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• Using INAA, elemental abundances of soil samples from ship-breaking yards and an adjacent island were determined. • Heavy minerals from similar geochemical settings were also analyzed for elemental composition by INAA. • Environmental indices, inter-element correlation study and PCA were performed to evaluate the elemental distribution. • Elemental enrichments in ship-breaking yards are higher than UCC while Sandwip island possesses crustal origin. • Acknowledging the anthropogenic input, heavy mineral's distribution is also accountable for elemental distribution. Ship-breaking yards in the world mostly reside along the coastal areas which possess diverse elemental contents due to the presence of heavy minerals. So to explain the heavy elemental enrichment of ship-breaking sites in terms of only anthropogenic contribution is insufficient. While studying elemental distribution of ship-breaking sites, choosing appropriate control sample is vital. To evaluate the elemental distribution in ship-breaking yards of Bangladesh and in an adjacent island (Sandwip), soil samples from each site and some heavy minerals have been analyzed for Na, K, Sc, Cr, Fe, Co, As, Sb, Cs, La, Ce, Sm, Hf and Th abundances by neutron activation analysis. For assessing elemental distribution, pollution load index (PLI), geo-accumulation index and inter-element correlation study were performed. Co-related variation of Cr and Fe (r = 0.651) and chemical compositions of heavy minerals invoke that a significant portion of elemental enrichment in ship-breaking yards seems to have mineralogical origin while the enrichments of As, Sb and Cs (mean abundances: 11.3 ± 3.9, 5.66 ± 4.97 and 10.9 ± 6.6 ppm, respectively) are solely originated from anthropogenic activities (e.g., ship-breaking). On the other hand, elemental distribution of Sandwip (which is sometimes used as control sample) seems to be unaffected by the mainland ship-breaking activities and possesses crustal origin, though a minute fractionation of heavy metals is observed within the east (PLI: 0.84 ± 0.05) and west (PLI: 0.52 ± 0.04) side of the island. For the first time, this study reveals the mineralogical contribution of heavy elements in ship-breaking site and will be decisive for choosing proper elemental abundances of control site. [ABSTRACT FROM AUTHOR]

• We evaluated the geochemical composition of Padma River sediments. • Major, Trace, REEs were determined to infer the provenance, weathering and tectonic. • Sediments were derived from felsic to intermediate source rock. • Sediments were deposited under semi-arid to semi-humid climatic conditions. • Different Himalayan Rivers are compared with Padma River sediments. The major, trace, and rare earth element (REE) compositions of sediments from the Padma River, Bangladesh have been examined using XRF and INAA analysis to determine their geochemical compositions, provenance, climate, weathering intensity and tectonic setting. The Padma River sediments from the region were remarkably comparable, demonstrating elemental depletion and pointing to a low geochemical maturation. Sediment samples are classified as arkose which are considered as chemically immature sediments, deposited under semi-arid to semi-humid climatic conditions due to the weakening of Indian summer monsoon. The low CIA values (48.6–58.8), PIA (48.1–63.4) and Rb/Sr ratios of the river sediments suggest low intensity of chemical weathering in the source area. The Padma River is originated from the Higher Himalaya and the sediments derived from metasediments (Higher Himalayan Crystalline Series) as are evident by major, trace elements discriminate diagram and REE pattern. Most of the sand samples were derived from felsic source rock (granite) whereas some samples are plotted in the intermediate rock types (granodiorite) in the A-CNK-FM and discriminant function diagrams. High LREE enrichment and relatively flat HREE fractionation in chondrite-normalized REE patterns (La N /Yb N = 7.50–13.20) demonstrated felsic source origin. TiO 2 versus Zr plot shows that Padma River sediments have felsic to intermediate provenance. According to Log (K 2 O/Na 2 O) vs. SiO 2 discriminant diagram and La–Th–Sc, Th–Sc–Zr/10 ternary plot, the Padma River sediments were deposited in passive continental margin. The Padma River sediments have been compared with Yarlung Zangbo River (YZR), Brahmaputra-Jamuna River (BJR), Ganges River (GR) and Upper Meghna River (UMR), which results suggest that there is contrast among the sediments of different Himalayan Rivers in relation to provenance, weathering intensity and tectonic setting. [ABSTRACT FROM AUTHOR]

An anthropogenically less affected transboundary river (Punarbhaba, Bangladesh) was studied to detect associated risks from the combined origin(s) of geochemically and toxicologically significant elements in benthic sediments. A total of 30 river bed sediments were analyzed by instrumental neutron activation analysis targeting the 15 chemical elements viz. , Na, Al, K, Ti, Cr, Mn, Co, Zn, As, Rb, Sb, Cs, Ba, Th, and U. Among the estimated elements, the mean abundances (μg/g) of Rb (136), Sb (0.66), Cs (6.66), Th (14.6), and U (3.92) were 1.4–1.7 times higher than the crustal origin. These elements are primarily responsible for the contaminated state of the Punarbhaba River. The studied area is 'moderately polluted' (I geo : 2.01 to 0.02) and possesses 'minor enrichment' (EF: 1.98 to 0.48) in terms of the measured elements. The output of statistical analyses projected that the studied elements are geochemically fractionated in an oxidizing environment (U/Th = 0.44) and mostly originated from felsic sources, thus confirming the mineral is comprised of aluminosilicates and alkali feldspar. However, SQGs-based and ecological risk indices invoked minor (Cr: 6.67%) to no potential ecotoxicological threats for Cr, Mn, Co, Zn, As, and Sb. Nonetheless, altered distribution patterns caused by geogenic activities increased Cr and Zn in the environment which may cause toxicity (Cr: 22–53%, Zn: 35–70%), and pose potential ecological risks, specifically in upstream locations (P-2, P-3, P-5). Further, this study broadened the perspective of sediment deposition from fractionation, fluvial transportation, and weathering events beyond the industrial disintegration of elements, which will aid researchers and policymakers to comprehend combined risks from suspended sediments. [ABSTRACT FROM AUTHOR]

This study has been conducted on an anthropogenically less influenced transboundary river (Atrai: Indo-Bangladesh) to comprehend the inherent geochemistry and identify potential elemental sources. In doing so, across the Bangladeshi portion, 30 river-bed samples were culled and studied by neutron activation analysis to quantify the abundances of 15 geochemically and toxicologically significant elementals (Na, Al, K, Ti, Cr, Mn, Co, Zn, As, Rb, Sb, Cs, Ba, Th, and U). The results revealed that the mean concentrations (μg/g) of Rb (154.6), Cs (7.53), Th (20.90), and U (4.88) were 1.5–2.0 times higher than crustal values. Besides, geo-environmental indices revealed 'uncontaminated to moderately contaminated' pollution status with minor enrichment or contamination for Rb, Th, Sb, U, and Cs, relatively concentrated in the mid-to-downstream zone possessed geogenic and non-crustal origins. The positive matrix factorization and other statistical approaches revealed predominant geogenic enrichment of Na, K, Al, Ti, Zn, Cs, Rb, As, Th, and U from differential mineralogical compositions via weathering, elemental fractionations, and biogeochemical mobilization. Contrariwise, several anthropogenic sources (for Cr, Sb, Co, Mn, Th) were also ascertained in the vicinity of Atari River. However, sediment characterization based on SQG threshold values manifested that Cr and Mn possess rare biological effects on local aquatic organisms. Nevertheless, SQGs-based and ecological risk indices invoked minor to no potential ecotoxicological intimidations for the considered metal(oid)s (Cr, Mn, Co, Zn, As, and Sb). Hence, this study manifested the usefulness of a less anthropogenically affected river to reckon geogenic and non-crustal elemental origins in the compounded riverine sediment. • Elemental abundances in an Indo-Bangla transboundary river sediments are presented. • Mean concentrations of Rb, Cs, Th & U were 1.5–2.0 times higher than crustal values. • Among the divergent sources, fluvial actions-based geogenic origins are predominant. • Mineralogical sorting governs the elemental distributions. • SQGs-based ecotoxicological and ecological indices invoke trivial risks. [ABSTRACT FROM AUTHOR]