Assessment of Natural Enrichment of Heavy Minerals along Coastal Placers of India: Role of Lake and River Mouth Embayment and Its Implications

Abstract

AbstractThe study delineates the heavy mineral enrichment of beach sands situated along the eastern coastal areas of India, which has been extensively studied for its economic resources. The results obtained are discussed in terms of radioactive element and rare earth element (REE) concentration in the study area. Certain radiological attributes like radium equivalent, absorbed dose rate, and annual effective dose rate values have been presented. In the study area, the average Th/U ratio is found to be about 22. The absorbed dose rate and the thorium concentration show a positive correlation. The average TREE concentration varies between 774 and 1066 ppm with an average of about 6749 ppm. The TREE and thorium concentrations show a good concordance, which is indicative of the fact that these are sourced primarily from the radioactive mineral monazite. This is important as the strategic and critical minerals, specifically the rare earths, are primarily extracted from naturally occurring radioactive minerals like bastnaesite, monazite, and loparite, all of which are primarily radioactive in nature. The study discusses the effect of lacustrine and estuarine environment on the heavy mineral deposition, enhancement along the beach placers, and its implications. The effect of consistent mining along the beach area on the elevated radioelement concentration as well as the beach geomorphology has been discussed. Additionally, the chapter also highlights the disruption caused by the dredging activities to the marine species dwelling along the beach areas.KeywordsEstuarine environmentHeavy mineralsRadioelement analysisRare earth elements