988 resultados para lime mud
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A detailed survey of the present knowledge on the physical aspects of the mud banks has been presented in chapter 1.The physical geographical and geological aspects of the kerala coast, the shore-line and the sea bed and the various views on the formation,movements and dissipation of the mud banks have been discussed.The scope of the present work and a description of the area of study have also been given in this chapter. The horizontal and vertical distribution and the seasonal variations of the concentration of suspended matter in the mud bank region are discussed in chapter 3.it is seen that the mud bank reses above the bottom in the form of a ridged ,irregular,solid come with a flat top. Chapter vi deals with waves and currents in the region of the mud bank. The orientation of the breakers on either side of the mud bank suggests the possibility of formation of opposing alongshore currents and convergence of energy caused by wave refraction.The distribution of currents during the formative nature and dissipating stages of the mud bank show that the converging alongshore currents give rise to offshore flows
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There is very little information on the subtidal bottom fauna of the shelf regions in the seas around India. What little is known is restricted to macro benthos. The paucity of the work on bottom fauna and the importance of mud banks in the fishery of the South West Coast of India has initiated the present study. Attempts have been made to obtain a picture of the bottom fauna of a mud bank region of the Kerala Coast. The difficulties involved in the sampling and analysis, especially the availability of a suitable vessel during the S.W. Monsoon, resulted in the work being restricted mainly to the Narakal mud bank region 6 Km. north of Cochin Detailed sampling is conducted using grab, dredge and to a small extent beam trawl, to assess the qualitative and quantitative nature of the macro benthos. Important species contributing to the fauna are identified and the standing crop estimated for different seasons. The meiobenthos was studied using core samples taken from the grab. Animals were identified to the major taxa. Standing crop of meiobenthos and the quantitative importance of different groups were also studied. The data collected have been interpreted and discussed. As an understanding of the physico-chemical aspects of the environment is essential in order to obtain a true picture of the benthos, attempts were made in this direction. Environmental parameters such as temperature of the sediment, salinity, temperature, and dissolved oxygen in the overlying water were studied .during the period of benthos investigation. Monthly observations on the dissolved inorganic and organic phosphorus in the area of investigation have been made. The physico-chemical nature of the sediment was also studied. Influence of these ecological variables on the bottom fauna is discussed.
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This thesis is an attempt to Provenence, Sedimentetion and Geochemistry of the Modern Sediments of the Mud Banks off the Central Kerela Coast, India. In the present doctoral work, an attempt has been made to study in detail the mud banks of central Kerala, i.e. of Narakkal, Saudi and Purakkad areas which are reported as permanent mud banks, since olden days. The studies have been conducted during the years 1985 and 1986. The important findings of the study is stated as clay mineralogical studies of the rivers, lake and mud bank sediments reveal that the dominant clay mineral is kaolinite followed by montmorillonite, illite and gibbsite. Geochemical analysis of the Vembanad lake and mud bank sediments show that the iron and manganese are widely distributed both in the lake and mud bank sediments
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Kerala has been one of the leading maritime states in India for the exploitation and export of mud crabs (Raj, 1992). Many brackishwater systems like the Ashtamudi lake, Vembanad lake, Cochin backwaters and Korapuzha estuary are well known for their rich population of mud crabs. Realizing the imperative need to build up a strong scientific base for proper management and conservation of the resource and also to develop proper technologiesfor seed production and farming of mud crabs, a detailed study was undertaken on the mud crabs of Kerala coast and the results are described in the thesis. The thesis is presented in four chapters
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The study mainly intends to investigate the meteorological aspects associated with the formation of mud banks along southwest coast of India. During the formation of mud bank, the prominent monsoon organized convection is located in the equatorial region and relatively low clouding over Indian mainland. The wind core of the low level jet stream passes through the monsoon organized convection. When the monsoon organized convection is in the equatorial region, the low level wind over the southwest coast of India is parallel to the coastline and toward south. This wind along the coast gives rise to Ekman mass transport away from the coastline and subsequently formation of mud bank, if the high wind stress persists continuously for three or more days. As a result of the increased alongshore wind stress, the coastal upwelling increases. An increase in chlorophyll-a concentration and total chlorophyll can also be seen associated with mudbank formation
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Soft clays known for their high compressibility, low stiffness and low shear strength are always associated with large settlement. In place soil treatment using calcium-based stabilizers like lime and cement is a feasible solution to readdress strength deficiencies and problematic shrink/swell behaviour of unstable subgrade soils. Out of these, lime has been proved unambiguously as the most effective and economical stabilising agent for marine clays. Lime stabilisation creates long-term chemical changes in unstable clay soils to create strong, but flexible, permanent structural layers in foundations and other pavement systems. Even though calcium-based stabilizers can improve engineering properties of soft clays, problems can arise when they are used in soils rich in sulphates. It is possible for marine clays to be enriched with sulphates, either by nature or due to the discharge of nearby industrial wastes containing sulphates. The presence of sulphates is reported to adversely affect the cation exchange and pozzolanic reactions of cement and lime treated soil systems. The anions of sulphates may combine with the available calcium and alumina, and form insoluble ettringite in the soil system. Literature on sulphate attack in lime treated marine clays reports that formation of ettringite in lime-sodium sulphate-clay system is capable of adversely affecting the engineering behavior of marine clays. Only very few studies have been conducted on soft marine clays found along the coastal belt of Kerala and that too, is limited to Cochin marine clays. The studies conducted also have the limitation that the strength behaviour of lime stabilised clay was investigated only for one year. Practically no data pertaining to long term adverse effects likely to be brought about by sulphates on the strength and compressibility characteristics of Cochin marine clays is available. The overriding goal of this investigation was thus to examine the effectiveness of lime stabilisation in Cochin marine clays under varying sulphate contents. The study aims to reveal the changes brought about by varying sulphate contents on both physical and engineering properties of these clays stabilised by lime and the results for various curing periods up to two years is presented in this thesis. Quite often the load causing an unacceptable settlement may be less than the load required to cause shear failure and therefore attempt has been made in this research to highlight sulphate induced changes in both the compressibility and strength characteristics of lime treated Cochin marine clays. The study also aimed at comparing the available IS methods for sulphate quantification and has attempted to determine the threshold level of sulphate likely make these clays vulnerable by lime stabilisation. Clays used in this study were obtained from two different sites in Kochi and contained sulphate in two different concentrations viz., 0.5% and 0.1%. Two different lime percentages were tried out, 3% and 6%. Sulphate content was varied from 1% to 4% by addition of reagent grade sodium sulphate. The long term influence of naturally present sulphate is also investigated. X-ray diffraction studies and SEM studies have been undertaken to understand how the soil-lime reactions are affected in the presence of sodium sulphate. Natural sulphate content of 0.1% did not seem to have influenced normal soil lime reactions but 0.5% sulphate could induce significant changes adversely in both compressibility and strength behaviour of lime treated clays after long duration. Compressibility is seen to increase drastically with increasing sulphate content suggesting formation of ettringite on curing for longer periods. Increase in compression index and decrease in bond strength with curing period underlined the adverse effects induced in lime treated marine clays by the presence of sulphates. Presence of sulphate in concentrations ranging from 0.5 % to 4% is capable of adversely affecting the strength of lime treated marine clays. Considerable decrease is observed with increasing concentrations of sulphate. Ettringite formation due to domination of sodium ions in the system was confirmed in mineralogical studies made. Barium chloride and barium hydroxide is capable of bringing about beneficial changes both in compressibility and strength characteristics of lime treated Cochin marine clays in the presence of varying concentrations of sulphate and is strongly influenced by curing time. Clay containing sodium sulphate has increased strength values when either of barium compounds was used with lime ascompared with specimens treated with lime only. Barium hydroxide is observed to remarkably increase the strength as compared to barium chloride,when used in conjunction with lime to counteract the effect of sulphate.
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Se han elaborado diez unidades didácticas que se subdividen en 41 mini unidades didácticas (MUD), con las que el alumnado de ciclo superior de primaria podrá trabajar objetivos curriculares del área del medio social y cultural.
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El trabajo no ha sido publicado
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Registro con c??digo de documento duplicado y modificado posteriormente
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Lime treatment of hydrocarbon-contaminated soils offers the potential to stabilize and solidify these materials, with a consequent reduction in the risks associated with the leachate emanating from them. This can aid the disposal of contaminated soils or enable their on-site treatment. In this study, the addition of hydrated lime and quicklime significantly reduced the leaching of total petroleum hydrocarbons (TPH) from soils polluted with a 50:50 petrol/diesel mixture. Treatment with quicklime was slightly more effective, but hydrated lime may be better in the field because of its ease of handling. It is proposed that this occurs as a consequence of pozzolanic reactions retaining the hydrocarbons within the soil matrix. There was some evidence that this may be a temporary effect, as leaching increased between seven and 21 days after treatment, but the TPH concentrations in the leachate of treated soils were still one order of magnitude below those of the control soil, offering significant protection to groundwater. The reduction in leaching following treatment was observed in both aliphatic and aromatic fractions, but the latter were more affected because of their higher solubilty. The results are discussed in the context of risk assessment, and recommendations for future research are made.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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A calagem e a gessagem influenciam a disponibilidade e a absorção de nutrientes, podendo alterar a quantidade de ácidos orgânicos na parte aérea das culturas. Essas alterações, quantificadas por meio da análise de nutrientes solúveis em água, podem potencializar o efeito da correção do solo, garantindo a sustentabilidade do sistema de semeadura direta. Nesse sentido, objetivou-se avaliar o efeito da aplicação superficial de calcário e gesso no teor de nutientes solúveis em água nos resíduos vegetais das culturas de amendoim e aveia-branca. O experimento foi realizado em Latossolo Vermelho distroférrico em Botucatu (SP), nos anos agrícolas de 2004/2005 e 2005/2006. O delineamento experimental foi em blocos casualizados em esquema de parcelas subdivididas, com quatro repetições, em que as parcelas foram constituídas por doses de calcário, e as subparcelas, pela presença ou ausência da aplicação de gesso. Foi cultivado amendoim no verão e aveia-branca no inverno, em toda a área experimental. Na cultura do amendoim a aplicação de gesso elevou os teores de Ca solúvel em água apenas na primeira safra, em razão do curto período entre a aplicação do produto e a determinação dos teores de nutientes solúveis no extrato vegetal da cultura. A calagem realizada nas culturas de amendoim e aveia-branca elevou os teores solúveis de Ca, Mg, K e não alterou o teor de Cu e reduziu os teores de Zn, Mn e Fe nos dois anos de cultivo. Já a gessagem reduziu os valores da condutividade elétrica do amendoim (2004/2005 e 2005/2006) e da aveia-branca (2004/2005).
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The post-larval development of the mud crab Eurytium limosum was studied under laboratory conditions by using the offspring of ovigerous females collected at the Comprido River mangrove, SP, Brazil. The first crab stage is fully described and the juvenile development, until crab stage 10, is examined with emphasis on morphological change, sexual differentiation and growth patterns. The carapace of the first crab stage is nearly square as observed in other xanthids, becoming similar to adults only at stage 15. The sexes can be distinguished from stage four, based on the number of pleopods and their morphology. While the intermoult period increases, the moult percentage decreases at each stage. The abdominal allometric growth is sex-dependent, with males showing a negative (b=0.71) and females an isometric (b=0.95) relative growth pattern. Male gonopods undergo a positive allometric growth, and their shape changes remarkably until sexual maturity. The cheliped dentition can be observed after stage 4. Regardless of sex, most crabs have a molariform right cheliped, which is thought to aid the handling of asymmetric prey such as gastropods.