Long-Term Trend in Ozone and Erythemal UV at Indian Latitudes     

Nandita D. Ganguly  K. N. Iyer 《Journal of Atmospheric Chemistry》2006,55(3):227-239

The role of atmospheric ozone to protect the living organisms and vegetation from the harmful effects of ultraviolet irradiation is well known. Depletion of the ozone layer is a great threat to the human society. In this paper we have discussed the lethal effects of ozone depletion and have presented the ozone and UV-B scenarios from 1979 to 2005 at different Indian latitudes using satellite data. The erythemal UV irradiance data obtained from Nimbus-7 and Earth probe total ozone mapping spectrometer (TOMS) and the tropospheric and stratospheric ozone data obtained from the convective cloud differential (CCD) method have been used to study the variability of erythemal UV irradiance and the stratospheric and tropospheric column ozone, respectively, over a period from 1979 to 2005. The observed results along with the expected upper and lower tolerance limits for tropospheric and stratospheric ozone, respectively, for different Indian latitudes, which have been estimated statistically using monthly mean CCD ozone data from 1979 to 2005 have been discussed in detail.  相似文献   

Geospatial–temporal dependence among weekly precipitation extremes with applications to observations and climate model simulations in South America     

Gabriel Kuhn  Shiraj Khan  Auroop R. Ganguly  Marcia L. Branstetter   《Advances in water resources》2007,30(12):2401-2423

A quantification of the spatio-temporal dependence among precipitation extremes is important for investigating the properties of intense storms as well as flood or flash-flood related hazards. Extreme value theory has been widely applied to the hydrologic sciences and hydraulic engineering. However, rigorous approaches to quantify dependence structures among extreme values in space and time have not been reported in the literature. Previous researchers have quantified the dependence among extreme values through the concept of (pairwise bivariate) tail dependence coefficients. For estimation of the tail dependence coefficients, we apply a recently developed method [Kuhn G. On dependence and extremes. PhD thesis (Advisor: C. Klüppelberg), Munich University of Technology, 2006] which utilized the multivariate tail dependence function of a subclass of elliptical copulas. This study extends the previous approach in the context of space and time by considering pairs of spatial grids in South America and quantifying the dependence among precipitation extremes based on the time series at each spatial grid. In addition, Kendall’s τ is used to estimate the pairwise copula correlation (for an elliptical copula) of precipitation between all grids in South America. The geospatial–temporal dependence measures are applied to precipitation observations from 1940 to 2005 as well as simulations from the Community Climate System Model version 3 (CCSM3) for 1940–2099. New insights are obtained regarding the spatio-temporal dependence structures for precipitation over South America both with regard to correlation as well as tail dependence.  相似文献   

Fe²⁺–Mg fractionation between orthopyroxene and spinel: experimental calibration in the system FeO–MgO–Al₂O₃–Cr₂O₃–SiO₂, and applications     

H. P. Liermann  J. Ganguly 《Contributions to Mineralogy and Petrology》2007,154(4):491

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Hazardous area map: an approach of sustainable urban planning and industrial development—a review     

Ganguly  Madhurima  Aynyas  Rahul  Nandan  Abhishek  Mondal  Prasenjit 《Natural Hazards》2018,91(3):1385-1405

Natural Hazards - A hazard map is a map which shows about all the vulnerable regions present in any country or at any specific place or location which is affected or will be affected by natural...  相似文献   

Biogeochemical controls of arsenic occurrence and mobility in the Indian Sundarban mangrove ecosystem   总被引：1，自引：0，他引：1  

S.K. Mandal  D. Ganguly  T.K. Jana 《Marine pollution bulletin》2009,58(5):652-657

This study aims to investigate the control of arsenic distribution by biogeochemical processes in the Indian Sundarban mangrove ecosystem and the importance of this ecosystem as an arsenic source for surrounding coastal water. The As(V)/As(III) ratio was found to be significantly lower in both surface and pore waters compared to sea water, which could be attributed to biogeochemical interconversion of these arsenic forms. The biological uptake of arsenic due to primary and benthic production occurs during the post-monsoon season, and is followed by the release of arsenic during the biochemical degradation and dissolution of plankton in the pre-monsoon season. These results suggest that arsenic is immobilized during incorporation into the arsenic-bearing initial phase, and unlikely to be released into pore water until the complete microbial degradation of arsenic-bearing organic compounds.  相似文献   

Velocity inversion in cross-hole seismic tomography bycounter-propagation neural network, genetic algorithmand evolutionary programming techniques     

Sankar Kumar Nath  Subrata Chakraborty  Sanjiv Kumar Singh  & Nilanjan Ganguly 《Geophysical Journal International》1999,138(1):108-124

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Vanadium bearing titaniferous magnetite ore bodies of Ganjang,Karbi-Anglong District,Northeastern India     

Abhishek Saha  Sohini Ganguly  Jyotisankar Ray  Avik Dhang 《Journal of the Geological Society of India》2010,76(1):26-32

A new occurrence of (syenite-hosted) Vanadium bearing titaniferous magnetite ore body has been reported from Ganjang (26°09′35″ N: 93°20′ E), Karbi-Anglong, Northeastern India. The magnetite ore bodies have lumpy and sporadic occurrences within the host syenite pluton intrusive into gneissic country rocks. Ore microscopic studies reveal that magnetite is often associated with haematite and ilmenite depicting different textural patterns. Critical consideration of several elemental patterns suggests magmatic differentiation to be main ore-forming process. The ore body is suggested to have been formed as late stage segregation from a differentiating alkaline magma in a fluid enriched milieu.  相似文献   

Evaluation of phase chemistry and petrochemical aspects of Samchampi-Samteran differentiated alkaline complex of Mikir Hills,northeastern India     

Abhishek Saha  Sohini Ganguly  Jyotisankar Ray  Nilanjan Chaterjee 《Journal of Earth System Science》2010,119(5):675-699

The Samchampi-Samteran alkaline complex occurs as a plug-like pluton within the Precambrian granite gneisses of Mikir Hills, Assam, northeastern India and it is genetically related to Sylhet Traps. The intrusive complex is marked by dominant development of syenite within which ijolitemelteigite suite of rocks is emplaced with an arcuate outcrop pattern. Inliers of alkali pyroxenite and alkali gabbro occur within this ijolite-melteigite suite of rocks. The pluton is also traversed by younger intrusives of nepheline syenite and carbonatite. Development of sporadic, lumpy magnetite ore bodies is also recorded within the pluton. Petrographic details of the constituent lithomembers of the pluton have been presented following standard nomenclatorial rules. Overall pyroxene compositions range from diopside to aegirine augite while alkali feldspars are typically orthoclase and plagioclase in syenite corresponds to oligoclase species. Phase chemistry of nepheline is suggestive of Na-rich alkaline character of the complex. Biotite compositions are typically restricted to a uniform compositional range and they belong to ‘biotite’ field in the relevant classification scheme. Garnets (developed in syenite and melteigite) typically tend to be Ti-rich andradite, which on a closer scan can be further designated as melanites. Opaque minerals mostly correspond to magnetite. Use of Lindsley’s pyroxene thermometric method suggests an equilibration temperature from ∼450°–600°C for melteigite/alkali gabbro and ∼400°C for syenite. Critical assessment of other thermometric methods reveals a temperature of equilibration of ∼700°–1350°C for ijolite-melteigite suite of rocks in contrast to a relatively lower equilibration temperature of ∼600°C for syenite. Geobarometric data based on pyroxene chemistry yield an equilibration pressure of 5.32–7.72 kb for ijolite, melteigite, alkali pyroxenite, alkali gabbro and nepheline syenite. The dominant syenite member of the intrusive plug records a much higher (∼11 kb) equilibration pressure indicating a deeper level of intrusion. Major oxide variations of constituent lithomembers with respect to differentiation index (D.I.) corroborate a normal magmatic differentiation. A prominent role of liquid immiscibility is envisaged from field geological, petrographic and petrochemical evidences. Tectonic discrimination diagrams involving clinopyroxene chemistry strongly suggest within plate alkaline affinity for the parental magma which is in conformity with the regional plume tectonics.  相似文献   

Isolation of hydrocarbonoclastic bacteria from bilge oil contaminated water   总被引：1，自引：1，他引：0  

C. Sivaraman  A. Ganguly Ph.D.  M. Nikolausz Ph.D.  S. Mutnuri Ph.D. 《International Journal of Environmental Science and Technology》2011,8(3):461-470

Two bacterial strains, i.e. Pseudomonas mendocina and Ochrobactrum sp. were isolated from bilge oil contaminated water of Mormugao harbour, Goa, India and grown in a culture medium with hexadecane as the sole carbon source. Pseudomonas mendocina was used in further studies as it was the dominant strain. This strain effectively degraded tetradecane, hexadecane and octadecane leaving a residual concentration of about 73 %, 54 % and 40 % respectively in 120 h. Sequence analysis of the dominant bands from the denaturing gradient gel electrophoresis profiles revealed the differences between the genera of bilge oil contaminated sea water and its enrichment culture on hexadecane indicating a shift in community structure based on the type of substrate available. Pseudomonas mendocina amplified for the following catabolic genes namely C23O, nid and ndo. Based on the catabolic gene study the potential of the bacterial strain isolated, i.e. Pseudomonas mendocina seems to be interesting as it will be able to degrade polyaromatic hydrocarbons as well. Physicochemical properties of Pseudomonas mendocina indicates production of exopolysaccharides based on the value of its isoelectric point.  相似文献   

Exploratory Study of Archaebacteria and their Habitat in Underground,Opencast Coal Mines and Coal Mine Fire Areas of Dhanbad     

D. Mukherjee  V. A. Selvi  J. Ganguly  L. C. Ram  R. E. Masto 《Journal of the Geological Society of India》2018,91(5):575-582

Coal contains abundant microbial genera which include archaebacteria. The study of archaea kingdom in coal mines is a significant tool for knowing the relationship between coal and archaebacteria, the major role in geochemical cycle and application for further coal bio–beneficiation. The present study related to exploration of archaebacteria and their habitat in coal mining area of Dhanbad with reference to their ecology and nutrient availability that have evolve to grow under extreme conditions. Total six different sites such as two underground coal mines (Sudamdih shaft and Chasnalla underground mine), two opencast coal mines (Chandan project and Bhowra abandoned mine), Jharia mine fire and Sudamdih coal washery of Dhanbad was selected. Seven gram negative obligate anaerobic bacteria were isolated from the selected sites. The isolated species were rod and cocci shaped and the colony was round, smooth, off white in colour and with entire margin and little are cluster of cocci in shape. The isolated species were identified as Methanococcus spp, Methanobacterium spp and Methanosarcina spp. Apart from that two thermoacidophilic sulfur oxidizing bacteria Sulfolobus spp was also isolated from Jharia Coal Mine Fire. The physicochemical and biological characterization of the habitat was also studied for the entire selected area.  相似文献