Radiation exposure and health concerns associated with the environmental geochemistry of relatively higher radioactivity in a fresh water basin.

This study was carried out on a negligible anthropogenically impacted Indo-Bangla transboundary river basin (Atrai, Bangladesh) to elicit radionuclides' and elemental distributions. Thirty sediment samples were collected from the Bangladesh portion of the river, and instrumental neutron activation analysis and HPGe γ-Spectrometry techniques were used to determine environmental radionuclides (e.g., 232Th, 226Ra, 40K) and associated elemental concentrations, respectively. Metal concentrations (Sc, V, Fe, Eu, Sm, La, Yb, Ce, Lu, Ta, Hf) were determined to comprehend the genesis of greater radioactivity. Recognizing the mean concentration of absorbed gamma dose rate (158.7 hGyh-1) is 2.88-times more than the recommended value (55 hGyh-1) that describes ionizing radiation concerns regarding potential health risks to the surrounding communities and the houses of native residents, which are constructed by Atrai river sediment. This work will assist relevant policymakers in exploring valuable heavy minerals and provide information regarding radiological health risks from a fluvial system.

Receptor model-based source tracing and risk assessment of elements in sediment of a transboundary Himalayan River.

This study utilized surface sediments from a potentially less polluted transboundary Himalayan River (Brahmaputra: China-India-Bangladesh) to investigate the abundance of 15 geochemically and ecologically significant elements and to predict their sources and ecological consequences. INAA was applied to determine the elemental concentrations. The average abundances (µg.g-1) of Rb (94.20), Cs (4.49), Th (20.31), & U (2.73) were 1.12-2.26 folds elevated than shale. Environmental indices disclosed a pollution status ranging from "uncontaminated to moderately contaminated," with minimal Rb, U, and Th enrichment in the downstream zone. Consensus-based sediment quality guideline (SQG) threshold values suggested that only Cr (60% samples > TEL) may impose rare biological effects. Ecological risk indices suggested "minor to no" possible eco-toxicological risks for the accounted elements (Cr, Co, Mn, Zn, Sb, & As). The positive matrix factorization (PMF) model predicated the predominance of geogenic or crustal contributions (∼72.69%) for Al, K, Na, Ti, Co, Zn, Ba, Cs, As, Rb, Th, & U derived from elemental fractionations, mineral weathering, and bio-geo-chemical mobilization. The relative contributions of anthropogenic sources (∼27.31%; such as the construction of roads, settlement expansion, litter disposal, municipal waste discharge, mining activities, agricultural encroachment, etc.) on elemental distribution were significantly lower. The abundance of Cr and Mn was mainly influenced by anthropogenic sources. This study demonstrated the effectiveness of utilizing geo-environmental guidelines and receptor models in discriminating the natural & anthropogenic origins of metals in the complex riverine sediments of a less anthropogenically affected river.

Indexical and statistical approaches to investigate the integrated origins of elements in the sediment of Teesta River, Bangladesh: sediment quality and ecological risk assessment.

This study investigates ecological consequences from the combined provenance (natural and manmade) of fifteen metal(oid)s (Na, Al, K, Ti, Cr, Mn, Co, Zn, As, Rb, Sb, Cs, Ba, Th, and U) from a major Indo-Bangla transboundary river (Teesta). Instrumental neutron activation analysis has been performed to calculate the elemental concentration for a total of thirty sediment samples which accumulated from the upper, middle and downstream section of the Teesta River. In comparison with the crustal origin Rb, Th, and U were 1.5-2.8 times elevated. Elements from upstream and midstream sediments showed greater spatial variability than those from downstream sediments in terms of Na, Rb, Sb, Th, and U. Statistical approaches suggested the dominance of geogenic sources (Na, K, Al, Ti, Co, and Ba) of elements over anthropogenic sources (Cr and Zn). Alkali feldspar and aluminosilicates release lithophilic minerals into the sediments under the redox condition (U/Th = 0.18). Site-specific ecotoxicological indices advocated that some specific locations are highly hazardous relative to Cr and Zn. From SQG-based guidelines, Cr showed higher potential toxicity in some upstream locations relative to Zn, Mn, and As. In order to attain the knowledge limitation of northern transboundary rivers from Bangladesh, this study of origin and relative environmental impact will be beneficial for policy makers.

Natural and anthropogenic contributions to the elemental compositions and subsequent ecological consequences of a transboundary river's sediments (Punarbhaba, Bangladesh).

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' (Igeo: 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.

Reconciling the geogenic and non-crustal origins of elements in an Indo-Bangla transboundary river, Atrai: Pollution status, sediment quality, and preliminary risk assessment.

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.