Assessing groundwater quality and its sustainability in Joypurhat district of Bangladesh using GIS and multivariate statistical approaches

Sustainable groundwater quality is a key global concern and has become a major issue of disquiets in most parts of the world including Bangladesh. Hence, the assessment of groundwater quality is an important study to ensure its sustainability for various uses. In this study, a combination of multivariate statistics, geographical information system (GIS) and geochemical approaches was employed to evaluate the groundwater quality and its sustainability in Joypurhat district of Bangladesh. The results showed that the groundwater samples are mainly Ca–Mg–HCO₃ type. Principal component analysis (PCA) results revealed that geogenic sources (rock weathering and cation exchange) followed by anthropogenic activities (domestic sewage and agro-chemicals) were the major factors governing the groundwater quality of the study area. Furthermore, the results of PCA are validated using the cluster analysis and correlation matrix analysis. Based on the groundwater quality index (GWQI), it is found that all the groundwater samples belong to excellent to good water quality domains for human consumption, although iron, fluoride and iodide contaminated to the groundwater, which do not pose any significant health hazard according to World Health Organization’s and Bangladesh’s guideline values. The results of irrigation water quality index including sodium adsorption ratio (SAR), permeability index and sodium percentage (Na %) suggested that most of the groundwater samples are good quality water for agricultural uses. The spatial distribution of the measured values of GWQI, SAR, Fe (iron), EC (electrical conductivity) and TH (total hardness) were spatially mapped using the GIS tool in the study area.     

Assessment of solid waste generation and greenhouse gas emission potential in Yangon city,Myanmar

Due to booming economy, growing population and rapid urbanization, solid waste generation in the cities of developing countries has significantly increased. Yangon is the largest and most densely populated city, with over five million residents in Myanmar. Open dumping is the major waste disposal method and recycling sector remains at an early development stage. With increasing waste generation, current waste management activities in Yangon have significant environmental impacts. Therefore, the study developed two linear models to predict annual solid waste generation, regarding per capita waste generation, population growth scenarios, literacy rates and gross domestic products. The Intergovernmental Panel on Climate Change and Institute for Global Environmental Strategies calculation methods were used for greenhouse gas (GHG) emission prediction from recycling, waste transportation and final disposal sites (FDSs). As a result, the total annual waste generation and GHG emission in 2015 may double over the next decade. Two major FDSs, Htawe Chaung and Hteinpin, may contribute waste disposal of 272–797 kilotons per year and emit 177–518 Gg of CO₂-eq per year by 2025. The assessment of annual solid waste generation and GHG emission potential may offer advantages in assisting development of waste management plans in Yangon.     

Situational and dispositional predictors of displays of positive emotions

The study examined the effects of situational (store busyness and customer demand) and dispositional (extraversion, neuroticism, and psychoticism) factors on the display of positive emotions. We found that for situational factors, customer demand was positively related to displayed positive emotions. For personality factors, extraversion was positively related to displayed positive emotions and neuroticism was negatively related to displayed positive emotions. Usefulness analysis showed that both situational and personality factors contributed significantly to explain the level of positive displayed emotion. Copyright © 2003 John Wiley & Sons, Ltd.     

Use of waste rubber as concrete additive.

For resource reutilization, scrap tyres have long been investigated as an additive to concrete to form 'Rubcrete' for various applications and have shown promising results. However, the addition of rubber particles leads to the degradation of physical properties, particularly, the compressive strength of the concrete. In this study, a theoretical model was proposed to shed light on the mechanisms of decrease in compressive strength due to the addition of rubber particles as well as improvement in compressive strength through modification of particle surfaces. The literature suggests that the compressive strength can be improved by soaking the rubber particles in alkaline solution first to increase the inter-phase bonding between the rubber particles and cement. Instead, we discovered that the loss in compressive strength was due to local imperfections in the hydration of cement, induced by the addition of heterogeneous and hydrophobic rubber particles. Microscopic studies showed that the rubber particles disturbed the water transfer to create channels, which were prone to cracking and led to a loss in the compressive strength. Unexpectedly, no cracking was found along the surfaces of the rubber particles, indicating that the bonding strength between the rubber particles and cement phases was not the critical factor in determining the compressive strength. Therefore, a theoretical model was proposed to describe the water transfer in the Rubcrete specimens to explain the experimental data. In the model, the local water available for hydration (Q) is: Q = -A(slv)/6piv, where Q, A(slv), and v are mass flow rate (kg s(-1)), Hamaker constant (J), and dynamic viscosity (m2 s(-1)), respectively. By maximizing the quantity Q and, in turn, the Hamaker constant A(slv), the compressive strength could be improved. The Hamaker constant A(slv) for water film on rubber particle surfaces was smaller than that for the hydrated cement particles; the water transfer rate was lower in the presence of rubber particles because the Hamaker constant A(slv) for water film on rubber particle surfaces was smaller than that on the hydrated cement particles. Thus, the compressive strength of Rubcrete could be improved by increasing the Hamaker constant of the system. This was achieved by increasing the refractive indices of the solids (n(s)). The refractive indices of materials increase with increases in functional groups, such as OH and SH on the surface. The model provided a possible mechanism for the efficacy of treating rubber particles with NaOH in improving the compressive strength. By using NaOH solution treatment, an oxygen-containing OH group was formed on the rubber surface to increase the Hamaker constant of the system, leading to higher compressive strength. Based on this mechanism, a novel method for modification of the rubber particles was also proposed. In this process, the rubber particles were partially oxidized with hot air/steam in a fluidized bed reactor to produce the hydrophilic groups on the surface of the particles. Preliminary results obtained so far are promising in accordance with the theory.     

A Note on the Emission of Nitrogen Oxides from Silage in Opened Bunker Silos

The evolution of NO_x from grass and maize silages wasmeasured using chemiluminescence in samples kept in airtightcontainers, in the silos and in a 750 kg mass removed to a mixer waggon. Measurements were made on the grass and maizesilos in two consecutive years. The results show that thereis continuous evolution of NO_x after silos have been opened and that high concentrations persist in the mass whichare rapidly released on agitation at the feed-out. The maximumrecorded concentrations of NO and NO₂ were 1985 and 152 ppbv respectively. These values are orders of magnitude greaterthan for rural background levels and exceed the maximum hourlyexposure of 50 ppbv for NO₂ recommended by the UK expertpanel for quality standards.