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241.
Singh SK Rai JP 《Journal of environmental biology / Academy of Environmental Biology, India》2004,25(3):299-306
The present study aims to analyze the interaction of prevailing biotic pressure on plant species diversity in Nanda Devi Biosphere Reserve (NDBR) which lies in northern part of Uttaranchal hills between 79 degrees 40'E to 80 degrees 05'E longitude and 30 degrees 17' N to 30 degrees 41'N latitude and covers an area of 2236.7 km2. A total of 75 species has been found which included the herbaceous plants viz., grasses, sedges and forbs. Generally, the plants have a short life span of 3-4 months. However, few species persist throughout the growth period i.e. May-October. Phytosociological study performed in plots of varying slope and grazing pressure intensity revealed that the dominant grasses were Danthonia cachemyriana and Poa annua and dominant forbs were Trachydium roylei and Geum elatum in all the plots. Grasses were abundant on west facing slopes while forbs preferred the even topography of east facing meadows. The grasses and sedges together had optimum density during July and August. In general, short lived species exhibited more diversity for one or two months whilst the long lived species exhibited optimum diversity althrough the snow free period. The species diversity is maximum (100%) in moderately grazed bughiyals i.e. Pacchu and minimum in intensively grazed bughiyals i.e. Martoli. The species distribution among the plots was 60-90% contagious and 11.2-38.0% randomirrespective of grazing pressure, thus highlighting the significance of grazing pressure in management of alpine meadows. 相似文献
242.
Bhaskar AS Jayaraj R Dangi RS Prasad GK Singh B Rao PV 《Journal of environmental biology / Academy of Environmental Biology, India》2005,26(3):511-515
Most frequently encountered freshwater cyanobacterial toxin is Microcystin-LR (MC-LR). Microcystins released from cells into water have been responsible for the death of humans, domestic and wild animals. Removal of microcystin by active carbon has been one of the best methods available so far. This study evaluates three grades of active carbon namely 40, 60 and 80 CTC for their removal efficiency of MC-LR from contaminated water. Kinetics of toxin removal was studied in time course experiments. Protection in mouse model was studied for the samples after the adsorption. Toxin quantitation was done by HPLC method. The MC-LR concentration after 24 hr treatment with 40, 60 and 80 CTC carbons were 4.8, 3.3 and 1.3 microg/ml respectively from an initial concentration of 5.2 microg/ml. Protection in mouse bioassay was seen after 48, 24 and 2 hr of adsorption time respectively for 40, 60 and 80 CTC carbons. 80 CTC carbon was found to be most efficient in removing MC-LR from contaminated water. 相似文献
243.
Bansal SK Singh KV 《Journal of environmental biology / Academy of Environmental Biology, India》2003,24(1):113-116
Seasonal prevalence and insecticide susceptibility tests were carried out on the adults of Aedes aegypti, the vector of dengue and dengue hemorrhagic fever(DF/DHF), in three desert (Bikaner, Jaisalmer and Jodhpur) and three non-desert (Alwar, Ajmer and Jaipur) districts of Rajasthan. Among the three species viz. Ae. aegypti, Ae. vittatus and Ae. w-albus encountered during the survey the former was the most prevalent species. Studies were carried out both in rural and urban areas against different concentrations of two organochlorines (DDT and Dieldrin). In rural areas resistance has been observed with DDT and dieldrin both in desert and non-desert parts while an intermediate resistance has been observed in the urban areas with both the insecticides which required further verification. Resistance was more pronounced in rural areas as compared to urban areas. LC50 along with regression equation and Chi-square values have been determined for both the insecticides. 相似文献
244.
Singh A Agrawal SB Rai JP Singh P 《Journal of environmental biology / Academy of Environmental Biology, India》2002,23(3):283-288
Assessment of agropotentiality of the effluent coming out from century pulp and paper mill, Ghanshyamdham, Lalkua (Uttaranchal) has been made on wheat (Triticum aestivum var. UP-2329) crop grown in two soils differing in texture with different effluent concentrations. Diluted effluent increased the chlorophyll content, plant height, shoot and root biomass, grain yield, protein, carbohydrate and lipid contents in wheat grains, while undiluted effluent caused inhibition in plant growth resulting in a sharp decline of yield. Pure soil provided better growth and yield results than those soil mixed with sand. 相似文献
245.
Singh AK Kumar A Singh IJ Ram RN 《Journal of environmental biology / Academy of Environmental Biology, India》2005,26(3):557-565
Seasonal ovarian cycle, based on histophysiological changes, and correlative variations in liver were studied in an Indian major carp, Labeo rohita reared in captivity under ambient environmental conditions in Tarai region of Uttaranchal. The oocyte features used for marking ovarian cycle included nuclear-ooplasmic ratio, yolk vesicle incorporation into ooplasm, number and size of nucleolus and differentiation of follicular layer. Based on these features the ovarian cycle in L. rohita was divided into five phases i.e. resting, preparatory, pre-spawning, spawning and post-spawning/regression. The resting and preparatory phases were characterized by the dominating presence of chromatin-nucleolar and yolk-vesicle stage oocytes. The pre-spawning phase ovary was marked by the prevalence of yolk globule stage oocytes having cortical alveoli and differentiating follicular wall. The oocytes containing densely packed yolk-granules and large masses of yolk vesicles and also exhibiting germinal vesicle movement (GVM) signified the ovary of spawning phase. The ovary in regression phase contained pre-ovulatory atretic oocytes and significant number of oogonia. The histophysiological changes in liver showing augmented biosynthetic activity during preparatory and pre-spawning phases seemed well correlated with the gonadal development. The increasing water temperature and day-length apparently was favourable for the gonadal development in L. rohita. 相似文献
246.
Small and medium enterprises (SMEs) are under pressure to adopt sustainable practices in their business due to increasing environmental challenges. This study aims to identify and prioritize the solutions to overcome the barriers in the implementation of ecodesign practices in SMEs. This study helps the companies to develop and implement the strategies on priority using higher ranked solutions. In this study, a framework is proposed that is based on fuzzy analytical hierarchy process and fuzzy technique for order preference by similarity to ideal solution to rank the solutions that overcome the barriers in ecodesign implementation in SMEs. The proposed framework is illustrated by conducting a case study of an Indian ring and piston manufacturing company. This framework provides an effective support in the decision-making of the company for producing eco-friendly products through the implementation of ecodesign practices. Results of this study emphasize that training of designers to use different ecodesign tools is an essential practice for SMEs. 相似文献
247.
The fractional dispersion model for natural rivers, extended by including a first order reaction term, contains four parameters. In order to estimate these parameters a fractional Laplace transform-based method is developed in this paper. Based on 76 dye test data measured in natural streams, the new parameter estimation method shows that the fractional dispersion operator parameter F is the controlling parameter causing the non-Fickian dispersion and F does not take on an integer constant of 2 but instead varies in the range of 1.4–2.0. The adequacy of the fractional Laplace transform-based parameter estimation method is determined by computing dispersion characteristics of the extended fractional dispersion model and these characteristics are compared with those observed from 12 dye tests conducted on the US rivers, including Mississippi, Red, and Monocacy. The agreement between computed and observed dispersion characteristics is found to be good. When combined with the fractional Laplace transform-based parameter estimation method, the extended fractional dispersion model is capable of accurately simulating the non-Fickian dispersion process in natural streams. 相似文献
248.
The effects of host-plant resistance on cowpea phytophagous insects and their natural enemies under pure and mixed crop conditions was evaluated at Minjibir, Kano State, Nigeria, in 1992–1994 crop seasons. Cowpea Vigna unguiculata cv ‘IT86D-715' (susceptible to insect pests) and a wild Vigna line Vigna vexillata ‘TVnu 72' (resistant to most insect species) were planted alone and in mixtures with millet (Pennisetum glaucum) in plots of 25×25 m.Mixed cropping had limited effect on major insects and natural enemies. Colonies of Aphis craccivora were significantly smaller and there were more adults of Maruca vitrata in crop mixtures than in monocultures. However, flower and raceme infestation by larval M. vitrata, Megalurothrips sjostedti, and Sericothrips sp. were similar in crop mixtures and monocultures. Empoasca sp. populations and seedling infestation by beanfly Ophiomyia phaseoli were also similar in mixtures and monocultures as well as pod damage by M. vitrata and populations of Clavigralla tomentosicollis. Parasitization rates of M. vitrata, C. tomentosicollis and O. phaseoli and predator–prey ratios of spiders and Orius sp. were similar across cropping systems. Host-plant resistance in TVnu 72 drastically reduced insect populations and damage. Grain yield per hill was high in cowpea IT86D-715 and was not affected by intercropping with millet. Grain yield of TVnu 72 was poor and reflected the low yield potential of this accession.Host-plant resistance is an effective means of controlling insect pest damage in cowpea and there is no evidence that high levels of resistance reduced natural biological control. 相似文献
249.
The Science of Nature - 相似文献
250.
Neha Parkhi Dilip Chate Sachin D. Ghude Sunil Peshin Anoop Mahajan Reka Srinivas Divya Surendran Kaushar Ali Siddhartha Singh Hanumant Trimbake Gufran Beig 《环境科学学报(英文版)》2016,28(5):265-272
A network of air quality and weather monitoring stations was established under the System of Air Quality Forecasting and Research(SAFAR) project in Delhi. We report observations of ozone(O_3), nitrogen oxides(NO_x), carbon monoxide(CO) and particulate matter(PM_2.5and PM_(10)) before, during and after the Diwali in two consecutive years, i.e., November 2010 and October 2011. The Diwali days are characterised by large firework displays throughout India. The observations show that the background concentrations of particulate matter are between 5 and 10 times the permissible limits in Europe and the United States. During the Diwali-2010, the highest observed PM_(10) and PM_2.5mass concentration is as high as2070 μg/m~3 and 1620 μg/m3, respectively(24 hr mean), which was about 20 and 27 times to National Ambient Air Quality Standards(NAAQS). For Diwali-2011, the increase in PM_(10) and PM_2.5mass concentrations was much less with their peaks of 600 and of 390 μg/m~3 respectively, as compared to the background concentrations. Contrary to previous reports,firework display was not found to strongly influence the NO_x, and O_3 mixing ratios, with the increase within the observed variability in the background. CO mixing ratios showed an increase. We show that the large difference in 2010 and 2011 pollutant concentrations is controlled by weather parameters. 相似文献