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   

Determining the climatic boundary between the Chinese loess and palaeosol: evidence from aeolian coarse-grained magnetite   总被引：3，自引：0，他引：3  

Qingsong Liu  Subir K. Banerjee  Michael J. Jackson  Fahu Chen  Yongxin Pan  Rixiang Zhu 《Geophysical Journal International》2004,156(2):267-274

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New insights into partial oxidation model of magnetites and thermal alteration of magnetic mineralogy of the Chinese loess in air   总被引：10，自引：0，他引：10  

Qingsong Liu  Subir K. Banerjee  Michael J. Jackson  Chenglong Deng  Yongxin Pan  Zhu Rixiang 《Geophysical Journal International》2004,158(2):506-514

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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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Syn-sedimentary tectonics and facies analysis in a rift setting: Cretaceous Dalmiapuram Formation,Cauvery Basin,SE India     

Nivedita Chakraborty  Subir Sarkar 《古地理学报》2018,(2)

The Cretaceous(Albian-Cenomanian) Dalmiapuram Formation is one of the economically significant constituents in the hydrocarbon-producing Cauvery rift basin, SE India that opened up during the Late Jurassic e Early Cretaceous Gondwanaland fragmentation. The fossil-rich Dalmiapuram Formation,exposed at Ariyalur within the Pondicherry sub-basin of Cauvery Basin, rests in most places directly on the Archean basement and locally on the Lower Cretaceous(Barremian-Aptian) Basal Siliciclastic Formation. In the Dalmiapuram Formation, a facies association of tectonically-disturbed phase is sandwiched between two drastically quieter phases. The early syn-rift facies association(FA 1), records the first carbonate marine transgression within the basin, comprising a bar-lagoon system with occasionally storms affecting along the shore and a sheet-like non-recurrent biomicritic limestone bed on the shallow shelf that laterally grades into pyrite e glauconite-bearing dark-colored shale in the deeper shelf. Spectacular breccias together with varied kinds of mass-flow products comprise the syn-rift facies association(FA 2). While the breccias occur at the basin margin area, the latter extend in the deeper inland sea. Clast composition of the coarse clastics includes large, even block-sized limestone fragments and small fragments of granite and sandstone from the basement.Marl beds of quieter intervals between tectonic pulses occur in alternation with them. Faulted basal contact of the formation, and small grabens filled by multiple mass-flow packages bear the clear signature of the syntectonic activity localized contortions, slump folds, and pillow beds associated with mega slump/slide planes and joints, which corroborates this contention further. This phase of tectonic intervention is followed by another relatively quieter phase and accommodates the late syn-rift facies association(FA 3). A tidal bar-interbar shelf depositional system allowed a transgressive systems tract motif to grow eventually passing upwards into the Karai Shale Formation, whose contact with the Dalmiapuram Formation is gradational.  相似文献   

Rock-magnetic proxies of climate change in the loess-palaeosol sequences of the western Loess Plateau of China   总被引：5，自引：0，他引：5  

Christopher P. Hunt  Subir K. Banerjee  Jiamao Han  Peter A. Solheid  Eric Oches  Weiwei Sun  Tungsheng Liu 《Geophysical Journal International》1995,123(1):232-244

Results of the first detailed study of the climate proxy record in the loess-palaeosol sequence at Xining-one of the few palaeoclimate sites in the currently arid western Loess Plateau of China-illustrate the importance of making many types of rock-magnetic measurements other than susceptibility. A multiparameter approach yielded confirmation that here, as elsewhere in the Loess Plateau, the susceptibility enhancement in palaeosols was caused primarily by ultrafine magnetite and maghaemite. Nevertheless, magnetic enhancement was caused not exclusively by changes in relative grain size, but also by variations in concentration and mineralogy of the magnetic fraction.
The effects of concentration variations were removed through normalization of susceptibility and anhysteretic remanence with saturation magnetization and saturation remanence, respectively. the resulting signal was ascribed more confidently to variation in magnetic grain size, which in turn was interpreted as a better proxy of pedogenesis than simple susceptibility. Variations in magnetic mineralogy were also determined to constrain interpretations further. the data were then used to discuss climate history at Xining. Finally, results from Xining were compared with other western sites and contrasted with eastern sites.
In summary: (1) data is presented from a new Loess Plateau site which also appears to yield a global climate signal; (2) a demonstration is made of a more rock-magnetically robust way to separate concentration, composition and grain-size controls on susceptibility and other magnetic parameters; and (3) models are provided for inter-regional comparisons of palaeoclimate proxy records.  相似文献