Instrumental neutron activation analysis of ambient air dust particulates from metropolitan cities in India

Ambient air dust samples were collected from industrial, commercial and residential areas of four metropolitan cities (Delhi, Calcutta, Madras and Cochin) in India, and were analysed for 27 elements (As, Ba, Br, Ce, Co, Cr, Cs, Cu, Eu, Hf, Hg, Fe, Ga, La, Lu, Na, P, Sb, Sc, Se, Sr, Ta, Tb, Th, Rb, Yb and Zn) by Instrumental Neutron Activation Analysis (INAA). Samples were irradiated with thermal neutrons in a nuclear reactor for 1 day and counted by high resolution gamma spectrometry at different intervals. Several environmental standards such as Coal (SRM 1932b); Urban Particulate Matter (SRM 1648) from NIST, USA; Vehicle Exhaust from NIES, Japan; and Soil-5 from IAEA, Vienna were also analysed for quality assurance. The results reveal that the concentrations of several pollutant elements in dust samples from the four cities are highly variable. Wide differences were observed for elemental concentrations of As, Ba, Br, Cu, Cr, Hg, Fe, Sb, Se and Zn and these variations are explained in terms of their possible sources of origin.     

Detection of anomalous nitrogen dioxide (NO2) concentration in urban air of India using proximity and clustering methods

Owing to accurate future air quality estimates, need for detecting the anomalously high increase in concentration of pollutants cannot be adjourned. Plentiful approaches were proposed in the past to substantially determine the abnormal conditions, but most of the statistical approaches were computationally expensive and ignored the false alarm ratios. Thus, a hybrid of proximity- and clustering-based anomaly detection approaches to identify anomalies in the air quality data is suggested in this work. The Gaussian distribution property of the real-world data set is utilized further to segregate out anomalies. The results depicted twofold advantages of our approach, by efficient extraction of anomalies and with increased accuracy by reducing the number of false alarms. Specifically, the presence of NO₂ concentration in air is investigated in this work, considering its constant increase over decades as well as its inevitable health risks. Furthermore, spatiotemporal segments with anomalously high NO₂ concentrations for 14 residential, industrial, and commercial areas of five cities in India are extracted. To validate the results, a comparative analysis with existing approaches of anomaly detection and with two benchmark data sets is performed. Results showed that our method outperformed the existing methods of anomaly detection, when evaluated over metrics such as sensitivity, miss rate, and false alarms. Further, a detailed analysis of extracted anomalies and a detailed discussion about the factors responsible for such anomalies are presented in this work. This study is helpful in educating government and people about spatiotemporal, geographical, and economic conditions responsible for anomalously high NO₂ concentrations in air.

Implications: Using our methodology, days with extremely high concentration of any pollutant in air, at any particular location, can be extracted. The reasons for such extremely high pollutant concentration on particular days of a year can be studied and preventive measures can be taken by the government. Thus, by identification of causes of anomalies, future similar events can be avoided. This would also help in people’s decision making in case such events occur in the future.     

Neurotoxic and genotoxic effects of methylmercury

The toxic form of methylmercury is of concern in terms of its neurotoxicity, genotoxicity and reproductive toxicity. Extensive research has been carried out on the effects of exposure to high levels of this toxic compound, but this is not true for research on exposure to lower levels. The harmful effects of methylmercury are a cause for concern irrespective of the exposure levels. The problem becomes more serious because of biomagnifications of methylmercury. Disorders may develop during neonatal stage and then develop further during the lifetime. The common effects which can be seen are retarded brain development and permanent disorders like cerebral palsy. This can also cause neurogenerative disorders like Alzheimer’s and Parkinson’s. Research on animals has also shown toxicity. Inorganic Hg was found to be present in brains of neonatal rats, in monkeys prenatal exposure to MeHg resulted in a reduced number of births, and birds laid a lesser number of eggs and the infant mortality rate was higher.     

Effects of fuel reactivity and injection timing on diesel engine combustion and emissions

Recent strategies for simultaneously reducing NOx and soot emissions have focused on achieving nearly premixed, low-temperature combustion (LTC) in diesel engines. A promising approach in this regard is to vary fuel reactivity in order to control the ignition delay and optimize the level of premixing and reduce emissions. The present study examines such a strategy by performing 3-D simulations in a single-cylinder of a diesel engine. Simulations employ the state-of-the-art two-phase models and a validated semi-detailed reaction mechanism. The fuel reactivity is varied by using a blend of n-heptane and iso-octane, which represent surrogates for gasoline and diesel fuels, respectively. Results indicate that the fuel reactivity strongly influences ignition delay and combustion phasing, whereas the start of injection (SOI) affects combustion phasing. As fuel reactivity is reduced, the ignition delay is increased and the combustion phasing is retarded. The longer ignition delay provides additional time for mixing, and reduces equivalence ratio stratification. Consequently, the premixed combustion is enhanced relative to diffusion combustion, and thus the soot emission is reduced. NO_x emission is also reduced due to reduced diffusion combustion and lower peak temperatures caused by delayed combustion phasing. An operability range is observed in terms of fuel reactivity and SOI, beyond which the mixture may not be sufficiently well mixed, or compression ignited. The study demonstrates the possibility of finding an optimum range of fuel reactivity, SOI, and EGR for significantly reducing engine out emissions for a given load and speed.     

Is rainfall gradient a factor of livelihood diversification? Empirical evidence from around climatic hotspots in Indo-Gangetic Plains

Farmers in the Indo-Gangetic Plains are constantly seeking ways to adapt to changing circumstances and opportunities that include new technologies, institutions, policies, socio-economic and cultural shifts, as well as a changing climate. The relationship between rainfall and local livelihoods is important to devise policies to improve adaptive capacity of farmers to different drivers of changes. The present study investigates whether the spatial variations in rainfall have prompted the location-specific livelihood diversification by using data from 2660 farm families in the climatic risk areas in India, Nepal and Bangladesh. The results show a higher on-farm livelihood diversification in the areas with high rainfall (1500–2100 mm) compared to medium (900–1500 mm) and very high rainfall regimes (>2100 mm). Based on this study, the optimal range of rainfall for better agricultural livelihood in the context of changing environmental circumstances is from 1500 to 2100 mm. In terms of farm practices changed (proxy of adaptability), farmers responded more frequently to the market-related drivers than climatic stressors. Farmers in climate vulnerable areas (Bihar and coastal Bangladesh for instance) responded more to climatic stressors than those living in relatively less vulnerable areas (Terai for instance). The results imply that livelihood strategies should be tailor-made along the climatic resources such as rainfall, considering other biophysical and socio-economic variations at the spatial scale. Identifying household and farm-level coping strategies along the rainfall gradient can also be useful in targeting interventions to build resilience to shocks.     

Cost Effective Production of Poly-β-Hydroxybutyrate by Bacillus subtilis NG05 Using Sugar Industry Waste Water

The present study describes the treatment of sugar industry waste water and its use as a potential low cost substrate for production of bioplastic by Bacillus subtilis NG05. The B. subtilis NG05 grow at the rate of 0.14 g h^?1 L^?1 of production media used and accumulate the 50.1 % of poly β-hydroxybutyrate (PHB). The phase contrast microscopy revealed the presence of PHB granules in B. subtilis NG05 which was further confirmed by Fourier transform infrared spectroscopy and ¹H-nuclear magnetic resonance. The polymer was further analysed by differential scanning calorimetry. PHB production yield was achieved up to 4.991 g L^?1 with Sugar industry waste water as sole nutrient source. Thus the process provided dual benefits of conversion of a waste material into value added product, PHB and waste management.     

Monitoring of toxic elements present in sludge of industrial waste using CF-LIBS

Industrial waste is one of the main causes of environmental pollution. Laser-induced breakdown spectroscopy (LIBS) was applied to detect the toxic metals in the sludge of industrial waste water. Sludge on filter paper was obtained after filtering the collected waste water samples from different sections of a water treatment plant situated in an industrial area of Kanpur City. The LIBS spectra of the sludge samples were recorded in the spectral range of 200 to 500 nm by focusing the laser light on sludge. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique was used for the quantitative measurement of toxic elements such as Cr and Pb present in the sample. We also used the traditional calibration curve approach to quantify these elements. The results obtained from CF-LIBS are in good agreement with the results from the calibration curve approach. Thus, our results demonstrate that CF-LIBS is an appropriate technique for quantitative analysis where reference/standard samples are not available to make the calibration curve. The results of the present experiment are alarming to the people living nearby areas of industrial activities, as the concentrations of toxic elements are quite high compared to the admissible limits of these substances.     

Effect of Temperature on Absorption Efficiency of NO2 in Arsenite Method

The sodium arsenite method developed by Jacobs andHochheiser is one of the most widely used manualmethods for nitrogen dioxide (NO₂) monitoring inambient air, particularly in developing countries. Asreported, the method gives 82% NO₂ absorptionefficiency (NAE) in the concentration range from 40 to750 g/m³, when only one impinger tube isemployed in the sampling train at a flow rate of 0.2lpm and for 24 h sampling duration. Accordingly,a uniform correction factor (0.82) is used indenominator to calculate the ultimate concentration ofNO₂ in ambient air.In the present investigation, the effect oftemperature on absorption efficiency of NO₂ isstudied employing four impinger tubes in series tocollect the maximum NO₂ generated in the gasstream. The study conducted at 16, 26 and 36 °Ctemperatures shows maximum absorption efficiency(average) of 87.8% at 26°C in 1st impingertube. At lower and higher temperatures, it is foundconsiderably less. A suitable correction factor,therefore, must be applied to estimate actual NO₂concentration in ambient air using arsenite method, intropical countries like India, where atmospherictemperature variations are large (less than 5°Cin winter and more than 45°C in summer).     

Quality of water obtained by tapping shallow seepages in the Almota Hills,India

We studied the quality of water obtained using a new method of tapping underground water seepages by digging shallow water collection chambers in the Almora Hills of the state of Uttar Pradesh, India; quality of this water was compared with that of water obtained using traditional water sources in this region, namely naulas (surface seepages) and springs.Water from both the new and the traditional water sources had an excess of chromium and, in some samples, of iron and lead. Microbiological analysis showed that water from new water sources was safer than that obtained from tradional sources; however, only 40% of the shallow seepages provided water conforming to WHO standards on water quality.We conclude that tapping of underground water seepages may be a useful method of providing potable water to populations living in the hills. However, further improvement is necessary in the maintenance of the clean catchment area and in disposal of waste water from these water sources to ensure water quality.     

Development of a novel myconanomining approach for the recovery of agriculturally important elements from jarosite waste

In this study, an ecofriendly and economically viable waste management approach have been attempted towards the biosynthesis of agriculturally important nanoparticles from jarosite waste. Aspergillus terreus strain J4 isolated from jarosite(waste from Debari Zinc Smelter,Udaipur, India), showed good leaching efficiency along with nanoparticles(NPs) formation under ambient conditions. Fourier-transform infrared spectroscopy(FT-IR) and transmission electron microscopy(TEM) confirmed the formation of NPs. Energy dispersive X-ray spectroscopy(EDX analysis) showed strong signals for zinc, iron, calcium and magnesium,with these materials being leached out. TEM analysis and high resolution transmission electron microscopy(HRTEM) showed semi-quasi spherical particles having average size of 10‐50 nm. Thus, a novel biomethodology was developed using fungal cell-free extract for bioleaching and subsequently nanoconversion of the waste materials into nanostructured form. These biosynthesized nanoparticles were tested for their efficacy on seed emergence activity of wheat(Triticum aestivum) seeds and showed enhanced growth at concentration of 20 ppm. These nanomaterials are expected to enhance plant growth properties and being targeted as additives in soil fertility and crop productivity enhancement.