023412   Veeraputhiran R;Balasubramanian T N (Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore-641 003) : North west monsoon rainfall of Tamil Nadu - retrospective analysis. Madras agric J 2000, 87(4-6), 235-7.

Retrospective analysis of north east monsoon rainfall climatology in respect of Tamil Nadu indicated the following, lesser than Tamil Nadu NEM average rainfall with higher CV's were recorded for North Arcot, Salem, Dharmapuri, Coimbatore, Periyar, Trichy, Pudukkottai and Madurai districts, whereas Chennai and Chengalput districts recorded above normal rainfall with lower CV values, in all the districts of Tamil Nadu, 60-70% of years were within ± of years were under with ± one standard deviation, in 80% of El-Nino years, Thanjavur and Chengalput districts had shown above normal rainfall while Madurai, North Arcot, Dharmpuri and Coimbatore districts did exhibit such events in only 60% of El-Nino years.

023411   Sondge V D;Sontakke J S;Shelge B S (Water Management Research Centre, Marathwada Agricultural University, Parbhani-431 402) : Aberrations in monsoons in assured rainfall area of Parbhani .I. - meteorologic characterization. Madras agric J 2000, 87(7-9), 384-8.

Rainfall records of 52 years (1944-95) of Parbhani station located in the assured rainfall zone of Maharashtra state were critically examined for establishing the long term averages of monthly rainfall and its temporal variability by deploying appropriate statistical techniques. The deviations of normal times(s) of onset and withdrawal of monsoon, depths of monthly rainfall and their distribution were defined as aberrations. There results revealed that the average monsoon rainfall (monthly total) of 849-.96 mm was distributed in the proportion of 18.13, 26.94, 25.28, 21.61 and 7.93 per cent during June to October, respectively. The variabilities in normal rainfall during crucial months of August (67.69%) and October (119.48%) were relatively higher than remaining monsoon months. The probabilities of normal onset (25th MW) and withdrawal (39th and 50 per cent. The per cent probabilities of aberrations in seasonal (June to October) amount of rainfall was 56.54 per cent, with higher proportion of below normal (39.23) than its abnove normal (27.31) rainfall during June to October. The per cent probabilities of recupation of proceeding deficiency in succeeding months decreased with the advancement of time of occurrence of deficiency.

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023410   Sarojini Y;Sarma N S (Department of Botany, Andhra University, Visakhpatnam-530 003) : Vertical distribution of phytoplankton around Andaman and Nicobar Islands Bay of Bengal. Indian J Mar Sci 2001, 30(2), 65-9.

Vertical distribution of phytoplankton in the upper 200 m water column was studied at 5 stations around the Andaman islands during October, 1996. About 143 species, belonging to 8 classes of algae area identified. Cyanophyta, particularly Trichodesmium erythreae, contributed most to the biomass but the species diversity was maximum for Bacillariophyceae and Pyrrophyceae. Dense maxima were noted at <126>25 m depth in waters of the Bay of Bengal side and less dense maxima at surface in waters of the Andaman Sea side. The maxima of Pyrrophyceae occurred up to 50 m depth and that of Bacillariophyceae in the 25-75 m depth range. A vertical stratification was also observed for several species. There are differences in hydrographic features between the Bay of Bengal and Andaman Sea waters. In the former, a tongue of warmer, more saline water present at 25-150 m depth, orginating from the Arabian Sea, apart from biotic factors, is held responsible for differences in the phytoplankton distribution on the two sides off the islands.

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023409   Sarkar P K;Chakranarayan A B;Deshwandikar A K;Fernandes M R;Raut S D (Department of Geology, Fergusson College, Pune-411 004) : Development of pencil joints in a red bole bed at Dighi, Raiged district, Maharashtra, India. Curr Sci 2000, 79(10), 1422-3.

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023408   Mukhophadhya S K;Biswas H;Das K L;De T K;Jana T K (Department of Marine Science, University of Calcutta, 35, B.C. Road, Calcutta-700 019) : Diurnal variation of carbon dioxide and methane exchange above Sundarbans mangrove forest, in NW coast of India. Indian J Mar Sci 2001, 30(2), 70-4.

A micrometerological method was used to measure the diurnal exchange of carbon dioxide and methane over Sundarbans mangrove forest at Lothian island under lapse and inversion micrometerological conditions during 18th-19th May, 1999. Concentration of CO2 and CH4 in the air were fojnd to be 587.9±51.5 and 0.903±0.318 mg/m³ and both vertical and lateral transport could cause their variation in the atmosphere. This island was a net source of both CO2 and CH4 during the study period and their overall diurnal emission rates estimated to be 113.06 and 1.51x10⁶ mg/d, respectively. Micrometeorological condition of the atomsphere played an important role for the exchange of carbon dioxide and methane between atmosphere and biosphere.

023407   Majumdar T J;Mohanty K K;Mishra D C;Arora K (Marine and Water Resources Division, Remote Sensing Applications Area, , Space Applications Centre, Ahmedabad-380 015) : Gravity image generation over the Indian subcontinent using NGRI/EGM96 and ERS-1 altimeter data. Curr Sci 2001, 80(4), 542-54.

New technique for merging of land gravity using NGRI/EGM96 and ocean gravity using mainly ERS-1 altimeter-derived gravity data has been described. Methods for generation of residual/prospecting geoids and free-air gravity anomaly over Indian oceans surrounding Indian land mass using satellite altimeter data have already been developed. Recently Earth Gravity Model (EGM) 1996 data over the Indian land mass were available through Internet. It is, therefore, emphasized that a joint gravity image over the whole subcontinents, which includes land and ocean, will be of paramount importance for further studies in geophysical exploration/earth science studies in this region. Also, comparison of EGM96 data over certain profiles with satellite-derived information has shown the efficacy of the Satellite Gravity Method. Maps of gravity anomaly generated over the Indian subcontinent using ERS-1 altimeter/EGM96 data are presented along with their interpretation. A number of known megastructures over the study area, e.g. Bombay High, Saurastra Platform, 90° East ridge over the oceans, etc. and Himalayan Thrust Belt, Narmada-Son Lineament, Saurastra Block, Dharwar Block and other major tectonic/structural features and their subsequent extension inside the sea could be successfully interpreted from these maps. Similar attempts have also been made with National Geophysical Research Institute (NGRI) generated gravity over land and altimetric/EGM generated gravity over oceans.

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023406   Kunte P D;Wagle B G (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Littoral transport along west coast of India. Indian J Mar Sci 2001, 30(2), 57-64.

Presents an overview of investigations that were carried out to determine the dynamics of littoral transport along the west of India, during last three decades. Sedimentological methods, wave refraction diagrams, tracer tracking, geomorphic indicators etc. have been used for determination of littoral dynamics at various locations and along larger areas of west cost of India. Wave refraction studies have been conducted to determine locations of wave convergence and divergence, rip currents and to provide quantitative measurements of littoral drift and drift direction for local as well as regional areas. However, studies based on geomorphic indicators aided with remote sensing techniques were reliable to determine littoral drift cells and drift direction within each cell and net littoral drift direction along west coast of India. Review indicates that though littoral drift is variable, bi-directional and season dependent, long-term net littoral drift along west coast of India is southwards. Efforts have also been made to highlight the neglected aspects, merits and demerits of various methods used.

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023405   Ghosh S N (Civil Engineering Department, Indian Institute of Technology, Kharagpur) : Assessment of relative movement of sedimental a tidal reach with special reference to navigation in rice Hooghly. ISH J Hydraul Engng 2000, 6(1), 1-11.

Outlines the various issues involved in estimating sediment transport in a tidal reach and the methodology to be followed in assessing the relative movement of sediment in a tidal reach. Based on field observations and survey records it has been observed that the predominance concept provides satisfactory results of relative sediment movement in their river Hooghly when total sediment transport is expressed as propertional to velocity raised to the power 5.

023404   Farooqui A;Vaz G G (Birbal Sahni Institute of Palaeobotany, , 35, University Road, Lucknow-226 001) : Holocene sea-level and climatic fluctuations: Pulicat lagoon. Curr Sci 2000, 79(10), 1484-8.

Pulicat lagoon situated in the Palar Basin, is the second largest lagoon on the east coast of India. The north-western margin of the desiccated lagoon is an irregular and elevated hard surface. Palynological studies were carried out in sedimentary soil samples from four pits dug across this part of the lagoon. Vegetational reconstruction from peat beds at 4.98 m (a.m.s.l.) and 1 m (a. m.s.l.) in the west at Sulurpet and Kasdredinilem, respectively, is indicative of a palaeoshoreline. The sea level reached its maximum around 6650±110 yrs BP in Sulurpet, 18 km west from the present shoreline. The radiocarbon dates of peat bed at Kasdreddinilem reveals an age of 4608±122 yrs BP, indicating the shift in mangrove line eastwards during the regressive phase. The Late Holocene radiocarbon dates of shells (bivalves) at Attakanitippa and Sriharikota island are the chain of intermittent regressive phases since then. The peat sediment below this shell bed at 9 and 15 m below the mean sea level was perhaps deposited during the transgressive phase. No evidence of mangrove pollen in the late Holocene soil sediments indicates that sealevel fluctuation and climatic conditions during mid and late Holocene led to the decline in mangroves in the area.

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023403   Anil Kumar K S;Abdul Azis P K;Natarajan P (NO, School of Applied Life Sciences, Pathanamthitta-689 645) : Sediment characteristics of Poonthura estuary (Southwest coast of India) in relation of pollution. Indian J Mar Sci 2001, 30(2), 75-80.

Texture, redox potential and organic carbon of sediments in Poonthura estuary, Thiruvananthapuram, presently to sewage pollution were evaluated over a period of one year. Textural study revealed the presence of highest percentage of finer particles at the sheltered upstream stations. Oxidation-reduction potential varied betwen -211 and + 156. Strong negative potentials recorded from the most polluted stations while freshwater and oceanic stations always recorded positive values. Organic carbon widely varied between 2.4 to 83.3 mg/g, and showed enrichment always at the polluted zone. Organic carbon content was more than the prescribed limit for unpolluted estuaries at some stations and reflects the level of pollution in the estuary. Significant variation in organic carbon and redox potential during the monsoon shows that better dilution can diminish the high organic load to a great extent.

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023402   Acharyya S K (Geological Survey of India, , 27, J.L. Nehru Road, Calcutta-700 016) : Mapping of Indus ophiolites: need for introspection. Curr Sci 2000, 79(10), 1423-5.

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023423   Jiang K;Hu X (Center for Energy, Environment and Climate Change, Energy Research Institute, Beijing, China) : Integrated environmental policy assessment for climate change and local environment in China. Opsearch 2001, 38(1), 27-43.

In order to explore the benefit of policies on both GHG emission control and local environmental control, this study simulates the effect of policies on CO2 emission and SO2 emission. A model framework was designed to analyze the effect from technology options, and develop the relationship of these two gases emissions from long-term view point. It is observed from the results that climate change oriented policies could simultaneously reduce SO2 emission by encouraging advanced technologies, and from the long-term view point, SO2 emissions will be reduced due to the concern that is, to some degree, a product of local air pollution with the income raising. These SO2 trajectories show that decreases may occur after 2020. CO2 emissions may keep increasing for several decades.

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023422   Dimri A P;Mohanty U C;Naresh P (NO, Snow and Avalanche Study Establishment, Chandigarh-160 023) : Estimation of minimum surface temperature at stage II. Def Sci J 2001, 51(2), 171-4.

An attempt has been made to develop a statistical model for forecasting minimum temperature at ground level using previous years' data. Surface data were collected at Stage II (longitude 73°E, latitude 34°N, and altitude 2650 m). Atmospheric variables are influenced by complex orography and surface features to a great extent. Statistical relationship between atmosphere parameters and minimum temperature at the site has been established. Multivariate linear regression analysis has been used to establish the relationship to predict the minimum surface temperature for the following day. A comparison between the observed that the calculated forecast minimum temperature has been made. Most of the cases are well predicted (multiple correlation coefficient of 0.94).

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021486   Yapa K K A S (Department of Physics, University of Ruhuna, Matara, Sri Lanka) : Seasonal variability of sea surface chlorophyll-a of waters around Sri Lanka. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 427-32.

Remotely sensed data on ocean colour of waters surrounding Sri Lanka received from the Coastal Zone Colour Scanner (CZCS) are processed and analyzed. Raw data of 1 km resolution on relatively cloud free days during 1978-1986 are processed to produce sea surface chlorophyll maps within latitudes 4.5N-11N and longitudes 78E-85E, a region in the Indian Ocean surrounding Sri Lanka. The processed data include about 110 single day maps and composite averages for each month and season. The months of July, August and September are omitted in the calculation of averages due to insufficient data. The waters in the Gulf of Mannar and Palk Bay areas show high chlorophyll-a concentrations throughout the year. However, these high values may represent other suspended particles and dissolved organic matter besides chlorophyll-a as this region is shallow (<60>100 m). Regions with high chlorophyll concentrations (<62> 0.5 mg m^_3) along the coast and western ocean region can be seen in the months of October and November, after the southwest monsoon period. As high surface chlorophyll concentrations may indicate high productivity, these regions need extensive measurements of primary production and also continuous monitoring of fish catches, during and after the southwest monsoon. Studies of particle composition in shallow water areas, in particular waters in Palk Bay and GUlf of Mannar, should be carried out in order to elucidate the effect of non-phytogenic.

021485   Swathi P S;Sharada M K;Yajnik K S (CSIR Centre for Mathematical Modelling and Computer Simulation, , Bangalore-560 037) : Coupled aphysical-biological-chemical model for the Indian ocean. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 503-37.

Coupled physical-biological-chemical model has been developed at C-MMACS for studying the time-variation of primary productity and air-sea carbon-dioxide exchange in the Indian Ocean. The physical model is based on the Modular Ocean Model, Version 2 (MOM2) and the biological model describes the nonlinear dynamics of a 7-component marine ecosysem. The chemical model includes dynamical equation for the evolution of dissolved inorganic carbon and total alkalinity. The interaction between the biological and chemical model is through the Redfield ratio. The partial pressure of carbon dioxide (pCO₂) of the surface layer is obtained from the chemical equilibrium equations of Peng et al 1987. Transfer coefficients for air-sea exchange of CO₂ are computed dynamically based on the wind speeds. The coupled model reproduces the hitgh productivity observed in the Arabian Sea off the Somali and Omani coasts during the Southwest (SE) monsoon. The entire Arabian Sea is an outgassing region for CO₂ in spite of high productivity with transfer rates as high as 80 m-mol C/m²/day during SW monsoon near the Somali Coast on account of strong winds.

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021484   Sukumaran S;Ravindra Kumar G R (NO, Centre for Earth Sciences Studies, Akkulam, Thiruvananthapuram-695 031) : K-feldspar metasomatism in granulite-facies rocks of Palghat region, Kerala: evidence and implications of brines in charnockite-forming metamorphism. Curr Sci 2000, 79(11), 1594-8.

Formation of granulites requires low H2O activity and fluids play a major role in their evolution. A wide variety of granulite-forming processes has been discussed. Among the models proposed, the presence of fluid inclusions, alkali metasomatism and loss of large ion lithophile (LIL) elements support the fluid-driven granulite-forming process. Documents abundant petrographic evidence in the Palghat region for the alkali metasomatism and evidence for metamorphic fluid of low H2O in rocks like banded charnockite, hornblende-biotite gneiss and incipient charnockite. Evidence of potash metasomatism is noted as : rims of K-feldspar along orthopyroxene, opaque, plagioclase and K-feldspar grains; veins of secondary K-feldspars traversing plagioclase and hornblende and in the form of blebs in plagioclase grains and as exsolution. Excellent evidence of K-feldspar veins growing along the borders of orthopyroxene grains indicates that the vein network represented deposition of migrating XH2O haliderich fluids. These low H2O brines may have created a conducive environment for localized breakdown of biotite and development of arrested charnockite.

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021483   Singh I D;Pal B;Singh S P (NO, R.B.S. College, Bichpur, Agra-283 105) : Electrical conduction in Makrana stone powder. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 32-3(abstr).

The frequency response of electrical conduction (√4) of Makrana stone powder at 95% relative humidity and temperature 35°C has been studied. The correlation coefficient improves to 0.998 for frequency range from 1 KHz to 1 MHz. The distilled water (D.W.) saturated powder's response is flat upto 100 KHz and linear 100 KHz. The relative response of four probe (√4) to two probe (√2) is flat up to 100 KHz. Beyond 100KHz it is logarithmic. Analytically the electrical conduction in this case is similar to conduction in pure clay. The √4 measurement is better than √2. The energy relaxation occurs in radio frequency range. It satisfies clay type large and complex molecular polar system of this powder.

021482   Sharma O P;Gupta K D;Tripathi P S M;Singh N N (Coal Survey Laboratory, , Canal Road, Jammu-180 001) : Mineral characteristics of Mahagola coalfield of Jammu coal by X-ray diffraction. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 32(abstr).

Mineralogical studies of Jammu coal of Mahagola coalfield (viz-Mahagola mine) and its low temperature ash (L.T.A.) have been carried out for characterization of minerals, using X-ray diffraction technique. The x-ray studies established the presence of Kaolinite in major phase and quartz and mica in the minor phase in the Mahagola mine coal. The mineralogy has been discussed in the light of the geological factors. The utilization potential of Jammu coal of Mahagola coalfield (viz-Mohagola mine) on the basis of its mineralogy is examined.

021481   Sarma V V S S;Dileep Kumar;Gauns M; Madhupratap M (National Institute of Oceanography, , Dona Paula, Goa-403 004) : Seasonal controls on surface pCO₂ in the central and eastern Arabian sea. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 471-9.

Variability in partial pressure of carbon dioxide (pCO₂) and its control by biological and physical processes in the mixed layer (ML) of the central and eastern Arabian Sea during inter-monsoon, northeast monsoon, and southwest monsoon seasons were studied. The ML varied from 80-120 m during NE monsoon, 60-80 m and 20-30 m during SW- and inter-monsoon seasons, respectively, and the variability resulted from different physical processes. Significant seasonal variability was found in pCO₂ levels. During SW monsoon, coastal waters contain two contrasting regimes; pCO₂ levels of 520-685 μatm were observed in the SW coast of India, the highest found so far from this region, driven by intense upwelling and low levels of pCO₂ (266 μatm) were found associated with monsoonal fresh water influx. It varied in ranges of 416-527 μatm and 375-446 μatm during inter- and NE monsoon, respectively, in coastal waters with higher values occurring in the north. The central Arabian Sea pCO₂ levels were 351-433, 379-475 and 385-432 μatm during NE-inter and SW monsoon seasons, respectively. The mixed layer pCO₂ relations with temperature, oxygen, chlorophyll a and primary production revealed that the former is largely regulated by physical processes during SW-and NE monsoon whereas both physical and biological processes are important in inter-monsoon.

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021480   Ramaiah N;Sarma V V S S;Gauns M;Dileep Kumar M;Madhupratap M (National Institute of Oceanography, , Dona Paula, Goa) : Abundance and relationship of bacteria with transparent exopolymer particles during the 1996 summer monsoon in the Arabian sea. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 443-51.

Bacterial abundance and production, numbers, sizes and concentrations of transparent expolymer particles (TEP) and total organic carbon (TOC) were measured during the 1996 summer monsoon to understand the relationship between TEP, the most labile particulate organic carbon, and bacteria. While high regional variability in the vertical distribution of TOC was discernible, TEP concentrations were high in surface waters at 18-20° N along 64°E with concentrations well over 25 mg alginic acid equivalents 1^-1 due to upwelling induced productivity. Their concentrations decreased with depth and were lower between 200 and 500 m. Bacterial concentrations were up to 1.99 x 10⁸ 1^-1 in the surface waers and decreased by an order of magnitude or more at depths below 500m. A better relationship has been found between bacterial abundance and concentrations of TEP than between bacteria and TOC, indicating that bacterial metabolism is fueled by availability of TEP in the Arabian Sea. Assuming a carbon assimilation of 33%, bacterial carbon demand (BCD) is estimated to be 1.017 to 4.035 g C m^-1 d^-1 in the surface waters. THe observed TEP concentraitons appear to be sufficient in meeting the surface and subsurface BCD in the northern Arabian Sea.

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021479   Purvaja R;Ramesh R (NO, Institute of Ocean Management, Anna University, Chennai-600 025) : Biogeochemical cycle of methane and its impact on global climate change. Proc Indian Sci Congr Ass - Pt IV, Sect-I 1999, (NULL), 51-2(abstr).

Deals with the CH4 emission studies conducted in surface waters of the Arabian sea and from the coastal wetlands of India. The world's oceans, as a natural source of CH4 play only a minor role in the global budget of atmospheric CH44 emission differ considerably and range from 0.4 to 15 Tg CH4Yr^-1, indicating a need for further study. More than 2000 measurements of atmospheric and dissolved CH4 were performed in the central and northwestern Arabian Sea during the intermonsoon and the southwest monsoon periods of 1997. Mean CH4 saturations in the surface waters of the central Arabian Sea were in the range of 103-107%. Significantly enhanced saturations were observed in the coastal upwelling area at the coast Oman (up to 156%) and in an upwelling filament (up to 145%). The CH4 surface concentrations in the upwelling area were negatively correlated to sea surface temperatures. Area weighted, seasonally adjusted estimated of the sea-air fluxes of CH4 gave annual emissions from the Arabian Sea of 11-20 Gg CH4, suggesting that previously reported very high surface CH4 concentrations are a typical and that the emissions derived from them are probably overestimates.

021478   Prasanna Kumar S;Madhupratap M;Dileep Kumar M;Gauns M;Muraleedharan P M;Sarma V V S S;De Souza S N (National Institute of Oceanography, , Dona Paula, Goa-403 004) : Physical control of primary productivity on a seasonal scale in central and eastern Arabian sea. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 433-41.

Using in situ data collected furing 1992-1997, under the Indian programme of Joint Global Ocean Flux Study (JGOFS), It is shown that the biological productivity of the Arabian Sea is tightly coupled to the physical forcing mediated through nutrient availability. The Arabian Sea Becomes productive in summer not only along the coastal regions of Somalia, Arabia and southern parts of the west coast of India due to coastal upwelling but also in the open waters of the central region. The open waters in the north are fertilized by a combination of divergence driven by cyclonic wind stress curl to the north of the Findlater Jet and lateral advection of nutrient-rich upwelled waters from Arabia. Productivity in the southern part of the central Arabian Sea, on the other hand, is driven by advection from the Somalia upwelling. Surface cooling and convection resulting from reduced solar radiation and increased evaporation make the northern region productive in winter. During both spring and fall inter-monsoons, this sea remains warm and stratified with low prodution as surface waters are oligotrophic. Inter-annual variability in physical forcing during winter resulted in one-and-a-half times higher production in 1997 than in 1995.

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021477   Prabhu B N;Vijan A R;Rathore S S;Ramesh P; Ghosh N (KDM Institute of Petroleum Exploration, ONGC, , Dehradun-248 195) : Strontium isotope stratigraphy and biostratigraphy of cenozoic sediments from Mumbai offshore area, India. Proc Indian Sci Congr Ass - Pt IV, Sect-I 1999, (NULL), 46-7(abstr).

Deals with the strontium isotope stratigraphic studies carried out on the Cenozoic sub-surface samples from the Panna-Bassein block of Mumbai offshore Basin. The foraminifera separated from CC - 1 to CC - 12 (depth : 1720 - 1785m) of well BS-3 from the Bassein Field of this block have yielded Sr isotopic ages in accordance with their depth of occurrance/stratigraphic position. Ranging from 40.6 Ma for C - 1 to 50.2 Ma for CC - 12. These chronostratigraphic ages are consistent with Middle to Early Eocene ages suggested for this interval based on paleontological studies.

021476   Periakali P;Eswaramoorthi S;Mahesh M; Rajeshwara Rao N (Department of Applied Geology, University of Madras, Guindy Campus, Chennai-600 025) : Geochemistry of trace elements (Fe, Mn, Al, Cu and Zn) in the sediments of Karikkattukuppam near Madras, east coast of India. Proc Indian Sci Congr Ass - Pt IV, Sect-I 1999, (NULL), 45-6(abstr).

Four seasonal sediment samples were collected off Karikkattukuppam, near Madras, for the study of geochemical behaviour of trace elements Fe, Mn, Al, Cu and Zn. The samples were analysed for acid (1:1HCl) soluble Fe, Mn, Al, Cu and Zn in the sediments. In addition, organic carbon Calcium carbonate, sand, silt and clay content of the sediments were also determined. The calcium carbonate and organic carbon are higher for the postmonsoon season. During photosynthesis the ΣCO2 of the water column decreases resulting in the precipitation of calcium carbonate to the sediments. Increased photoproduction also releases excess organic matter to the sediments. Increased photoproduction also releases excess organic matter to the water column resulting from the decay of phytoplanktons, and this is deposited in the sediments along with calcium carbonate. The lower sedimentary organic carbon for the premonsoon season might be due to the lower quantity of silt and clay fractions which it is normally associated. The study indicated that the amount of trace metals Cu and Zn in the sediments is mainly controlled by the quantity of silt, clay, acid-soluble fractions of Fe and Mn and organic carbon.

021475   Muzuku A N N (University of Dar Es Salaam, Institute of Marine Sciences, P O Box-668, Zanzibar, Tanzania) : 350 ka organic delta <. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 481-9.

Stable isotope compositions of sedimentary organic carbon and content of organic carbon for sediment cores recovered at two sites (sites 724C and 725C) during Ocean Drilling program (ODP) Leg. 117 on the oman continental margin are used to document variability of the monsoon winds for the past 350 ka. Although both sites have a mean δ¹³C value of -20.1%, three zones depleted in ¹³C are observable at site 724C during isotope stages 3,8 and 10, while only one zone is recognizable at site 725C. Increased coastal upwelling during isotope stages 3 owing to intense SW monsoon winds resulted in higher concentration of CO₂ in the water column causing the formation of organic matter that was depleted in ¹³C. The other two zones deposited during oxygen isotope stages 8 and 10, which are also characterized by low values of organic carbon, nitrogen and C/N ratios, could be attributed to the dilution by terrestrial material derived from paleosol transported by northwesterlies. Because of utilization of ¹³C enriched dissolved CO₂ during the last glacial maximum Holocene sedimentary organic materials are depleted in ¹³C relative to the former. The content of Residual organic carbon (ROC) is higher at site 724C (with an average of 2.3±1.2%) relative to site 725C, which averages to 0.9±0.4% probably because of differences in the degree of preservation.

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021474   Mislankar P G;Iyer S D (National Institute of Oceanography, , Dona Paula, Goa-403 004) : Petrographical indicators of petrogenesis: examples from Central Indian Ocean Basin basalts. Indian J Mar Sci 2001, 30(1), 1-8.

Petrographical features of the Central India Ocean Basin (CIOB) basalts were studied to understand their genetic significance. The fresh basaltic pillows show three textural zones from the top glassy (zone A) through the intermediate (Zone B) to the holocrystalline interior (zone C), with each characterised by varying assemblages of plagioclase and olivine that form different textures. Based on the presence and morphotypes of the plagioclase and olivine, the CIOB basalts are classified as aphyric, plagioclase dominant, plagioclase+olivine bearing and rarely plagioclase+olivine+augite bearing. The mineral phases and the textures reflect the magmatic conditions under which the basalts crystallised from a tholeiitic magma.

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021473   Mishra S;Patil I D;Patil Y P (University Department of Chemical Technology, North Maharasthra University, Jalgaon-425 001) : Comparative study of polyacrylamide and homopolymer of acrylonitrile as antiscaling agent on Jalgaon ground water. J scient ind Res 2000, 59(1), 44-8.

Hardness of water results in scale formation and affects efficiency and life span of heat exchangers and evaporators by salt deposition. Low molecular weight water soluble polymers are used to prevent scale formation. Polyacrylamide and polyacrylonitrile are used as scale inhibitors. Ground water is refluxed from 1 to 24 h with an without polymers. When only water is boiled the effect of salt precipitation is found to increase with increase in time of reflux. But when the polymers are added individually, the precipitation of salt decreases with increase in amount of polymer (200 ppm to 800 ppm) as well as with increase in reflux time for all of the polymer concentrations. It is also observed that polyacrylamide is more effective than polyacrylonitrile as an antiscaling agent. Polyacrylonitrile shows better results up to 12 h of refluxing and thereafter polyacrylamide appears better. Antiscaling activity of an inhibitor compound involves either diminution of the crystal growth rate and prevention of the homogeneous and/or heterogeneous germination mechanism.

021472   Lellouche J M;OUberdous M;Eifler W (Joint Research Centre of the European Commission, Space Applications Institute, Marine Environment Unit, TP 690, I-21020 Ispra, VA, Italy) : 4D-var data assimilation system for a coupled physical-biological model. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 491-502.

A 3-compartment model of phytoplankton growth dynamics has been coupled with a primitive-equation circulation model to better understand and quantify physical and biological processes in the Adriatic Sea. Presents the development and application of a data assimilation procedure based on optimal control theory. The aim of the procedure is to identify a set of model coefficient values that ensures the best fit between data and model results by minimizing a function that measures model and data discrepancies. Twin experiments have been successfully implemented in order to have a better estimation of biological model parameters and biological initial conditions.

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021471   Kriest I;Evans G T (Instiut fur Meereskunde, , Diisternbrooker Weg 20, 24105 Kiel, Germany) : Vertically resolved model for phytoplankton aggregation. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 453-69.

Presents models of the vertical distribution and flux of phytoplankton aggregates, including changes with time in the distribution of aggregate sizes and sinking speeds. The distribution of sizes is described by two parameters, the mass and number of aggregates, which greatly reduces the computational cost of the models. Simple experiments demonstrate the effects of aggregation on the timing and depth distribution of primary production and export. A more detailed ecological model is applied to sites in the Arabian Sea; it demonstrates that aggregation can be important for deep sedimentation even when its effect on surface concentrations is small, and it presents the difference in timing between settlement of aggregates and fecal pellets.

51 ref

021470   Jayendra Singh;Yadav R R (NO, Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226 007) : Tree-ring indications of recent glacier fluctuations in Gangotri, western Himalaya, India. Curr Sci 2000, 79(11), 1598-1601.

A 41-year-old (AD 1590-1999) ring-width chronology of Himalayan pine (Pinus wallichiana) based on large replication of samples derived from a pure, mixed age stand growing on thick soil with almost even topography near Chirbasa, Gangotri has been developed. This makes the longest chronology of this species developed so far from the Indian region. The chronology shows abrupt surge in tree growth during the late 20th century, with the highest growth indices recorded in the 1990s. Strong correlation noted between tree growth and winter temperature shows that the winter warmth is one of the main factors responsible for the twentieth century growth surge. This growth surge is closely associated with the area vacated by the Gangotri glacier. Low growth prior to the 1950s reflecting cooler conditions indicates that the glacier should have been stationary for a long time with some episodic advances.

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021469   Hussain S M;Mohan S P (Department of Geology, University of Madras, A C College Campus, Madras-600 025) : Distribution of recent benthic Ostracoda in Adyar river estuary, east coast of India. Indian J Mar Sci 2001, 30(1), 53-6.

Fifteen surface sediment and bottom water samples were collected from the Adyar river estuary, Chennai, starting from the mouth of the river upstream, Twenty-six species belonging to 23 genera have been encountered, of which Caudites javana and Tanella gracilis were abundant and widespread in the study area. The distribution of the species in each sample is given. Water parameters such as temperature, salinity, dissolved oxygen and sediment characteristics like CaCO₃, and organic matter content of each sample were estimated and correlated against the ostracod population recovered in the respective sample. Sand, silt and clay ratios have been estimated and plotted on trilinear diagrams. The four sediment types represented in the study area are sand, siltysand, claysilt and sandyclaysilt. The distribution of ostracods in the Adyar river estuary seems to be controlled by salinity and substrate.

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021468   emmanuel D;Phillipe D;Malik C (Laboratorie Interdisciplinaire des Sciences de l'Environnment, Maison, , 32, Avenue Foch B.P. 59, 62930 Wimereux) : Radiative transfer code: application to the calculation of PAR. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 407-13.

Production of carbon in the ocean, the so-called primary production, depends on various physico-biological parameters: the biomass and nutrient amount in oceans, the salinity and temperature of the water and the light available in the water column. Focused on the visible spectrum of the solar radiation defined as the Photosynthetically Active Radiation (PAR). Developed a model (Chami et al. 1997) to simulate the behaviour of the solar beam in the atmosphere and the ocean. Described the theoretical basis of the code and the method used to solve the radiative transfer equation (RTE): the successive orders of scattering (SO). The second part deals with a sensitivity study of the PAR just above and below the sea surface for various atmospheric conditions. In a cloudy sky, computed a ratio between vector fluxes just above the sea surface and spherical fluxes just beneath the sea surface. When the optical thickness of the cloud increases this ratio remains constant and around 1.29. This parameter is convenient to convert vector flux at the sea surface as retrieved from satellite to PAR. Subsequently, showed how solar radiation as vector flux rather than PAR leads to an underestimate of the primary production up to 40 for extreme cases.

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021467   Deka H (Department of Geology, Cotton College, Guwahati-781 001) : Petrology and petrochemical study of the amphibolites of Rani-Pamohi area, Kamrup district, Assam. Proc Indian Sci Congr Ass - Pt IV, Sect-I 1999, (NULL), 44-5(abstr).

Amphibolites of the Rani-Pamohi area, Kamrup, Assam, occur as lenses, patches, dykes, sills etc. in granite genesis grey porphyritic gramite. The amphibolites are categorised as Hornblende amphibolites and Diopside amphibolites. The petrochemical evidences show trends towards the magnetic origin of basaltic and doleritic composition.

021466   Breves W;Reuter R (Carl von Ossietzky Universitiat Oldenburg, Fachbereich Physik, , D-26111 Oldenburg, Germany) : Bio optical properties of gelbstoff in the Arabian sea at the onset of the southwest monsoon. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 415-25.

As part of the German JGOFS Indian Ocean Programme, a cruise occurred in the Arabian Sea in May 1997 at the onset of the southwest monsoon. Data on gelbstoff, chlorophyll a and tryptophan-like fluorescence as well as gelbstoff absorption were obtained. They indicate, that these optical parameters support the interpretation of hydrographic and biogeochemical conditions. Tryptophan-like fluorescence seems to be a useful indicator of changes in the constitution of the biomass. A comparison of gelbstoff absorption and fluorescence data from the upper 100 m reveals only a weak covariance. Special emphasis is given to the fit procedure used for retrieving the exponential slope S of the spectral absorption coefficient. S values with a mean of 0.016 nm^-1 are found in the 350 to 480 nm wavelength range. A mean slope S set to the frequently reported value of 0.014 nm^-1 in the exponential description of gelbstoff absorption might lead to a systematic over/underestimation, and thus to systematic errors, if single-wavelength absorption values are extrapolated to other spectral regions on the basis of this parameter.

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021465   Asharaf T T M;Nair Ratish P;Sanjana M C; Muraleedharan G;Kurup P G (National Institute of Oceanography, Regional Centre, Cochin-682 014) : Surface wave statistics and spectra for Valiathura coastaline, SW coast of India. Indian J Mar Sci 2001, 30(1), 9-17.

A series of 12 monthly graphical three-dimensional plots were produced for Valiathura, SW coast of India, taking significant wave height, zero up-crossing period and direction as the three axes. Joint distributions of significant wave height and zero-up crossing period have also been developed for these months to understand the combination of these parameters in random waves. The fair weather period (November-April) was characterized by comparatively moderate wave activity with period ranging from 6 to 17.5 sec and direction of wave approach from 190° to 200°. During rough weather period (May - October), the waves exhibit a wider spread of direction ranging from 190° to 260° with periods ranging from 6 to 13.5 sec and significant wave height ranging from 0.6 to 3.2 m. Wave spectrum curves show that the TMA model gives better results and follows the observed spectra in large number of cases during fair weather. During rough weather, TMA and Shadrin's models show almost identical behavior.

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021464   Ajoy Kumar;Minnett P;Podesta G;Evans R; Kilpatrick K (Meteorology and Physical Oceanography Division, Rosenstiel School of Marine and Atmospheric Science, University of Mi, Miami, FL 33149) : Analysis of pathfinder SST algorithm for global and regional conditions. Proc Indian Acad Sci-Earth Planet Sci 2000, 109(4), 395-405.

As part of the Pathfinder program developed jointly by National Aeronautics and Space Administration (NASA) and National Oceanic and Atmospheric Administration (NOAA) a large database of in situ sea surface temperature (SST) measurements coincident with satellite data is now available to the user community. The Pathfinder Matchup Database (PMDB) is a multi-year, multi-satellite collection of coincident measurements from the Advanced Very High Resolution radiometer (AVHRR) and broadly distributed buoy data (matchups). This database allows the user community to test and validate new SST algorithms to improve the present accuracy of surface temperature measurements from satellites. In this paper we investigate the performance of a global Pathfinder algorithm to specific regional conditions. It is shown that for zenith angles less than 45°, the best-expected statistical discrepancy between satellite and buoy data is about <126> 0.5 K. In general, the bias of the residuals (satellite - buoy) is negative in most regions, except in the North Atlantic and adjacent seas, where the residuals are always positive. A seasonal signal in SST residuals is observed in all regions and is strongest in the Indian Ocean. The channel-difference term used as a proxy for atmospheric water vapor correction is observed to be unresponsive for columnar water vapor values greater than 45 mm and high zenith angles.

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020273   Srinivasan J (Centre for Atmospheric and Oceanic Sciences and Department of Mechanic, Indian Institute of Science, Bangalore-560 012) : A simple thermodynamic model for seasonal variation of monsoon rainfall. Curr Sci 2001, 80(1), 73-7.

Monsoons occur in the tropics on account of complex interaction between the continents, the ocean and the atmosphere and hence no sample model of the monsoon has been proposed so far. A simple diagnostic model of the monsoon has been proposed based on the constraints imposed by energy and the moisture balance in a vertical column of the tropical atmosphere. The model demonstrates that the monthly mean rainfall depends upon evaporation, the net energy available in the atmosphere and the vertical stability of the atmosphere. The model simulates the seasonal variation of rainfall in India, Africa and South America remarkably well with explicitly invoking the concept of land-sea contrast in temperature. The model is useful to understand the impact of deforestation, greenhouse gases and aerosols on monsoon rainfall.

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020272   Sinha H S S;Chandra H;Rastogi R G (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : Longitudinal inequalities in the equatorial electroject. Proc Natn Acad Sci India-Sect A 1999, 69(1), 89-96.

The calculations of Pedersen, Hall and Cowling conductivities have been made using the same plasma and neutral parameters and actual observed ground magnetic field values for both the Indian and Amercian regions. It is shown that it is the parameter Ri which seems partly responsible for the altitude difference of peak current densities in both the regions. The second inequality can be understood if the ground ΔH variations of both the regions are normalized to the same epoch of the solar activity. It is also shown that peak current density and peak Cowling conductivity are higher by 29% and 73%, respectively in the American region as compared to that in the Indian region.

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020271   Sahai A K (Climate & Global Modelling Division, Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune-411 008) : Brief review of climate change : causes, observations and modelling studies. Proc Natn Acad Sci India-Sect A 1999, 69(1), 1-17.

Droughts and periods of prolonged flooding occur naturally every year somewhere on the earth. When unusual climate anomalies are sustained over several years or even decades, the stress on human population can be profound. In the last few decades humankind's everexpanding activities have caused environmental changes that reach beyond localities and regions to become global in space and there has been growing awareness among the people of issues such as whether the human activities are changing the frequency of occuring climate anomalies and extreme weather events that often accompany them. Thus it is important to determined likely climate change in the next century, and therefore a brief account of various causes of climate change and the observed climatic changes from remote past to present time is presented in the global and Indian context. It is also mentioned that up to what extent future climate can be predicted using general circulation models.

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020270   Hareesh Kumar P V;Prasada Rao C V K;Swain J; Madhusoodanan P (NO, Naval Physical and Oceanographic Laboratory, Thrikkakara, Kochi-682 021) : Intra-seasonal oscillations in the central Bay of Bengal during summer monsoon 1999. Curr Sci 2001, 80(6), 786-90.

Intra-seasonal oscillations were observed in the meterological and oceanographic fields of Bay of Bengal during the summer monsoon season of 1999. Spectral analysis revealed prominent peaks in the intra-seasonal (10 to 32 days), inertia (2.2 days), diurnal and semi-diurnal bands. Oscillation of intra-seasonal periodicity significantly influences the circulation pattern. The variations in oceanographic fields were dominated by remote forcing compared to local forcing.

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020269   Goswami B N;Ajaya Mohan R S (Center for Atmosphere and Oceanic Sciences, Indian Institute for Science, Bangalore-560 012) : Estimate of predictability of monthly means in tropics from observations. Curr Sci 2001, 80(1), 56-63.

Method of separating the contributions from slowly varying boundary forcing and internal dynamics (e.g. intraseasonal oscillations) that determine the predictability of the monthly mean tropical climate is presented. Based on 33 years of daily low level wind observations and 24 years of satellite observations of outgoing long wave radiation, it shows that the Indian monsoon climate is only marginally predictable, as the contribution of the boundary forcing in this region is relatively low and that of the internal dynamics is relatively large. It is also shown that excluding the Indian monsoon region, the predictable region is larger and predictability is higher in the tropics during northern summer. Even though the boundary forced variance is large during nothern winter, the predictable region is smaller as the internal variance is larger and covers a larger region during that period (due to stronger intraseasonal activity.

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020268   Dwivedi R;Singh R N (Department of Applied Physics, Institute of Technology, Banaras Hindu University, Varanasi-221 005) : Heating of solar filamentary magnetic flux tubes. Curr Sci 2001, 80(1), 64-6.

The sunspot regions are well-known sources of energetic charged particle emissions and numerous wave mode generations. it is shown that the high frequency electromagnetic waves generated by synchrotron process, at time, could be cross-modulated by low frequency p-mode oscillations. The analyses of recorded electromagnetic field strength and seismic waves would depict interesting features of the originating sunspot regions.

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020267   Dhyani B L;Nirmal Kumar;Tandon R;Ram Babu (NO, Central Soil and Water Conservation Research and Training Institute, 218, Kaulagarh Road, Dehradun-248 195) : Rainfall erosion potential and iso-erodent map of Madhya Pradesh. J Agrometeorol 2000, 2(2), 103-12.

Presents monthly, seasonal and annual Erosion Index (EI) values of 32 stations in Madhya Pradesh. Iso-Erodent values for 97 stations were computed using relationship between mean annual rainfall and mean annual EI. Iso-Erodent maps for M.P. for annual and seasonal (June-September) periods are shown. Distribution curves expressing average monthly EI values as percentage of average annual values are given for 24 stations. Values of Erosion Index for return periods of 2, 5 and 10 years are indicated to assist in assessing soil loss with 10, 20 and 50% probability.

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020266   Agarwal N;Kishtawal C M;Pal P K (Atmospheric Sciences Division, Meteorology and Oceanography Group, Spa, , Ahmedabad-380 053) : Analogue prediction method for global sea surface temperature. Curr Sci 2001, 80(1), 49-55.

New analogue method for predicting the global sea surface temperature (SST) is presented. In order to predict the SST for the future week, the method searches for a similar time evolution of SST in the historical data set. Weekly analysed SST fields of Reynold and Smith have been used as the main database for the study. Algorithm shows reasonable skill in predicting global SST patterns for a lead-time up to 25 weeks.

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019045   Virendra Kumar (NO, Geological Survey of India, Western Region, 15-16, Jhalana Institutional Area, Jaipur-302 004) : Eocambrian sedimentation in Nagaur-Ganganagar evaporite basin, Rajathan. J Indian Ass Sedimentologists 1999, 18(2), 201-10.

It is an intracratonic basin and lies in the western part of the Indian shield. Marine sediments of the Marwar Supergroup comprising Jodhpur Group, subsurface Hanseran Evaporite Group (homotaxial facies variant of the Bilara Group exposed on the surface) and Nagaur Group lie on top of the Malani Igneous Suite and/or Delhi metamorphites. Tertiary and Quaternary sediments overlie the Marwar Supergroup. The Hanseran Evaporite Group (HEG) contains cyclic deposits of halite, potash minerals and alternate with anhydrite, clays, dolomite, magnesite and occasional glauconite. Seven halite cycles H1 to H7 have been identified and the cumulative thickness of halite zone ranges from zero to over 488 m while the thickness of the HEG vary from 103 to 652 m. H2 cycle is the main repository of potash minerals which include polyhalite, sylvite, sylvinite, langbeinite and carnallite. A total reserve of 2476 million tonnes of potash bearing minerals averaging 4.70 percent K has been estimated in three important sub-basins containing potash mineralisation. The depocentres of halite and the intervening zones kept changing suggesting tectonic instability during the formation of these evaporites. The thickness of HEG increases from the margins of the basin towards the centre. The deepening is caused by steep gravity faults which accommodated huge thickness of the sediments of the Marwar Supergroup.

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019044   Sreenivasa Rao A;Ramamohana Rao P;Someswara Rao N (Department of Inorganic and Analytical Chemistry, School of Chemistry, Andhra University, Visakhapatnam-530 003) : Quality of drinking water from ponds in villages of Kolleru lake region. Indian J envir Hlth 2001, 43(1), 45-52.

Kolleru Lake is the largest natural freshwater lake in the districts of East and West Godavari of Andhra Pradesh. The major population centre in the Kolleru Lake region are the 148 villages of which 50 bed villages and 98 belt villages. All bed and belt villages in lake region have atleast one drinking water pond. Drinking water ponds are filled with lake water during monsoon season and directly supplied to the public throughout the year. The water samples were collected from village drinking water ponds in a year by covering three seasons and analysed for different physico-chemical parameters to assess the quality of drinking water.

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019043   Pandita S K;Bhat G M (Department of Geology, G G M Science College, Jammu-180 001) : Vertical and lateral facies variations and their cyclicity in middle and upper Siwalik subgroups, Jammu. J Indian Ass Sedimentologists 1999, 18(2), 159-85.

Various lithofacies encountered across the Middle and Upper Siwalik Subgroup succession in the Jammu area reveal symmetrical and asymmetrical cyclic sequences. Quantification of the data on these lithofacies using the embedded Markov Chain Analysis infer distinct cyclic character of the lithofacies associations for the Middle and Upper Siwalik Subgroups. The Middle Siwalik Subgroup facies associations are characteristic of braid- and transverse bars reflecting a braided river system. Whereas, the Upper Siwalik Subgroup facies associations are characteristic of point bars reflecting a meandering river system. The shift in the drainage pattern in the area seems to have taken place gradually as is reflected by gradual change in the facies associations and increase in the frequency of Fm→Sh→Fm facies association across the Middle and Uppere Siwalik Subgroup boundary.

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019042   Mallick R K;Kataky D;Gogoi K D (NO, Prize Petroleum Company Ltd., 7th Floor, Kailash Building, 26, Kasturba Gandhi Marg, New Delhi-110 001) : Control of the depositional environments on the source and reservoir rock characteristics of the lower eocene sequence of Upper Assam basin, India. J Indian Ass Sedimentologists 1999, 18(2), 123-45.

Majority of oil and gas producing horizons are located within the middle part of the Lakadong Member (Lithounit-II) as this is the best available lithounit composed to clean, medium grained and well sorted sandstone, characterised by high porosity and permeability. As these highly productive oil and gas bearing reservoirs were deposited in a strandplain/barrier bar complex, the sandbodies occur as multiple paleoshore-parallel sand deposits which are more extensive and better developed along the direction of paleoshoreline. The kerogens are predominantly type II/III with significant input of terrestrial organic matter. As these were deposited in a nearshore marshy-lagoonal regime representing the onset of a transgressive cycle, mixing of terrestrial and marine OM has been seen with spatial variation in organic facies within the basin.

019041   Joy Chandra Singha L;Das P K (Department of Geological Sciences, Gauhati University, Guwahati-14) : Petrographic studies of the barail sandstones in and around Sonapur, Jaintia hills, Meghalaya, India. J Indian Ass Sedimentologists 1999, 18(2), 249-59.

Deals with petrographic studies of the Barail Sandstones (Oligocene) around Sonapur in Jaintia Hills district, Meghalaya. Modal composition of the detrial constituents such as mono- and poly-crystalline quartz, feldspars, micas and lithic fragments have been estimated. The quantitative mineralogical classification of the standstones have been done and the sandstones are found to be quartz-arenite. Petrographic characters further indicate a nearby detritus derivation mainly from igneous and metamorphic rocks of Shillong Plateau. It may help to conclude that these sandstones can be fitted in the continental block provenance under humid conditions of reducing environment affected by tectonic disturbances leading to the development of mature sandstones.

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019040   Gupta S C;Rathore G S;Mathur G C D (Central Chemical Laboratory, Ground Water Department, , Jodhpur) : Hydro-chemistry of Udaipur lakes. Indian J envir Hlth 2001, 43(1), 38-44.

The hydro-chemical character of lakes around Udaipur city has been studied for a period of five years. But for the lake Udaisagar, the salinity of water in lakes Badi, Fatehsagar, Pichhola and Swaroopsagar is less than 750 microSiemens per centimeter and fluctuates marginally in dry and wet period. The waters are Ca-Mg-HCO3 type and have calcite saturation. All the lakes have shown dissolved oxygen more than 8.0 mg/L despite of varying level of pollution. The lake Udaisagar is most polluted and exhibits eutrophic character along with the lakes Swaroopsagar and Pichhola.