This study evaluates the potential industrial suitability of red clay from Sapahar Upazila, Naogaon District, Bangladesh. Comprehensive laboratory tests were conducted, including Atterberg limits, grain size analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF), Scanning electron microscopy (SEM) and Thermogravimetric analysis (TG), to investigate the mineralogical, geological, ceramic, and plastic properties of the samples. The mineralogical analysis reveals that the red clay is composed of illite, kaolinite, montmorillonite and quartz. Chemically, the red clay primarily composed of SiO2 (55.06-57.73 %), followed by Al2O3 (16.96-18.89 %), Fe2O3 (8.29-10.15 %), K2O (2.98-3.42 %), TiO2 (1.28-1.38 %), trace amounts of other oxides (<1 %) and LOI (8.34 %-9.99 %). TG/DSC curve trends indicate the stability of red clay up to 900 degrees C. Firing experiments conducted at 800 degrees C, 900 degrees C, 1000 degrees C and 1100 degrees C show changes in firing shrinkage (0.05 %-1.15 %), water absorption (7.66 %-4.31 %), apparent porosity (13.58 %-9.53 %), bulk density (1.77 g/cm(3)-2.21 g/cm(3)) and unconfined compressive strength (1.35-7.22 MPa). These findings suggest that the local red clay is suitable for manufacturing vitrified and semi-vitrified ceramic tiles, indicating its potential for industrial applications in the ceramics sector. Future studies should aim to upscale the experimental findings and comprehensively evaluate the performance of the clay under industrial production.

This study assesses the concentrations of heavy metals and their distribution as well as ecological status in the major waterfalls at Chattogram, namely Khoiyachora, Kupikatakhum, Napittachhara, Bagbiani, Sohosrodhara, and Suptadhara. The water from these waterfalls are being used by the local inhabitants for household, drinking and irrigation purposes. Eighteen water samples from six water waterfall were collected during the summer, rainy and winter seasons in 2022-2023. The concentrations of Na, K, Ca, Mg, Fe, Mn, Cu, Cd, Hg, Cr, and As in water samples were measured by Atomic Absorption Spectrometer (AAS), and compared with the national (ECR, 2023) and international standards (WHO, 2015). Heavy Metal Pollution Index (HPI) were calculated (18.51 to 22.87) showed below the critical limit of 100, indicating suitability for drinking. However, %Na (0.92) and the magnesium adsorption ratio (MAR) value (32.49) suggested that the water is unsuitable for irrigation but suitable for drinking. On the other hand, metrics such as the sodium adsorption ratio (SAR) (26.74) and Kelly's ratio (KR) (9.83) indicated suitability for irrigation. HPI values (0–25) indicate excellent water quality, safe for consumption. Heavy Metal Pollution Indices (HPIs) and multivariate statistical models (PCA, CA, and Pearson correlation) were applied to evaluate spatial-temporal variations, distribution, and pollution sources. CA grouped monitoring sites into two clusters based on anthropogenic and geo-genic inputs. PCA identified five significant principal components explaining 73.79% of total variance. Seasonal and geographical variations in Mn, Fe, Cu, Cr, Cd, Pb, Zn, and As concentrations were observed, especially in northern and southern study areas, highlighting spatial differences in pollution patterns. The policymakers should take proper steps for monitor the waterfalls to ensure water security and environmental protection as well as water management for the nearby inhabitants.

Environmental contamination increased as a result of the extensive use of fossil fuels, large-scale industrialization, and population growth. It has become an urgent need to reduce carbon emissions for environmental sustainability. The revolution in renewable energy may be the best option for lowering carbon emissions. In this research, rice straw was considered as a possible wellspring of bioenergy production. The aim of the study is to determine the best way to use biomass by comprehending its thermal qualities. Several state-of-the-art techniques were used to characterize the rice straws to understand their potential as a solid fuel for clean energy production. Elemental analysis reveals the predominance of carbon and oxygen content while nitrogen and sulfur are minor constituents in the studied rice straws. Fourier transform infrared (FTIR) spectroscopy analysis suggested the presence of cellulosic and ligneous constituents. Pyrolysis is one of the appropriate choices to make esteem expansion and contributes to biomass utilization. The thermogravimetric analysis (TGA) analyses revealed that rice straw pyrolysis has occurred in three distinct stages i.e., dehydration, active pyrolysis, and passive pyrolysis. The differential thermogravimetric graph (DTG) depicts how the temperature peak at the greatest weight loss shifts as the heating rate rises. Based on the characterization and subsequent analysis, it can be concluded that rice straw is a critical biomass and suitable to be used in clean energy production and maintain environmental sustainability.

In the delta region of Bangladesh, Sonneratia apetala, also known as Keora and mangrove apple, is widely recognized for its dual role as a source of both food and medicine. Seasonal S. apetala fruits were gathered from Hatiya, Noakhali, in October 2021. The samples were segregated into pericarps and seeds, then fractionated into methanol segments. The anti-proliferative activities of these samples against lung A549 cells were evaluated using the Trypan blue exclusion method. Additionally, High-Performance Liquid Chromatography (HPLC) was employed to quantify phenolic compounds, while standard protocols facilitated the identification of specific phytochemical constituents. Chemical profiling via Gas Chromatography-Mass Spectrometry (GC-MS) and the isolation and detection of bioactive compounds through column chromatography and Nuclear Magnetic Resonance (NMR) analysis were undertaken. The methanol fractions of the seeds and pericarp were found to contain carbohydrates, tannins, flavonoids, steroids, alkaloids, glycosides, and terpenoids, with the absence of saponins and anthraquinones. Notably, the antiproliferative effect demonstrated statistical significance at a concentration of 300 mu g/mL for both extracts. Furthermore, HPLC analysis identified and quantified six polyphenols: catechin hydrate, (-)-epicatechin, rutin hydrate, trans-ferulic acid, trans-cinnamic acid, myricetin, and kaempferol, with the following concentrations: 46.65 and 12.72; 349.29 and 140.39; 5.26 and 33.06; 10.35 and 29.28; ND and 11.93; and 10.03 and 7.90 mg/100 g in the methanol fraction of the seed and pericarp, respectively. GC-MS analysis of S. apetala fruit revealed five notable compounds with significant peak areas (%): 2-methyltetracosane, tetratetracontane, heptacosane, 1-chloro-2hexyl-1-octanol, and phenol, 3,5-bis(1,1-dimethylethyl), exhibiting peak areas of 43.96, 35.8, and 15.95, respectively. Meanwhile, the notable peak in S. apetala seeds was 1,3-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, with a peak area (%) of 100. These compounds are known for their anticancer and antioxidant properties. Therefore, S. apetala, particularly its seeds and fruits, shows promising potential for development into dietary supplements and functional foods.

Sonneratia apetala, a nutrient-rich mangrove fruit, presents an opportunity for innovative food product development, offering potential health benefits and economic value through the creation of jam, jelly, and pickle. This innovative invention reveals the nutritional content including vitamins and minerals of Sonneratia apetala jam, jelly, and pickles from Nijhum Dwip in Hatiya Upazila, Noakhali District. These products contain Na, Mg, K, Ca, Mn, Fe, Cu, and Zn, which are essential for human nutrition. The texture and sensory qualities of the products depend on their Total Soluble Solids (TSS), acidity, moisture, pH, and total sugar content, with each parameter receiving an average score of 7 to 8 out of 9 (hedonic scale). Trace amounts of Cd, Cr, Pb, and Hg were found to be significantly below the safe consumption limits. F-, Cl-, SO42-, soluble and total PO43- concentrations were also below safety thresholds. The moisture, ash, protein, fat, fiber, pectin, sugar, carbohydrate, and caloric values highlight the dietary benefits and energy content of these products. The products exhibited higher levels of vitamin C and minerals compared to other citrus fruits. All tested parameters met safe consumption standards, ensuring product safety. These products underwent testing for Heterotrophic Bacterial Count to guarantee their safety. A one-year shelf life is ensured by conducting quarterly storage data checks and organoleptic tests by a 10-member jury panel. The one-way ANOVA test for sensory analysis and shelf life detection indicates statistically significant results. These products help mitigate nutrient deficiencies and promote health by regulating the diet. Applying this technology in grassroots jam, jelly, and pickle production could potentially boost the local economy by approximately $10,000 annually through the creation of small industries among the coastal population.

Saltwater intrusion in the coastal areas of Bangladesh is a prevalent phenomenon. However, it is not conducive to activities such as irrigation, navigation, fish spawning and shelter, and industrial usage. The present study analyzed 45 water samples collected from 15 locations in coastal areas during three seasons: monsoon, pre-monsoon, and post-monsoon. The aim was to comprehend the seasonal variation in physicochemical parameters, including water temperature, pH, electrical conductivity (EC), salinity, total dissolved solids (TDS), hardness, and concentrations of Na+, K+, Mg2+, Ca2+, Fe2+, HCO3-, PO43-, SO42-, and Cl-. Additionally, parameters essential for agriculture, such as soluble sodium percentage (SSP), sodium absorption ratio (SAR), magnesium absorption ratio (MAR), residual sodium carbonate (RSC), Kelly’s ratio (KR), and permeability index (PI), were examined. Their respective values were found to be 63%, 16.83 mg/L, 34.92 mg/L, 145.44 mg/L, 1.28 mg/L, and 89.29%. The integrated water quality index was determined using entropy theory and principal component analysis (PCA). The resulting entropy water quality index (EWQI) and SAR of 49.56% and 63%, respectively, indicated that the samples are suitable for drinking but unsuitable for irrigation. These findings can assist policymakers in implementing the Bangladesh Deltaplan-2100, focusing on sustainable land management, fish cultivation, agricultural production, environmental preservation, water resource management, and environmental protection in the deltaic areas of Bangladesh. This research contributes to a deeper understanding of seasonal variations in the hydrochemistry and water quality of coastal rivers, aiding in the comprehension of salinity intrusion origins, mechanisms, and causes.

Groundwater is a significant water resource for drinking and irrigation in Satkhira district, Bangladesh. The depletion of groundwater resources and deterioration in its quality are the results of the confluence of factors such as industrialization, intensive irrigation, and rapid population growth. For this reason, this study focused on the evaluation of tubewell water of six unions of Kaligonj upazila in Satkhira district, which is situated in the coastal southwest part of Bangladesh. Major and trace elemental concentrations were assimilated into positive matrix factorization (PMF) to identify potential sources and their respective contributions. Principal component analysis (PCA) revealed that groundwater salinization and manmade activities were the primary causes of heavy metals in the coastal groundwater. Its average pH value was found to be 7.5, while Dissolved oxygen, Total dissolved solids, salinity, and conductivity, with values ranging from 1.18 to 7.38 mg/L, 0.5–4.88 g/L, 0.4–5%, and 0.95 to 8.56 mS/cm, respectively. The total hardness average value was 561.7 mg/L, classified into the very hard water categories, which is why 90% of the tubewell water samples were unfit for household purposes. All samples had an excessive level of arsenic present. The iron concentration of fifteen (15) samples crossed the standard limit according to WHO 2011 value. Around 63% of the samples were of the Na+-K+-Cl--SO42- type, and about 72% were sodium-potassium and alkali types. 98% of samples were covered in chloride and bicarbonate. The findings showed that 45.83% of the groundwater samples had negative Chloroalkaline index (CAIs), while 54.16% had positive. The permeability index (PI) was an average of 73%, and residual sodium carbonate (RSC) averaged 260.2 mg/L, and the findings clearly showed that 80% of the samples weren't appropriate for irrigation. According to the sodium adsorption ratio (SAR) value, 65% of the samples fell into the unsuitable category. These calculations indicated a high overall salinity hazard in the study area, which may be caused by the intrusion of sea water given that the study area is close to the coastal region. Findings compared to standards revealed that the majority of the samples were deemed unfit for drinking and irrigation purposes. Hence, additional attention must be paid to this area to ensure the availability of drinkable water and to preserve sustainable farming practices.

Eleven trace metals (Cd, Cr, Fe, Mn, Cu, Ni, Co, Zn, As, Pb, and Ag) in sediments of Bangladesh’s ship breaking area were measured by an atomic absorption spectrometer to determine origin, contamination extent, spatial distributions, and associated ecological and human health hazards. This study found considerable quantities of Pb, Cd, Mn, Zn, and Cu when compared with standards and high levels of Pb, Cd, Zn, Cu, As, and Ag contamination according to pollution evaluation indices. Different indices indicate most of the sampling sites were highly polluted. However, spatial distribution maps indicate that trace metals were predominantly deposited in the northern and southern region. The ecological risk index revealed that Cd has the highest while Pb and As had moderate risk. Based on the health index values, Zn for both adults and children were higher than the safe limit while Mn, Pb, Cr, As, Fe, Cu, Ni, and Co for children were close to the threshold. The mean total carcinogenic risk values of Cr, As, and Ni for children and Ni for adults exceeded the permissible threshold. The cancer risk possibilities were further assessed using Monte Carlo simulation. Most trace metals have anthropogenic origins, which were attributed to ship breaking activities.

Background Sonneratia apetala and Nipa fruticans are mangrove species, perennial wild plants with significant therapeutic, ecological, and environmental value. They are extensively utilized by the local communities of the Sundarbans and coastal estuaries for various purposes. Aim of the study: This study aims to provide an in-depth review of these plants, relying on secondary data and information. Methods Compile the secondary data from at least 50 relevant pieces of literature. Results S. apetala fruits exhibit substantial antioxidant, antimicrobial, analgesic, antidiarrheal, and anti-diabetic properties. Additionally, the bark and leaves offer considerable therapeutic benefits. The plant contains various phytochemicals such as polyphenols include flavonoids, anthocyanins and alkaloids along with carbohydrates, proteins, fiber, minerals (such as Ca, K, Mg, S, Cu, Fe, Zn, Mn), and vitamins (including thiamine and riboflavin). Its leaf and fruit extracts show potential for applications in the food industry and green chemistry. The seed extract demonstrates the highest cytotoxic properties (LC50=36 μg/mL) among other parts of the plant, along with antibacterial effects and dose-dependent analgesic and antidiarrheal properties. The leaf and bark extracts exhibit significant antidiabetic potential, with IC50 values of 0.286±0.022 and 0.432±0.01 mg/mL respectively. The seeds are particularly rich in polyphenols (300.1 mg GAE/g), flavonoids (30.6 mg CE/g), anthocyanins (2.3 μmol/g), and vitamin C (4.0 mg/g), showcasing their strong antioxidant properties. The pericarp, though lower in these compounds, still presents significant nutritional value, containing 55.4 mg GAE/g polyphenols and 14.6 mg CE/g flavonoids. Nutritional analysis shows the pericarp's moisture content is 84.2%, along with high carbohydrates (29.6%) and proteins (8.8%), while the seed has 55.6% moisture and 11.5% proteins. Nipa fruticans presents lucrative findings, including vinegar production, low-fat biscuits with high nutrient values, bioethanol, among others. Various parts of this plant contain essential elements in significant amounts and only trace amounts of heavy metals, indicating its safety for medicinal purposes. Conclusion The phytochemical, nutritional, and elemental analyses of these plants highlight its potential health benefits, food value and significance in research. This comprehensive analysis underscores S. apetala's and N. fruticans broad nutritional and phytochemical significance, making it a valuable subject in studies of natural products and human health.

This work focused on removing iron with oxalic acid from red clay samples collected from Kapasia Upazila, Gazipur District, Bangladesh. To characterize the red clay, the study employed several techniques: particle size analysis, WDXRF (wavelength-dispersive X-ray fluorescence), AAS (atomic absorption spectroscopy), XRD (X-ray diffraction), TGA (thermogravimetric analysis), and FESEM (field emission scanning electron microscopy). Additionally, leaching experiments were conducted with varying concentrations of oxalic acid, temperatures and times. After leaching, the red clay composition changed significantly: SiO₂ increased from 53.6 % to 63.13 %, Fe₂O₃ decreased from 17.1 % to 3.64 %, Al₂O₃ remained relatively stable at 18 %-18.22 %, and other oxides showed minor variations. 78.71 % of the iron was removed at optimal leaching conditions (1.0 M oxalic acid, 100 °C, 150 min, and 250 rpm). Mineralogically, the red clay samples are composed of illite, kaolinite, quartz, feldspar, hematite and chlorite. Thermal analysis showed significant weight loss at temperatures between 300 and 600 °C. Ceramic trials were conducted at firing temperatures of 900 °C and 1100 °C to evaluate the mechanical properties of tiles. The results obtained showed significant improvements in red clay quality for ceramics. Being a low-cost and eco-friendly process, this becomes a very prominent alternative to conventional iron removal techniques and helps produce high-quality ceramic tiles, contributing towards economic growth in Bangladesh.

This study investigates the potential of renewable energy sources to address the growing energy demands of developing nations while ensuring environmental sustainability. Here, a model-based analysis to assess the feasibility of utilizing rice straw pyrolysis as a renewable energy source is investigated. The thermogravimetric analysis identified the optimal temperature range for pyrolysis (230–400 °C) and the Coats–Redfern model was employed for kinetic analysis. Diffusion models, particularly D3, exhibited the best fit with an activation energy of 16–18 kJ/mol. Thermodynamic analysis confirmed the endothermic nature of the process, with positive enthalpy and negative entropy changes indicating an increase in energy and a more ordered product. These findings suggest that rice straw pyrolysis holds promise as a viable renewable energy option. This study contributes to understanding the rice straw pyrolysis mechanism which could be helpful for its effective utilization at commercial scale.

Early detection and effective cancer treatment are critical to improving metastatic cancer cell diagnosis and management today. In particular, accurate qualitative diagnosis of metastatic cancer cell represents an important step in the diagnosis of cancer. Today, biosensors have been widely developed due to the daily need to measure different chemical and biological species. Biosensors are utilized to quantify chemical and biological phenomena by generating signals that are directly proportional to the quantity of the analyte present in the reaction. Biosensors are widely used in disease control, drug delivery, infection detection, detection of pathogenic microorganisms, and markers that indicate a specific disease in the body. These devices have been especially popular in the field of metastatic cancer cell diagnosis and treatment due to their portability, high sensitivity, high specificity, ease of use and short response time. This article examines biosensors for metastatic cancer cells. It also studies metastatic cancer cells and the mechanism of metastasis. Finally, the function of biosensors and biomarkers in metastatic cancer cells is investigated.

The Jamuna River, a vital tributary of the Brahmaputra River, significantly influences Bangladesh’s hydrology and geomorphology. This dynamic river causes extensive erosion, accretion, and riverbank migration, displacing thousands of people annually. Despite its impact, previous research has not combined satellite and seismic data to examine the neotectonic activities driving these changes. This study aims to address this gap by analyzing Landsat satellite imagery from 1987 to 2021, digital elevation models, and 2D seismic data to assess the impact of neotectonics on riverbank dynamics. Findings reveal that from 1987 to 2021, the Jamuna River shifted 8.4 km westward, particularly affecting the Sariakandi and Madarganj areas. Additionally, the western part of Madarganj Upazila was found to be tilted compared to its eastern side due to lineament orientation. Subsurface seismic images indicate that the central region of the study area, including Sariakandi and Madarganj, is uplifted and deformed by six NE-SW trending faults bounded by anticlinal folds. These tectonic activities have contributed to the westward shift of the Jamuna River. Policymakers must consider these neotectonic factors to develop effective management strategies for riverine environments, optimize water resource management, mitigate natural hazards, and plan land use in affected areas.

Arsenic (As) contamination in groundwater is emerging as a significant global concern, posing serious risks to the safety of drinking water and public health. To understand the release mechanisms, mobilization processes, spatial distribution, and probabilistic health risks of As in western Bangladesh, forty-seven samples were collected and analyzed using an atomic absorption spectrometer (AAS). The As concentrations in groundwater ranged from 1.97 to 697.4 μg L⁻1 (mean: 229.9), significantly exceeding recommended levels. The dominant hydrochemistry of As-enriched groundwater was Ca–Mg–HCO₃, with the primary sources of arsenic in groundwater being the dissolution of arsenic-bearing minerals in sediment and the recharge of aquifers from the Ganges River Basin. The assessment using the Entropy Water Quality Index revealed that the groundwater is unsuitable for drinking, with 89.36% (n = 42) of the samples surpassing the WHO's limit for arsenic. Rock-water interactions, including calcite dissolution and silicate weathering within the confined aquifer, predominantly influenced hydrochemical properties. The significant relationships among Fe, Mn, and As indicate that the reductive dissolution of FeOOH and/or MnOOH considerably contributes to the release of As from sediment into groundwater. Geochemical modeling analysis revealed that siderite and rhodochrosite precipitate into aquifer solids, suggesting a weak to moderate relationship among As, Fe, and Mn. The long residence time of groundwater, combined with the presence of a clayey aquitard, likely controls the mobilization of arsenic in the aquifer. For the first time, Monte Carlo simulations have been used in arsenic-prone areas to assess the severity of arsenic contamination in western Bangladesh. The analysis indicates that out of 100,000 people, 10 may develop cancer as a result of drinking arsenic-contaminated water, with children being more susceptible than adults.

This study presents the development and implementation of an Internet of Things (IoT)-based real-time water quality monitoring system tailored for water treatment plants (WTPs). The system integrates advanced sensor technologies to continuously monitor key water quality parameters such as pH, dissolved oxygen (DO), total dissolved solids (TDS), and temperature. Data collected by these sensors is transmitted through a robust communication network to a centralized monitoring platform that utilizes cloud-based storage and analytics. The system's design includes a PLC-based control mechanism, allowing for flexible setup modifications and the easy addition of new monitoring parameters. The IoT-based system, powered by a low-energy 29-W configuration, offers accurate and reliable data with a minimal error margin of 0.1-0.2 across various parameters. The research highlights the system's ability to provide real-time alerts, historical data logging, and remote monitoring, all of which contribute to enhanced operational efficiency, proactive maintenance, and informed decision-making. This innovative approach to water quality management not only improves the effectiveness of WTP operations but also ensures environmental sustainability and public health safety. The study underscores the significant potential of IoT technologies in revolutionizing water quality monitoring practices.

The scarcity of freshwater in most of the megacities in the world is an important concern. In this regard, scientifically harvested rainwater could provide an effective measure to this crisis. In this attempt, we developed a cost-effective sensor-based automated first-flush rainwater harvesting system (RHS) to improve the freshwater scarcity and economic development of megacities like Dhaka, Bangladesh. To investigate the performance of the developed system, a suit of representative rainwater samples was systematically collected, preserved, and assessed between the months of July-December 2021 for water quality parameters such as physicochemical (pH, EC, TDS, DO, hardness, and alkalinity), anions (F-, Cl-, NO2-, NO3-, Br-, and SO42-), elemental (Ca, Mg, Cr, As, Cd, Hg, Pb, Be, Ni, Se, and Fe), and microbial contamination analysis. A Multiparameter digital meter and a titrimetric method were employed for measuring the physicochemical properties whereas elemental concentration was detected using an inductively coupled plasma-mass spectrometer and atomic absorption spectrometer. The changes in microbial contamination in the preserved rainwater were investigated from time to time during the whole experimental period. The findings showed that the mean pH (6.90) and concentrations (mg/L) of other concerning parameters such as TDS (15.5), DO (7.26), hardness (14.9), Cl- (3.59), NO3- (4.84), SO42- (4.62), Fe (<0.2), Cr (0.086 mu g/L), As (0.224 mu g/L), Cd (0.260 mu g/L), Hg (0.270 mu g/L), and Pb (5.530 mu g/L) in the harvested rainwater samples were below the WHO drinking water guidelines and literature data implying that the harvested rainwater derived from the developed RHS is completely safe for drinking and other uses even in respect to the microbial contamination (total bacterial counts: 0-15 CFU/mL, and total and fecal coliform less than 1.8 MPN/100 mL) for long storage. Hence, this technology has a huge opportunity to mitigate safe freshwater scarcity and groundwater depletion issues, especially in megacities such as Dhaka, Bangladesh.

Abstract The sessional variation of heavy metals pollution and potential health risks in sediments to local people were studied using a flame atomic absorption spectroscopy (FAAS). Ten (10) different khals that serve as the natural drainage of Chittagong City were chosen for collecting the surface sediments samples from the confluence of the Karnaphuli River. The mean concentration of Cu, Cr, Cd, Pb, Ni, Mn, As and Zn in sediments samples were 38.83, 46.92, 2.18, 42.98, 43.39, 63.04, 1.34 and 91.93 mg kg− 1 respectively for the wet session, while the respective values in dry season were found 51.12, 59.23, 2.52, 61.04, 49.66, 58.54, 2.21 and 104.44 mg kg− 1. The enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), degree of contamination (Cd), geoaccumulation index (Igeo), potential ecological index (PERI) and nemerow pollution index (PN) were calculated to estimate the pollution level of the study areas. Potential carcinogenic and non-carcinogenic health risks through dermal contact were also calculated using respective mean values of heavy metals. Statistical analyses were applied in order to findout the establish the association and source of heavy metals between pollutants in river sediments. The results showed that concentration of heavy metals was higher in the dry season than in the wet season at most of the locations. The obtained comprehensive data for toxic heavy metals in the surface sediment of the Karnafuly River along the Chittagong City Corporation may help the policy maker to take effective legislation for monitoring and protecting the ecological risks of the Karnafuli River.

[This corrects the article DOI: 10.1016/j.heliyon.2023.e13027.].

Renewable energy resources become an alternative to fossil fuels and help to mitigate the issues relevant to environmental sustainability. Some organic waste materials are harmful to the environment, but they offer a useful bioresource for renewable energy production. In this study, municipal solid waste (MSW) collected from Chattogram City was characterized for its effective utilization of energy production. Proximate analysis showed that the MSW has high ash and moisture content which needs further separation and purification. Elemental analysis reveals the presence of a lower amount of sulfur and nitrogen content. Fourier transform infrared (FTIR) spectroscopy analysis depicted that it has hydrocarbons with some compounds of sulfur and nitrogen. Thermogravimetric analysis (TGA) showed that MSW can be degraded through three stages corresponding to the presence of moisture content, lower hydrocarbons, and higher hydrocarbons. Based on the characterization and subsequent analysis, it can be concluded that municipal solid waste has potential for utilization as an alternative source of energy, after proper separation and purification.

The present study focuses on the indiscriminate disposal of personal protective equipment (PPEs) and resulting environmental contamination during the 3rd wave of COVID-19-driven global pandemic in the Chittagong metropolitan area, Bangladesh. Because of the very high rate of infection by the delta variant of this virus, the use of PPEs by the public is increased significantly to protect the ingestion/inhalation of respiratory droplets in the air. However, it is a matter of solicitude that general people throw away the PPEs to the dwelling environment unconsciously. With the increase of inappropriate disposal of PPEs (i.e., mostly the disposable face masks made from plastic microfibers), the possibility of transmission of the virus to the general public cannot be neglected completely. This is because this virus can survive for several days on the inanimate matter like plastics and fibers. At the same time, the result of environmental contamination by microplastic/microfiber has been widespread which eventually creates the worst impact on ecosystems and organisms. The present results may help to increase public perception of the use and subsequent disposal of PPEs, especially the face masks.