Influence of biotic-abiotic factors on the degradation of novaluron in tropical soil   总被引：2，自引：2，他引：0  

P. Das Ph.D.  R. Pal Ph.D.  A. Chowdhury 《International Journal of Environmental Science and Technology》2008,5(3):425-429

In this study, the degradation of novaluron (benzoylphenyl urea insect growth regulator) was investigated under controlled laboratory conditions in clay loam alluvial and coastal saline soils of West Bengal, India. The application rates were field rate (FR); 2FR and 10FR. The incubation study was carried out at 30 °C and 60% of maximum water holding capacity of both the soils. Degradation of novaluron in both the soils followed first order reaction kinetics at all application rates under non-sterile and sterile conditions. The half-lives of novaluron in non-sterilized soils ranged from 17.0–17.8 days (alluvial soil) and 11.4–12.7 days (coastal saline soil), while the values in case of the sterilized soils were 53.7–59.0 days (alluvial soil) and 28.9–29.8 days (coastal saline soil) respectively. The novaluron degradation patterns were found to be highly influenced by soil types, application rates, and biotic abiotic factors. Abiotic factors strongly influenced novaluron degradation in both the soils. Biotic degradation was higher in alluvial soil compared to the coastal saline soil.  相似文献   

Geologic features and durability of limestones at the sphinx     

K. L. Gauri  A. N. Chowdhury  N. P. Kulshreshtha  A. R. Punuru 《Environmental Geology》1990,16(1):57-62

Geologic features considered to influence durability of the limestone at the sphinx are depositional history, evolution of porosity, and development of joints. These strata have two orthogonal groups of vertical joints. Where these joints intersect, wedge-shaped blocks are separating, causing loss of material from the core. Major reduction of the sphinx, however, is occurring due to salt crystallization aided by the ink-bottle pore systems prevailing in these rocks.The weathering profile exhibits alternating layers, less and more highly weathered. The less weathered rock is a biomicritic grainstone with smaller quantities of halite and gypsum and a larger large-pore-to-throat ratio than the indented, predominantly micritic, layers with larger concentration of salts and a smaller large-pore-to-throat ratio. Based upon poresize distributions, pressures generated in the pores have been calculated using thermodynamic principles, and an equation has been derived that provides a quantitative measure of durability of these rocks.  相似文献   

Destroying hills in the northeastern part of Bangladesh: A qualitative assessment of extent of the problem and its probable impact     

Md. Sirajul Islam  G. M. Jahid Hasan  Md. Aktarul Islam Chowdhury 《International Journal of Environmental Science and Technology》2006,2(4):301-308

Indiscriminate cutting of hills in the Sylhet region has become a major environmental issue. The nature and life style of Sylhet intimately related with the hills are thus under the threat of a drastic imbalance in its ecosystem. Due to such hill cutting the mostly affected sectors of this region will be its weather and climate, geomorphology and hydrology, and the indigenous flora and fauna. As a result the frequency of natural calamities like earthquake, flash flooding etc may increase considerably. Deforestation and resulting increased soil erosion, decreased ground water recharge and deteriorated water quality might also be as consequences of such hill cutting. This paper investigates the cause and extent of the problem along with its probable impact and finally suggests actions for conservation of hills for ecological balance of the region.  相似文献   

Driving forces of tropical deforestation: The role of remote sensing and spatial models   总被引：2，自引：0，他引：2  

Rinku Roy Chowdhury 《Singapore journal of tropical geography》2006,27(1):82-101

Remote sensing technologies are increasingly used to monitor landscape change in many parts of the world. While the availability of extensive and timely imagery from various satellite sensors can aid in identifying the rates and patterns of deforestation, modelling techniques can evaluate the socioeconomic and biophysical forces driving deforestation processes. This paper briefly reviews some emerging spatial methodologies aimed at identifying driving forces of land use change and applies one such methodology to understand deforestation in Mexico. Satellite image classification, change analysis and econometric modelling are used to identify the rates, hotspots and drivers of deforestation in a case study of the southern Yucatán peninsular region, an enumerated global hotspot of biodiversity and tropical deforestation. In particular, the relative roles of biophysical and socioeconomic factors in driving regional deforestation rates are evaluated. Such methodological approaches can be applied to other regions of the forested tropics and contribute insights to conservation planning and policy.  相似文献   

Cloud — Aerosol interaction during lightning activity over land and ocean: Precipitation pattern assessment   总被引：1，自引：0，他引：1  

Jayanti Pal  Sutapa Chaudhuri  Arumita Roy Chowdhury  Tanuka Bandyopadhyay 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(3):251-261

The present study attempts to identify the land - ocean contrast in cloud - aerosol relation during lightning and non-lightning days and its effect on subsequent precipitation pattern. The thermal hypothesis in view of Convective Available Potential Energy (CAPE) behind the land - ocean contrast is observed to be insignificant in the present study region. The result shows that the lightning activities are significantly and positively correlated with aerosols over both land and ocean in case of low aerosol loading whereas for high aerosol loading the correlation is significant but, only over land. The study attempts to comprehend the mechanism through which the aerosol and lightning interact using the concept of aerosol indirect effect that includes the study of cloud effective radius, cloud fraction and precipitation rate. The result shows that the increase in lightning activity over ocean might have been caused due to the first aerosol indirect effect, while over land the aerosol indirect effect might have been suppressed due to lightning. Thus, depending on the region and relation between cloud parameters it is observed that the precipitation rate decreases (increases) over ocean during lightning (non-lightning) days. On the other hand during non-lightning days, the precipitation rate decreases over land.  相似文献   

Seasonal variation in heavy metal contaminations in water and sediments of Jamshedpur stretch of Subarnarekha river,India     

Subhabrata Banerjee  Adarsh Kumar  Subodh Kumar Maiti  Abhiroop Chowdhury 《Environmental Earth Sciences》2016,75(3):265

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Variations in diagenetic environments of the coral rag and underlying oolite of the osmington oolite formation (upper oxfordian) of the Oxford—Berkshire area,U.K., and their implications     

Ahad N. Chowdhury 《Sedimentary Geology》1982,32(4):247-263

Petrographic and geochemical evidence shows convincingly that the diagenetic environment changes from marine phreatic through freshwater phreatic to vadose during lithification of the oolites and the overlying Coral Rag of the Osmington Oolite Formation in the Oxford—Berkshire area. This change is thought to be a consequence of tectonic uplift following deposition of the Coral Rag. Extensive neomorphic replacement of the corals took place in a freshwater phreatic environment created by tectonic uplift. Retention of Sr in the Coral Rag is related to differing diagenesis: pore-fluids remained for protracted periods within the Coral Rag as the downward flow was greatly retarded because of obliteration of porosity in the oolites by marine phreatic cementation before deposition of the Coral Rag.  相似文献   

Amplitude effects due to multiscale impedance contrasts and multiple scattering: implications for Ivrea‐type continental lower crust     

Huub Douma  Kabir Roy&#;Chowdhury 《Geophysical Journal International》2001,147(2):435-448

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Electricity consumption patterns within cities: application of a data-driven settlement characterization method     

Pranab K. Roy Chowdhury  Jeanette E. Weaver  Eric M. Weber  Dalton Lunga  St. Thomas M. LeDoux  Amy N. Rose 《International Journal of Digital Earth》2020,13(1):119-135

ABSTRACT

Urban areas presently consume around 75% of global primary energy supply, which is expected to significantly increase in the future due to urban growth. Having sustainable, universal energy access is a pressing challenge for most parts of the globe. Understanding urban energy consumption patterns may help to address the challenges to urban sustainability and energy security. However, urban energy analyses are severely limited by the lack of urban energy data. Such datasets are virtually non-existent for the developing countries. As per current projections, most of the new urban growth is bound to occur in these data-starved regions. Hence, there is an urgent need of research methods for monitoring and quantifying urban energy utilization patterns. Here, we apply a data-driven approach to characterize urban settlements based on their formality, which is then used to assess intra-urban urban energy consumption in Johannesburg, South Africa; Sana’a, Yemen; and Ndola, Zambia. Electricity is the fastest growing energy fuel. By analyzing the relationship between the settlement types and the corresponding nighttime light emission, a proxy of electricity consumption, we assess the differential electricity consumption patterns. Our study presents a simple and scalable solution to fill the present data void to understand intra-city electricity consumption patterns.  相似文献   

Analysis of the vajont slide — new approach   总被引：1，自引：0，他引：1  

R. Chowdhury 《Rock Mechanics and Rock Engineering》1978,11(1):29-38

SummaryAnalysis of the Vajont Slide — New Approach This paper is concerned with the analysis of the 1963 Vajont slide in Italy. Attention is drawn to the fact that numerous investigations have been consistently unsuccessful in explaining the slide. A new approach consistent with a progressive failure mechanism established by all comprehensive investigations is suggested in this paper. The analysis simulates the transformation of the slope from a condition of stability to one of limit-equilibrium and failure in a step-by-step process. It is shown that the enormous velocities calculated on the basis of external observations of the slide can be explained by the new analytical approach.

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ZusammenfassungAnalyse der Felsgleitung bei Vajont — Neuer Erklärungsversuch Dieser Artikel beschäftigt sich mit der Felsgleitung bei Vajont in Italien im Jahre 1963. Es wird darauf hingewiesen, daß es in einer Vielzahl anderer Untersuchungen bislang nicht möglich war, eine Erklärung für die Felsgleitung zu finden. Ein neues Modell, basierend auf dem Mechanismus des progressiven Zusammenbruchs wird vorgeschlagen. Die Untersuchung simuliert den Übergang des Hanges vom stabilen Zustand in ein Grenzgleichgewicht und schließlich den Zusammenbruch in einem Prozeß, der Schritt für Schritt abläuft. Es wird gezeigt, daß die enormen Geschwindigkeiten, die aufgrund von Beobachtungen berechnet wurden, im Rahmen dieses Modells erklärt werden können.

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RésuméAnalyse de l'éboulement de Vajont — Nouvelle approche Cette communication constitue une analyse de l'éboulement de Vajont (Italie) en 1963. On souligne le fait que les nombreuses enquêtes entreprises pour expliquer cet éboulement se sont montrées infructueuses. Cette communication propose une nouvelle approche conforme à un mécanisme progressif de défaillances établi par toutes les enquêtes compréhensives. L'analyse simule la transformation graduelle de la pente: de la stabilité à l'équilibre limité et enfin à la défaillance. On démontre que les vélocités énormes calculées à base des observations externes de l'éboulement peuvent s'expliquer par cette nouvelle approche analytique.

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Notation c unit effective cohesion - ø effective angle of shearing resistance (residual) - n proportion of the slip surface along which failure has progressed - K conjugate stress ratio for a slope - K ₀ ratio of effective horizontal normal stress to effective vertical normal stress in the slope With 3 Figures  相似文献