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Evaluating the elemental composition of sediment cores is essential for understanding environmental changes, including depositional variations, soil formation processes, and human influences. Such investigations offer insights into the biological, geochemical, and industrial impacts on sediment quality and the health of marine ecosystems. This study evaluates the pollution levels and their sources along the coast of Karachi, Pakistan, as well as the effects of pollution on human and ecological health. The core sediment's elemental composition was determined by Neutron Activation Analysis. The mean values in mg/kg of the elements are Al (34800), As (11.15), Ba (371), Br (18.40), Ca (118850), Ce (41.43), Co (10.29), Cr (62.41), Cs (5.27), Eu (0.80), Fe (22855), Hf (2.43), K (11210), La (20.84), Lu (0.26), Mg (21750), Mn (416), Na (8350), Nd (18.92), Rb (66.35), Sb (1.04), Sc (8.31), Se (8.23), Sm (3.88), Sn (17.05), Ta (0.77), Th (7.17), U (3.96), V (71.80), Yb (1.28) and Zn (581). Various pollution indices were used to assess the pollution level of these elements in the sediment core. Statistical tools like Pearson's correlation matrix and Factor analysis were utilized for source apportionment of these elements. Source apportionment showed the sources of heavy metals and rare earth elements are Ship breaking facilities, different types of refuse effluents carried by the Malir river into the sea and the geology of the area. Carcinogenic and non-carcinogenic health hazards associated with exposure to toxic metals were also calculated. The ecological risk factor and sediment quality index showed As and Zn may harm the marine environment. In conclusion, this study found that the sediment of Karachi's coast is polluted with high levels of As, Br, Ca, Cr, Sn, and Zn; with As, Cr and Zn posing a threat to the marine ecology as well as human health., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Twenty surface sediment samples were gathered from Chasma Lake, deciding the radionuclides 137 Cs, 226 Ra, 228 Ra, 232 Th, and 40 K and their associated hazard indices. The deliberate radionuclide activities of present research have been contrasted with earlier research, and acquired outcomes in the present study are found below the results in the world. The radiation hazard indices following the presence of natural radionuclides in sediment samples were estimated, and the results assigned the values of all the determined radiological indices found inside the worldwide suggested limits. It was concluded from the current review that the sediment of Chashma Lake is safe for construction and agriculture and does not make radiation dangerous to the nearby local area of the lake., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)