Use of remote sensing data in comprehending an extremely unusual flooding event over southwest Bangladesh     

Chowdhury  Ehsan H.  Hassan  Quazi K. 《Natural Hazards》2017,88(3):1805-1823

Natural Hazards - Flooding is one of the natural disasters that affect the livelihood of the people living in the floodplains, like Bangladesh. Here, we proposed to employ SAR satellite images in...  相似文献   

Maintenance of Environmental Sustainability Through Microbiological Study of Pharmaceutical Solid Wastes          下载免费PDF全文

Fouzia Ferdous Khan Chowdhury  Mrityunjoy Acharjee  Rashed Noor 《洁净——土壤、空气、水》2016,44(3):309-316

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Rice Husk Ash as a Low Cost Adsorbent for the Removal of Methylene Blue and Congo Red in Aqueous Phases     

Anirban K. Chowdhury  Anupam D. Sarkar  Amitava Bandyopadhyay 《洁净——土壤、空气、水》2009,37(7):581-591

Adsorption is of significant importance for effluent treatment, especially for the treatment of colored effluent generated from the dyeing and bleaching industries. Low cost adsorbents have gained attention over the decades as a means of achieving very high removal efficiencies to meet effluent discharge standards. The present article reports on batch investigations for color removal from aqueous solutions of Methylene Blue (MB) and Congo Red (CR) using Rice Husk Ash (RHA) as an alternative low cost adsorbent. The performance analysis was carried out as a function of various operating parameters, such as initial concentration of dye, adsorbent dose, contact time, shaker speed, interruption of shaking and ionic concentration. Performance studies revealed that a very high percentage removal of color was achievable for both dyes. The maximum percentage removal of MB was 99.939%, while 98.835% removal was observed for CR. These percentage removals were better than existing systems. Detailed data analysis indicated that adsorption of MB followed the Temkin isotherm, while CR followed the Freundlich isotherm. These isotherms were feasible within the framework of experimentation. Batch kinetic data, on the other hand, indicated that pseudo second order kinetics governed adsorption in both cases. Sensitivity analysis further indicated that the effects of initial dye concentration, shaker speed, pH and ionic strength had no noticeable effect on the percentage dye removal at equilibrium. Batch desorption studies revealed that 50% acetone solution was optimum for CR, while desorption of MB varied directly with acetone concentration.  相似文献   

Control of porosity on durability of limestone at the great sphinx,Egypt     

Adinarayana R. Punuru  Ahad N. Chowdhury  Niraj P. Kulshreshtha  K. L. Gauri 《Environmental Geology》1990,15(3):225-232

The study of the porosimetric data obtained from intrusion, extrusion, and reintrusion of mercury in limestone samples from the region of the sphinx reveals the characteristics of the pore system and allows analysis of durability factors.The pore system in all these rocks consists of ink-bottle pores. As the initial intrusion and extrusion have been completed, some mercury always remains in the sample. This trapped mercury represents the volume of large voids of the ink-bottle pore system. The distribution of the volume of the narrow throats of this system is revealed by the reintrusion curves.The curves obtained by plotting extrusion and reintrusion volumes against corresponding pressures enclose a loop. These curves relate to pore throats only. As entrapment of mercury does not occur in these pores, their distribution frequency and sorting seem to cause this hysteresis.The pressure/volume data also have been interpreted in terms of work needed to inject and extrude mercury from the pores. This thermodynamic analysis of the data has provided an additional, although less well-defined, means to characterize the porous stones.We have used in this study the model-dependent pore-size distributions and model-independent thermodynamic properties to develop durability factors. The factors based upon the combination of pore sizes in the range of <0.5, 0.5-5, and >5 µm precisely fit the observed durability of limestones at the sphinx, some of which have been exposed for more than 5,000 yr to the ambient atmosphere.  相似文献   

Weathering of limestone beds at the great sphinx     

Ahad N. Chowdhury  Adinarayana R. Punuru  K. L. Gauri 《Environmental Geology》1990,15(3):217-223

The weathering characteristics of the sphinx limestones are evaluated in the context of their pore system. The latter consists of ink-bottle pores. This pore system varies from one stratum to another. In the lower micritic rocks the large cavities of the ink-bottle pores are interconnected through the fine capillary network of the narrow throats. In the upper skeletal-rich rocks the interconnections are provided by large as well as small throats.The pore systems in these limestones reflect the depositional regime as well as the diagenetic alterations. The development of microspar from the micritic mud resulted in the formation of microporosity, and the extended circulation of freshwater enlarged some micropores preferentially, forming large cavities.The relationship of micro- and macropores has strongly influenced the weathering of the sphinx rocks.  相似文献   

A New Report of Serpentinites from Northern Central Indian Ridge (at 6°S)—An Implication for Hydrothermal Activity   总被引：1，自引：1，他引：0  

Dwijesh RAY  Ranadip BANERJEE  Sridhar D.IYER  Subir MUKHOPADHYAY 《《地质学报》英文版》2008,82(6)

Serpentinites from the inside corner high (6°38.5'S/ 68°19.34'E) from the Northern Central Indian Ridge (NCIR) are comprised mainly of high Mg-rich lizardite and chrysotile pseudomorphs with varying morphologies.'Mesh rim','window', 'hourglass'and'bastite'are the most common textures displayed by both chrysotile and lizardite.Numerous chrysotile veins in association with cross cutting magnetite veins indicate an advanced stage of serpentinisation.The relatively high abundance of chrysotile and lizardite suggest their close association and formation at a temperature below 250°C. Abundant 'mesh rim' and 'bastite'texture and variegated matrix reveal that the present Serpentinites might have formed due to the interaction of harzburgite and seawater.Positive Eu anomaly (Eu/Eu*up to 3.38), higher La/Sin (up to 4.40) and Nb/La (up to 6.34) ratios suggest substantial hydrothermal influence during the formation of the Serpentinites.  相似文献   

Statistical downscaling of rainfall: a non-stationary and multi-resolution approach     

Md. Mamunur Rashid  Simon Beecham  Rezaul Kabir Chowdhury 《Theoretical and Applied Climatology》2016,124(3-4):919-933

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Simultaneous monitoring of soil 222Rn in the Eastern Himalayas and the geothermal region of eastern India: an earthquake precursor     

Chowdhury  Saheli  Deb  Argha  Barman  Chiranjib  Nurujjaman  Md.  Bora  Dipok K. 《Natural Hazards》2022,112(2):1477-1502

Natural Hazards - Activity of 222Rn gas in soil has been recorded continuously at three monitoring centres, namely Ravangla and Diphu in the Eastern Himalayan region and Tantloi in the geothermal...  相似文献   

Revisiting the Environmental Kuznets Curve: An introduction to the special issue     

Rinku Roy Chowdhury 《Applied geography (Sevenoaks, England)》2012,32(1):1-2

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Homogeneous freezing of single sulfuric and nitric acid solution drops levitated in an acoustic trap     

Karoline Diehl  Matthias Ettner-Mahl  Anke Hannemann  Subir K. Mitra   《Atmospheric Research》2009,94(2):356-361

The freezing temperatures of single supercooled drops of binary and ternary sulfuric and nitric acid solutions were measured while varying the acid concentration. An acoustic levitator was used which allows to freely suspend single solution drops in air without electrical charges thereby avoiding any electrical influences which may affect the freezing process. The drops of typically 500 µm in radius were monitored by a video camera during cooling cycles down to − 85 °C to simulate the upper tropospheric and stratospheric temperature range. The present data confirm that liquid solution droplets can be supercooled far below the equilibrium melting point by approximately 35 °C. They follow the general trend of the expected freezing temperatures for homogeneous ice nucleation.  相似文献