Arsenic in shallow aquifer in the eastern region of Bangladesh: insights from principal component analysis of groundwater compositions

Probable sources and mechanisms of arsenic (As) release in shallow aquifer in eastern Bangladesh are evaluated using statistical analysis of groundwater compositions. Dissolved As in 39 samples ranged from 8.05 to 341.5 μg/L with an average of 95.14 μg/L. Ninety seven percent of wells exceed the WHO limit (10 μg/L) for safe drinking water. Principal component analysis is applied to reduce 16 measured compositional variables to five significant components (principal components—PCs) that explain 86.63% of the geochemical variance. Two component loadings, namely PC 1 and PC 2 (45.31% and 23.05%) indicate the natural processes within the aquifers in which organic matter is a key reactant in the weathering reactions. Four groups of wells are defined by the PCA and each group of wells represents distinct physicochemical characteristics. Among them, group III groundwater shows higher As concentration together with high concentrations of Fe, Mn, dissolved organic carbon, $\text{PO}_{4}^{3-}$ and $\text{HCO}_{3}^{-}$ than groups I and II. Speciation calculations suggest that only wells of group III are saturated with respect to siderite, and all groups of samples are supersaturated with respect of rhodochrosite. The relationship of As with these parameters in the different groups of wells of the study area suggests that reductive dissolution of Fe–Mn oxyhydroxides with microbially mediated degradation of organic matter is considered to be the dominant processes to release As in groundwater.     

Biosynthesis of Poly(3-hydroxybutyrate) from Cheese Whey by <Emphasis Type="Italic">Bacillus megaterium</Emphasis> NCIM 5472

Microbial polyhydroxyalkonate such as homopolyester of poly(3-hydroxybutyrate) (PHB) was produced from cheese whey by Bacillus megaterium NCIM 5472. Due to their numerous potential industrial applications, the focus was given to competently enhance the amount of PHB produced. The amount of PHB produced from whole cheese whey, and ultrafiltered cheese whey was first compared, and after observing a rise in PHB production by using ultrafiltered cheese whey, cheese whey permeate was chosen for further analysis. The presence of PHB was then confirmed by GCMS. Since the main aim of the study was to increase the amount of PHB produced through batch fermentation, various process parameters like time, pH, C/N ratio, etc. were optimized. After optimization, it was found that B. megaterium NCIM 5472 was capable of accumulating 75.5% of PHB of its dry weight and a PHB yield of 8.29 g/L. The chemical structure of the polymer was further analyzed by using FTIR and NMR spectroscopy methods. Also, the physical and thermal properties were studied by using Differential scanning calorimetry and Thermogravimetric analysis. It was found that the polymer produced had excellent thermal stability, thus allowing the possibility to exploit its properties for industrial purposes such as adhesives, packaging materials, etc.     

Mammalian toxicity of Technical X-factor I. An acute oral study

Intragastric administration of acute doses of Technical X-factor (beta-isomer free BHC, a byproduct obtained during separation of Lindane from Tech. BHC) carried in peanut oil elicited typical signs of central nervous system depression in adult rats. The computed oral LD50 values of X-factor were 4174 and 5673 mg/kg. body weight for male and female rats respectively indicating that its acute toxicity was of relatively low order compared to Tech. BHC. It is suggested that the low acute mammalian toxicity of X-factor could possibly be due to a direct antagonism of the delta isomer (present in larger proportion in X-factor) with the gamma isomer.     

Environmental change of coastal Sundarbans: Impact on livelihood and standard of living status of indigenous people

There is overwhelming scientific consensus that environmental change is currently having ecological and socioeconomical impacts at the micro and macrolevel. Over the coming decades, the impact of development, climate change, and urbanization on the ecosystem is likely to become even more ruthless in the Sundarbans. Like many other ecologically sensitive areas, the Sundarbans of the Indian state of West Bengal and of Bangladesh are being stressed climatically to the extreme due to their geographical location. This study explores both the ways in which residents of communities in the West Bengal and Bangladesh Sundarbans perceive changes in the environment, as well as intergenerational changes in livelihoods to be driven in a large part by environmental changes. Persons from a total of 368 households were interviewed using a structured interview tool. As an example of differences in perception between residents of the two areas, survey respondents from communities of the Sundarbans of Bangladesh were more likely to perceive that rainfall amounts are changing than did the residents interviewed from the Sundarbans of West Bengal. From the sample data, it is shown that in the Sundarbans of Bangladesh, 59% of the respondents, as compared to 63% of the respondents in West Bengal, reported that they had chosen to enter their parents’ occupations. From the multivariate logistic regression analysis, it was observed that, especially in Bangladesh when compared to West Bengal, the state of the environment plays a vital role in whether respondents adopt occupations other than those of their parents.     

Metal-oxide coated Graphene oxide nano-composite for the treatment of pharmaceutical compound in photocatalytic reactor: Batch,Kinetics and Mathematical Modeling using Response Surface Methodology and Artificial Neural Network

Environmental Science and Pollution Research - Titanium dioxide (TiO2) photocatalyst has gained constant interest in the treatment of wastewater because of its greater stability, lower cost,...     

Inorganic arsenic: A non-genotoxic carcinogen

Inorganic arsenic induces a variety of toxicities including cancer. The mode of action for cancer and non-cancer effects involves the metabolic generation of trivalent arsenicals and their reaction with sulfhydryl groups within critical proteins in various cell types which leads to the biological response. In epithelial cells, the response is cell death with consequent regenerative proliferation. If this continues for a long period of time, it can result in an increased risk of cancer. Arsenicals do not react with DNA. There is evidence for indirect genotoxicity in various in vitro and in vivo systems, but these involve exposures at cytotoxic concentrations and are not the basis for cancer development. The resulting markers of genotoxicity could readily be due to the cytotoxicity rather than an effect on the DNA itself. Evidence for genotoxicity in humans has involved detection of chromosomal aberrations, sister chromatid exchanges in lymphocytes and micronucleus formation in lymphocytes, buccal mucosal cells, and exfoliated urothelial cells in the urine. Numerous difficulties have been identified in the interpretation of such results, including inadequate assessment of exposure to arsenic, measurement of micronuclei, and potential confounding factors such as tobacco exposure, folate deficiency, and others. Overall, the data strongly supports a non-linear dose response for the effects of inorganic arsenic. In various in vitro and in vivo models and in human epidemiology studies there appears to be a threshold for biological responses, including cancer.     

Efficacy of indigenous soil microbes in arsenic mitigation from contaminated alluvial soil of India

Selected arsenic-volatilizing indigenous soil bacteria were isolated and their ability to form volatile arsenicals from toxic inorganic arsenic was assessed. Approximately 37 % of AsIII (under aerobic conditions) and 30 % AsV (under anaerobic conditions) were volatilized by new bacterial isolates in 3 days. In contrast to genetically modified organism, indigenous soil bacteria was capable of removing 16 % of arsenic from contaminated soil during 60 days incubation period while applied with a low-cost organic nutrient supplement (farm yard manure).     

Isomerization of beta-HCH in aqueous solution

beta-HCH was shaken with distilled water at 25 +/- 1 degree C for different time intervals and filtered. The ether extract of the filtrate on analysis by gas liquid chromatography showed the presence of four isomers, alpha, beta, gamma and delta, besides other compounds, thereby indicating isomerization of the beta-isomer in aqueous solution. Further, the ether extract, when dried and dissolved in acetone, showed high toxicity to mosquito larvae, flour beetle larvae and house-flies thereby indicating conversion of the inert beta-isomer to more toxic forms corroborating GLC analysis. Acetone solution of pure beta-HCH was found nontoxic against the insects tested.     

Environmental quality in India: Application of environmental Kuznets curve and Sustainable Human Development Index

This study explores the trend of selected air pollutants, carbon dioxide (CO₂), nitrogen dioxide NO₂), sulfur dioxide (SO₂) and particulate matter 10 microns in diameter (PM₁₀) in India. Environmental Kuznets curves (EKC), which show the association of the economy and pollution, are fitted for selected Indian states to understand whether EKC in India fits well with the inverted “U” shape. We observed that CO₂ and PM₁₀ are steadily increasing in India. The states of Kerala and Punjab follow the inverted “U” shape of EKC, while Bihar, Uttar Pradesh, West Bengal, and Maharashtra may take decades to reduce pollutants. A new Sustainable Human Development Index calculated in this paper indicates a diverse picture of Indian states, especially in regard to environmental parameters. The government needs to implement stringent, state‐specific laws and regulations to assist in curbing air pollutants. The time has also come to represent the rankings of states in terms of an environmentally inclusive development index.