Organic and inorganic components of aerosols over the central Himalayas: winter and summer variations in stable carbon and nitrogen isotopic composition

The aerosol samples were collected from a high elevation mountain site, Nainital, in India (1958 m asl) during September 2006 to June 2007 and were analyzed for water-soluble inorganic species, total carbon, nitrogen, and their isotopic composition (δ¹³C and δ¹⁵N, respectively). The chemical and isotopic composition of aerosols revealed significant anthropogenic influence over this remote free-troposphere site. The amount of total carbon and nitrogen and their isotopic composition suggest a considerable contribution of biomass burning to the aerosols during winter. On the other hand, fossil fuel combustion sources are found to be dominant during summer. The carbon aerosol in winter is characterized by greater isotope ratios (av. ?24.0?‰), mostly originated from biomass burning of C₄ plants. On the contrary, the aerosols in summer showed smaller δ¹³C values (?26.0?‰), indicating that they are originated from vascular plants (mostly of C₃ plants). The secondary ions (i.e., SO₄ ^2?, NH₄ ⁺, and NO₃ ^?) were abundant due to the atmospheric reactions during long-range transport in both seasons. The water-soluble organic and inorganic compositions revealed that they are aged in winter but comparatively fresh in summer. This study validates that the pollutants generated from far distant sources could reach high altitudes over the Himalayan region under favorable meteorological conditions.     

An investigation into the acid content of aerosols in the ambient air at the Taj Mahal, Agra

A chemical analysis of suspended particulate matter (SPM) collected near the world famous Taj Mahal monument at Agra has been carried out. SPM samples collected on glass fibre filters were analysed for water-soluble sulphate, nitrate, chloride and ammonium ions. The data were derived from over 200 samples (each of 24 h), collected continuously during the winter periods (October through to March) of 1984-1985 and 1985-1986. The SO(4)(2-) and NO(3)(-) components are acidic in nature causing corrosion and effects on visibility, and so were studied in more detail. Mean values for SO(4)(2-) and NO(3)(-) derived from two-year data are 7.2 microg m(-3) and 8.2 microg m(-3), respectively. The SO(4)(2-)/SO(2) and NO(3)(-)/NO(2) ratiosobserved indicate faster conversion of SO(2) to SO(4)(2-) than NO(2) to NO(3)(-), the maximum levels being in January. Thus, both SO(4)(2-) and NO(3)(-) results appear to offer more promising indices of air quality than do SPM data alone.     

Ecotoxicological risk assessment of pentachlorophenol,an emerging DBP to plants: evaluation of oxidative stress and antioxidant responses

Environmental Science and Pollution Research - Chlorophenols are not only noticed in an effluvium of industries but also can emerge from the water treatment plants for domestic supply which poses a...     

Potential of <Emphasis Type="Italic">Coriaria nepalensis</Emphasis> for establishment of tree seedlings: Implication for restoration of degraded hill slopes of Central Himalaya

Seedling establishment in harsh environment was a rare and sporadic event due to the prevalent high temperatures and low moisture regimes. Also in response to harsh conditions seedlings establishment of many species appear to be more frequent under canopies of nurse plants. In these interactions the seedling benefit from the micro environment created by the adult nurse plants. In Himalaya some of the host plants are typically colonizer of nutrient-poor soils in habitats such as eroded soils and rocky surfaces. Many of the plants themselves do not yield economic goods, but they can promote the growth of more useful plants and have potential for reclamation of nutrient poor soils.     

Avian species distribution in different elevation zone forest (Sal, Pine Mixed And Oak) in nainital district of uttarakhand, India

The present study were made to estimate the avian fauna in terms of species richness and diversity and guild structure in forest habitats of Nainital district of Uttarakhand (350–2.450 m asl; 29° N). Field studies were conducted during January 2007 to December 2008. Total 43, 62 and 42 species were recorded from, Haldwani, Bhowali and Nainital forest habitats. Results indicate the species relationship between Bird species richness (BSR) and elevation sections (forest habitats) was not decline simultaneously along elevation; it shows hump shaped. BSR varied considerably along elevational gradient (43 to 62 species), was highest (62 species) at mid elevation (Mixed pine forest, 1.350–1.700 m asl) and decreased (20 species) at high elevation (Conifer forest, 1900–2450 m asl). It seems that mid altitude bulge is not caused by the presence of a group of mid altitude specialists but rather that there is an overlap in the distribution of low land and high elevation specialists at this altitude. A checklist of 79 avian species has also produced of Nainital district forest habitats. It is suggested that this study provide a base line structure for further study on species distribution in different forest habitats and along different elevation section in Western Himalayas (India).     

Predicting the distributional range shifts of Rhizocarpon geographicum (L.) DC. in Indian Himalayan Region under future climate scenarios

Environmental Science and Pollution Research - Himalaya, the highest mountain system in the world and house of important biodiversity hotspot, is sensitive to projected warming by climate change....     

Thermo-physical modeling of die-sinking EDM process

This paper reports the development of a thermo-physical model for die-sinking electric discharge machining (EDM) process using finite element method (FEM). Numerical analysis of the single spark operation of EDM process has been carried out considering the two-dimensional axi-symmetric process continuum. The analysis is based on more realistic assumptions such as Gaussian distribution of heat flux, spark radius equation based on discharge current and discharge duration, latent heat of melting, etc., to predict the shape of crater cavity and the material removal rate (MRR). Using the developed model, parametric studies were carried out to study the effect of EDM process parameters such as discharge current, discharge duration, discharge voltage and duty cycle on the process performance. Experimental studies were carried out to study the MRR and crater shapes produced during actual machining. When compared with the reported analytical models, our model was found to predict results closer to the experimental results. The thermo-physical model developed can further be used to carry out exhaustive studies on the EDM process to obtain optimal process conditions.     

Effects of Mn(II) and Fe(II) on microbial removal of arsenic (III)

Goal, scope, and background  Arsenic contamination in groundwater creates severe health problems in the world. There are many physiochemical and biological methods available for remediation of arsenic from groundwater. Among them, microbial remediation could be taken as one of the least expensive methods, though it takes longer treatment time. The main objective of this research was to study the improvement on remediation by addition of some essential ion salts such as Mn and Fe. Materials and methods   Staphylococcus aureus, Bacillus subtilis, Klebsiella oxytoca, and Escherichia coli were taken as model microbes from Dhulikhel, 30 km east from Kathmandu, Nepal. Results and discussion  Microbes used in this study showed different abilities in their removal of As(III) with and without addition of Mn and Fe salts. The trend of remediation increased with time. S. aureus was found to be the best among the microbes used. It showed almost 100% removal after 48-h culture, both with and without Fe and Mn salts. Rate of removal of As increased with addition of Fe and Mn for all microbes. Removal efficiency was found to increase by about 32% on average after addition of salts in 24-h cultures of S. aureus.     

Irregularity in frequency of mast seed years in <Emphasis Type="Italic">Quercus floribunda</Emphasis> a late successional species of Central Himalaya

The mid altitudinal oak, Quercus floribunda forms predominantly evergreen forest in Central Himalaya between 2000–2400 m. It is late successional, mature phase species that has limited regeneration on disturbance prone sites. This oak produces mast seed crops at an interval of 2–3 years. During masting in Q. floribunda the seed fall and germination is upto ten times greater than in normal years, emphasizing the importance of mast year crop in forest maintenance. However, no mast year in this species since the last nine years (1997–2005) is a matter of serious concern. The rise in the summer and winter temperature over a period of 15 years appear to have affected the frequency of masting in this oak. The importance of masting can be adjudged from the fact that 97% of the surviving seedlings m⁻² are of the mast year crop.     

A model to estimate the methane generation rate constant in sanitary landfills using fuzzy synthetic evaluation.

This paper presents a model using fuzzy synthetic evaluation to estimate the methane generation rate constant, k, for landfills. Four major parameters, precipitation, temperature, waste composition and landfill depth were used as inputs to the model. Whereas, these parameters are known to impact the methane generation, mathematical relationships between them and the methane generation rate constant required to estimate methane generation in landfills, are not known. In addition, the spatial variations of k within a landfill combined with the necessity of site-specific information to estimate its value, makes k one of the most elusive parameters in the accurate prediction of methane generation within a landfill. In this paper, a fuzzy technique was used to develop a model to predict the methane generation rate constant. The model was calibrated and verified using k values from 42 locations. Data from 10 sites were used to calibrate the model and the rest were used to verify it. The model predictions are reasonably accurate. A sensitivity analysis was also conducted to investigate the effect of uncertainty in the input parameters on the generation rate constant.