eChapters

ABSTRACT

The coastal zone is environmentally sensitive and economically valuable, which has great attention from researchers especially from geoscientists. Coastal zone has great threat from pollution and natural calamities like cyclones, flood and tsunami. Natural calamity is a frequent phenomenon over coast. Therefore, it is very essential to monitor the changes over coastal ecosystem and geomorphic features like beach, shoreline and sand dunes. In this case, one of the basic requirements in managing and monitoring these features is the topographic data. The recently emerged technique of Airborne Altimetric LiDAR provides accurate topographic data. It is in preparatory stage in India. By this technique, we can collect the data at high speed when disaster happens. This paper attempts to provide a general overview of the role of LiDAR in coastal management.

ABSTRACT

The present paper highlights the implication of geochemical strategic tools to choose suitable site selection on the coastal region. Geochemical tools and geomorphological survey have been also deployed to identify the suitable site. The geomorphology of the site A reveals enough fresh water accumulation was found and the two elevated crest and the adjacent trough (low land) with surrounding areas further support the fact. The water quality of this site exposes very good quality (< 200ppm TDS) and the dissolved major anions (HCO3, SO4, Cl) and cations (Ca, Mg, Na, K) concentration are well within drinking water standards. The soil samples are of medium to coarse sand nature showing high porosity (40 to 50%) with mica flakes acting as less permeable in nature. The water quality shows very good in nature and similar to Site A. The soil characters additionally proved good in porosity and permeability (SAR 1.5 to 2.1).

ABSTRACT

The use of Geographic information system to locate groundwater possible zone in Valapadi taluk of Salem was carried out using remote sensing and geophysical studies. The remote sensing methods involved in the visual interpretation of the satellite images for hydrogeomorphological and hydro structures favourable for groundwater. The geophysical method involved vertical electrical soundings to predict the sub-surface variation and to locate the water domain. Three geoelectric layers were delineated from the interpretation of vertical electrical sounding data and the map of the above results predict the depth extent of groundwater zone. The spatial distribution of the above results was identified through GIS.

ABSTRACT

A watershed is a topographically delineated area that is drained by a stream system, i.e. the total land area above some point on a stream or river that drains past that point. The watershed is a hydrologic unit that often is used as a physical – biological unit and a social – economic political unit for the planning and management of natural resources. Remote Sensing (RS) and Geographic Information System (GIS) techniques can be used effectively to generate the land use/land cover for evaluating the changes in an area. Conventional methods of runoff measurements are not easy for inaccessible terrain of Tamilnadu. Remote sensing technology can augment the conventional method to a great extent in rainfall-runoff studies. In this study, SCS Curve Number technique modified for Indian condition has been used for generation of CN for an ungauged watershed. A sub watershed of Manimuktha watershed is considered as study area. The daily rainfall data of Virudhachalam rain gauge station is collected and used to predict the daily runoff from the watershed using GIS based Soil Conservation Service -Curve Number (SCS – CN) method (USDA, 1972). Monthly and annual runoff values are obtained from the daily runoff values of the watershed. Base map, Soil map and Land use map of the study area are prepared by using Remote Sensing data and Survey of India (SOI) toposheets. PC Arc/Info GIS software is used for analysis.

ABSTRACT

The occurrence of fluoride more than permissible limit has been observed in ground water near Danishpet, Rajammannar Colony, Vayapurikombai, Melkombai, Umbilikampatty, Andikottai HC in Kadyampatty area, Salem district. Fluoride reaches to a maximum of 2.8 mg/l. Fluoride concentrations in ground water in various areas are as follows: Danishpet(2.0mg/l), Rajammannar Colony (2.8mg/l), Vayapurikombai (2.4 mg/l), Melkombai (2.4mg/l), Umbilikampatty (2.2 mg/l), and Andikottai HC (2 mg/l).. Granite gneiss and associated secondary vein filling minerals may be the source of high fluoride in ground water. The high concentration of Fluoride in ground water has led to human health hazard in the form of dental and skeletal deformation in the parts of Danishpet, Rajammar Colony, Vayapurikombai, Melkombai, Umbilikampatti and Andikottai HC villages.

ABSTRACT

The sources of fluoride in groundwater are minerals like fluorite, apatite, mica, amphiboles,cryolite and fluor.spar. The undue concentration of fluoride greater than 1 mg/l has befallen a major toxicological and geoenvironmental issue in India. Excess of fluoride in groundwater causes skeletal and dental fluorisis. The study area forms part of Salem district with records of endemic fluorisis. To decipher process and chemistry of fluoride, a total of 46 groundwater samples were collected from major litho units of the study area (Peninsular gneiss and Charnockite) and analyzed for fluoride using standard procedures for two seasons viz. pre and post monsoon. In pre-monsoon, maximum and minimum fluoride in Peninsular gneiss and charnockite were ranging from 2.85 to 0.4 mg/l and 4.02 to 0.37 mg/l respectively. The coresspnding figures in post monsoon ranges from 2.84 to 0.32 mg/l and 1.91to 0.37 mg/l respectively. Higher concentration was noted in charnockite folowed by peninsular gneiss in pre monsoon and the effect of dilution was well noted in post monsoon season. Statistical analysis undercovers the relationship of fluoride minerals with other ions. Modeling results represent the leaching of fluoride minerals and their variation along with seasons.

ABSTRACT

Microalgae in general and Cyanobacteria in particular are considered to be ideal biotechnological tools for their importance in the production of food, feed, fuel, fertilizers, fine chemicals and pharmaceuticals and their role in pollution abatement. So far, only 20 strains of microalgae have been cultivated for industrial purposes. To make use of more such organisms, it is essential to first identify their biodiversity in the naturally occurring populations and establish their germplasm for further characterization. With this in view, a detailed survey was made to study the biodiversity of Cyanobacteria in the Veeranam lake soil microflora in the Cuddalore district of Tamil Nadu. Influence of physico-chemical parameters habitat preferences of these soil microalgae, and their light and Electron microscopic features have been documented. The selected species of Cyanophyceae were subjected to energy dispersive spectroscopic analysis (EDS). They were found to accumulate different elements such as Zn, P, Mg, Ca, Mn, S and N. Thus these observations would determine the chemical dialogue between the cell structures and role of the elements. Further, it gives the clue about the soil microflora growth requirements.

ABSTRACT

Hydrogeochemistry of a region is a reflection of hydrodynamic process, composition of lithology and physical constraints. The water chemistry is the resultant of all biogeochemical processes and reactions, which have acted on water from the moment it has condensed in atmosphere till the time it is discharged. A case study has been carried out in a varied lithological terrain with Archean, Alluvium and Tertiary rocks to unravel the hydrogeochemical process. A geochemical model relays the distribution of mineral species in the groundwater. Geochemical modeling WATEQ4F has been carried out for pre-monsoon and monsoon period of various litho units in Gadilam river basin, Tamilnadu to find out the disequilibrium indices of carbonate (calcite, dolomite, magnesite and aragonite) and sulfate minerals (anhydrite and gypsum). The result of the model reveals that carbonate minerals show the over saturation state in monsoon period and the Sulfate minerals exhibit under saturation state in both the seasons.

ABSTRACT

The chemical characteristics of the groundwater in and around the Valapadi taluk of Salem district have been studied to evaluate the suitability of water for domestic and irrigation uses. Twenty three groundwater samples representing the shallow and deep aquifer of the area were collected and analyzed for pH, TDS, Ca, Mg, Na, K, HCO3, CO3, SO4 and Cl. It is observed that the quality of the groundwater is suitable for domestic use with some exception. The observed high quantity of Cl, SO4 and Mg at some places require immediate attention and detailed study. The value of EC and SAR indicate good to medium q of water for irrigation.

ABSTRACT

Ground water is an important source of water supply throughout the world for irrigation, industries, municipalities and rural homes and the dependence of an Indian village is on its water source only. The quality of water is as important as its quality. The quality required of a groundwater supply depends on its purpose such as drinking or agricultural or industries. To establish quality criteria, measures of chemical, physical, biological constituents must be specified as well as standard methods for reporting and comparing results of water analysis .For that a case study is to be made. Cuddalore district is a rapidly growing urbanized industrial area and lies at the east coast of Tamil Nadu in India. It mainly depends on the ground water. Water quality data for the observation wells from the year 1989 to 1999 were collected and spatial distribution of the groundwater quality is analysed using geographic information system. The important factors such as pH, Chloride shows higher level and generally occur in the central belt of the study area which is rich in mineral wealth. Compared to the eastern half the western half shows better quality of water. From the analysis, 80% of the study area is suitable for agricultural purpose and 75% of the study area is suitable for domestic and drinking purpose.

ABSTRACT

An integrated geological, hydrogeological and geophysical analyses have been made to delineate groundwater potential zones in the Omalur Panchayat Union, Salem district, Tamilnadu. Sarabanga river is a major stream originating from western slope of Shevaroy hills. The tributaries are essentially consequent types. They are ephemeral in nature and the flow is restricted to the monsoon seasons. The flows of the streams are controlled by lineaments. Low drainage density, stream frequency and low relief indicate relatively high recharges and low runoff. The main lithological units are unclassified gneiss, grantite, charnockite, younger ultramafic rocks and recent alluvium. Ten vertical electrical soundings (VES) were carried out using Schlumberger electrode configuration. The maximum depth of investigation was 150meters when the electrode spread was generally in steps of 5 meters interval up to 50 meters and 10 meter intervals up to 150 meters. The field data were interpreted with the help of inverse slope method. Inverse slope field graphs reveal that in most of the locations, the aquifer consistsof five layers and third and fourth layersare normally weathered and highly fractured layers. These layers have attained a thickness range from 10 to 60 meters at the Tholasampatti, Sikkampatti, Pagalpatti and Sakkaraichettipatti. Correlation between the result of the VES data and the well lithology will be very useful in evolving ground water potential zones. Bore wells, dug wells in this area are normally sinking type wells. It will receive water only from the weathered, fissured and fractured zones which act as a favorable layers zones for tapping groundwater.

ABSTRACT

The estimation of the water requirement of crop is one of the basic needs for crop planning on the farm and for the planning of any irrigation project. Water requirements of crops include the losses due to Evapotranspiration (ET) plus the losses during the application of irrigation water (unavailable losses) and the quantity of water required for special operations such as transplanting and leaching of excess salts for crop growth. It is therefore necessary to estimate the ET and Crop Water Requirement (CWR) for the efficient use of water and increased crop production. In the present study, meteorological data were collected and the crop ET (ETc) and the CWR were estimated using FAO Penmann – Monteith method for the cropping pattern of the Buthangudy canal command area situated at a distance of 2Km from the popular village Sethiathope, Cuddalore district, of Tamil Nadu, India, which is located in between the Kumbhakonam – Chennai NH – 45 main road. The methodology combines the capability of GIS and CWR to produce maps showing spatial distribution of water resources over large areas.

ABSTRACT

The study narrates the importance of occurrence of groundwater in the crystalline terrain and its yield in different lithologies. In general, yield of well in the crystalline terrain of the study area is low. Average or mean yields for groups of wells in various regions are most commonly between 7 to 20 gpm: The smallest yields are encountered in granulitic terrain and this may be due to fracture closing rapidly with depth. The jointed and weathered geneses yield small but steady supply of water at shallow depth. Chemical quality of the groundwater from this terrain is generally satisfactory for most purposes.

ABSTRACT

Mecheri Panchayat union lies in the northwestern part of Salem district and adjascent to Dharmapuri district of Tamil Nadu. It lies between the latitudes 11°43’ -12° and longitudes 77° 48’ -78° 03’ of Toposheet No. 58 E/13 of scale 1:50,000 published by survey of India in 1973. Mecheri Panchayat union covers a total area of about 177.6 Sq.Km with a population nearly 1 lakh, live in 150 hamlets. Groundwater is the only replenshable nature resources available to man. The use of groundwater has been growing steadily over the years for domestic, agricultural and industrial purposes. Hydrogeochemical study is a dynamic process undergoing constant change in space and time. In unconfined aquifers, the change likely to be quite rapid and cyclic in nature with respect to the mode of recharge and discharge and related to the nature of host aquifer. In this study an attempt has been made for understanding the chemical quality of groundwater in theunconfined aquifer of Mecheri union. Groundwater samples have been collected from 10 representative dug wells lying in the Mecheri union during December 2004 and analysed by the standard procedures of water analyses. It is essential in determining its usefulness for domestic, industrial and agricultural purposes. Presentation of Geochemical data in the form of graphical charts such as Collin’s bar, Stiff’s polygon diagram, Pie diagram, Piper tri linear diagram, USSL classification and thematical maps were prepared for recognizing various hydrogeochemical types in the Mecheri union. Deleterious effects of fluoride on the human beings are well known. Fluoride are known to be beneficial, when present in concentration ranging from 0.5 ppm to 1.2 ppm. But when it exceeds the limit 1.2 ppm it is found to cause fluorosis. Dental, skeletal and non-skeletal fluorosis may be caused depending upon the concentration of fluorides in drinking water. The main source of drinking water for the majority of people of Mecheri union is groundwater obtained through dug and bore wells. The analysis of groundwater samples showing high (> 1.5 ppm) fluorite content observed in the following villages, viz Mallikundam, Kuttapatti Aranganur, Banapuram, Sathappadi, Mecheri town, Virudasampatti and Amaram.

ABSTRACT

Trace Elements were analysed from water samples collected from bore wells from block 2, 5, 14, 26 and 29 at Neyveli Township. Lead Concentration has crossed the limit of ISI standard prescribed for drinking which is 0.100 ppm. Lead concentration in the order of 0.082 ppm at block 5 and 0.11 ppm in block 29 were observed. Cadmium concentration has also crossed the limit of ISI (0.010 ppm) for drinking purpose, which is 0.02 ppm in block 26. Chromium concentration has also crossed the permissible limit of ISI standards (0.05 ppm) for drinking, which is 0.098 ppm in Block 14.

The above elements when compared with ISI standards for drinking water have shown a slight increase in concentration of lead, cadmium & chromium. Concentration of lead in Neyveli basin may be attributed to basement geochemical sources influenced by physical and chemical weathering. High concentration of chromium and cadmium in the aquifer may be due to anthropogenic activity probably from effluents of closed briqueting & carbonization plant, which is due south of block 14.

ABSTRACT

Identification and mapping of fractures/lineaments and hydrogeomorphic units is prerequisite for undertaking ground water exploration and development in any terrain. Remote sensing and GIS techniques have been used for ground water potential mapping in Theni District. The study area has been divided into various geomorphic units based on visual interpretation of LISS III and PAN merged data in false colour composite on 1:50,000 scale. Ground water potential of each of the geomorphic units was assessed and correlated with geology, structure and recharge factors prevailing in the Theni District.

ABSTRACT

Kadayampatty Panchayat Union is situated in the northern part of Salem district, adjoining the Dharmapuri district of Tamil nadu. It lies between the latitudes 11°45’ -12°N and longitudes 78° -78°15’E in the Toposheet No.58I/1. The study area mainly consists of the rocks of late Precambrian age that are characterised by migmatitic gneisses, Ultramafic rocks and Pyroxenite. In this study an attempt has been made for demarcating groundwater techniques. Resistivity of rock formation varies over a wide range, depending on the material density, porosity, pore size and shape, water content, quality and temperature. In relatively porous, highly jointed and fractured formation the resistivity is controlled more by water content and quality with in the formation then by the rock resistivity. For demarcating groundwater potential zones in the Kadayampatty Panchayat Union water table analysis and ten Vertical Electrical Sounding (VES) followed by Schlumberger electrode configuration were carried out. The maximum depth of investigation was 150mts. The electrode spreads were generally in steps of five meters interval up to 50 mts and 10 mts interval up to 150 mts. VES location were selected with in the study area with respect to their topographic features. Inverslope method proposed by Sankaranarayan (1974) et.al has been used to evaluate the geoelectrical parameters in order to demarcate to potential groundwater zones for new dug well and bore well locations. The lithological interpretation reveals that the presence of a maximum of five geoelectrical formations in the study area viz. Topsoil, weathered zone, fissure and fractured zone, fracture basement and fresh basement. Howevers all five formations do not occur throughout the study area, as the maximum and minimum of geoelectric layers are four and three respectively. Similarly a thin geoelectric layer was observed in some places also. The comparatively high resistivity values with corresponding high values of thickness are indicative of a wide stretch of unweathered and unfractured fresh rock layers. A highly weathered (saturated) basement is indicated by the extremely low resistivity value. The depth to the fresh basement varies.

ABSTRACT

The disposal of industrial effluents in rivers causes groundwater contamination. It is necessary to assess how these contaminants are likely to migrate in the groundwater system. In the present study, an attempt is made to study the migration of contaminants in the groundwater of Palar River basin in Tamil Nadu. Simulation of the contaminants was carried out by using numerical methods. The finite difference computer code MODFLOW (Modular 3-d finite difference flow) and MT3D (Mass transport 3-d) with Groundwater Modelling System (GMS) as pre and post processor was used to simulate the groundwater flow and transport in this study. The simulation was done in transient state for a time period of one year. It predicted the migration of plume of chlorides in groundwater. The changes in the distance and concentration rate of chlorides are identified for a particular period. Modelling provides a useful basis for contaminant transport studies, as well as in the evaluation of the hydrogeologic parameters relevant in the context of the transport problem.

ABSTRACT

With the increasing use of ground water for various activities, the fast decline in groundwater takes place. In order to prevent the aquifers from fast depletion, the ground water recharge is necessary. This study attempts to identify the favourable areas for groundwater recharge and suggest suitable recharge structures toaugment the aquifer system of the study area using Remote Sensing and GIS. The various thematic maps such as Geomorphology, Geology and lineaments, Soil, Slope, Land use, Drainage, Runoff, Depth to weathered zone, Groundwater level fluctuation and Water quality are used in the analysis. The favourable areas for groundwater recharge have been categorized into highly favourable, moderately favourable, less favourable and poor. To delineate areas favourable for recharge zone various themes are interpreted. The identification of ground water recharge zones for the study area is useful for improvement of water quality, quantity and better augmentation & management of Groundwater recharge.

ABSTRACT

Airborne geophysical methods are presently used all over the world to support mineral exploration by providing basic geological information to supplement existing geological maps. The popularity of airborne geophysics is due to its lower cost for unit of area surveyed, as compared to all other methods of exploration. South India has been extensively covered by high altitude regional aeromagnetic surveys jointly by GSI and NRSA, low altitude multi-sensor surveys by foreign agencies, viz. M/s. Parsons, U.S.A. (Operation Hard rock Project) and BRGM/CGG, France, on contractual basis for GSI and by GSI (Twin Otter surveys) in selected belts and low altitude aeromagnetic surveys by NGRI in the SW part of the Cuddapah basin and the adjoining crystallines. Integrated studies of geophysical (airborne and ground), geological and remote sensing data have greatly helped not only in augmenting the geological knowledge of the region, but also in identifying several metallic prospects/ deposits. The present paper illustrates several case studies in demonstrating the utility of aerogeophysical data in geological mapping (identifying lithologies, structures and basement characteristics) and locating metallic prospects/ deposits.

ABSTRACT

Over the past four decades groundwater has become a topic of discussion and investigation and as a result the knowledge of understanding groundwater conditions has radically improved. For the past quarter century, remote sensing has played a vital role to target the groundwater resources for the essential survival of horticulture and agriculture crops in drought-prone areas. GIS technology has made a rapid stride for the past one decade to amalgamate the data generated from various space-born platforms and the ground based surveys to facilitate the generation and use of various thematic information for groundwater resources assessment. The present study aims for the demarcation of various groundwater prospective zones in the West Doon Valley and its environs, falling in the SOI toposheet 53 F/15. The role of various parameters namely, Geomorphology, Geology, Lineaments, Drainage, Land Use, Water table and Slope has been integrated for delineating groundwater prospective zones. IRS IC LISS-III geocoded satellite image on 1:50,000 scale was used. Index overlay model has been applied for GIS analysis. The resultant map indicates five prospective zones, such as poor, low, moderate, high and very high groundwater prospective zones in the study area.

ABSTRACT

Due to complex hydrogeological conditions it becomes very difficult to prospect the ground water resources especially in drought prone areas where the water table is very deep. The interpretation of geoelectrical sounding curves also becomes ambiguous. A semi empirical method namely theinverse slope method [Shankar Narayan and Ramanujachari, NGRI] is widely used since it is simple to operate without standard curves etc and it gives fairly good results. In some Government organizations like PWD [Ground Water Department] and TWAD Board of Tamilnadu, this inverse slope method is widely used for ground water exploration. Based on this methodology, ample of bore well points have been recommended in complicated hard rock terrains and the success rate is found to be encouraging. The study area, Kavalpatti, of Palani taluk in Dindigul district is a crystalline rock terrain, where geological, hydrogeological and geoelectrical investigations have been carried out to explore the ground water potential zone for agricultural purpose. The bore well drilled to a depth of 32 m has yielded 370 lpm. The interpreted geoelectrical section has been correlated with the litholog of bore well. Some bore well statistics [bore well points recommended based on this method] has been furnished, which reveals that this methodology is encouraging.

ABSTRACT

The upper Agniar and Vellar river basins principally consist of three major rock typesnamely pink granite, gneiss and charnockite. The major geochemical pattern of these igneous rocks when studied indicate that charnockites have a trend of low Mg2+ and high Ca2+ + Na O to high K+ end, whereas the same is vice – versa for hornblende biotite gneiss and also for granite gneiss. The pink granite has an intermediate trend between the charnockite and hornblende biotite gneiss. The value of SiO2 in all the rock types was found to increase with the increase of K2O, Na2O and Al2O3. Further, a decrease in the values of MgO, Fe2O3, TiO2 and CaO was noticed with an increase in SiO2. On the basis of the distribution pattern of these elements, the origin of the igneous suites in the above two basins was inferred.

ABSTRACT

Assessment of groundwater potential has wide importance in the exploration, management and development of groundwater resource. The fact that geologic and topographic factors, such as, geomorphology, lithology, structure, soil and slope control the occurrence and movement of groundwater in a region has been made use of in satellite remote sensing to aid groundwater exploration. In hard rock terrains, due to lack of primary porosity, lineaments have greater importance as those can be zones of secondary porosity trapping groundwater in its pore spaces.

In the present study, an attempt has been made to delineate groundwater potential zones in the hard rock terrain in the Gayatri River basin in Kerala, India, using satellite data. The study area which lies between 10o 26’N and 10o 45’N latitudes and 76o 21’E and 76o 54’E longitudes covering an area of about 1000 square kilometers is a drought-prone area. Landsat 7 ETM image of Gayatri River basin has been interpreted visually in a digital environment using ERDAS Imagine software to create geomorphology and lineament maps. Further, with the help of ancillary data, various thematic layers like, lithology, soil, drainage density, etc. have been created and subsequently updated using information obtained from the satellite data. Slope map of the basin has been created using Shuttle Radar Topographic Mission (SRTM) data. Integration of the thematic layers has been done in Arc/Info GRID GIS environment by giving weights to various thematic layers according to their importance in terms of groundwater occurrence. Finally, groundwater potential map of the basin has been prepared by classifying groundwater potential zones as good, moderate and poor.

ABSTRACT

The exponential growth of population and rapid industrialization, urbanization, deforestation and improper landuse practices have led to depletion and pollution of surface and ground water resources in Tamilnadu, India. In addition, a recurrent monsoonal failure further aggravates the problem of water even for drinking water. Water plays vital role in our day to day life and other developmental activities in the area. Thus, the availability of surface and sub surface water potential governs the processes of planning and development. The surface water resources are inadequate to fill the water demand and productivity through ground water is quite high as compared to surface water. Keeping this in view, the present study is aimed to identify the potential location of potable groundwater exploration in hard rock terrain. Thematic information on geomorphic landforms, Landuse/landcover and lineament details are extracted from remotely sensed data. Geology, Soil class, Drainage network and Slope map of the terrain were prepared using existing maps and collateral data by conventional method. GIS based model was developed and appropriate rank and weightage had been assigned to all categories based on local conditions/variations in each layer according to relative contribution towards the desired output. Since the present study built with logical condition and reasoning rule based approach for groundwater targeting, it has been successfully used and clearly demonstrated the capability of Remote Sensing and GIS techniques in identification of potable ground water potential zones.

ABSTRACT

The present paper discusses about the Geoelectrical response over Charnockite rocks and Biotite Gneiss rock types of Sankaran kovil and Tenkasi Taluks of Tirunelveli District, Tamilnadu. The study area is adjoined to the Western Ghats which geologically comprises Archean crystalline hard rocks. In this attempt, about 7 Vertical Electrical Soundings (3 in Gneiss and 4 in Charnockite) have been carried out in both terrains. The VES values were interpreted with Schlumberger Sounding Dada Processing and Interpretation Program .The resistivity values varied from 68 m to 808 m with the layer thickness of 10m, 20 m and 29m in the biotite gneiss terrain. Similarly, the resistivity values varied from 48 m to 444 m with the layer thickness of 4m, 6m, 9m,18m & 29m in the charnockite terrain. But the depth to massive rock for both the rock types has been observed below 29m. In this study, a difference in resistivity with high resistivity values in gneissic terrain and lower values in charnockite terrain have been observed. The observed resistivity differences are mainly due to the presence of resisting minerals such as biotite and hornblende. Besides, other factors like weathering and water table also influence the resistivity values. Hence, it is summerised that the geoelectric methods are the best methods to understand the subsurface lithostudies.

ABSTRACT

The geological and geomorphological features could be clearly demarcated in and around Salem area using IRS -IB LISS II satellite data. Geologically,the study area is classified into four major rock types fissile hornblende biotite gneiss, banded magnetite quartzites, peninsular gneiss, charnockites and quartzites. The geomorphological study reveals the buried pediments medium, buried pediments deep, bazada zone, along with lineaments. Intersections of the lineaments are the most prospective zones for further groundwater targeting. Shallow pediments and pediments are the less groundwater prospective zones. But detailed geophysical survey as required to sink new bore well, dug well, dug cum bore wells.

ABSTRACT

In Tamilnadu majority of the people are engaged in agricultural work and they mainly depend upon the water resources. But at present both surface and subsurface water has become deficient because of over exploitation. Since last few years, conventional methods were employed to improve the surface and subsurface water conditions. But these methods provide less accurate result and consume more time. So to improve the conditions modern tools, such as remote sensing and GIS are being used to identify the ground water potential zones in Tamilnadu. It provides accurate resulst and consumes less time.

A project was carried out in Gadilam lower sub basin which falls in the part of Cuddalore District, Tamilnadu. The IRS 1D imagery was collected and interpreted using image processing software and Geo media GIS Software in conjunction with collateral data to prepare Hydro geomorphology, land use, geology and lineament maps Field checks were made and transferred the field data on the base map. By application of overlay analysis of the above thematic maps, using GIS techniques, the recharge zones were identified.

The satellite image mosaic map of Gadilam lower sub basin was generated to identify ground water potential zones. Average monthly rainfall data for the past 50 years were collected. Using Remote sensing and GIS techniques, the thematic maps such as Geology, Geomorphology, Soil, Drainage, Land use, Lineament zones have been generated for this study. Geophysical survey was also conducted in various locations and the aquifer parameters were measured. Details related to land and water resources, cropping pattern, water levels and water qualities from PWD ground water division, land use and well censes data of villages from village Administrative Officer, tank details from PWD were collected and analyzed

After analyzing the various thematic maps, they were finally overlaid. Thus the groundwater potential zones of Gadilam lower sub basin was identified.

ABSTRACT

Mapping and exploration of iron ore deposits in parts of Salem District is carried out based on the detailed field work and the interpretations of IRS-1C PAN data in the scale of 1:12,500 and aerial photographs (NRSA, Scale 1:4,000). The study results that the major rock types of the study area are banded magnetite quartzite, garnetiferous pyroxene granulite, amphibolite, garnetiferous pyroxenite, charnokite, talc tremolite, actionalite and dunite rocks. The Banded Magnetite Quartzite’s (BMQ) occur as enclaves within the hornblende gneisses at several parts of the study area. Topographically, the rocks constitute small low-lying linear ridges at some places it is found to be closely associated with garnet pyroxene granulites. A remarkable feature about the mode of occurrence of magnetite quartzite is its linear nature and the physical form, which could be described as a “Band”. All the bands possess an ENE-WSW strike and the dip is found to be steep (above 70 degrees) towards north. The rock in the hills of Godumalai, Vellalagundam, and Singipuram are highly deformed and contact with garnetiferous pyroxene granulite and hornblende gneisses. In hand specimen, the magnetite quartzite rock exhibits fine banding. In general no variation in grain size or thickness of banding could be seen megascopically. However, occasional increase in size of magnetite might be possible as seen from the coarser magnetite pebbles strewn in the channels of the area. There are two types of folds observed namely F1 and F2. The axial plane trace of the F1 varies in trend from WNW-ESE to WSW – ENE. The joints are traced in the directions of NNW-SSE to NNE – SSW and WNW – ESE to ENE-WSW. The interpretation of lineaments shows their trend directions of NNE-SSW, NE-SWand NNW-SSE. The above said work has carried out through detailed field work and interpretations using by IRS-1C PAN data in the scale of 1:12,500 and aerial photographs of NRSA, in the scale of 1:4,000 for the study area.

ABSTRACT

Coastal zones are credited for the important role they play in the economic, industrial and commercial activities of many countries. Starting from the early fifties of the last century, coastal zones have attracted greater attention from the earth scientists owing to the discovery of huge hydrocarbon deposits in the Persian Gulf, Africa and South America. In addition, coastal zones especially those bordering Precambrian Cratons house significant quantities of economically important placer minerals which are being explored and exploited vigorously. In the present paper, sedimentary basins located along the continental margins of Tamil Nadu state, their geology and hydrocarbon potential are discussed. In addition, an attempt has also been made to demonstrate the usefulness of remote sensing techniques in the exploration of this strategic mineral.

ABSTRACT

Lineaments are the surficial expression of sub-surface phenomena which are well discerned from low-orbital data, satellite data with its synoptic view and repetitive coverage and help to bring out more information on structural features hither to unknown by conventional geological surveys. Their study paved way to many new concepts on tectonism, mineralization, structural deformity etc. of an area both in regional and local perspective. In the present study, a small area was selected after careful observation, for their importance in mineral deposits. The lineaments are mostly structurally controlled and analysed for their relationship with the base metal deposits of the area. Moreover satellite parameters like spatial resolution, scale etc., and are observed for their changes in their orientation and relationship with the deposit of the study area, Jambughoda of Panchmahal District, Gujarat Satellite data of Landsat MSS and TM are used for the analysis. The results proved that the satellite parameters are important criteria and play a vital role in lineament analysis for mineral investigation.

ABSTRACT

Using a hand auger of 2 m length, upper, middle and lower core sediment samples of seventy nine in number have been collected from the Vaippar river, its tributaries and Vaippar beach in order to understand the role of Vaippar river and its tributaries in making up the Vaippar beach placer deposits. The heavies are found to be concentrated abundantly in fine and very fine size grades of all the samples collected from both the environments. The average heavy mineral concentration varies from 3.13 to 17.40 % in river bed while it is 6.19 – 64.82 % in the beach. In river bed, the pattern of concentration of heavies in upper, middle and lower core samples does not show any characteristic uniform pattern and inferred that it is controlled by the grain size of the parent rock, supply of sediments from the source, geomorphological features of the river and hydrological characters of running water. In the beach, the concentration of heavies are effected mainly due to the winnowing action of waves. However, a phenomenal increase in the heavy mineral concentration of beach samples might be due to the supply of sediments from other source besides the Vaippar river.

ABSTRACT

54 foraminiferal species belonging to 29 genera, 23 families, 17 superfamilies and 5 suborders have been identified from Nagaland. Of the total species 16 are planktic and 38 are benthic forms. The age for the Upper Disang Group of Nagaland is assigned as Late Eocene, based on the presence of Late Eocene markers i.e. Globigerinatheka semiinvoluta, Cribrohantkenina inflata, Hantkenina alabamensis and Turborotalia cerroazulensis. As per the present study the Disang succession in Nagaland can be grouped into five biofacies. The Uvigerina dominated biofacies consisting Uvigerina cocoaensis, U. continuosa, U. eocaena, U. glabrans, U. jacksonensis and U. cf. steyeri. In some samples even up to 100 % Uvigerina were present. The localized occurrence of thick “Uvigerinids” in high percentage with pyritized test in this section indicates anoxic conditions, suggestive of possible source rock for oil.

ABSTRACT

The Cretaceous formation of Ariyalur area is well known for its lithological and faunal variation. It contains rich assemblages of fossils as well as the occurrence of economic deposits of limestone, gypsum, phosphatic nodules and clays. Representative Uttatur clay samples have been collected and analysed for physical and chemical properties. The physical properties such as fired colour, plasticity, fusing temperature, slaging nature, shrinkage test, bulk density, liquid limit, and plastic limit and Atterberg number etc. of uttatur clays have been determined. The chemical properties of the clays show low in silica and alumina and high iron and lime which make them suitable for low duty refractories and stoneware works.

ABSTRACT

Sedimentological studies such as textural, heavy mineral and clay mineralogy have been carried out for Warkalli Formations at Varkala, situated in the southern part of Kerala, India. The X-ray diffraction study reveals that kaolinite is the only clay mineral present in all the samples with trace amounts of gibbsite and goethite. The higher amount of kaolinite and gibbsite indicates warm and humid paleoclimatic conditions. The textural analysis shows that the sediments are moderate to poorly sorted, nearly symmetrical to fine skewed and lepto to mesokurtic in nature. A plot of skewness against sorting shows fluvial trend. The major heavy minerals present in the samples are magnetite, ilmenite, rutile, sillimanite, anatase and zircon. It can be inferred from these studies that these sediments would have been deposited in a lagoon by fluvial action. During that time, the source region has experienced tropical humid climate with mean annual precipitation (MAP) above 200 cm and intensive chemical weathering. Heavy mineral assemblage indicates medium to high grade metamorphic source rocks.

ABSTRACT

We report here the occurrence of chrysoberyl bearing gem pegmatitesof Southern India. The Pan-African Chrysoberyl mineralization is associated with intrusive event of grey pegmatites within granulite facies parametamorphic aluminous khondalites. Lithological and structural controls of chrysoberyl mineralization are discussed. The chrysoberyl occurrences in southern India, southern Madagascar and Sri Lanka provide strong evidence for India-Sri Lanka-Madagascar juxtaposition in the East Gondwana assembly with the Achankovil Shear Zone of Southern India one side extending into Ranotsara Shear Zone in Southern Madagascar and other side into southern tip of Sri Lanka.

ABSTRACT

Mineral exploration is not only highly imaginative and creative but a very costly activity as well. The fast emerging Geomatics technology is a real boon in mineral exploration as it encompasses a whole spectrum of solutions and services which are of great help for exploration geologists. Geological maps which generally form the basic requirement for any kind of natural resources inventory operations currently witness tremendous changes and the same is mainly attributed to the integration of Geomatics technology. Usage of Geomatics has revolutionized the art of mineral exploration as geological maps can be easily integrated with other important details like geomorphology, structure and tectonic pattern, geophysical data etc. This kind of data integration facilitates for the better identification of mineralized zones. In addition, GIS with its powerful analyzing capability provides tools at several stages in the process of mapping for building up a database containing various types of data for quantifying and extracting features related to mineralization. The present paper narrates an overview of mineral exploration using Geomatics technology.

ABSTRACT

India is blessed with large reserves of strategic and economically important heavy minerals such as ilmenite, rutile, leucoxene, zircon, monazite, garnet and sillimanite. These deposits are mostly located in the coastal stretches of Peninsular India especially between the high tide line and 200-250m inland, with the exception of few inland deposits. Ilmenite is the largest constituent of the Indian beach sand deposits, followed by sillimanite and garnet. These minerals are one of the largest and higher grades in the World. The Indian Ilmenite resource base totals 348 million tones (Mt), along with 18 Mt of rutile, 21 Mt of zircon, 8 Mt of Monazite, 107 Mt of garnet and 107 Mt of sillimanite. Although Indian heavy mineral resources are one of the largest in the world, it is observed that the Production to Reserve Ratio (PRR) is a meager 0.0013; that is insignificant compared to other countries with similar resources.

ABSTRACT

Worldwide reinterpretation of evolutionary history of sedimentary basins had commenced with the introduction of sequence stratigraphic concepts by geoscientists of Exxon. The eustatic sea level controlled deposition in sedimentary basins together with synchronous excursions of many trace elemental and stable isotopic compositions of sedimentary strata have led to a proposition that geographically widely separated sedimentary strata could be classified and correlated with ease by application of sequence stratigraphy and chemostratigraphy, relatively younger branches. This paper reviews the key definitions of these stratigraphic methods, presents an overview on their applicability in petroleum exploration, reservoir characterization and stratigraphic correlation. Considering the man-hours required for interpretation of sequences and chemozones from large quantum of core samples being generated from exploration activities and the possibility of human-error and biased nature of interpretations, an automation scheme involving statistical discrimination is suggested. The statistical discrimination method has been tested to have 76-100 % distinction of depositional units of Recent – Cretaceous in age in terms of sequences, chemozones, lithostratigraphic units, petrographic types and sedimentary microenvironments with 100% reproducibility of predictions. Hence, creation of a large database with well constrained subpopulations and putting it to use for recognition of depositional units and correlation of strata and reservoir characterization is suggested which may reduce operational inconsistencies and improve exploration strategies.

ABSTRACT

The carbonatites are genetically and geochemically distinct and contain several rare earth minerals that are unknown or are very rare in other types of rocks. A useful review of the REE’s in carbonatites is given by Cullers and Graf (1984), who point out that carbonatite contains the highest concentration of REE’s and highest LREE: HREE (La:Lu) ratio of any igneous rock. High REE abundances are considered as the diagnostic character of carbonatites to discriminate them against recrystallized limestone. Rare earth mineralization in carbonatities can be classified into three categories. The first is primary magmatic crystallization (bastnaesite). The second is hydrothermal mineralization and the third is supergene mineralization produced by weathering of carbonatitie bodies. The only economic Nb mineral in carbonatite is pyrochlore. Apatite deposits constitute the largest bulk mining in carbonatites and have higher phosphate content than marine phosphorites. Pyrochlore, cubic fergusonite, eschynite, Fe-Nb rutile, monazite apatite, bastnaesite and allanite are the rare earth minerals that are enriched in Tamil Nadu carbonatites. Such enrichment of above rare earths is typical of undersaturated alkaline complexes. The lanthanides are seen associated with these minerals, mainly the light lanthanides are predominant than heavier ones. Thus the carbonatite complexes provide the locus for several metal deposits that are presently of strategic importance, containing elements, which are otherwise largely dispersed in earth crust.

ABSTRACT

The multi-sensor airborne geophysical survey was carried out over Nalgonda district, Andhra Pradesh, during the field season 2002-03, with an objective to locate potential areas for mineral exploration. The area comprises older metamorphic rocks of Peninsular Gneissic Complex of Archaeanage represented by gneisses, granite, amphibolite and banded magnetite quartzite. Leucocratic intrusive granite, extending over a length of about 40 km around Suryapet in NNW-SSE direction exhibits intense fracturing. Two sets of vertical to sub-vertical fractures have been noted in granite. Yellow stains observed in granite near fracture planes reveal the presence of secondary radioactive mineral encrustation. The ground magnetic and spectrometric observations indicated that the uranium mineralization is confined to these fractures in granite. Petrographic, ore-microscopic and scanning electron microscopic studies revealed evidences of metamict alteration surrounding monazite/apatite inclusions within biotite, and magnetite grains in granite. These studies also indicated evidences of discrete grains of uraninite / coffenite / pitchblende (containing Thand Ce). Chemical analysis of the rock samples (by NAA) collected from anomalous zone reveal high uranium concentration of the order of 1200 ppm, marked by high values of total Rare Earth Element concentration (800 ppm).

The leucogranites are characterized by high LREE and a negative Eu anomaly suggesting plagioclase fractionation. An ultramafic enclave near village Kutubsahipur shows highest concentration of both uranium (1240 ppm) and REE (890 ppm) analyzed by BARC and NAA Lab, GSI.

ABSTRACT

Frankia is a gram-positive, microaerophilic, actinomycete that enters into symbiotic associations with a number of woody dicotyledonous plants called actinorhizal plants. Frankia can fix atmospheric nitrogen through such associations. The actinorhizal-Frankia association is beneficial for the environment, since it increases the fertility of soils. Extensive studies on the biochemical and molecular aspects helped in the classification of Frankia. PCR-RFLP studies of the 16S rRNA and the nif regions of Frankia revealed considerable information regarding the diversity of Frankia strains, isolated from different parts of the world. The completion of three whole genomes of Frankia has bolstered the study of the molecular organization of the genome. Comparative genomics study of the three complete genomes revealed that, the strains reflected the biogeographical history of the host plants they infected. Striking similarity in the codon usage patterns highlights the fact that they may have evolved as a unit. In the present review we highlighted the taxonomy of Frankia and the host plants, the Frankia-actinorhizal association, regulation of infectivity, biochemical and molecular characterization, phylogeny and genomics of Frankia and stressed the need for metabolomic study of the Frankia-actinorhizal association.

ABSTRACT

Serious infections caused by bacteria that have become resistant to commonly used antibiotics have become a major global healthcare problem in the 21^st century. Antibiotic resistance, initially a problem of the hospital setting associated with an increased number of hospitals acquired infections usually in critically ill and immuno-suppressed patients, has now extended into the community causing severe infections difficult to diagnose and treat. In hospitals, most common resistant bacteria include methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci and gram-negative rods including Enterobacteriaceae and Pseudomonas aeruginosa. Vancomycin intermediate and resistant S. aureus, represent a new treatment challenge. In the community, penicillin and macrolide-resistant pneumococci developed several decades ago and are now present all over the world. More recently, communityacquired methicillin-resistant S. aureus has become a problem in several countries causing skin infections but also severe diseases. The molecular mechanisms by which bacteria have become resistant to antibiotics are diverse and complex. Bacteria have developed resistance to all different classes of antibiotics discovered to date. The most frequent type of resistance is acquired and transmitted horizontally via the conjugation of a plasmid. In recent times new mechanisms of resistance have resulted in the simultaneous development of resistance to several antibiotic classes creating very dangerous multidrug-resistant (MDR) bacterial strains, some also known as ‘‘superbugs’’. In many cases the use of antibiotics is unnecessary or questionable. The indiscriminate and inappropriate use of antibiotics in outpatient clinics, hospitalized patients and in the food industry is the single largest factor leading to

ABSTRACT

The continuing depletion of the stratospheric ozone layer mainly due to release of man-made atmospheric pollutants such as chlorofluorocarbons (CFCs) have resulted in the increase of solar ultraviolet-B radiation (UV-B; 280-315 nm) reaching to the Earth’s surface. UV-B is a small (less than 1% of total energy) but highly active component of the solar spectrum that can penetrate to biologically significant depths in lakes, ponds, rivers and oceans. It has been demonstrated that UV-B can cause wide ranging effects including mutagenesis, destruction of proteins/enzymes, inhibition of a number of vital metabolic processes and formation of thymine dimers in DNA leading to death of a number of organisms. A number of microbes including strict photoautotrophs always grow in lighted habitats and thereby always sense and face the stress of solar UV-B radiation. Similarly, humans are also exposed to varying levels of UV-B radiation depending upon the altitudes and latitudes of the location. A wide ranging effect of UV-B such as cataracts, skin cancer, immunosupression etc. has been reported in human. Damaging effects of increased UV-B radiation has also been shown in a number of microbes. These effects include inhibition of growth and survival, decrease in photosynthetic pigments, loss of PS II and RuBISCO activity, inactivation of nitrogenase enzyme and inhibitory effects on several other metabolic processes. Among photosynthetic pigments, phycobiliproteins seem to be the primary target of action since phycobilisomes are completely disintegrated after UV-B exposure. In this contribution an attempt has been made to put in perspective the main effects of UV-B radiation on microbes and human health.

ABSTRACT

Heavy metal contaminated soils are biologically inactive and extremely poor in soil fertility status. These metals are highly resistant and cannot be easily degraded by either chemical reactions or amendments. Microorganisms are biological softwares capable of degrading the metals efficiently. Among microorganisms, mycorrhizas are known to circumvent metal toxicities through a series of processes that assist in immobilization in biological systems which converts toxic metals into less or nontoxic forms. There are five mechanisms such as biosorption, solubilization, hyphal transport, detoxification and dilution are involved in promoting tolerance of host plants to heavy metal toxicities. These processes are strategies that can be exploited to phytoremediate the contaminated soils. The phytoremediation strategies encompass tolerance of mycorrhizal fungi, phytostabilization (preventing entry of heavy metals into plants), phytoextraction (luxuriant uptake and transport to shoots) and intercropping or crop rotation with mycorrhizal dependent hyperaccumulators or non-hyperaccumulators. Despite mycorrhizas are natural, the indigenous population is not sufficient enough to induce tolerance of host plants to abiotic and biotic stress conditions. This necessitates adopting recommended agronomic practices to promote mycorrhizal colonization in natural agro-ecosystem or to derive full benefits from phytoremediation strategies. Thus mycorrhizas are important naturally occurring microorganisms capable of withstanding highly contaminated metal sites and offer protection against phytotoxicities caused by heavy metals.

ABSTRACT

Plasmids are circular, double-stranded DNA molecules which replicate autonomously from the chromosome of the host organism. Plasmids are found in many bacterial species and often confer upon the host cell phenotypic characteristics such as resistance to antibiotics, resistance to heavy metals, ability to produce particular protiens, conjugative (mating) ability and ability to degrade xenobiotc compounds. One of these degradative plasmids may encode a complete catabolic pathway (such as toluene to pyruvate, formate and acetaldehyde) or partial degradative steps, such as octane to octanol. In this later case, the remainder of the pathway may be encoded by chromosomal genes, by genes of other plasmid present in the host, or by other microorganisms. Many degradative plasmids possess a broad host range, especially among the gram-negative bacterial species.

There are different mechanisms which may be involved in the evolution of aromatic pathways in general and in the process of adaptation of microorganisms to xenobiotic substrates in particular. Gene transfer, the occurrence of plasmids in bacteria in the natural environment is an important pool of genetic information residing on plasmid vehicles may flow among indigenous microorganisms. Since many examples of self-transmissible plasmids that carry genes for degradation of aromatic or other xenobiotic compounds are known, and their role in spreading these genes to other microorganisms is well characterized. Early, studies of TOL, NAH, and SAL plasmids revealed strong homologies among these plasmids in regions both inside and outside the catabolic gene clusters. Plasmids, pJP4, pAC25, and PSS50, catabolic plasmids carrying genes for chloroaromatic degradation, have strongly homologous plasmid backbone that determine replication and transfer function. Furthermore, the chlorobenzoate plasmid p51 was also shown to be homologous to pJP4 outside regions of the catabolic genes. These observations suggest that a few common self-transmissible ancestor replicons (includes origin of replication and replication gene) may have been involved in acquisition and spread of different catabolic genes. DNA

ABSTRACT

An understanding of the metabolism of heavy metals facilitates biotechnological use of these functions just recently, although heavy metals comprise the major part of the elements in the periodic table. Due to their ability to form complex compounds, some heavy metals are essential trace elements. In any case, essential or not, most heavy metals are toxic at higher concentration. Heavy metal pollution from last few decades has led to an increased environmental concern. Heavy metal like cadmium is a non-essential toxic heavy metal and is also being increased in soil during last few years posing a serious threat to environment and human health worldwide. Therefore, remediation strategies of the contaminated sites are great concerns and can be achieved by a number of different physico-chemical and biological means.

ABSTRACT

Industrial and agricultural activities and the disposal of waste products have resulted in the contamination of many terrestrial environments. Industrial effluents often contain considerable amount of potentially toxic compounds such as Cd, As, Pb and Hg. Due to their small size, which provides a large contact area that can interact with the surrounding environment, microorganisms are the first biota showing the impact of toxic compounds. Microorganisms being in intimate contact with the soil environment are considered to be the best indicators of soil pollution. In general, they are very sensitive to low concentrations of contaminants and provide a rapid response to soil perturbation. Rhizobium spp. are ubiquitous gram-negative soil bacteria that have a profound scientific and agronomic significance due to their ability to establish nitrogen-fixing symbiosis with legumes, which is of major importance to the maintenance of soil fertility and to feed livestock and populations in many developing countries. Therefore, the present work aimed to evaluate the impact of heavy metals on Rhizobium populations isolated from different locations contaminated with heavy metals. In order to reach this goal some physicochemical parameters that influence metal bioavailability were determined, as well as their concentrations in soil. Cadmium tolerance of Rhizobium isolates was screened in artificial media and the highest cadmium concentration allowing growth was defined as the maximum resistance level (MRL). The heavy metal tolerance variability found among Rhizobium isolates, suggests that beyond basic metabolic machinery also exist variations that allow isolates to display distinct tolerance responses to Cd stress. To better understand Rhizobium cadmium tolerance, wall-bound and intracellular Cd was determined. Sensitive and moderately tolerant isolates showed low intracellular Cd amounts when compared to extremely tolerant isolates, which were able to withstand intracellular Cd concentrations 40 times higher. Lipopolysaccharides (LPS) bind cations unspecifically, so they constitute the initial defence mechanism to heavy metals since they sequestrate cations and therefore prevent their entry into the cell. LPS quantity varied significantly between isolates. LPS increases were observed in most sensitive, moderately tolerant and tolerant isolates, evidencing an attempt of cells to adjust to cadmium entry. These results may be of great importance for understanding how Rhizobium persists in contaminated soils. They also provide important data to the development of bioremediation processes and to the improvement of soil productivity.

ABSTRACT

The world ocean with a coastline of approximately 3,50,000 km is the largest ecosystem on earth. Marine organisms are the major, sustaining components of ecosystem processes and are responsible for biogeochemical reactions that drive our climate changes. Despite this, many marine organisms are poorly described and little is known of broad spatial and temporal scale trends in their abundance and distribution. With new molecular and analytical techniques we can advance our knowledge of marine biodiversity at the species level to understand how marine biodiversity supports ecosystem structure, dynamics and resilience. We can then interpret environmental, ecological and evolutionary processes controlling and structuring marine ecosystem biodiversity. In biotechnology applications marine microbes represent a potential source for numerous commercially important biomolecules and their bioremediation capabilities are also remarkable. They also play a crucial role in decomposition of organic matter and cycling of nutrients. Microbes also serve as food for some bottom-living organisms. Understanding and preserving biodiversity was one of the most important global challenges for the past 20 years and will continue to be an important scientific issue into the new millennium. Our knowledge of marine microbial diversity has, however, been severely limited by relying on microorganisms that have been cultured which are less than 1%.

ABSTRACT

Endophytes are microorganisms that live inside the host plant tissues without causing symptoms of disease. There has been a crescent interest in the prospecting of these microorganisms as sources of novel and bioactive natural products. In fact, a significant number of interesting natural products have been reported in the last years. In this chapter some aspects regarding the endophytes are detailed: the relationship with their host plants, isolation, preservation, taxonomy, cultivation, frequently isolated strains, tropical endophytes, novel structures isolated and also their biological activities.

Key words: natural product, endophytic fungi, plant fungus interaction, secondary metabolites.