排序方式： 共有32条查询结果，搜索用时 15 毫秒
21.
Multivariate statistical approach to identify significant sources influencing the physico-chemical variables in Aerial Bay,North Andaman,India 总被引：1，自引：0，他引：1
Dilip Kumar Jha N.V. Vinithkumar Biraja Kumar Sahu Apurba Kumar Das P.S. Dheenan P. Venkateshwaran Mehmuna Begum T. Ganesh M. Prashanthi Devi R. Kirubagaran 《Marine pollution bulletin》2014
Aerial Bay is one of the harbor towns of Andaman and Nicobar Islands, the union territory of India. Nevertheless, it is least studied marine environment, particularly for physico-chemical assessment. Therefore, to evaluate the annual spatiotemporal variations of physico-chemical parameters, seawater samples collected from 20 sampling stations covering three seasons were analyzed. Multivariate statistics is applied to the investigated data in an attempt to understand the causes of variation in physico-chemical parameters. Cluster analysis distinguished mangrove and open sea stations from other areas by considering distinctive physico-chemical characteristics. Factor analysis revealed 79.5% of total variance in physico-chemical parameters. Strong loading included transparency, TSS, DO, BOD, salinity, nitrate, nitrite, inorganic phosphate, total phosphorus and silicate. In addition, box-whisker plots and Geographical Information System based land use data further facilitated and supported multivariate results. 相似文献
22.
Summary In this study, a detailed examination on the evolution of summer monsoon onset over southern tip of the Indian peninsula, its advancement and withdrawal over the Indian sub-continent is carried out by utilizing the analysis/forecast fields of a global spectral model for Monsoon-1995. The data base used in this study is derived from the archives of global data assimilation and forecasting system of NCMRWF, India, valid for 00UTC at 1.5° latitude/longitude resolution for the summer monsoon period of 1995. By utilizing the analyses and forecast fields, and the established knowledge of the Indian monsoon, objective criteria are employed in this study for determining the onset, advancement, and withdrawal of the monsoon.It is found that all the major characteristics of Monsoon-1995 are captured well by the analysis-forecast system even though the criteria adopted in this study are more objective and different in nature as compared to the conventional procedures. The onset date of monsoon over the southern tip of the Indian peninsula as determined by the dynamical onset procedure is found to be matching well with the realized date. Further, the evolution of monsoon onset characteristics over the Arabian Sea both in the analyses and forecasts is found to be in good agreement with the earlier studies. However, the magnitudes of net tropospheric moisture build-up and tropospheric temperature increase differ with respect to analyses and corresponding forecast fields. In addition, all important characteristics of the advancement and withdrawal of monsoon over the Indian sub-continent viz. stagnation, revival etc., are brought out reasonably well by the analysis and forecast system.With 10 Figures 相似文献
23.
The water and bed-sediment pollution status of the Padma River was determined by analysis of representative samples for selected
metals and ions. Water and bed-sediment samples were collected at a T-dam, Rajshahi, Bangladesh, for 7 months. Water and silt-metal
content analysis was performed using atomic absorption spectrophotometry or other analytical methods. The data showed the
variation of the metal ion-levels in water as follows: Ca 17.11–48.37 ppm, Na 17.51–20.09 ppm, K 1.00–3.60 ppm, Cr 2.80–7.00 ppm,
and SO4 4.17–5.48 ppm; in bed sediment, the levels were Cr 35–1050 ppm and Pb 12–48 ppm. The occurrence of Na, K and Ca was in the
normal range (US EPA permissible limit), but the levels of Cr in water were much higher than the permissible limit. The SO4 ion content was well below the pollution level. The concentration of Pb in the bed sediment was within the permissible limit
for the standard International Atomic Energy Agency (IAEA) Soil-5a, but the concentration of Cr in the bed sediment was significantly
higher than the permissible limit for the standard IAEA Soil-5a. Thus the Padma river water was polluted with Cr. The occurrence
of some ions showed a monthly variation.
Received: 19 August 1999 · Accepted: 12 October 1999 相似文献
24.
25.
Exact analytical solutions are obtained for a higher dimensional spherically symmetric inhomogeneous metric in presence of
a mass-less scalar field with a flat potential within the framework of Lyra geometry. Assuming a homogeneous scalar field,
we have shown that the metric can be reduced to a generalized FRW type. 相似文献
26.
27.
F.?RahamanEmail author N.?Begum G.?Bag B.?C.?Bhui 《Astrophysics and Space Science》2005,299(3):211-218
Bermann [Nuovo Cimento B (1983), 74, 182] presented a law of variation of Hubble’s parameter that yields constant deceleration
parameter models of the Universe. In this paper, we study some cosmological models with negative constant deceleration parameter
within the framework of Lyra geometry.
PACS Nos: 98.80 cq, 04.20 jb, 04.50 相似文献
28.
Z.N. Begum 《Journal of Atmospheric and Solar》1998,60(18):1751-1754
A theoretical model based on some physical assumptions has been integrated to study the scattering of solar radiation by aerosol particulates of any size present in the atmosphere. Using this model, which incorporates multiple scattering, scattered fluxes of radiation with varying optical depths and also the optical depth versus wavelengths are computed. The present results are found to be in close agreement with the observations of the Pre-Indian Ocean Experiment (INDOEX) 1996. This provides evidence of the direct effect of aerosol particulates on the radiative forcing of the atmosphere. 相似文献
29.
The study aims to simulate the peri-urban growth dynamics in a growing region of India using Weights of Evidence (WOE) based cellular automata model. The growth process was expressed as a function of four causative variables corresponding to which seven data layers were generated in a Geographic Information Systems environment. The model was calibrated for the period 2000–2005 using Kappa indices and fuzzy set theory based two way comparison method. The Kappa value was 0.7, while the value of Klocation and Khisto were 0.81 and 0.93, respectively. The fuzzy similarity values increased for small to large neighbourhood sizes which showed that the model was able to simulate the contiguous and dense growth. However, for dispersed and isolated growth the model showed less accuracy. The model was validated for period 2005–2010 and revealed a Kappa value of 0.88, while value of Klocation and Khisto were 0.91 and 0.96, respectively. 相似文献
30.
Natural Hazards - Landslide and human mortality have been a common phenomenon in the Rangamati district over the past several years. This study examined the geotechnical properties (e.g., grain... 相似文献