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Community transmission of COVID-19 is happening in Bangladesh—the country which did not have a noteworthy health policy and legislative structures to combat a pandemic like COVID-19. Early strategic planning and groundwork for evolving and established challenges are crucial to assemble resources and react in an appropriate timely manner. This article, therefore, focuses on the public perception of comparative lockdown scenario analysis and how they may affect the sustainable development goals (SDGs) and the strategic management regime of COVID-19 pandemic in Bangladesh socio-economically as well as the implications of the withdrawal of partial lockdown plan. Scenario-based public perceptions were collected via a purposive sampling survey method through a questionnaire. Datasets were analysed through a set of statistical techniques including classical test theory, principal component analysis, hierarchical cluster analysis, Pearson’s correlation matrix and linear regression analysis. There were good associations among the lockdown scenarios and response strategies to be formulated. Scenario 1 describes how the death and infection rate will increase if the Bangladesh Government withdraws the existing partial lockdown. Scenario 2 outlines that limited people’s movement will enable low-level community transmission of COVID-19 with the infection and death rate will increase slowly ( r  = 0.540, p  < 0.01). Moreover, there will be less supply of necessities of daily use with a price hike ( r  = 0.680, p  < 0.01). In scenario 3, full lockdown will reduce community transmission and death from COVID-19 ( r  = 0.545, p  < 0.01). However, along with the other problems gender discrimination and gender-based violence will increase rapidly ( r  = 0.661, p  < 0.01). Due to full lockdown, the formal and informal business, economy, and education sector will be hampered severely ( R  = 0.695). Subsequently, there was a strong association between the loss of livelihood and the unemployment rate which will increase due to business shutdown ( p  < 0.01). This will lead to the severe sufferings of poor and vulnerable communities in both urban and rural areas ( p  < 0.01). All these will further aggravate the humanitarian needs of the most vulnerable groups in the country in the coming months to be followed which will undoubtedly affect the Bangladesh targets to achieve the SDGs of 2030 and other development plans that need to be adjusted. From our analysis, it was apparent that maintaining partial lockdown with business and economic activities with social distancing and public health guidelines is the best strategy to maintain. However, as the government withdrew the partial lockdown, inclusive and transparent risk communication towards the public should be followed. Recovery and strengthening of the health sector, economy, industry, agriculture, and food security should be focused on under the “new normal standard of life” following health guidelines and social distancing. Proper response plans and strategic management are necessary for the sustainability of the nation. Graphic abstract

Increasing salt intake has substantial negative impacts on human health and well-being. This article focused on the construction of Driver-Pressure-State-Impact-Response (DPSIR) framework for drinking water sodium (DWS) followed by a review on the published studies regarding salinity intrusion, DWS, and their effects on health perspectives in Bangladesh. Saline water is an important factor for hypertension or high blood pressure in the coastal areas. DWS can also lead women, especially pregnant women, to an increased risk of (pre)eclampsia, hypertension, as well as infant mortality. Several interventions, such as rainwater harvesting, pond sand filter (PSF) system, managed aquifer recharge (MAR), and pilot scale solar-powered desalination plants, such as reverse osmosis (RO), were reviewed on the context of their effectiveness in controlling drinking water sodium. Although rainwater consumption has the positive impact of low or no sodium intake, it still possesses negative impacts from not having vital minerals. A steady increment in sodium concentration through the span of the dry season was observed in MAR. It is, subsequently, important to increase awareness on DWS intake by providing and adopting correct technological interventions and training communities on the maintenance of the adaptive measures.

Monthly 24-h real-time high-resolution monitoring was conducted for 1 year to investigate the carbon dioxide (CO 2 ) dynamics in the lower Brahmaputra River. The partial pressure of CO 2 ( p CO 2 ) was observed between 136 and 1213 µatm. The p CO 2 was almost 1.5 times higher during the wet season (May–October) than during the dry season (November–April). Diurnal variation in p CO 2 was pronounced during the dry season. In contrast, no clear diurnal pattern was observed during the wet season. The combined measurements of O 2 –CO 2 in river water provide insights into net chemical and microbial activity. In January and March, there was a bidirectional exchange of CO 2 , occurring from air to water (sink) and from water to air (source). However, in April, the CO 2 exchange was unidirectional, taking place solely from air to water, whereas in all other months, it occurred from water to air. The carbon dioxide flux ( F CO 2 ) in the river ranged from − 31.12 to 137.74 mmol m −2  day −1 , with an average of 25.26 mmol m −2  day −1 during the dry season and 78.56 mmol m −2  day −1 in the wet season. This flux significantly contributes to the regional net carbon budget of the world's largest delta.

As COVID-19 spreads quickly across the whole of Bangladesh, the increased uses of Personal Protective Equipment (PPE) could lead to secondary environmental catastrophes. It is urgent for respective authority to maintain a safe waste disposal system to save the environment and protect public health from impending health threats.

Occurrences and exposure to high levels of microbial bioaerosols such as pathogenic bacteria, fungi, fungal spores, and viruses can be linked to the deterioration of the environment and public health. This study aimed to review the results available for the unusual bioaerosol distribution scenario in the Asian regions. The amount of bioaerosol load and their environmental behavior in the atmosphere is heavily influenced by air pollution such as haze, fog, dust, and particulate matter (PM) and thus strongly affect the air quality index (AQI). Human factors such as heavy traffic, overcrowds, and biomass burning also affected the prevalence or occurrences of bioaerosols in the atmosphere. Seasonal/temporal and diurnal variation was significantly observed from these studies and in the case of South Asia, post-monsoon and winter months were incredibly concentrated with pathogenic bioaerosols. Many human infections, for example, pneumonia, tuberculosis, brucellosis, anthrax, and query fever (Q-fever), are linked to pathogenic bacterial bioaerosols. Respiratory diseases such as asthma and chronic pulmonary obstructiveness are related to fungal bioaerosols, spores, and viral infections. To facilitate the testing and monitoring appraisal of airborne bioaerosols, artificial intelligence, deep neural networks, and machine learning can be used to develop real-time PCR-based bioaerosol sensors. Moreover, mobile apps and compatible electronic gadgets can be developed for the city dwellers to real-time monitor the concentration of bioaerosols in the air they are breathing.

This study aimed to assess the current water quality, identify the sources of fluorescent dissolved organic matter (fDOM), and quantify the CO 2 flux from Kaptai Lake surface water. A water quality multiparameter analyzer, a membrane-enclosed pCO 2 sensor, and a weather monitoring device were deployed to continuously record data over 48 hours to observe daily and spatial shifts. All measured water quality parameters remained within the acceptable limits set by the Department of Environment (DoE). The three-dimensional excitation-emission matrix (3D-EEM) analysis identified distinct fluorophores at peak A (Ex/Em = 245/404 nm), peak M (Ex/Em = 310/404 nm), peak T (Ex/Em = 280/338–346 nm), and peak Tuv (Ex/Em = 230/338–350 nm). Parallel factor analysis (PARAFAC) modelling further resolved these into protein-like components and fulvic-like substances, specifically C-like and M-like fluorophores, indicating the presence of both microbial and terrestrial sources. Spatial distribution patterns of fDOM intensity suggest variability driven by localized pollution sources across the lake. Optical indices further indicated that the fDOM components were predominantly biologically derived, characterized by low aromaticity, lower molecular weight and size, and were largely influenced by microbial degradation processes. Diurnal monitoring of partial pressure of CO 2 (pCO 2 ) in the lake water revealed values ranging from 577 to 1045 µatm. Correspondingly, the CO 2 flux (FCO 2 ) varied between 45 and 56 mmol CO 2 m ⁻  2 d ⁻  1 . The positive average FCO₂ indicates that the lake acts as a net source of CO 2 to the regional atmosphere. Higher pCO 2 levels are linked to lower dissolved oxygen and increased protein-like DOM that fuels microbial respiration, while humic-like DOM helps stabilize carbon by limiting CO 2 release.

Upon exposure to sunlight extracellular polymeric substances (EPS) were partially transformed into transparent exopolymer particles (TEP) and unstable flocs of different sizes without the addition of any precursors. Parallel factor (PARAFAC) modelling of the sample fluorescence spectra identified humic-like and protein-like or tyrosine-like components in both untreated and irradiated EPS samples. After 58 hours of solar irradiation, humic-like substances were entirely decomposed, while the regenerated protein-like substance from EPS was the key component in the irradiated samples. Degradation and reformation of EPS occurred which was confirmed by the results of size exclusion chromatography, dissolved organic carbon, total protein and total polysaccharide analyses. Irradiated EPS was composed of –COOH or C = O (amide I band) and –NH and –CN (amide II band), while Fourier transform infrared spectroscopy (FTIR) of TEP revealed more acidic –COOH and –C–O groups, indicating typical acidic protein-like TEP. The regenerated protein-like substances could form complexes with free metals originating from degraded EPS in irradiated samples, which could be responsible for the formation of TEP/floc in the aqueous media. These results suggest that TEP/floc formation from EPS could occur by a complexation mechanism between dissolved organic matter and metals, thereby causing ionic charge neutralisation upon sunlight exposure.

A set of hydrochemical analysis, drinking water evaluation indices along with multivariate statistics and geostatistical model are applied to evaluate the groundwater quality of Gopalganj District, Bangladesh. A total of 46 groundwater samples are analyzed for the pre and postmonsoon seasons to assess the possible consumptive human health risk among the adults and children of the study area. It is found that most of the studied hydrochemical parameters (pH, EC, TDS, Na + , Cl − , HCO 3 − , CO 3 − , As, Mn, Fe, B, NO 3 − , etc.) exceeded the limits stipulated by different standards for drinking water. From multivariate statistical analysis, high-salinity characteristic of groundwater resulting from seawater intrusion is observed. Spatial extensions of EC, Cl − , As, Fe, and Mn vary significantly around the study area. Strong, moderate, and weak spatial dependences are found for both seasons. The exponential semivariogram model is found to be dominant when considering the best-fit model analyzed for both seasons. In addition, mean Hazard Quotient and Hazard Index values based on As, Fe, Mn, B, NO 3 − , and F − imply that the groundwater poses substantial health risk for both adults and children and fluctuates in accordance with seasonal variation. The carcinogenic risk among adults and children due to As is high in the study area during both seasons. The groundwater of the study area was characterized by high salinity possessing high level of noncarcinogenic as well as cancer-risk (As) vulnerability of the local community.

Novel coronavirus (SARS-CoV-2) causing COVID-19 disease has arisen to be a pandemic. Since there is a close association between other viral infection cases by epidemics and environmental factors, this study intends to unveil meteorological effects on the outbreak of COVID-19 across eight divisions of Bangladesh from March to April 2020. A compound Poisson generalized linear modeling (CPGLM), along with a Monte-Carlo method and random forest (RF) model, was employed to explore how meteorological factors affecting the COVID-19 transmission in Bangladesh. Results showed that subtropical climate (mean temperature about 26.6 °C, mean relative humidity (MRH) 64%, and rainfall approximately 3 mm) enhanced COVD-19 onset. The CPGLM model revealed that every 1 mm increase in rainfall elevated by 30.99% (95% CI 77.18%, − 15.20%) COVID-19 cases, while an increase of 1 °C of diurnal temperature (TDN) declined the confirmed cases by − 14.2% (95% CI 9.73%, − 38.13%) on the lag 1 and lag 2, respectively. In addition, NRH and MRH had the highest increase (17.98% (95% CI 22.5%, 13.42%) and 19.92% (95% CI: 25.71%, 14.13%)) of COVID-19 cased in lag 4. The results of the RF model indicated that TDN and AH (absolute humidity) influence the COVID-19 cases most. In the Dhaka division, MRH is the most vital meteorological factor that affects COVID-19 deaths. This study indicates the humidity and rainfall are crucial factors affecting the COVID-19 case, which is contrary to many previous studies in other countries. These outcomes can have policy formulation for the suppression of the COVID-19 outbreak in Bangladesh.

The study was designed to collect water samples over two seasons—wet-monsoon season ( n  = 96) (March–April) and dry-monsoon season ( n  = 44) (September–October)—to understand the seasonal variation in anion and cation hydrochemistry of the coastal rivers and estuaries contributing in the spatial trend in salinity. Hydrochemical examination of wet-monsoon season primarily revealed Ca–Mg–HCO 3 type (66%) and followed by Na–Cl type (17.70%) water. In the dry-monsoon season, the scenario reversed with primary water being Na–Cl type (52.27%) followed by Ca–Mg–HCO 3 type (31.81%). Analysis of Cl/Br molar ratio vs. Cl (mg/L) depicted sampling area affected by seawater intrusion (SWI). Spatial analysis by ordinary kriging method confirmed approximately 77% sample in the dry-monsoon, and 34% of the wet-monsoon season had shown SWI. The most saline-intruded areas in the wet-monsoon seasons were extreme south-west coastal zone of Bangladesh, lower Meghna River floodplain and Meghna estuarine floodplain and south-eastern part of Chittagong coastal plains containing the districts of Chittagong and Cox’s Bazar adjacent to Bay of Bengal. In addition, mid-south zone is also affected slightly in the dry-monsoon season. From the analyses of data, this study could further help to comprehend seasonal trends in the hydrochemistry and water quality of the coastal and estuarine rivers. In addition, it can help policy makers to obligate some important implications for the future initiatives taken for the management of land, water, fishery, agriculture and environment of coastal rivers and estuaries of Bangladesh.