropogenic inputs in natural environment, this study mainly focused on Geogenic variability and anthropogenic imprints of Light Rare Earth Elements (LREE), in the recently deposited sediments of the Ganga Alluvial Plain. All the Sediment samples were analyzed by using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). LREE comprises about ~91% of total REE in the Gomati River Sediments and Cerium (300 µg/g) was the most abundant LREE in the bedload sediments. Average LREE concentrations in bedload (170 µg/g) and suspended load (184 µg/g) sediments of the Gomati River were observed higher than the Average Sediments and the World Major Rivers Suspended Sediments and therefore, characterizing the LREE contamination in sediments. This contamination level assessed on the basis of Potential Ecological Risk Assessment (PERI), Contamination Factors (CF), Degree of Contamination (CD) and Geo-accumulation Index (Igeo), the trend of element contamination showed that Sm>La>Pr>Ce>Nd and PERI shows that LREE pose moderate to strong ecological risk, mostly by Pr and Sm in the study area. The spatial and temporal enrichment of LREE in sediments were observed in the Basin since last two decades. This paper mainly highlights the effects of socio-economic development linked modern high-tech processes on LREE contamination in the river sediments and cycling by the sub-tropical fluvial environment of southern Asia; where rivers supply ~30% of the global sediment input to the world’s ocean.