Comparative Biodegradation Studies of Non-poronized and Poronized LDPE Using Indigenous Microbial Consortium

Seventeen bacterial isolates were screened for the utilization of low density polyethylene (LDPE) as the sole carbon source, out of which five potential strains were selected for the development of a consortium. In vitro biodegradation efficiency of the consortium was studied for two differently textured forms of LDPE viz. non-poronized and poronized. Although, both the forms were acted-upon well by the consortium, but the degradation was found to be better in the poronized form. This was substantiated by λ-max shift, FTIR spectra and simultaneous TG-DTG-DTA. The analysis revealed the breakage and formation of chemical bonds in the polymer backbone, as a result of microbial activity. The biodegraded samples of non-poronized and poronized LDPE exhibited similar weight losses at 400 °C (24.12% and 24.48%, respectively) as compared to their controls (4% and 4.5% respectively), but the latter could achieve it with greater ease as reveled by its lower heat of reactions (ΔH values). The study signifies the influence of poronization of polyethylene on its rate of biodegradation.     

A Composting Study of Membrane-Like Polyvinyl Alcohol Based Resins and Nanocomposites

This study presents the effect of biodegradation, in a composting medium, on properties of membrane-like crosslinked and noncrosslinked polyvinyl alcohol (PVA) and nanocomposites. The composting was carried out for 120 days and the biodegradation of these materials was characterized using various techniques. The changes in the PVA resin and nanocomposite surface topography and microstructure during composting were also characterized. The results from the analyses suggest biodegradation of PVA based materials in compost medium was mainly by enzymes secreted by fungi. The results also indicate that the enzymes degraded the amorphous regions of the specimens first and that the PVA crystallinity played an important role in its biodegradation. The surface roughness of the specimens was seen to increase with composting time as the microbial colonies grew which in turn facilitated further microorganism growth. All specimens broke into small pieces between 90 and 120 days of composting as a result of deep biodegradation. Glyoxal and malonic acid crosslinking decreased the PVA biodegradation rate slightly. Addition of highly crystalline microfibrillated cellulose and naturally occurring halloysite nanotubes in PVA based nanocomposites also decreased the biodegradation rate. The three factors: PVA crystallinity, crosslinking and additives, may be utilized effectively to extend the life of these materials in real life applications.     

Dietary Spirulina platensis alleviates aluminum and aluminum fluoride induced histopathological and biochemical alterations in mice kidney

Aluminum and its salts widely used in our daily life have been reported nephrotoxic to humans and animals following prolonged exposure. Therefore, the present study was made to examine the renoprotective role of Spirulina platensis against Al³⁺ and AlF₃ in male Swiss albino mice. Exposure to these chemicals decreased feed and water intake, and body and kidney weights. Histology of kidney and their biochemistry were also markedly altered along with that of serum biochemistry. Spirulina not only minimize toxic effects of test chemicals but also favored faster recovery of treated mice after their withdrawal.     

Decentralization and people's participation in conservation: a comparative study from the Western Terai of Nepal

Nepal formally embarked on decentralized participatory conservation programmes in 1990. To assess who participates in and benefits from such programmes, stratified random questionnaire surveys of 234 households and interviews with 29 user group chairs were conducted in the buffer zones of two protected areas of the Nepalese Terai: Bardia National Park and Suklaphanta Wildlife Reserve. The Poisson regression shows that gender, education, household affluence, and conservation attitudes were significant predictors of people's participation in decentralized conservation programmes, while family size, ethnicity and resource dependency were not. The benefits of participation outweighed the costs based on respondents' estimates. The performance of grassroots organizations and levels of participation were correlated. Nepal's decentralized participatory conservation has achieved efficiency, relative equity and effectiveness to some extent. Yet the central government should devolve more power to local communities to sustain the achievements as well as to provide more equitable benefits to residents to ensure the effectiveness and sustainability of conservation programmes.     

Enumeration of methanogens with a focus on fluorescence in situ hybridization

Methanogens, the members of domain Archaea are potent contributors in global warming. Being confined to the strict anaerobic environment, their direct cultivation as pure culture is quite difficult. Therefore, a range of culture-independent methods have been developed to investigate their numbers, substrate uptake patterns, and identification in complex microbial communities. Unlike other approaches, fluorescence in situ hybridization (FISH) is not only used for faster quantification and accurate identification but also to reveal the physiological properties and spatiotemporal dynamics of methanogens in their natural environment. Aside from the methodological aspects and application of FISH, this review also focuses on culture-dependent and -independent techniques employed in enumerating methanogens along with associated problems. In addition, the combination of FISH with micro-autoradiography that could also be an important tool in investigating the activities of methanogens is also discussed.     

Bioefficacy of insecticides against Leucinodes orbonalis on brinjal

Studies on bioefficacy of insecticides against brinjal shoot and fruit borer, Leucinodes orbonalis Guenee on brinjal were carried out during 2007 and 2008. The results on bioefficacy of insecticides showed that in terms of shoot infestation, emamectin benzoate (0.002%), endosulfan (0.05%), novaluron (0.01%) and lambda-cyhalothrin (0.004%) were found superior. The total number of drooping shoots was minimum (4.17) in emamectin benzoate followed by endosulfan (6.83) and novaluron (7.00), as compared to spinosad (9.17), deltamethrin (11.67) and Bacillus thuringiensis (13.17). In terms of reduction in fruit infestation, emamectin benzoate (0.002%) was highly effective followed by endosulfan (0.05%), agrospray oil T (0.2%) and spinosad (0.0024%). However, cost benefit ratio was highest in agrospray oil T (0.2%) followed by lambda-cyhalothrin (0.004%), endosulfan (0.05%) and deltamethrin (0.0028%).     

Solar photocatalytic degradation of the herbicide isoproturon on a Bi–TiO2/zeolite photocatalyst

The photocatalytic degradation of the herbicide isoproturon under solar light was investigated in aqueous solution containing a Bi–TiO₂/zeolite photocatalyst. The catalysts were characterized using X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The effect of Bi–TiO₂ loading onto the zeolite support and influence of the parameters such as catalyst amount, pH, and initial concentration of isoproturon on the degradation rate were evaluated. The recycling ability of the catalyst was found to be sustainable for elongated periods. The high activity of the Bi–TiO₂/zeolite was attributed to its absorptivity of visible light and its high adsorption capacity for the pollutant molecules.     

Phytoplankton community structure in relation to environmental factors from the New Mangalore Port waters along the southwest coast of India

Seasonal and spatial phytoplankton distribution in relation to environmental factors was investigated in New Mangalore Port, a major port along the west coast of India. A well-mixed water column characterized the non-monsoon seasons, whereas it was weakly stratified during monsoon. Water quality index (TRIX) scores indicated good water quality except during pre-monsoon (inner zone surface) and monsoon (near bottom waters). Surface abundance of tychopelagic diatoms (Paralia sulcata, Melosira nummuloides, Cylindrotheca closterium, and Nitzschia sigma) was higher during non-monsoon seasons. Certain centric diatoms, e.g., Leptocylindrus danicus, P. sulcata, and Rhizosolenia imbricata, dominated during pre-monsoon (inner zone) and positively correlated with TRIX. High Skeletonema costatum and dinoflagellate abundance during the monsoon season coincided with high nutrient concentrations. Five potential toxic and fourteen harmful/bloom forming algal species were encountered at abundances below the level that can be considered as harmful to the ecosystem. In addition to a baseline database, this study highlights the potential use of certain diatom species as indicators of hydrography and water quality for monitoring dynamic coastal marine ecosystems.     

Influence of real and synthetic municipal solid waste leachates on consolidation and shear strength behaviour of bentonites

Environmental Science and Pollution Research - For safe disposal of wastes in landfills, compacted bentonite is recommended as bottom liners due to their significant cation exchange (CEC) and...     

Enforcement Authority and Vegetation Change at Kumbhalgarh Wildlife Sanctuary,Rajasthan, India

Land cover change in protected areas is often associated with human use, especially illicit extraction, but the direction and spatial distribution of such effects and their drivers are poorly understood. We analyze and explain the spatial distribution of vegetation change at the Kumbhalgarh Wildlife Sanctuary in the Aravalli range of Rajasthan, India using remotely sensed data and observation of conservation institutions. Two satellite images are examined in time series over the 13 years following the founding of the sanctuary through a cross-tabulation technique of dominant classes of vegetation density. The resulting change trajectories are compared for their relative distance to high-traffic forest entrance points for local users. The results show 28% of the study area undergoing change, though in multiple trajectories, with both increasing and decreasing density of vegetation in discrete patches. Areas of change are shown to be closer to entrance points than areas experiencing no change. The patchiness of change results from complex issues in local enforcement authority for middle and lower-level officials in Forest Department bureaucracy, leading to further questions about the efficacy and impact of use restrictions in Protected Areas.