Sulfur and oxygen isotope tracing in zero valent iron based In situ remediation system for metal contaminants

In the present study, controlled laboratory column experiments were conducted to understand the biogeochemical changes during the microbial sulfate reduction. Sulfur and oxygen isotopes of sulfate were followed during sulfate reduction in zero valent iron incubated flow through columns at a constant temperature of 20 ± 1 °C for 90 d. Sulfur isotope signatures show considerable variation during biological sulfate reduction in our columns in comparison to abiotic columns where no changes were observed. The magnitude of the enrichment in δ³⁴S values ranged from 9.4‰ to 10.3‰ compared to initial value of 2.3‰, having total fractionation δS between biotic and abiotic columns as much as 6.1‰. Sulfur isotope fractionation was directly proportional to the sulfate reduction rates in the columns. Oxygen isotopes in this experiment seem less sensitive to microbial activities and more likely to be influenced by isotopic exchange with ambient water. A linear relationship is observed between δ³⁴S and δ¹⁸O in biotic conditions and we also highlight a good relationship between δ³⁴S and sulfate reduction rate in biotic columns.     

The use of multiple tracers for tracking wastewater discharges in freshwater systems

The assessment of potential impacts of wastewater effluent discharges in freshwater systems requires an understanding of the likely degrees of dilution and potential zones of influence. In this study, four tracers commonly present in wastewater effluents were monitored to compare their relative effectiveness in determining areas in freshwater systems that are likely to be impacted by effluent discharges. The four tracers selected were the human pharmaceutical carbamazepine, anthropogenic gadolinium, fluorescent-dissolved organic matter (fDOM), and electrical conductivity (EC). The four tracers were monitored longitudinally in two distinct freshwater systems receiving wastewater effluents, where one site had a high level of effluent dilution (effluent <1 % of total flow) and the other site had a low level of effluent dilution (effluent ～50 % of total flow). At both sites, the selected tracers exhibited a similar pattern of response intensity downstream of discharge points relative to undiluted wastewater effluent, although a number of anomalies were noted between the tracers. Both EC and fDOM are non-specific to human influences, and both had a high background response, relative to the highly sensitive carbamazepine and anthropogenic gadolinium responses, although the ease of measuring EC and fDOM would make them more adaptable in highly variable systems. However, the greater sensitivity and selectivity of carbamazepine and gadolinium would make their combination with EC and fDOM as tracers of wastewater effluent discharges highly desirable to overcome potential limitations of individual tracers.     

How Should Support for Climate-Friendly Technologies Be Designed?

Stabilizing global greenhouse gas concentrations at levels to avoid significant climate risks will require massive “decarbonization” of all the major economies over the next few decades, in addition to the reduced emissions from other GHGs and carbon sequestration. Achieving the necessary scale of emissions reductions will require a multifaceted policy effort to support a broad array of technological and behavioral changes. Change on this scale will require sound, well-thought-out strategies. In this article, we outline some core principles, drawn from recent social science research, for guiding the design of clean technology policies, with a focus on energy. The market should be encouraged to make good choices: pricing carbon emissions and other environmental damage, removing distorting subsidies and barriers to competition, and supporting RD&D broadly. More specific policies are required to address particular market failures and barriers. For those technologies identified as being particularly desirable, some narrower RD&D policies are available.     

Arsenic accumulation in native plants of West Bengal, India: prospects for phytoremediation but concerns with the use of medicinal plants

Arsenic (As) is a widespread environmental and food chain contaminant and class I, non-threshold carcinogen. Plants accumulate As due to ionic mimicry that is of importance as a measure of phytoremediation but of concern due to the use of plants in alternative medicine. The present study investigated As accumulation in native plants including some medicinal plants, from three districts [Chinsurah (Hoogly), Porbosthali (Bardhman), and Birnagar (Nadia)] of West Bengal, India, having a history of As pollution. A site-specific response was observed for Specific Arsenic Uptake (SAU; mg kg(-1) dw) in total number of 13 (8 aquatic and 5 terrestrial) collected plants. SAU was higher in aquatic plants (5-60 mg kg(-1) dw) than in terrestrial species (4-19 mg kg(-1) dw). The level of As was lower in medicinal plants (MPs) than in non-medicinal plants, however it was still beyond the WHO permissible limit (1 mg kg(-1) dw). The concentration of other elements (Cu, Zn, Se, and Pb) was found to be within prescribed limits in medicinal plants (MP). Among the aquatic plants, Marsilea showed the highest SAU (avg. 45 mg kg(-1) dw), however, transfer factor (TF) of As was the maximum in Centella asiatica (MP, avg. 1). Among the terrestrial plants, the maximum SAU and TF were demonstrated by Alternanthera ficoidea (avg. 15) and Phyllanthus amarus (MP, avg. 1.27), respectively. In conclusion, the direct use of MP or their by products for humans should not be practiced without proper regulation. In other way, one fern species (Marsilea) and some aquatic plants (Eichhornia crassipes and Cyperus difformis) might be suitable candidates for As phytoremediation of paddy fields.     

Plant steroid hormones produced under Ni stress are involved in the regulation of metal uptake and oxidative stress in Brassica juncea L

Brassinosteroids (BRs) are involved in the amelioration of various biotic and abiotic stresses. With an aim to explore the role of BRs under heavy metal stress, plants of Brassica juncea L. were grown in pots. The plants were subjected to various concentrations of Nickel metal (0.0, 0.2, 0.4 and 0.6 mM) and harvested on 60th day in order to observe the expression of these hormones. The isolated BRs from the leaves of Brassica plants characterized by GC-MS include 24-Epibrassinolide (24-EBL), Castasterone, Dolicholide and Typhasterole. The effect of isolated 24-EBL was studied on Ni metal uptake and antioxidative defense system in 60 d old plants of Brassica. It was observed that 24-EBL significantly increased the activities of stress ameliorating enzymes and lowered the metal uptake in plants. This is the first report in B. juncea L. plants showing the expression of BRs under metal treatments and effect of the isolated 24-EBL on metal uptake and in oxidative stress management.     

Dibenzazepin hydrochloride as a new spectrophotometric reagent for determination of hydrogen peroxide in plant extracts

A rapid, simple, accurate, and sensitive visible spectrophotometric method for the determination of trace amounts of hydrogen peroxide in acidic buffer medium is reported. The proposed method is based on the oxidative coupling of Ampyrone with dibenzazepin hydrochloride by hydrogen peroxide in the buffer medium of pH?4.0 which is catalyzed by ferrous iron. The blue-colored product formed with maximum absorption at 620?nm was found to be stable for 2?h. Beer's law is obeyed for hydrogen peroxide concentration in the range of 0.03-0.42?μg?ml(-1). The optimum reaction conditions and other important optical parameters are reported. The molar absorptive and Sandell's sensitivity are found to be 5.89?×?10(4)?mol(-1)?cm(-1) and 0.57?g/cm(2), respectively. The interference due to diverse ions and complexing agents was studied. The method is successfully applied to the determination of hydrogen peroxide in green plants satisfactorily.     

Land use patterns and urbanization in the holy city of Varanasi, India: a scenario

Rapid urbanization and increasing land use changes due to population and economic growth in selected landscapes is being witnessed of late in India and other developing countries. The cities are expanding in all directions resulting in large-scale urban sprawl and changes in urban land use. The spatial pattern of such changes is clearly noticed on the urban fringes or city peripheral rural areas than in the city center. In fact, this is reflected in changing urban land use patterns. There is an urgent need to accurately describe land use changes for planning and sustainable management. In the recent times, remote sensing is gaining importance as vital tool in the analysis and integration of spatial data. This study intends to estimate land use pattern in a planned and unplanned urban setup and also to analyze the impact of change in land use pattern in the Varanasi urban environment. The results indicate that the planned urban setup had a higher tree cover to that of unplanned area in the Varanasi City, although a considerable disparity existed within the planned urban setups. The results emphasize the need to critically review concepts of urban planning and give more consideration to the preservation and management of urban tree cover/greenspace.     

Biodegradable Water Soluble Copolymer for Antimicrobial Applications

Synthesis and characterization of novel biodegradable, water soluble and optically active DL-malic acid (DMA) and citric acid (CA) copolymers were studied for possible use as antibacterial agents. The copolymers were synthesized by direct bulk melt condensation in the absence of a catalyst above 150 °C. Characterization of obtained copolymers was carried out with the help of infrared absorption spectra, differential scanning calorimetry and thermo gravimetric analysis. The antibacterial activity of copolymers against bacteria was investigated. The results obtained shows the above copolymers possess a broad wound dressing activity against different types of bacteria and may be useful as antibacterial agents.     

Multiresidue analysis of neonicotinoids by solid-phase extraction technique using high-performance liquid chromatography

For routine monitoring of pesticides, a multiresidue analysis through solid-phase extraction technique and using high-performance liquid chromatography (HPLC) in cotton seed cake (CSC) has been developed. Extraction of fortified samples was carried out with aqueous acetone under vacuum. The concentrated extract was loaded onto the solid-phase extraction units, preconditioned with acetonitrile. The extraction units were then washed with hexane and finally eluted with acetonitrile. The pesticide residues were determined using a multiresidue method by reversed-phase HPLC. The average percentage recoveries were found to range between 65.47% and 110% at spiking levels of 10 to 40 mg/kg. The method developed shows a healthy rate of recovery and can successfully be utilized for the extraction and screening of neonicotinoid residues in CSC. The detection limits for imidacloprid, acetamiprid, and thiacloprid using this method were found to be 5, 10, and 20 mg/kg, respectively.     

How should support for climate-friendly technologies be designed?

Stabilizing global greenhouse gas concentrations at levels to avoid significant climate risks will require massive "decarbonization" of all the major economies over the next few decades, in addition to the reduced emissions from other GHGs and carbon sequestration. Achieving the necessary scale of emissions reductions will require a multifaceted policy effort to support a broad array of technological and behavioral changes. Change on this scale will require sound, well-thought-out strategies. In this article, we outline some core principles, drawn from recent social science research, for guiding the design of clean technology policies, with a focus on energy. The market should be encouraged to make good choices: pricing carbon emissions and other environmental damage, removing distorting subsidies and barriers to competition, and supporting RD&D broadly. More specific policies are required to address particular market failures and barriers. For those technologies identified as being particularly desirable, some narrower RD&D policies are available.