Geochemistry and Minerology of Chaliyar River Sediments with Special Reference to the Occurrence of Placer Gold

The present work deals with the texture, mineralogy and geochemistry of bedload sediments of the main stream of the Chaliyar basin, a typical small drainage system of the tropics enjoying heavy rain fall and moderate climate, located essentially in the Northern Kerala and flowing over the crystalline rocks (and their laterized duricrust) of the South Indian granulite terrain. As the Chaliyar is the major river draining the Wynad Gold Fields and is known for its placer gold occurrences, the thesis gives special emphasize on understanding the nature and distribution of detrital gold in sediments of the basin, while attempting to infer the provenance characteristics and factors involved in the evolution of sediments in general. Minerologically the chaliyar basin sands are quartzose. The quartz and feldspar contents in the coarse sand fraction of the basin range from 64 to 86% and 2 to 16% respectively. The Q/F ration ranges from 4 to 38 with a slight decrease in the lower reaches. Other minerals present include, hornblende, pyroxene and heavy minerals like opaques, garnet, rutile, biotite, spene, silliminite, zircon, apatite and monazite some of which are seen as inclusions in quartz. The major element composition of Chaliyar bedload sediments in the main channel and the headwater tributaries is related to the mineralogical and textual characteristics of sediments.

Highly conductive and transparent ZnO thin film using Chemical Spray Pyrolysis technique: Effect of doping and deposition parameters

In the present work we report the preparation details studies on ZnO thin films. ZnO thin films are prepared using cost effective deposition technique viz., Chemical Spray Pyrolysis (CSP). The method is very effective for large area preparation of the ZnO thin film. A new post-deposition process could also be developed to avoid the adsorption of oxygen that usually occurs after the spraying process i.e., while cooling. Studies were done by changing the various deposition parameters for optimizing the properties of ZnO thin film. Moreover, different methods of doping using various elements are also tried to enhance the conductivity and transparency of the film to make these suitable for various optoelectronic applications.

Provenance, Sedimentation and Geochemistry' of the Modern Sediments of time Mud Banks Off the Centrai Keraia Coast, India

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

Tide And River Runoff Interactions In The Cochin Estuary

Hydrodynamic characteristics of an estuary resulting from interaction of tide and river runoff are important since problems regarding flood, salinity intrusion, water quality, ecosystem and sedimentation are ubiquitous. The present study focuses on such hydrodynamic aspects in the Cochin estuary. Most of the estuaries that come under the influence of Indian Summer Monsoon and for which the salinity is never in a steady state at any time of the year are generally shallow and convergent, i.e. the width decreases rapidly from mouth to head. In contrast, Cochin estuary is wider towards the upstream and has no typical river mouth, where the rivers are joining the estuary along the length of its channel .Adding to the complexity it has dual inlets and the tidal range is 1 m which is lower than other Indian estuaries along west coast. These typical physical features lead to its unique hydrodynamic characteristics. Therefore the thesis objectives are: I) to study the influence of river runoff on tidal propagation using observations and a numerical model ii) to study stratification and property distributions in Cochin estuary iii) to understand salinity distributions and flushing characteristics iv) to understand the influence of saltwater barrage on tides and salinity v) To evaluate several classification schemes for the estuary

Dynamics And Speciation Of The Heavy Metals In The Lower Reaches Of Chithrapuzha- A Tropical Tidal River

The proposed study is an attempt to quantify and study the seasonal and spatial variations in the distribution of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb among the various geochemical phases in the surficial sediments of Chitrapuzha river. The study also estimates the concentration of heavy metals in dissolved, particulate and sediments and their variation in seasonal and spatial distribution. Chitrapuzha River originates as a small stream from the upper reaches of high ranges in the eastern boundary of Kerala, passes through the valley and finally joints in the Cochin backwaters. Numerous industrial units located along the banks of the river discharge treated and untreated effluents into the water. These are long standing local complaints about water pollution causing fish mortality and serious damage to agricultural crops resulting in extensive unemployment in the area. The river is thus of considerable social and economic importance.

Nutrient Mobility in Chalakudy River,Typified With Riparian Buffer Zone and Its Adjoining Estuary:Spatiotemporal Manifestation

This study was aimed at to characterize the spatio-temporal trends in the distributional characteristics of various species of nitrogen and phosphorus as well as to elucidate the factors and processes aflecting these nutrients in the dissolved, particulate and sedimentary phases of a river estuarine system. The main area of study is Chalakudy river in Kerala, which is a fresh water system originating from Anamalai hills and ending at Arabian Sea. Its basin is between I00 05 ’ to I00 35’ North latitude and 76” 15 ’ to 760 55’ East longitude. Being a riparian bufler zone, the dynamics of nutrient mobility tend to be more complex and variable in this river-estuarine system.The diflerent species of nitrogen estimated from the filtrate were nitrite-N, nitrateN, ammonia-N, urea-N, total nitrogen and residual nitrogen. The diflerent forms of phosphorus estimated from the filtrate were phosphate-P, total-P and residualP. Pre weighed sediments as well as particulate matter were analysed for quantijying nitrite-N, nitrate-N, ammonia-N and urea-N. Total nitrogen was estimated after digestion with potassium persulfate. Fractionation of phosphorus in sediment/particulate matter was performed by applying sequential extraction procedure. The dijferent forms of phosphorus thus estimated were loosely bound (exchangeable) P, Fe/Al bound P, polyphosphates, Ca bound P and refractory P. Sedimental total P was also measured directly by applying digestion method.The analyses carried out in this bimonthly annual survey have revealed specific information on the latent factors influencing the water quality pattern ofthe river. There was dependence among the chemical components of the river sediment and suspended matter, reflecting the water quality. A period of profound environmental change occurred and changes in various species had been noted in association with seasonal variations in the waterway, especially following enhanced river runoff during the monsoon. The results also successfully represented the distribution trend of nutrients during the rainy as well as dry season. Thus, the information gathered in this work will also be beneficial for those interested or involved in river management, conservation, regulation and policy making in regional and national levels.

Texture, composition and provinance of innershelf sediments between Narakkal and Purakkad, Kerala with special reference to the formation of Mud Banks

The continental shelf of southwest coast of India (Kerala) is broader and . flatter compared to that of the east coast. The unique characteristic feature of the study area (innershelf between Narakkal and Purakkad) is the intermittent appearance of 'mud banks' at certain locations during southwest monsoon. The strong seasonality manifests significant changes in the wind, waves, currents, rainfall, drainage etc., along this area. Peculiar geomorphological variation with high, mid and lowlands in the narrow strip of the hinterland, the geological formations mainly consisting of rocks of metamorphic origin and the humid tropical weathering conditions play significant role in regulating the shelf sedimentation. A complementary pattern of distri bution is observed for clay that shows an abundance in the nearshore. Silt, to a major extent, depicts semblance with clay distribution . Summation of the total asymmetry of grain size distribution are inferred from the variation of skewness and kurtosis.Factor I implies a low energy regime where the transportation and deposition phases are controlled mostly by pelagic suspension process as the factor loadings are dominant on finer phi sizes. The second Factor is inferred to be the result of a high energy regime which gives higher loadings on coarser size fractions. The third Factor which might be a transition phase (medium energy regime) representing the resultant flux of coastal circulation of the re-suspension/deposition and an onshoreoffshore advection by reworking and co-deposition of relict and modern sediments. The spatial variations of the energy regime based on the three end-member factor model exhibits high energy zone in the seaward portion transcending to a low energy one towards the coast.From the combined analysis of granulometry and SEM studies, it is concluded that the sandy patches beyond 20 m depth are of relict nature. They are the resultant responses of beach activity during the lower stand of sea level in the Holocene. Re-crystallisation features on the quartz grains indicate that they were exposed to subaerial weathering process subsequent to thei r deposition

Sedimentological and Geotechnical Studies of Coastal Sediments of Central Kerala.

All over the world, several Quaternary proxy data have been used to reconstruct past sea levels, mainly radiocarbon or OSL dating of exposures of marine facies or shore line indicators (e.g. Carr et al., 2010) as well as paleoenvironmental indicators in lagoon or estuary sediments (e.g. Baxter and Meadows, 1999). Estuaries and deltas develop at river mouths during transgressive and regressive phases, respectively (Boyd et al., 1992). In particular, the postglacial Holocene sea-level rise has contributed importantly to the estuary-to-delta transition (Hori et al. 2004). By analyzing radiocarbon ages of the basal or near-basal sediments of the world’s deltas, Stanley and Warne (1994) showed that delta initiation occurred on a worldwide scale after about 8500–6500 years BP and concluded that the initiation was controlled principally by the declining rate of the Holocene sea-level rise. Worldwide there were different regional sea-level changes since the last glacial maximum (LGM) (Irion et al., 2012). Along the northern Canadian coast, for example, sea level has been falling throughout the Holocene due to the glacial rebound of the crust after the last glaciation (Peltier, 1988). This is comparable to the development in Scandinavia (Steffen and Kaufmann, 2005) where sea level drops today. From about Virginia/USA to Mexico there is a constant sea-level rise similar to the Holocene sea-level development of the southern North Sea (e.g. Vink et al., 2007). From the border of Ceará/Rio Grande do Norte down to Patagonia, indicators of Holocene sea level point to a level that was up to 5 m higher than today's mean sea level (Angulo et al., 1999; Martin et al., 2003; Caldas et al., 2006a, b)

Modeling of Suspended Sediment Dynamics in Tropical River Basins

It is proposed to study the suspended sediment transport characteristics of river basins of Kerala and to model suspended sediment discharge mechanism for typical micro-watersheds. The Pamba river basin is selected as a representative hydrologic regime for detailed studies of suspended sediment characteristics and its seasonal variation. The applicability of various erosion models would be tested by comparing with the observed event data (by continuous monitoring of rainfall, discharge, and suspended sediment concentration for lower order streams). Empirical, conceptual and physically distributed models were used for making the comparison of performance of the models. Large variations in the discharge and sediment quantities were noticed during a particular year between the river basins investigated and for an individual river basin during the years for which the data was available. In general, the sediment yield pattern follows the seasonal distribution of rainfall, discharge and physiography of the land. This confirms with similar studies made for other Indian rivers. It was observed from this study, that the quantity of sediment transported downstream shows a decreasing trend over the years corresponding to increase in discharge. For sound and sustainable management of coastal zones, it is important to understand the balance between erosion and retention and to quantify the exact amount of the sediments reaching this eco-system. This, of course, necessitates a good length of time series data and more focused research on the behaviour of each river system, both present and past. In this realm of river inputs to ocean system, each of the 41 rivers of Kerala may have dominant yet diversified roles to influence the coastal ecosystem as reflected from this study on the major fraction of transport, namely the suspended sediments

Geochemistry of Rare Erath Elements and Trace Metals along the Western Continental Shelf of India

Rare earth elements have occupied an important role in marine geochemical research, particularly as used in the format of REE abundance patterns to describe the geochemical pathways in marine sedimentation and authigenesis. This study concentrates on the distribution pattern of Rare earth elements in the sediments, behavior of Eu and Ce with respect to their occurrence in multiple oxidation states. It also concentrate the depth wise variation of sediment REEs from near shore areas (30m) to deeper depths 200m) in the Arabian Sea. It includes the downcore variation of REEs and other trace elements in the sediment cores and a comparison between the REE distributions of Arabian Sea sediment with the sediments of Andaman Sea. The study gives a general introduction regarding the importance of RRE studies, its occurrence and abundance, electronic configuration, lanthanide contraction, oxidations states and REE supply to the ocean, seawater and sediments.

Growth and Characterization of ZnO based Heterojunction diodes and ZnO Nanostructuresby Pulsed Laser Ablation

Transparent conducting oxides (TCO’s) have been known and used for technologically important applications for more than 50 years. The oxide materials such as In2O3, SnO2 and impurity doped SnO2: Sb, SnO2: F and In2O3: Sn (indium tin oxide) were primarily used as TCO’s. Indium based oxides had been widely used as TCO’s for the past few decades. But the current increase in the cost of indium and scarcity of this material created the difficulty in obtaining low cost TCO’s. Hence the search for alternative TCO material has been a topic of active research for the last few decades. This resulted in the development of various binary and ternary compounds. But the advantages of using binary oxides are the easiness to control the composition and deposition parameters. ZnO has been identified as the one of the promising candidate for transparent electronic applications owing to its exciting optoelectronic properties. Some optoelectronics applications of ZnO overlap with that of GaN, another wide band gap semiconductor which is widely used for the production of green, blue-violet and white light emitting devices. However ZnO has some advantages over GaN among which are the availability of fairly high quality ZnO bulk single crystals and large excitonic binding energy. ZnO also has much simpler crystal-growth technology, resulting in a potentially lower cost for ZnO based devices. Most of the TCO’s are n-type semiconductors and are utilized as transparent electrodes in variety of commercial applications such as photovoltaics, electrochromic windows, flat panel displays. TCO’s provide a great potential for realizing diverse range of active functions, novel functions can be integrated into the materials according to the requirement. However the application of TCO’s has been restricted to transparent electrodes, ii notwithstanding the fact that TCO’s are n-type semiconductors. The basic reason is the lack of p-type TCO, many of the active functions in semiconductor originate from the nature of pn-junction. In 1997, H. Kawazoe et al reported the CuAlO2 as the first p-type TCO along with the chemical design concept for the exploration of other p-type TCO’s. This has led to the fabrication of all transparent diode and transistors. Fabrication of nanostructures of TCO has been a focus of an ever-increasing number of researchers world wide, mainly due to their unique optical and electronic properties which makes them ideal for a wide spectrum of applications ranging from flexible displays, quantum well lasers to in vivo biological imaging and therapeutic agents. ZnO is a highly multifunctional material system with highly promising application potential for UV light emitting diodes, diode lasers, sensors, etc. ZnO nanocrystals and nanorods doped with transition metal impurities have also attracted great interest, recently, for their spin-electronic applications This thesis summarizes the results on the growth and characterization of ZnO based diodes and nanostructures by pulsed laser ablation. Various ZnO based heterojunction diodes have been fabricated using pulsed laser deposition (PLD) and their electrical characteristics were interpreted using existing models. Pulsed laser ablation has been employed to fabricate ZnO quantum dots, ZnO nanorods and ZnMgO/ZnO multiple quantum well structures with the aim of studying the luminescent properties.

An optical fibre based evanescent wave sensor to monitor the deposition rate of thin films

A novel fibre optic sensor for the in situ measurement of the rate of deposition of thin films has been developed. Evanescent wave in the uncladded portion of a multimode fibre is utilised for this sensor development. In the present paper we demonstrate how this sensor is useful for the monitoring of the deposition rate of polypyrrole thin films, deposited by an AC plasma polymerisation method. This technique is simple, accurate and highly sensitive compared with existing techniques.

Studies on Laser Induced and RF Sputtered Plasma using Optical Emission Spectroscopy and Langmuir Probe

The main objective of the present study is to understand different mechanisms involved in the production and evolution of plasma by the pulsed laser ablation and radio frequency magnetron sputtering. These two methods are of particular interest, as these are well accomplished methods used for surface coatings, nanostructure fabrications and other thin film devices fabrications. Material science researchers all over the world are involved in the development of devices based on transparent conducting oxide (TCO) thin films. Our laboratory has been involved in the development of TCO devices like thin film diodes using zinc oxide (ZnO) and zinc magnesium oxide (ZnMgO), thin film transistors (TFT's) using zinc indium oxide and zinc indium tin oxide, and some electroluminescent (EL) devices by pulsed laser ablation and RF magnetron sputtering.In contrast to the extensive literature relating to pure ZnO and other thin films produced by various deposition techniques, there appears to have been relatively little effort directed towards the characterization of plasmas from which such films are produced. The knowledge of plasma dynamics corresponding to the variations in the input parameters of ablation and sputtering, with the kind of laser/magnetron used for the generation of plasma, is limited. To improve the quality of the deposited films for desired application, a sound understanding of the plume dynamics, physical and chemical properties of the species in the plume is required. Generally, there is a correlation between the plume dynamics and the structural properties of the films deposited. Thus the study of the characteristics of the plume contributes to a better understanding and control of the deposition process itself. The hydrodynamic expansion of the plume, the composition, and SIze distribution of clusters depend not only on initial conditions of plasma production but also on the ambient gas composition and pressure. The growth and deposition of the films are detennined by the thermodynamic parameters of the target material and initial conditions such as electron temperature and density of the plasma.For optimizing the deposition parameters of various films (stoichiometric or otherwise), in-situ or ex-situ monitoring of plasma plume dynamics become necessary for the purpose of repeatability and reliability. With this in mind, the plume dynamics and compositions of laser ablated and RF magnetron sputtered zinc oxide plasmas have been investigated. The plasmas studied were produced at conditions employed typically for the deposition of ZnO films by both methods. Apart from this two component ZnO plasma, a multi-component material (lead zirconium titanate) was ablated and plasma was characterized.

Spatio-Temporal Changes in the Wetland Ecosystem of Cochin City using Remote Sensing and GIS

Urban developments have exerted immense pressure on wetlands. Urban areas are normally centers of commercial activity and continue to attract migrants in large numbers in search of employment from different areas. As a result, habitations keep coming up in the natural areas / flood plains. This is happening in various Indian cities and towns and large habitations are coming up in low-lying areas, often encroaching even over drainage channels. In some cases, houses are constructed even on top of nallahs and drains. In the case of Kochi the situation is even worse as the base of the urban development itself stands on a completely reclaimed island. Also the topography and geology demanded more reclamation of land when the city developed as an agglomerative cluster. Cochin is a coastal settlement interspersed with a large backwater system and fringed on the eastern side by laterite-capped low hills from which a number of streams drain into the backwater system. The ridge line of the eastern low hills provides a welldefined watershed delimiting Cochin basin which help to confine the environmental parameters within a physical limit. This leads to an obvious conclusion that if physiography alone is considered, the western flatland is ideal for urban development. However it will result in serious environmental deterioration, as it comprises mainly of wetland and for availability of land there has to be large scale filling up of these wetlands which includes shallow mangrove-fringed water sheets, paddy fields, Pokkali fields, estuary etc.Chapter 1 School 4 of Environmental Studies The urban boundaries of Cochin are expanding fast with a consequent over-stretching of the existing fabric of basic amenities and services. Urbanisation leads to the transformation of agricultural land into built-up areas with the concomitant problems regarding water supply, drainage, garbage and sewage disposal etc. Many of the environmental problems of Cochin are hydrologic in origin; like water-logging / floods, sedimentation and pollution in the water bodies as well as shoreline erosion

Polyphase Implementation of Non-recursive Comb Decimators for Sigma-Delta A/D Converters

In a sigma-delta analog to digital (A/D) As most of the sigma-delta ADC applications require converter, the most computationally intensive block is decimation filters with linear phase characteristics, the decimation filter and its hardware implementation symmetric Finite Impulse Response (FIR) filters are may require millions of transistors. Since these widely used for implementation. But the number of FIR converters are now targeted for a portable application, filter coefficients will be quite large for implementing a a hardware efficient design is an implicit requirement. narrow band decimation filter. Implementing decimation In this effect, this paper presents a computationally filter in several stages reduces the total number of filter efficient polyphase implementation of non-recursive coefficients, and hence reduces the hardware complexity cascaded integrator comb (CIC) decimators for and power consumption [2]. Sigma-Delta Converters (SDCs). The SDCs are The first stage of decimation filter can be operating at high oversampling frequencies and hence implemented very efficiently using a cascade of integrators require large sampling rate conversions. The filtering and comb filters which do not require multiplication or and rate reduction are performed in several stages to coefficient storage. The remaining filtering is performed reduce hardware complexity and power dissipation. either in single stage or in two stages with more complex The CIC filters are widely adopted as the first stage of FIR or infinite impulse response (IIR) filters according to decimation due to its multiplier free structure. In this the requirements. The amount of passband aliasing or research, the performance of polyphase structure is imaging error can be brought within prescribed bounds by compared with the CICs using recursive and increasing the number of stages in the CIC filter. The non-recursive algorithms in terms of power, speed and width of the passband and the frequency characteristics area. This polyphase implementation offers high speed outside the passband are severely limited. So, CIC filters operation and low power consumption. The polyphase are used to make the transition between high and low implementation of 4th order CIC filter with a sampling rates. Conventional filters operating at low decimation factor of '64' and input word length of sampling rate are used to attain the required transition '4-bits' offers about 70% and 37% of power saving bandwidth and stopband attenuation. compared to the corresponding recursive and Several papers are available in literature that deals non-recursive implementations respectively. The same with different implementations of decimation filter polyphase CIC filter can operate about 7 times faster architecture for sigma-delta ADCs. Hogenauer has than the recursive and about 3.7 times faster than the described the design procedures for decimation and non-recursive CIC filters.