Photocatalytic reduction of organic pollutant under visible light by green route synthesized gold nanoparticles

We report a rapid method of green chemistry approach for synthesis of gold nanoparticles(AuNPs)using Lagerstroemia speciosa leaf extract(LSE). L. speciosa plant extract is known for its effective treatment of diabetes and kidney related problems. The green synthesis of Au NPs was complete within 30 min at 25°C. The same could also be achieved within 2 min at a higher reaction temperature(80°C). Both UV–visible spectroscopy and transmission electron microscopy results suggest that the morphology and size distribution of Au NPs are dependent on the pH of gold solution,gold concentration,volume of LSE,and reaction time and temperature. Comparison between Fourier transform infrared spectroscopy(FT-IR)spectra of LSE and the synthesized Au NPs indicate an active role of polyphenolic functional groups(from gallotannins,lagerstroemin,and corosolic acid)in the green synthesis and capping of Au NPs. The green route synthesized Au NPs show strong photocatalytic activity in the reduction of dyes viz.,methylene blue,methyl orange,bromophenol blue and bromocresol green,and 4-nitrophenol under visible light in the presence of Na BH_4. The non-toxic and cost effective LSE mediated Au NPs synthesis proposed in this study is extremely rapid compared to the other reported methods that require hours to days for complete synthesis of Au NPs using various plant extracts. Strong and stable photocatalytic behavior makes Au NPs attractive in environmental applications,particularly in the reduction of organic pollutants in wastewater.     

Bacterial and archaeal diversity in oil fields and reservoirs and their potential role in hydrocarbon recovery and bioprospecting

Environmental Science and Pollution Research - Hydrocarbon is a primary source of energy in the current urbanized society. Considering the increasing demand, worldwide oil productions are declining...     

Seasonal variation and sources of carbonaceous species and elements in PM2.5 and PM10 over the eastern Himalaya

Environmental Science and Pollution Research - The study represents the seasonal characteristics (carbonaceous aerosols and elements) and the contribution of prominent sources of PM2.5 and PM10 in...     

Nutrient concentrations affect the antimicrobial resistance profiles of cattle manures

Environmental Science and Pollution Research - Antimicrobial resistance (AMR) in cattle is widespread because of the increased use of antibiotics to combat microbial diseases and enhance milk...     

Gap acceptance behavior at unsignalized intersections: Effects of using a phone and a music player while driving

Objectives: The present study is an attempt to analyze and compare the distraction effects caused by the use of a phone and a music player at unsignalized intersections.

Method: Eighty-eight participants performed simulated driving experiments where they faced a sequence of gaps in the major road traffic at 2 unsignalized intersections. In this process, their driving behavior was evaluated in terms of gap acceptance probability, accepted lag, and maneuver completion time. These parameters were modeled with a generalized estimating equation (GEE) method by considering distraction, demographic factors, driving history, maneuver types, and driving attributes in the approach and completion zones as independent variables.

Results: The results showed that gap acceptance probability decreased by 46% during the conversation task, whereas it increased by 66% during the music player task. Lower gap acceptance could be a compensatory behavior adopted by drivers during the conversation task, whereas no such measure was adapted during the music player task. The results indicate that a higher approach speed during the music player task might have led to increased gap acceptance. Further, though the effect of distraction on the accepted lag was not evident, the completion time was reduced during the conversation task.

Conclusions: Overall, the results suggest that drivers are more likely to adopt a compensatory measure in complex driving situations only if they perceive a high risk. Hence, drivers are exposed to a greater risk while operating a music player, because this is not perceived as risky behavior.     

Environmental impact assessment of a ceramic tile supply chain – a case study

The beginning of the twenty-first century saw a surge in the growth of construction industry, particularly the housing sector in India. This led to the growing demand of ceramic tiles. This growth is responsible for large-scale consumption of natural resources and generation of solid waste. The objective of this paper is to assess the environmental impact of vitrified ceramic floor tile supply chain by performing life cycle assessment (LCA) following international standards of ISO 14040 series guidelines. The impact has been determined by conducting a LCA using Umberto NXT software (eco-invent 3.0 database) with ReCiPe endpoint and midpoint methods. It has been found that the manufacturing stage of supply chain is generating highest impact on environment in all the categories. Impact analysis of different input resources/material shows that red oxide used in glaze preparation, electricity in manufacturing, packaging material, distribution by trucks, installation of tiles using concrete and disposal of packaging material are responsible for most of the environmental impact. This study will offer the essential quantitative assessment to recognise the phases and materials which are highly responsible for the degradation of environment so that appropriate interventions by the different stakeholders can be planed.     

Assessment of background levels of trace metals in water and soil from a remote region of Himalaya

Selected trace metals were estimated by atomic absorption spectrometry in the water and soil samples collected from the remote region of Himalaya. The soil samples were analysed for soluble and acid extractable fraction of trace metals. In water samples, Ca, Na, Mg and K emerged as dominant contributors, whereas, Ca, Na, K, Mg, Fe and Pb were estimated at comparatively higher levels in the water extract of the soil. In case of acid extract of the soil samples, Ca, K, Fe, Mg, Mn and Na were found at elevated concentrations. Based on mean levels of the metals, following decreasing concentration order was observed in water samples: Ca > Na > Mg > K > Pb > Co > Cu > Zn > Mn > Cr > Fe > Cd > Li, however, in the acid extract of the soil, following order was noted: Ca > K > Fe > Mg > Mn > Na > Pb > Zn > Cr > Li > Cu > Co > Cd. The correlation study revealed appreciably diverse mutual relationships of trace metals in the water and soil samples. The multivariate cluster analyses exhibited divergent apportionment of trace metals in water and soil samples. Among the trace metals, Cd, Pb, Li, Zn, Cr, Cu, Mn and Co exhibited extreme to significant anthropogenic enrichment in the soil samples, while the rest of the metals were mostly contributed by the natural processes.     

Epibrassinolide ameliorates Cr (VI) stress via influencing the levels of indole-3-acetic acid, abscisic acid, polyamines and antioxidant system of radish seedlings

The present investigation determined the effects of epibrassinolide (EBL) on the levels of indole-3-acetic acid (IAA), abscisic acid (ABA), and polyamine (PA) and antioxidant potential of 7-d old Raphanus sativus L. cv. ‘Pusa chetki’ seedlings grown under Cr (VI) metal stress. Reduced titers of free (0.767 μg g⁻¹ FW) and bound (0.545 μg g⁻¹ FW) IAA in Cr (VI) stressed seedlings were observed over untreated control. Supplementations of EBL to Cr (VI) stressed seedlings were able to enhance both free (2.14-5.68 μg g⁻¹ FW) and bound IAA (2.45-7.78 μg g⁻¹ FW) concentrations in comparison to Cr (VI) metal treatment alone. Significant rise in free (13.49 μg g⁻¹ FW) and bound (12.17 μg g⁻¹ FW) ABA contents were noticed for Cr (VI) stressed seedlings when compared to untreated control. No significant increase in ABA contents were recorded for Cr (VI) stressed seedlings upon supplementation with EBL over Cr (VI) treatment alone. A significant increase in Put (18.40 μg g⁻¹ FW) and Cad (9.08 μg g⁻¹ FW) contents were found for 10⁻⁹ M EBL plus Cr (VI) metal treatments when compared to Cr (VI) treatment alone. Spermidine (Spd) contents were found to decline significantly for EBL treatment alone or when supplemented with Cr (VI) treatments over untreated controls and Cr (VI) treatment alone. Antioxidant levels were found to enhance, with glutathione (57.98 mg g⁻¹ FW), proline (4.97 mg g⁻¹ FW), glycinebetaine (39.01 μmol mL⁻¹), ascorbic acid (3.17 mg g⁻¹ FW) and phytochelatins (65.69 μmol g⁻¹ FW) contents noted for EBL supplemented to Cr (VI) metal solution over Cr (VI) treatment alone. Reduced activities of guaiacol peroxidase (0.391 U mg⁻¹ protein) and catalase (0.221 U mg⁻¹ protein) and enhanced activities of glutathione reductase (7.14 U mg⁻¹ protein), superoxide dismutase (15.20 U mg⁻¹ protein) and ascorbate peroxidase (4.31 U mg⁻¹ protein) were observed in seedlings treated with EBL plus Cr (VI) over Cr metal treatment alone. Reduced MDA (2.55 μmol g⁻¹ FW) and H₂O₂ (33.24 μmol g⁻¹ FW) contents were recorded for 10⁻⁹ M EBL supplemented to Cr (VI) stress over Cr (VI) treatment alone. Enhancement in free radical scavenging potential as indicated by higher values of 1,1-diphenylpicrylhydrazyl, deoxyribose and reducing power activity assays, and increased levels of phenols and soluble sugars also showed significant influence of EBL in alleviating Cr (VI) stress in radish seedlings.     

Chemical characteristics and source apportionment of PM<Subscript>2.5</Subscript> using PCA/APCS,UNMIX, and PMF at an urban site of Delhi,India

The present study investigated the comprehensive chemical composition [organic carbon (OC), elemental carbon (EC), water-soluble inorganic ionic components (WSICs), and major & trace elements] of particulate matter (PM_2.5) and scrutinized their emission sources for urban region of Delhi. The 135 PM_2.5 samples were collected from January 2013 to December 2014 and analyzed for chemical constituents for source apportionment study. The average concentration of PM_2.5 was recorded as 121.9 ± 93.2 μg m^?3 (range 25.1–429.8 μg m^?3), whereas the total concentration of trace elements (Na, Ca, Mg, Al, S, Cl, K, Cr, Si, Ti, As, Br, Pb, Fe, Zn, and Mn) was accounted for ～17% of PM_2.5. Strong seasonal variation was observed in PM_2.5 mass concentration and its chemical composition with maxima during winter and minima during monsoon seasons. The chemical composition of the PM_2.5 was reconstructed using IMPROVE equation, which was observed to be in good agreement with the gravimetric mass. Source apportionment of PM_2.5 was carried out using the following three different receptor models: principal component analysis with absolute principal component scores (PCA/APCS), which identified five major sources; UNMIX which identified four major sources; and positive matrix factorization (PMF), which explored seven major sources. The applied models were able to identify the major sources contributing to the PM_2.5 and re-confirmed that secondary aerosols (SAs), soil/road dust (SD), vehicular emissions (VEs), biomass burning (BB), fossil fuel combustion (FFC), and industrial emission (IE) were dominant contributors to PM_2.5 in Delhi. The influences of local and regional sources were also explored using 5-day backward air mass trajectory analysis, cluster analysis, and potential source contribution function (PSCF). Cluster and PSCF results indicated that local as well as long-transported PM_2.5 from the north-west India and Pakistan were mostly pertinent.     

Efficacy of fenvalerate as contact poison against the larval development and viability of mutant form (Sepia) of Drosophila melanogaster (Meigen)

Fenvalerate, a synthetic pyrethroid, was analysed for its toxic effects on Drosophila melanogaster. It has been estimated that LC50 0.0166 micro 1/100 ml food is threshold of lethality. These studies have also revealed that fenvalerate is toxic as it had a pronounced effect on the rate of development and viability.