Source specific sedimentary response towards the differential anthropogenic impacts in terms of potentially toxic elements in an urban river

To investigate the interplay between varying anthropogenic activities and sediment dynamics in an urban river (Turag, Bangladesh), this study involved 37-sediment samples from 11 different sections of the river. Neutron activation analysis and atomic absorption spectrometry were utilized to quantify the concentrations of 14 metal(oid)s (Al, Ti, Co, Fe, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn). This study revealed significant toxic metal trends, with Principal coordinate analysis explaining 62.91 % of the variance from upstream to downstream. The largest RSDs for Zn(287 %), Mn(120 %), and Cd(323 %) implies an irregular regional distribution throughout the river. The UNMIX-model and PMF-model were utilized to identify potential sources of metal(oid)s in sediments. ∼63.65-66.7 % of metal(oid)s in sediments originated from anthropogenic sources, while remaining attributed to natural sources in both models. Strikingly, all measured metal(oid)s' concentrations surpassed the threshold effect level, with Zn and Ni exceeding probable effect levels when compared to SQGs.

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.

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.

Assessment of radiation level and potential risk to public living around major hospitals in central and western Bangladesh

Human beings are continuously bathed in radiation coming from natural and artificial sources. Although the use of radiation in medical applications is beneficial to patients, it also contributes significantly to the health hazard for radiation workers and the public if radiation-generating equipment and radioactive sources are not handled properly. 96% dose contributed from medical uses of ionizing radiation in the US population among man-made sources as per NCRP Report No. 160. There is no extensive study conducted on the large hospitals in Bangladesh following the In-Situ method. We used a real-time digital portable radiation monitor with Garmin eTrex Global Positioning System at 320 monitoring points for radiation monitoring and positioning around the ten largest hospitals in central & western Bangladesh from September to November 2021. The mean radiation dose rates around Bangabandhu Sheikh Mujib Medical University, Dhaka Medical College Hospital, Evercare Hospital, Khulna Medical College Hospital, Mitford Hospital, National Institute of Cancer Research Hospital, Popular Hospital, Rajshahi Medical College Hospital, Shaheed Suhrawardy Medical College Hospital, and Square Hospitals were measured as 0.145 ± 0.012 μSv/h, 0.135 ± 0.009 μSv/h, 0.148 ± 0.008 μSv/h, 0.139 ± 0.01 μSv/h, 0.133 ± 0.007 μSv/h, 0.153 ± 0.011 μSv/h, 0.144 ± 0.012 μSv/h, 0.137 ± 0.008 μSv/h, 0.145 ± 0.01 μSv/h, and 0.153 ± 0.009 μSv/h, respectively. The mean excess lifetime cancer risk (ELCR) of the public who lives nearby the hospital's boundary was estimated at 1.05 × 10-3, 0.983 × 10-3, 1.071 × 10-3, 1.004 × 10-3, 0.964 × 10-3, 1.084 × 10-3, 1.043 × 10-3,0.996 × 10-3, 1.051 × 10-3 & 1.112 × 10-3 respectively. ELCR in most of the locations around the ten largest hospitals in central & western Bangladesh is higher than the global average value. Radiation monitoring is significant for minimizing the public's radiation risk and keeping hospital environments as radiation-free as possible.

Identifying factors influencing contraceptive use in Bangladesh: evidence from BDHS 2014 data

Background

Birth control is the conscious control of the birth rate by methods which temporarily prevent conception by interfering with the normal process of ovulation, fertilization, and implantation. High contraceptive prevalence rate is always expected for controlling births for those countries that are experiencing high population growth rate. The factors that influence contraceptive prevalence are also important to know for policy implication purposes in Bangladesh. This study aims to explore the socio-economic, demographic and others key factors that influence the use of contraception in Bangladesh.

Methods

The contraception data are extracted from the 2014 Bangladesh Demographic and Health Survey (BDHS) data which were collected by using a two stage stratified random sampling technique that is a source of nested variability. The nested sources of variability must be incorporated in the model using random effects in order to model the actual parameter effects on contraceptive prevalence. A mixed effect logistic regression model has been implemented for the binary contraceptive data, where parameters are estimated through generalized estimating equation by assuming exchangeable correlation structure to explore and identify the factors that truly affect the use of contraception in Bangladesh.

Results

The prevalence of contraception use by currently married 15–49 years aged women or their husbands is 62.4%. Our study finds that administrative division, place of residence, religion, number of household members, woman’s age, occupation, body mass index, breastfeeding practice, husband’s education, wish for children, living status with wife, sexual activity in past year, women amenorrheic status, abstaining status, number of children born in last five years and total children ever died were significantly associated with contraception use in Bangladesh.

Conclusions

The odds of women experiencing the outcome of interest are not independent due to the nested structure of the data. As a result, a mixed effect model is implemented for the binary variable ‘contraceptive use’ to produce true estimates for the significant determinants of contraceptive use in Bangladesh. Knowing such true estimates is important for attaining future goals including increasing contraception use from 62 to 75% by 2020 by the Bangladesh government’s Health, Population & Nutrition Sector Development Program (HPNSDP).

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5098-1) contains supplementary material, which is available to authorized users.