Experimental investigation of performance and emissions of a VCR diesel engine fuelled with <Emphasis Type="Italic">n</Emphasis>-butanol diesel blends under varying engine parameters

The continuous rise in the cost of fossil fuels as well as in environmental pollution has attracted research in the area of clean alternative fuels for improving the performance and emissions of internal combustion (IC) engines. In the present work, n-butanol is treated as a bio-fuel and investigations have been made to evaluate the feasibility of replacing diesel with a suitable n-butanol-diesel blend. In the current research, an experimental investigation was carried out on a variable compression ratio CI engine with n-butanol-diesel blends (10–25% by volume) to determine the optimum blending ratio and optimum operating parameters of the engine for reduced emissions. The best results of performance and emissions were observed for 20% n-butanol-diesel blend (B20) at a higher compression ratio as compared to diesel while keeping the other parameters unchanged. The observed deterioration in engine performance was within tolerable limits. The reductions in smoke, nitrogen oxides (NO _x ), and carbon monoxide (CO) were observed up to 56.52, 17.19, and 30.43%, respectively, for B20 in comparison to diesel at rated power. However, carbon dioxide (CO₂) and hydrocarbons (HC) were found to be higher by 17.58 and 15.78%, respectively, for B20. It is concluded that n-butanol-diesel blend would be a potential fuel to control emissions from diesel engines.

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Nickel accumulation and its effect on growth,physiological and biochemical parameters in millets and oats

With the boom in industrialization, there is an increase in the level of heavy metals in the soil which drastically affect the growth and development of plants. Nickel is an essential micronutrient for plant growth and development, but elevated level of Ni causes stunted growth, chlorosis, nutrient imbalance, and alterations in the defense mechanism of plants in terms of accumulation of osmolytes or change in enzyme activities like guiacol peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD). Ni-induced toxic response was studied in seedlings of finger millet, pearl millet, and oats in terms of seedling growth, lipid peroxidation, total chlorophyll, proline content, and enzymatic activities. On the basis of germination and growth parameters of the seedling, finger millet was found to be the most tolerant. Nickel accumulation was markedly lower in the shoots as compared to the roots, which was the highest in finger millet and the lowest in shoots of oats. Plants treated with a high concentration of Ni showed significant reduction in chlorophyll and increase in proline content. Considerable difference in level of malondialdehyde (MDA) content and activity of antioxidative enzymes indicates generation of redox imbalance in plants due to Ni-induced stress. Elevated activities of POD and SOD were observed with high concentrations of Ni while CAT activity was found to be reduced. It was observed that finger millet has higher capability to maintain homeostasis by keeping the balance between accumulation and ROS scavenging system than pearl millet and oats. The data provide insight into the physiological and biochemical changes in plants adapted to survive in Ni-rich environment. This study will help in selecting the more suitable crop species to be grown on Ni-rich soils.

     

Modeling soil organic matter dynamics as affected by soil water erosion

Soil organic carbon (SOC) stock is an important component of the global carbon (C) cycle, which has the potential to influence global climate. In this paper we presented an overview of soil organic matter (SOM) models in the context of soil erosion and discussed basic processes driving erosion-induced SOC loss. Although the mechanism of this loss is poorly understood, erosion influences SOC in two ways: redistribution of C within the watershed or ecosystem, and loss of C to the atmosphere. Erosion disperses soil, altering its microbiological activity as well as water, air and nutrient regimes. This, along with sediment enrichment, has an impact on greenhouse gas emission from soil. For most of agricultural settings, field studies suggest that cultivation along with soil erosion are the primary reasons for SOC loss. Tracing the fate of eroded C is a challenging task. Modeling is the approach taken most often. In this paper we discuss approaches used in various SOC models to assess erosion-induced C loss from soil in agricultural ecosystems. An example with Century model applied to meadow and corn-soybean rotation under chisel-till demonstrated the model's ability to respond well to different erosion scenarios. It was estimated that at soil loss rate of 10 t ha(-1) year(-1) (value often considered a threshold for maintaining productivity) 19% of the total SOC loss would be attributed to erosion after 90 years of cultivation.     

Carbon Sequestration in Dryland Ecosystems

Drylands occupy 6.15 billion hectares (Bha) or 47.2% of the worlds land area. Of this, 3.5 to 4.0 Bha (57%–65%) are either desertified or prone to desertification. Despite the low soil organic carbon (SOC) concentration, total SOC pool of soils of the drylands is 241 Pg (1 Pg = petagram = 10¹⁵ g = 1 billion metric ton) or 15.5% of the worlds total of 1550 Pg to 1-meter depth. Desertification has caused historic C loss of 20 to 30 Pg. Assuming that two-thirds of the historic loss can be resequestered, the total potential of SOC sequestration is 12 to 20 Pg C over a 50-year period. Land use and management practices to sequester SOC include afforestation with appropriate species, soil management on cropland, pasture management on grazing land, and restoration of degraded soils and ecosystems through afforestation and conversion to other restorative land uses. Tree species suitable for afforestation in dryland ecosystems include Mesquite, Acacia, Neem and others. Recommended soil management practices include application of biosolids (e.g., manure, sludge), which enhance activity of soil macrofauna (e.g., termites), use of vegetative mulches, water harvesting, and judicious irrigation systems. Recommended practices of managing grazing lands include controlled grazing at an optimal stocking rate, fire management, and growing improved species. The estimated potential of SOC sequestration is about 1 Pg C/y for the world and 50 Tg C/y for the U.S. This potential of dryland soils is relevant to both the Kyoto Protocol under UNFCCC and the U.S. Farm Bill 2002.

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Interaction of Endosulfan and malathion with blue-green algae Anabaena and Aulosira fertilissima

The growth of Anabaena and Aulosira fertilissima was adversely affected by endosulfan even at 1 microg ml(-1). The inhibition was significantly above 50% at 20 microg ml(-1) throughout the incubation. Anabaena survived up to 500 microg ml(-1) of malathion, but was completely bleached in the presence of 50 microg ml(-1) of endosulfan. Aulosira was more sensitive to malathion than Anabaena and recovered to control levels only at 10 microg ml(-1). The morphology and hetercyst frequency were not altered in Anabaena. Aulosira cultures were dull brown in colour at 20 microg ml(-1) of endosulfan with the filaments clumping, instead of the usual mat formation. Both malathion and endosulfan considerably lowered (14)C uptake and nitrogenase activities in Aulosira. Nitrogen fixation was unaffected in Anabaena as the amounts of ethylene produced were equal to, or above, control levels. The impact of these insecticides on photosynthesis in Anabaena was only slight.     

Are intensive agricultural practices environmentally and ethically sound?

Soil is fragile and nonrenewable but the most basic of natural resources. It has a capacity to tolerate continuous use but only with proper management. Improper soil management and indiscriminate use of chemicals have contributed to some severe global environmental issues, e.g., volatilization losses and contamination of natural waters by sediments and agricultural fertilizers and pesticides. The increasing substitution of energy for labor and other cultural inputs in agriculture is another issue. Fertilizers and chemicals account for about 25% of the production energy investment in agriculture. An additional 60% is accounted for by machinery, gasoline, electricity, and power-related inputs. Fertilizer additions to cropland are not utilized fully and significant amounts, depending on conditions, are either lost in surface runoff or leached into the ground water. The annual discharge of dissolved solids from agricultural lands to the waterways in the USA is substantial. The increasing use of herbicides in agriculture is a threat to the quality of surface and ground water, although this threat is dependent upon both the chemistry of the compound and the ecosystem in which it is used. Especially within the Third World, development of an environmental ethic and environmental laws have not kept pace with the increase in pesticide use. Above all is the severe and global problem of soil degradation currently occurring at the rate of five to seven million hectares per year. The policy and moral aspects of these issues are discussed.     

Risk of flood-related mortality in Nepal

In July 1993, severe flooding devastated Sarlahi district in Nepal. The next month, a follow-up study of a large population cohort was undertaken. The study is unique in that a prospective research database was used to verify residency prior to the flood and to confirm vital status afterwards. It evaluated 41,501 children aged between two and nine years and adults aged 15-70 in 7,252 households. Flood-related fatality rates were 13.3 per 1,000 for girls and 9.4 per 1,000 for boys, 6.1 per 1,000 for women and 4.1 per 1,000 for men. Flood-related fatality rates for children were six times higher than mortality rates in the same villages a year before the flood (relative risk (RR) = 5.9, 95 per cent confidence interval (CI) 5.0-6.8). Flood-related fatality was associated with low socio-economic status preflood (RR = 6.4, 95 per cent CI 2.7-20.0), and having a house constructed of thatch (RR = 5.1, 95 per cent CI 1.7-24.5).     

Ground level ozone concentrations and its association with NOx and meteorological parameters in Kathmandu valley, Nepal

This paper summarizes the results of a yearlong continuous measurements of gaseous pollutants, NO, NO₂, NO_x and O₃ in the ambient air at Kathmandu valley. Measured concentration of the pollutants in study area is a function of time. NO, NO₂ and O₃ peak occurred in succession in presence of sunlight. At the time of maximum O₃ concentration most of the NO_x are utilized. The diurnal cycle of ground level ozone concentrations, revealed mid-day peak with lower nocturnal concentrations and inverse relationship exists between O₃ and NO_x, which are evidences of photochemical O₃ formation. The observed ground level ozone during monsoon is slight lower than the pre-monsoon value. Further, lack of rainfall and higher temperature, solar radiation in the pre-monsoon have given rise to the gradual build up of ozone and it is lowest during winter. Ground level ozone concentrations measured during bandha (general strike) and weekend are 19% and 13% higher than those measured during weekdays. The most effective ozone abatement strategy for Kathmandu Valley may be control of NO_x emissions.     

Fog simulation using a mesoscale model in and around the Yodo River Basin, Japan

In this study,fog simulations were conducted using the Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) in and around the Yodo River Basin,Japan.The purpose is to investigate the MM5 performance of fog simulation for long-term periods.The simulations were performed for January,February,March,and July,2005 with a coarse 3-kin and a nested fine 1-km grid domains. Results of the simulations were compared with data from ten meteorological observatories,fog sampling site in Mt.Rokko,and visibility measu...