Exploring the alteration of environmental radioactivity in terms of compositional elements of heavy minerals in an anthropogenically affected urban river: Radiological and ecological risks assessment

This study explored the alteration of naturally occurring radioactive materials (NORMs: Ra-226 (approximate to U-238), Th-232, K-40) in an anthropogenically disrupted urban river-basin (Turag, Bangladesh) in terms of constitutional substances (Sc, Ti, V, Fe, La, Ce, Sm, Eu, Tb, Dy, Ho, Yb, Lu, Hf, Ta, W, Th, U) of heavy-minerals. Average activity concentrations of Ra-226 (approximate to U-238), Th-232, and K-40 were 41.5 +/- 12.9, 72.1 +/- 27.1, and 639 +/- 100 Bqkg(-1) , respectively which were relatively higher compared to crustal origin. Sigma REEs, Ta, W, Th, and U were similar to 2 times higher compared to crustal values with Ce and Eu-anomalies. APCS-MLR and PMF receptor models were used to determine the various anthropogenic and/or geogenic sources of NORMs and elements. Layer-wise variations of NORMs and elements were observed to trace the response of sedimentary processes towards the incoming pollution load. Presence of REEs indicates moderate degree of ecological risk to aquatic biota. However, carcinogenic risk (3.84 x 10(-4) Sv(-1)) were significantly higher than threshold limit.