Identifying the interfaces between perceived multi-hazards and socio-ecological risks to strengthen local adaptations.

Multi-hazards are a great concern in the present world. Likewise, the coastal part of Bangladesh is highly vulnerable to multi-hazards, including waterlogging, surface water salinity, land use change, prolonged dry seasons, and groundwater salinity. Multi-hazards and associated risks make local adaptations more difficult over time. Thus, the purpose of this study is to explore the connection between multi-hazards and their associated socio-ecological risks in the southwestern coastal part of Bangladesh. Mixed-methods approaches were used to collect all the data, and statistical analyses were performed to analyze the data. Results revealed that waterlogging significantly influenced local food access, poverty, child marriage, and divorce problems. Surface water salinity and land use change showed significant differences with the widening of salinity-affected areas. Waterlogging, land use change, and a prolonged dry season all showed significant differences in freshwater access. Prolonged dry seasons and groundwater salinity both have a significant impact on human health. Waterlogging and groundwater salinity significantly influence human migrations. These findings may strengthen local adaptation policies for salinity hazards, land use planning, household poverty, food access, livelihoods, water access, health effects, child marriage, and human migration. In addition, our findings indicate the potential to address the existing knowledge gaps pertaining to coastal hazards, risks, and adaptation issues.

Groundwater quality and human health risk assessment in selected coastal and floodplain areas of Bangladesh.

Groundwater aquifers are a common source of drinking water in Bangladesh. However, groundwater contamination is a major public health concern across the country. This research aims to examine the groundwater quality and health concerns using a random sampling process. Multivariate statistical and health risk analyses of elements were performed to determine the source of contaminants and their effects on human health. A total of 24 parameters were analyzed, where Na+, NH4+, K+, Mg2+, F-, NO3-, Mn, Fe, Se, U, and As concentrations were found to be high in different sampling points compared to the Department of Environment of Bangladesh (DoE), and the World Health Organization (WHO) groundwater quality standards. Principal Component Analysis (PCA) and Cluster Analysis (CA) identified the dominant and potential sources of contaminants in the groundwater aquifer, including geogenic, salinity intrusion, industrial, and agricultural. The results of the degree of contamination level (Cd) and the heavy metal pollution index (HPI) showed that 28% and 12% of the sampling points had high levels of heavy metal contamination, indicating a high risk for human health issues. Cr concentrations were found to have a higher carcinogenic (cancer) risk than As and Cd concentrations. Hazard quotient (HQ) and hazard index (HI) scores expressed the hazardous status and possible chronic effects in the context of individual sampling points. For both child and adults, 44% and 36% of the sampling points had a high HI score, indicating the possibility of long-term health risks for local populations.

Groundwater salinization and associated co-contamination risk increase severe drinking water vulnerabilities in the southwestern coast of Bangladesh.

Household drinking water security is one of the major issues among coastal communities in Bangladesh. To examine the groundwater quality and social consequences, groundwater samples and household questionnaires were administered across the study area. Instrumental and statistical tools were used to analyze the water quality and social survey data. The average concentrations of electrical conductivity (EC) (7135.67 µS/cm), total dissolved solids (TDS) (3691 mg/L), Na+ (1569.51 mg/L), Ca2+ (289.5 mg/L), Mg2+ (340.51 mg/L), Cl- (2940.78 mg/L), F- (11.85 mg/L), NO3- (54.44 mg/L), NO2- (162.95 mg/L), PO43- (105.19 mg/L), Fe (4.9 mg/L), Mn (1.22 mg/L), As (16.55 µg/L), B (833.28 µg/L), and Pb (34.22 µg/L) were observed in groundwater, and exceeded the drinking water standards from 30% to 100% depending on the sampling location. Thus, the remarkably high contents of EC, TDS, Cl-, and Na+ represented possible saltwater intrusion along the coastal aquifer. The positive correlations between EC and trace and toxic elements indicated the potential influence of groundwater salinization on the dissolution of more chemical contaminants in the aquifer. These results showed that 100% of samples were unsuitable for drinking purposes. Severe drinking water scarcity is a serious issue, and local people have been affected by water-related diseases owing to the long-term consumption of contaminated water. Salinity problems in drinking water and related health diseases have increased significantly in the past several years. In addition, climate change and its associated hazards, including sea-level rise, cyclonic storm surges, flooding, and resulting inundation problems, have intensified the drinking water scarcity and health problems at the community level. To ensure household water security, environmental exposure, hydrogeology, and anthropogenic interventions must be considered to determine future sustainable water policies.

Electronic Structure of In3-x Se4 Electron Transport Layer for Chalcogenide/p-Si Heterojunction Solar Cells.

In this article, we perform density functional theory calculation to investigate the electronic and optical properties of newly reported In3-x Se4 compound using CAmbridge Serial Total Energy Package (CASTEP). Structural parameters obtained from the calculations agree well with the available experimental data, indicating their stability. In the band structure of In3-x Se4 (x = 0, 0.11, and, 0.22), the Fermi level (E F) crossed over several bands in the conduction bands, which is an indication of the n-type metal-like behavior of In3-x Se4 compounds. On the other hand, the band structure of In3-x Se4 (x = 1/3) exhibits semiconducting nature with a band gap of ∼0.2 eV. A strong hybridization among Se 4s, Se 4p and In 5s, In 5p orbitals for In3Se4 and that between Se 4p and In 5p orbitals were seen for ß-In2Se3 compound. The dispersion of In 5s, In 5p and Se 4s, Se 4p orbitals is responsible for the electrical conductivity of In3Se4 that is confirmed from DOS calculations as well. Moreover, the bonding natures of In3-x Se4 materials have been discussed based on the electronic charge density map. Electron-like Fermi surface in In3Se4 ensures the single-band nature of the compound. The efficiency of the In3-x Se4/p-Si heterojunction solar cells has been calculated by Solar Cell Capacitance Simulator (SCAPS)-1D software using experimental data of In3-x Se4 thin films. The effect of various physical parameters on the photovoltaic performance of In3-x Se4/p-Si solar cells has been investigated to obtain the highest efficiency of the solar cells. The optimized power conversion efficiency of the solar cell is found to be 22.63% with V OC = 0.703 V, J SC = 38.53 mA/cm2, and FF = 83.48%. These entire theoretical predictions indicate the promising applications of In3-x Se4 two-dimensional compound to harness solar energy in near future.

An investigation of coastal vulnerability and internal consistency of local perceptions under climate change risk in the southwest part of Bangladesh.

Climatic threats force disruption on community lifestyles by impairing social factors, the fundamental components of ensuring social sustainability. This study investigates the situational factors affecting the consequences on coastal livelihoods, and social activities; it also considers the effectiveness of traditional knowledge in reducing possible risks. Both qualitative and quantitative methods were employed, including questionnaire survey for identifying the local perception of climatic impacts alongside the impacts on daily activities. Interviews, field observations, and multivariate analyses were performed to explain the vulnerability status in coastal communities. Results show that most livelihood sectors were severely affected by the long-term and repeated actions of climatic hazards, such as cyclones, associated with a number of unavoidable risks making people susceptible to damages in social wellbeing. In addition, saltwater intrusion damages drinking water supply and crop farming, which can cause diseases among coastal communities, but very few attempts have been made to provide alternative sources of drinking water at a household level. Moreover, principal component analysis (PCA) and cluster analysis (CA) revealed significant interfaces between local perceptions and the socio-and agro-environmental factors changing the overall status of regional hazards. Thus, the situation exhibits coastal hazards, social vulnerability, and social crisis. Local people use their traditional knowledge to cope with various levels of crisis under vulnerable conditions, but sometimes doing so exceeds their capacity owing to the unwanted changes in climatic variables and knowledge gaps or uncertainties. Challenges on the basis of the problematic points should be noted, however, it would be more significant to achieve social sustainability under adverse climatic conditions.