Eco-friendly dyeing of cotton with brown natural dye extracted from Ficus amplissima Smith leaves

Environmental Chemistry Letters - We have extracted a new brown-coloured natural dye from the leaves of Ficus amplissima Smith using Soxhlet extraction. The dye was assessed for...     

Duckweed: an effective tool for phyto-remediation

Effective wastewater treatment through conventional methods that rely on heavy aeration are expensive to install and operate. Duckweed is capable of recovering or extracting nutrients or pollutants and is an excellent candidate for bio-remediation of wastewaters. Such plants grow very fast, utilizing wastewater nutrients and also yield cost effective protein-rich biomass as a by-product. Duckweeds being tiny surface-floating plants are easy to harvest and have an appreciable amount of protein (15%–45% dry mass basis) and a lower fiber (7%–14% dry mass basis) content. Besides nutrient extraction, duckweeds has been found to reduce total suspended solids, biochemical oxygen demand (BOD), and chemical oxygen demand in wastewater significantly. Depending on the initial concentrations of nutrients, duckweed-covered systems can remove nitrate (NO₃^?) at daily rates of 120–590 mg NO₃^? m^?2 (73%–97% of initial concentration) and phosphate (PO₄^?) at 14–74 mg PO₄^? m^?2 (63%–99% of initial concentration). Removal efficiencies within 3 days of 96% and 99% have been reported for BOD and ammonia (NH₃). Besides several genera of duckweeds (Spirodela, Lemna, Wolffia), other surface-floating aquatic plants like water hyacinth (Eichhornia) are well known for their phyto-remediation qualities.     

Feasibility of PV–biodiesel hybrid energy system for a cement technology institute in India

This paper compares an existing unreliable grid supply with a proposed PV–biodiesel hybrid energy system in order to find the feasibility of the latter for improvement in reliability of power supply, lower pollutant emissions and saving of coal reserves. In the present study, the electrical load of a cement technology institute located in Bhilai, India, has been selected for the purpose of analysis. The results show that hybrid PV–biodiesel system comprising 25 kW PV array, 8 kW biodiesel generator-1, 20 kW biodiesel generator-2, 10 kW inverter and 10 kW rectifier will supply power to the institute avoiding addition of 27.744 tons of CO₂ in atmosphere and save 55,080 kg of coal per year with improvement in reliability from 93.15 to 100%.     

Exploring the Adaptation-mitigation Relationship: Does Information on the Costs of Adapting to Climate Change Influence Support for Mitigation?

Can information about adaptation costs influence citizens’ willingness to support climate change mitigation? Some scholars are concerned that policy discussions on adaptation might present climate change as a more manageable problem, and therefore crowd out mitigation efforts. On the other hand, providing information on adaptation costs may sensitize citizens to these costs, thereby increasing their willingness to support mitigation. To assess these conflicting predictions, we fielded a web-based survey experiment using a sample of 2,000 US-based respondents. We presented the respondents with a hypothetical newspaper article regarding a proposed gasoline tax (a mitigation strategy) and measured the support for this proposal across different treatment groups. In the control group, the respondents were told that failure to mitigate climate change could result in a potentially catastrophic outcome, whereas in each of the treatment groups the respondents were provided with information concerning possible adaptation costs. The respondents were then asked about their willingness to support a gasoline tax. Our key finding is that the provision of information about adaptation costs leads to a small increase in the respondents’ willingness to support mitigation efforts. Furthermore, we find that this effect becomes larger when the information regarding adaptation costs is made more specific.     

Heavy metal status of sediment in river Cauvery,Karnataka

The purpose of this research work was to appraise extent of heavy metals in sediment and the degree to which its quality tainted seasonally and spatially in river Cauvery. In this study, heavy metals such as Fe, Zn, Ni, Mn, Pb, Cu, Co, Cd and Cr were analysed in sediments. Results were compared with sediment quality guidelines from various derived criteria. Twenty-five sampling points were selected based on geographical proximity of agricultural fields and industrial discharges; river-tributary confluence points; settlements located along the river bank; ritual and recreational activities. Sampling was done for the period of 3 years (2007 to 2009). Digestion of the samples was done by microwave-assisted digestion technique. Analysis was carried out using flame furnace atomic absorption spectrophotometer, and results are expressed in micrograms per gram. The mean concentration of Fe (11144 μg/g) followed by Mn (1763.3 μg/g), Zn (93.1 μg/g), Cr (389 μg/g), Ni (27.7 μg/g), Cu (11.2 μg/g), Pb (4.3 μg/g), Co (1.9 μg/g) and Cd (1.3 μg/g) remained within the levels of sediment quality guidelines. Multivariate statistical techniques such as principal component analysis and cluster analysis (CA) were employed to better comprehend the controlling factors of sediment quality and spatial homogeneity among the stations. The sediment geo-accumulation index (I_geo) showed maximum value of Cd (2.69) and least value of Mn (−1.44). The geo-accumulation class (I_geo class) was in the sequence as follows: Cd>Zn>Pb>Cr>Cu>Co>Ni>Fe>Mn. Negative total geo-accumulation indices (I_tot) revealed that mean concentration of heavy metals in the river bed sediment are lower than their respective shale values. The statistical analysis of inter-metallic relationship revealed the high degree of correlation among the metals indicated their identical behaviour during transport. This study concludes that insignificant geo-accumulation with metals except Cd (moderate contamination), Pb and Zn (slight contamination) principally in downstream stretch may perhaps deteriorate the sediment quality due to intensification anthropogenic influences. It also proves that extent of existing metal concentrations in sediments of river Cauvery in Karnataka not exceeded the toxic limit, and there is no peril to the aquatic life.     

Sensitive spectrophotometric methods for the assessment of nitrite in water sample

Two spectrophotometric methods have been developed for the determination of nitrite using dapsone (DAP) with alpha-naphthol and 4-amino-5-hydroxynapthalene-2,7-disulphonic acid monosodium salt (AHNDMS) as chromogenic reagents with maximum absorbance wavelength at 540 and 520 nm respectively. For the method that utilizes dapsone with alpha-naphthol (DAP-alpha-naphthol), the beer's law range is obeyed between 0.05-0.8 microg ml(-1) with molar absorptivity of 5.749 x 104 l mol(-1) cm(-1). The second method that uses dapsone with AHNDMS (DAP-AHNDMS), the beer's law is valid over the range 0.2-1.4 mug ml(-1) and molar absorptivity 2.44 x 104 l mol(-1) cm(-1). The common interfering ions in the analytical procedures have been studied. This proposed methods are reliable, reproducible and have been successfully applied to determine nitrite in various water sources of environmental interest.     

Assessment of spatial-temporal patterns of surface and ground water qualities and factors influencing management strategy of groundwater system in an urban river corridor of Nepal

This study examined the spatial-temporal variations and factors influencing the management of groundwater along a section of the Bagmati river corridor in the Kathmandu valley (Nepal). The results showed that rural areas were less polluted than urban areas. In urban areas, the biochemical oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP) concentrations ranged from 8.41 to 29.74 mg/L, 6.7 to 128.96 mg/L and 0.06 to 1.5 mg/L, respectively. In rural areas, the BOD, TN and TP concentrations ranged from 0.78 to 18.25 mg/L, 4.8 to 11.56 mg/L and 0.07 to 0.65 mg/L, respectively. The level of organics was higher in the pre-monsoon season, while the level of nutrients was higher in post-monsoon season. A comparison of the groundwater and surface water in the upstream rural areas revealed that the TP concentration was higher in the groundwater than in the surface water, which was attributed to the sorption of phosphorus on iron, aluminum or calcium compounds contained in the surface water, which depends upon the temperature, pH and dissolved oxygen. In urban areas, a few wells were found at groundwater levels lower than the corresponding surface water levels and were subjected to a high risk of pollution. Overall, these findings reinforce the notion that the management of surface and ground waters in an integrated approach is essential for attaining sustainable development of groundwater systems.     

Spatial and temporal variations in traffic-related particulate matter at New York City high schools

Relatively little is known about exposures to traffic-related particulate matter at schools located in dense urban areas. The purpose of this study was to examine the influences of diesel traffic proximity and intensity on ambient concentrations of fine particulate matter (PM_2.5) and black carbon (BC), an indicator of diesel exhaust particles, at New York City (NYC) high schools. Outdoor PM_2.5 and BC were monitored continuously for 4–6 weeks at each of 3 NYC schools and 1 suburban school located 40 km upwind of the city. Traffic count data were obtained using an automated traffic counter or video camera. BC concentrations were 2–3 fold higher at urban schools compared with the suburban school, and among the 3 urban schools, BC concentrations were higher at schools located adjacent to highways. PM_2.5 concentrations were significantly higher at urban schools than at the suburban school, but concentrations did not vary significantly among urban schools. Both hourly average counts of trucks and buses and meteorological factors such as wind direction, wind speed, and humidity were significantly associated with hourly average ambient BC and PM_2.5 concentrations in multivariate regression models. An increase of 443 trucks/buses per hour was associated with a 0.62 μg/m³ increase in hourly average BC at an NYC school located adjacent to a major interstate highway. Car traffic counts were not associated with BC. The results suggest that local diesel vehicle traffic may be important sources of airborne fine particles in dense urban areas and consequently may contribute to local variations in PM_2.5 concentrations. In urban areas with higher levels of diesel traffic, local, neighborhood-scale monitoring of pollutants such as BC, which compared to PM_2.5, is a more specific indicator of diesel exhaust particles, may more accurately represent population exposures.