Elevated levels of environmental radioactivity in fluvial sediment: origin and health risk assessment.

To study the geogenic processes of naturally occurring radioactive materials' (NORMs') distribution, a transboundary Himalayan river (Punarbhaba) is chosen due to its trivial anthropogenic impacts. In explaining the genesis of radionuclides, transition elements (Sc, Ti, V, and Fe), rare-earth-elements (REEs: La, Eu, Ce, Yb, Sm, and Lu), Ta, Hf, Th, and U were analysed in 30 riverbed sediments collected from the Bangladeshi portion of the river. Elemental abundances and NORMs' activity were measured by neutron activation analysis and HPGe-gamma-spectrometry, respectively. Averagen=30 radioactivity concentrations of 226Ra (68.4 Bq kg-1), 232Th (85.7 Bq kg-1), and 40K (918 Bq kg-1) were 2.0-2.3-fold higher, which show elevated results compared to the corresponding world mean values. Additionally, mean-REE abundances were 1.02-1.38-times higher than those of crustal origin. Elevated (relative to earth-crust) ratios of Th/U (=3.95 ± 1.84) and 232Th/40K and statistical demonstrations invoke Th-dominant heavy minerals, indicating the role of kaolinite clay mineral abundance/granitic presence. However, Th/Yb, La/V, Hf/Sc, and Th/Sc ratios reveal the presence of felsic abundances, hydrodynamic sorting, and recycling of sedimentary minerals. Geo-environmental indices demonstrated the enrichment of chemical elements in heavy minerals, whereas radiological indices presented ionizing radiation concerns, e.g., the average absorbed-gamma-dose rate (123.1 nGy h-1) was 2.24-fold higher compared to the threshold value which might cause chronic health impacts depending on the degree of exposure. The mean excess lifetime cancer risk value for carcinogen exposure was 5.29 × 10-4 S v-1, which is ∼2-times greater than the suggested threshold. Therefore, plausible extraction of heavy minerals and using residues as building materials can alleviate the two-reconciling problems: (1) radiological risk management and (2) fluvial navigability.

Fractionation of environmental radioactivity in road dust from a megacity: external and internal health risks.

Naturally occurring radioactive materials (NORMs: 232Th, 226Ra, 40K) can reach our respiratory system by breathing of road dust which can cause severe health risks. Targeting the pioneering consideration of health risks from the NORMs in road dust, this work reveals the radioactivity abundances of NORMs in road dust from a megacity (Dhaka) of a developing country (Bangladesh). Bulk chemical compositions of U, Th, and K obtained from neutron activation analysis were converted to the equivalent radioactivities. Radioactivity concentrations of 226Ra, 232Th, and 40K in road dust ranged from 60-106, 110-159, and 488-709 Bq kg-1 with an average of 84.4 ± 13.1, 126 ± 11, and 549 ± 48 Bq kg-1, respectively. Estimated 226Ra, 232Th, and 40K radioactivities were, respectively, 1.7-3.0-, 3.7-5.3-, and 1.2-1.8-folds greater than the affiliated world average values. Mechanistic pathway of NORMs' enrichment and fractionation relative to the major origin (pedosphere) were evaluated concerning the water logging, relative solubility-controlled leaching and translocation, climatic conditions, and aerodynamic fractionations (dry and wet atmospheric depositions). Computation of customary radiological risk indices invokes health risks. Noticing the ingress of NOMR-holding dust into the human respiratory system along with the associated ionizing radiations, the computed radiological indices represent only the least probable health hazards. Nevertheless, in real situations, α-particles from the radioactive decay products of 232Th and 238U can create acute radiation damages of respiratory system. Policymakers should emphasize on limiting the dust particle evolution, and public awareness is required to alleviate the health risks.

Fluvial responses towards the tannery effluent: Tracing the anthropogenic foot-prints.

Tannery-effluent is one of the top-ranked hazardous waste which is generally discharged into the river. To study the fluvial response toward the tannery-effluents and to trace anthropogenic foot-prints in the fluvial-system, a suite of systematically collected sediment and water samples were analyzed for radioactive (226Ra, 232Th, and 40K) and non-radioactive elements (Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Sb, Hg, and Pb). Neutron activation analysis and atomic absorption spectroscopy were used for elemental analysis, whereas HPGe-gamma-detector was used for measuring the primordial-radionuclides. Ranges of Cr-abundances in sediment and water were 63-4373 µg.g-1 and 15.6-52.2 µg.L-1, respectively which were ∼4-14 times higher than the geological background. Radioactivity concentrations of 226Ra, 232Th, and 40K ranged from 17.7-48.5, 36.1-81.6, and 687-1041 Bq.kg-1, respectively which were significantly depleted in effluent discharge point. Hence, primordial-radionuclides were used as natural tracers for tracing anthropogenic foot-prints which were explained in terms of dilution effect, redox environment and differential geo-environmental events/characteristics. From statistical-approaches and geochemical reasoning, elemental sources and responses in fluvial system were explored. Surprisingly, ecological & radiological risks were reduced while sediment quality guideline-based ecotoxicity & water-mediated health risks were increased by the incorporation of tannery effluents. This study describes the sedimentary response toward the received tannery effluents which is particularly explored by the primordial radionuclides.

Corrigendum to "Tectonic setting, provenance, depositional, and paleo-climatic conditions of the late quaternary subcrop sediments of the southeastern coastal region of the Bengal basin".

[This corrects the article DOI: 10.1016/j.heliyon.2023.e12998.].

An analytical investigation of critical factors to prioritize coalfields for Underground Coal Gasification - Bangladesh case.

In recent decades, many countries have shown a growing interest in Underground Coal Gasification (UCG) as a potential clean and environmental-friendly means of harnessing coal energy for power generation, and production of hydrogen, diesel fuel, etc. While Bangladesh may have good UCG potential that can be utilized to alleviate the country's current energy scarcity, this avenue has remained completely untapped up to now. In this work, the possibility of UCG implementation in five (05) indigenous discovered coalfields of the country was evaluated for the first time by using the preference selection index (PSI) method. This novel technique was considered to prioritize coalfields for gauging UCG potential. The PSI method is chosen over numerous traditional multi-criteria decision-making (MCDM) techniques, because it selects the best alternative from given alternatives without deciding the relative importance between attributes. The study indicated Jamalganj coalfield as the most suitable for implementing the UCG technique with a 93.6% potential. The second priority is Khalaspir coalfield with around 70.0% prospect and the other three coalfields - Dighipara (64.7%), Barapukuria (63.5%), and Phulbari (58.3%) may have UCG suitability in decreasing order of preference. The deduction is expected to assist the cogitation of energy-sector researchers and facilitate the decision-making of relevant authorities, policy makers, planners, and entrepreneurs.

Receptor model-based source-specific health risks of toxic metal(loid)s in coal basin-induced agricultural soil in northwest Bangladesh.

Toxic metal(loid)s (TMLs) in agricultural soils cause detrimental effects on ecosystem and human health. Therefore, source-specific health risk apportionment is very crucial for the prevention and control of TMLs in agricultural soils. In this study, 149 surface soil samples were taken from a coal mining region in northwest Bangladesh and analyzed for 12 TMLs (Pb, Cd, Ni, Cr, Mn, Fe, Co, Zn, Cu, As, Se, and Hg). Positive matrix factorization (PMF) and absolute principal component score-multiple linear regression (APCS-MLR) receptor models were employed to quantify the pollution sources of soil TMLs. Both models identified five possible sources of pollution: agrochemical practice, industrial emissions, coal-power-plant, geogenic source, and atmospheric deposition, while the contribution rates of each source were calculated as 28.2%, 17.2%, 19.3%, 19% and 16.3% in APCS-MLR, 22.2%, 13.4%, 24.3%, 15.1% and 25.1% in PMF, respectively. Agrochemical practice was the major source of non-carcinogenic risk (NCR) (adults: 32.37%, children: 31.54%), while atmospheric deposition was the highest source of carcinogenic risk (CR) (adults: 48.83%, children: 50.11%). NCR and CR values for adults were slightly higher than for children. However, the trends in NCR and CR between children and adults were similar. As a result, among the sources of pollution, agrochemical practices and atmospheric deposition have been identified as the primary sources of soil TMLs, so prevention and control strategies should be applied primarily for these pollution sources in order to protect human health.

Human exposures to multiple water sources in the southwestern coastal region of Bangladesh: water quality, pollution sources, and preliminary health risks appraisals.

The coastal areas of Bangladesh have poor accessibility to fresh drinking water and the groundwater is not suitable for drinking, cooking, and other domestic uses due to high levels of salinity and potentially toxic elements. The current study focuses on understanding of the distribution of some physicochemical parameters (temperature, pH, EC, TDS, and salinity) and chemical elements (Fe, Mn, Zn, Ca, Mg, Na, K, Cu, Co, Pb, As, Cr, Cd, and Ni) with health perspective in drinking water from the southwestern coastal area of Bangladesh. The physicochemical properties of the water samples were examined with a multiparameter meter, while the elemental concentrations were analyzed using atomic absorption spectrometer. Water quality index (WQI) and irrigation indices were utilized to determine the drinking water quality and irrigation feasibility, respectively, whereas hazard quotients (HQs) and hazard index (HI) were used to assess the probable pathways and the associated potential risks to human health. The concentrations of some toxic elements in measured samples were relatively higher compared to drinking water guidelines, indicating that ground and surface water are not apt for drinking and/or domestic uses. The multivariate statistical approaches linked the source of the pollutants in the studied water body mostly to the geogenic origin including saline water intrusion. WQI values ranged from 18 to 430, reflecting excellent to unsuitable categories of water quality. The assessment of human health risks due to exposure to contaminated water demonstrated both carcinogenic and non-carcinogenic health risks in the exposed residents of the study area. Therefore, appropriate long-term coastal area management strategies should be adopted in the study region for environmental sustainability. The findings of this research will be supportive in understanding the actual situation of fresh drinking water in the area for policymakers, planners, and environmentalists to take effective necessary measures to ensure safe drinking water in the study area.

Perception and legacy of soil chromium and lead contamination in an operational small-scale coal mining community.

Operational small-scale coal mining (OSCM) is one of the most significant sources of chromium (Cr) and lead (Pb) pollution in Bangladesh. Attempts to minimize or lessen the use of Cr and Pb in OSCM have shown unsatisfactory results, mainly because they need to address the sociotechnical complexity of pollution concerns in OSCM. This research adopts a multidisciplinary, sociotechnical approach to addressing Cr and Pb problems, coupling soil sampling for Cr and Pb with questionnaires of miners' and inhabitants' perceptions of pollution and its distribution. The study was undertaken in the Barapukuria coal basin in northwest Bangladesh. Except for mining areas (average of 49.80 ± 27.25 mg/kg), Cr levels in soils exceeded the world average in the periphery (73.34 ± 24.39 mg/kg, ~ 1.2 times) and residential areas (88.85 ± 35.87 mg/kg, 1.5 times the world standard of 59.5 mg/kg). Pb levels in soils exceeded national and global averages in mining (53.56 ± 37.62 mg/kg, ~ 1.9 times), periphery (35.05 ± 21.77 mg/kg, ~ 1.3 times), and residential areas (32.14 ± 26.59 mg/kg, ~ 1.2 times) when compared to Bangladesh and global standards of 20 and 27 mg/kg. Pb levels were highest in mining areas, while Cr concentrations were highest in residential areas. The questionnaire findings indicated that miners and inhabitants did not correctly assume that the highest levels of Cr and Pb pollution would be found in these areas. Among all respondents, 54% are unaware of the health impacts of prolonged Cr and Pb exposure. They face respiratory problems (38.6%), skin diseases (32.7%), and other health issues. A large number of people (66.6%) agreed with the fact that Cr and Pb contamination has an impact on drinking water. Cr and Pb pollution has caused 40% crop loss and a 36% decrease in productivity in the agricultural sector. However, respondents underestimated the level of Cr pollution in mining areas, and most assumed that only individuals working directly with mines were impacted by the Cr and Pb content. Participants also rated the reduction of Cr and Pb contamination as of low importance. There is less awareness of Cr and Pb pollution among miners and inhabitants. Sincere efforts to reduce Cr and Pb pollution will likely be met with extra attention and hostility.

Risk assessment and source apportionment for metals in sediments of Kaptai Lake in Bangladesh using individual and synergistic indices and a receptor model.

Metal enrichment in lake sediments originating from multiple sources can threaten both the aquatic ecosystem and human health. Therefore, assessment of the eco-environmental risks and potential sources of metals in the sediments is essential for effective lake management. Here, we analyzed the sediment metal contents of Kaptai Lake, the largest lake in Bangladesh for the first time with this study. The results indicated that only Cr and Ni contents among the metals studied exceeded the probable effect concentrations (PEC) at 25.42 % and 55.93 % of the sampling stations, respectively. All metals at most sampling stations showed low contamination and low ecological risk based on the individual indices (geoaccumulation index, contamination factor, ecological risk factor, enrichment factor and modified hazard quotient). There was no significant risk from the combined metals in the sediments of the lake according to the synergistic indices (toxic risk index, Nemerow risk index, ecological risk index, Nemerow pollution index and pollution load index). Organic matter and silt were significant sediment parameters that favored the accumulation of Cr, Fe, Cu, Pb and Mn. In the absolute principle component scores-multiple linear regression model (APCS-MLR), five potential sources of metals were identified in the sediments: Zn, Mn, Co and Cd mainly from natural sources and to a lesser extent from agricultural and aquacultural activities, Ni, Cr and Fe from parent materials, Pb and Cu mainly from natural sources and to a lesser extent from vehicle emissions, Hg and U from lithogenic sources, and As from natural sources. This study will improve our knowledge of the sedimentary metal contents of Kaptai Lake and provide helpful information for developing effective lake management and pollution control strategies.

Tectonic setting, provenance, depositional, and paleo-climatic conditions of the late quaternary subcrop sediments of the southeastern coastal region of the Bengal basin.

This is a systematic attempt to depict the genetic evolution of the Late Quaternary sediments of the southeastern (SE) coastal region of the Bengal basin regarding paleotectonic settings, sedimentation, provenance, paleo-climatic conditions, weathering condition and age. The study has considered multiple attributes such as, lithology/lithofacies, sedimentary features/records, major oxides, clay minerals, foraminifera, and radiocarbon dating. The lithological characters along with associated clay minerals confirmed that a Pleistocene paleosol horizon (over-bank deposits) of warm-humid nature is commonly encountered immediately on top of the sub-crop bed-rock in the area overlain by Holocene fluvio-marine sediments of the same nature. The lithofacies, foraminiferal assemblages, and sedimentary structures of the analyzed samples suggest that the Holocene sediments have been presumably deposited in a fluvio-marine condition after the Last Glacial Maximum (LGM) due to the transgression of the sea. Geochemically, the sediments are classified as Fe-rich shale, shale, and wake and primarily intermediate to felsic orogen provenance. These are possibly derived from intense weathered sources from the upheaval of Himalayan ranges of both active continental margin and Island Arc paleotectonic setting. The plot of the Index of Compositional Variability versus the Chemical Index of Alteration indicates that the sediments seemingly experienced intense weathering associated with warm and humid climatic conditions. The sedimentation rates of the area vary from place to place and layer to layer due to the complex delta-building process. The reconstructed Relative Sea Level Curve reveals that presumably, the sea level has reached its current position after the LGM. The deduction possibly will facilitate the (1) reconstruction of Late Quaternary coastal evolution after LGM, (2) support for future urbanization, land use plans, etc., and (3) also be helpful for international researchers to understand the possible sources of sediment input in the area from the complex interplay of the Indian-, Eurasian- and Myanmar-plates.

Environmental geochemistry of higher radioactivity in a transboundary Himalayan river sediment (Brahmaputra, Bangladesh): potential radiation exposure and health risks.

This study of a downstream segment (Brahmaputra, Bangladesh) of one of the longest transboundary (China-India-Bangladesh) Himalayan rivers reveals elevated radioactivity compared to other freshwater basins across the world. Naturally occurring radioactive nuclides (226Ra, 232Th, and 40K) and metal contents (transition metals, Fe, Ti, Sc, and V; rare earth elements, La, Ce, Eu, Sm, Dy, Yb, and Lu; high field strength elements, Ta and Hf; and actinides, Th and U) in thirty sediment samples were measured by HPGe γ-spectrophotometry and research reactor-based neutron activation analysis, respectively. We systematically investigated the mechanism of the deposition of higher radioactivity concentrations and rare earth elements (REEs) associated with heavy minerals (HMs) and photomicrograph-based mineralogical analysis. The results show that total REEs (∑REE) and Ta, Hf, U, and Th are generally 1.5- to 3.0-fold elevated compared to crustal values associated with -δEu and -δCe anomalies, suggesting a felsic source provenance. The enrichment of light REEs (×1.5 upper continental crust (UCC)) and Th (×1.9 UCC), besides Th/U (=7.74 ± 2.35) and 232Th/40K ratios, along with the micrographic and statistical approaches, revealed the elevated presence of HMs. Fluvial suspended sedimentary transportation (from upstream) followed by mineralogical recycling and sorting enriched the HM depositions in this basin. Bivariate plots, including La/Th-Hf, La/Th-Th/Yb, and La/V-Th/Yb, revealed significant contributions of felsic source rock compared to mafic sources. The assessment of radiological hazards demonstrates ionizing-radiation-associated health risks to the local residents and people inhabiting houses made from Brahmaputra River sediments (as construction material).

Quantifying Source Apportionment, Co-occurrence, and Ecotoxicological Risk of Metals from Upstream, Lower Midstream, and Downstream River Segments, Bangladesh.

The positive matrix factorization (PMF) receptor model was used for the first time to quantify the source contributions to heavy metal pollution of sediment on a national basin scale in the upstream, midstream, and downstream rivers (Teesta and Kortoya-Shitalakkah and Meghna-Rupsha and Pasur) of Bangladesh. The metal contamination status, co-occurrence, and ecotoxicological risk were also investigated. Sediment samples were collected from 30 sites at a depth range of 0 to 20 cm for analysis of 9 metals using inductively coupled plasma-mass spectrometry. The mean concentrations of metals varied for upstream, lower midstream, and downstream river segments. The results showed that chromium (Cr) exhibited a strong significant co-occurrence network with other metals (e.g., manganese [Mn], iron [Fe], and nickel [Ni]). Monte Carlo simulation results of the geo-accumulation index (Igeo; 63.3%) and risk indices (48.5%) showed that cadmium (Cd) was the main contributor to sediment pollution. However, the cumulative probabilities of sediments being polluted by metals were ranked as "moderate to heavily polluted" (Igeo 46.6%; risk index 16.7%). Toxicity unit results revealed that zinc (Zn) and Cd were the key toxic contributors to sediments. The PMF model predicted metal concentrations and identified 4 potential sources. The agricultural source (factor 1) mostly contributed to copper (Cu; 78.9%) and arsenic (As; 62.8%); Ni (96.9%) and Mn (83.5%) exhibited industrial point sources (factor 2), with 2 hot spots in northwestern and southwestern regions. Cadmium (93.5%) had anthropogenic point sources (factor 3), and Fe (64.3%) and Cr (53.5%) had a mixed source (factor 4). Spatially, similar patterns between PMF apportioning factors and predicted metal sources were identified, showing the efficiency of the model for river systems analysis. The degree of metal contamination in the river segments suggests an alarming condition for biotic components of the ecosystem. Environ Toxicol Chem 2020;39:2041-2054. © 2020 SETAC.

Co-distribution, possible origins, status and potential health risk of trace elements in surface water sources from six major river basins, Bangladesh.

In this study, we appraised the concentrations of 8 major trace elements (TEs) in surface water sources from six river basins, Bangladesh: Meghna, Kartoya, Sitalakha, Teesta, Pashur and Rupsha River basins. Co-distribution, the status of water quality and potential health risks were assessed using statistical analyses, the entropy water quality index (EWQI), sodium adsorption ratio (SAR), spatial autocorrelation index (SAI), hazard index (HI), and Monte-Carlo (MC) simulation. The spatial variations of TEs concentrations differed notably among the studied river basins. The average concentrations of TEs (except Ni, As, and Zn) in six river basins exceeded the drinking water quality guidelines. About 20% of water samples in six basins were categorized as undrinkable to poor qualities for drinking uses, while good water quality for irrigation purposes. The entropy theory identified that Cr, Pb, and As are the key pollutants influencing the water quality. According to the results of non-carcinogenic risk, the hazard index (HI) values for adults and children surpassed the allowable limit (>1), demonstrating detrimental health effects on humans. The carcinogenic risk values of chromium (Cr) were much higher than As and Cd exposures which exceeded the benchmark recommended by US EPA (>10-6 to 10-4), with an elevated risk for adults than children through the oral intake as the primary exposure route. Overall, the results suggest that the local population exposed to surface water may pose an adverse health effect, thus, strict regulation and efficient management should be focused on Cr, Cd and As monitoring and appraisal in these basins.

Simultaneous appraisals of pathway and probable health risk associated with trace metals contamination in groundwater from Barapukuria coal basin, Bangladesh.

In this study, we analyzed 33 groundwater samples from the Barapukuria coal basin (BCB), Bangladesh for 10 trace metals (TMs) using Atomic Absorption Spectroscopy. Pathways and associated probable health risk were appraised by employing multivariate statistical approaches, health risk model and Monte-Carlo simulation. Except for the Cu, Cr and Zn concentrations, the mean concentrations of all TMs in the basin were above the permissible water quality limits set by Bangladesh and international standards. Correlation coefficient and principal component analysis, supported by cluster analysis indicated that anthropogenic inputs were more contributed to the elevated concentrations of TMs compared to geogenic sources as the major reasons of groundwater pollution in the basin. The results of non-carcinogenic risk appraisal depicted that hazard index (HI) values for both adults and children were exceeded the safe limits (>1.0) except for few locations, indicating serious health risks on the human via oral and dermal absorption pathways. However, the carcinogenic risk values of Cd and Cr exceeded the US EPA range of 1 × 10-6 to 1 × 10-4, with higher risk for children than adults, with oral intake as the key exposure pathway. A sensitivity study identified the concentration of Cr, exposure frequency and ingestion rate for carcinogenic effect as the most sensitive parameters influencing the probable health risk. Overall, the results suggest that Cr in drinking water could cause detrimental effects to exposed local residents; thus, strict health regulation and groundwater management should concentrate on Cr contamination in groundwater from the coal basin.

Correction to: Assessment of natural radioactivity in coals and coal combustion residues from a coal-based thermoelectric plant in Bangladesh: implications for radiological health hazards.

The original version of this article unfortunately contained an error in eq. 1. The denominator Ɛ of Eq. (1) was missing.

Assessment of natural radioactivity in coals and coal combustion residues from a coal-based thermoelectric plant in Bangladesh: implications for radiological health hazards.

To study the level of radioactivity concentrations from a coal-based power plant (Barapukuria, Bangladesh) and to estimate the associated radiological hazards, coal and associated combustion residuals from the power plant were analyzed by gamma-ray spectrometry with high-purity germanium (HPGe) detector. The results reveal that the mean radioactivity (Bq kg-1) concentrations in feed coal samples are 66.5 ± 24.2, 41.7 ± 18.2, 62.5 ± 26.3, and 232.4 ± 227.2 for U-238, Ra-226, Th-232, and K-40, respectively, while in coal combustion residuals (CCRs), they are 206.3 ± 72.4, 140.5 ± 28.4, 201.7 ± 44.7, and 232.5 ± 43.8, respectively. With the exception of K-40, all the determined natural radionuclides are considerably higher in the investigated feed coal and associated combustion residues as compared with the world soil and world coal mean activities. On the average, CCRs contains 3.10-3.37 times more natural radionuclides than the feed coal, except for K-40. The radioactivity of fly ash and bottom ash is fractionated, and ratio ranges from 1.40 to 1.57. The mean values of the radiological hazard indices in the coal and their associated residuals are 153.1 and 446.8 Bq kg-1 for radium equivalent activity, 0.41 and 1.21 for the external hazard index, 70 and 200.1 nGy h-1 for the absorbed gamma dose rate, 0.09 and 0.25 mSv year-1 for the annual effective dose rate, and 3.0 × 10-4 and 8.6 × 10-4 Sv-1 for the excess lifetime cancer risk, respectively, most of which exceed the UNSCEAR-recommended respective threshold limits. The outcome of this study suggests a potential radiological threat to the environment as well as to the health of occupational workers and nearby inhabitants from the examined samples.