Coastal processes of Central Tamil Nadu, India: clues from grain size studies

The sediments of the beaches along the central coast of Tamil Nadu from Pondicherry to Vedaranyam were studied for their textural variation. 108 sediment samples collected from the low-, mid-, and high-tidal zones, as well as the berms and dunes of different beach morpho-units were analysed. The study area was divided into three sectors (northern, central and southern) on the basis of prevailing energy conditions and oceanographic parameters. The poorly sorted, negatively skewed, coarser sediments of the northern sector are indicative of denudational processes taking place there. Medium-to-fine, moderately-to-well sorted, positive-symmetrically skewed sediments dominate the central sector, probably as a result of the influence of palaeo-sediments deposited by rivers from inland as well as by waves and currents from offshore. Fine, poorly sorted, positive-symmetrically skewed sediments dominate the southern sector, highlighting depositional processes. Linear Discriminant Function Analysis (LDF) of the samples indicates a shallow marine environment origin for all the three sectors. These results show that reworked sediments, submerged during the Holocene marine transgression, are being deposited on present-day beaches by waves, currents and rivers in the study area

Distribution of phosphorus and organic carbon in the nearshore sediments of Goa

84-89Samples collected from sediment water interface from the inner shelf region of Goa coast are examined for their phosphorus and organic carbon, which indicate the geochemical environment under which the present day deposits are laid down. As the colour, texture and lithology of the sediment varies considerably from north to south, so also the degree of concentration of organic carbon and phosphorus varies suggesting that they are in direct relationship with each other. Organic carbon is low (0.85%) at 5-10 m depth, but it is over 5% at 10-20 m depth with a few patchy areas of high and low values beyond and up to 50 m depth. Similarly, phosphorus is low (0-0.1%) at 0-10 m depth, but it is high (0.4-0.98%) at the mouths of the rivers. Both organic carbon and phosphorus are delineated into 2 zones (of high and low concentrations) along Marmugao Head (up to Tiracol river transect). Though organic carbon and phosphorus are related with each other, their variability fluctuates in terms of pre and postmonsoon periods in the region. The organic carbon has a proportional relationship with the clay fraction of the sediment. Higher concentration of phosphorus noticed in postmonsoon periods is considered to be due to a large supply of the terrigenous apatite brought in by the rivers; this is, in addition to contributing factors like organic productivity, upwelling and pollutants in the region. Since the sediment in the region falls within the zone of 0.5-5.0% P2O5, it can be considered to be 'phosphate bearing'

Wave refraction pattern and its role in the redistribution of sediment along southern coast of Tamilnadu, India

173-178Wave convergent zones are identified at Manappad, Tiruchendur, Tamirabarani river mouth, Tuticorin, Kallar, Vaippar, Vembar and Valinokkam beaches. Wave divergent zones especially from Mandapam to Chinna Ervadi are marked by strong progradational activities in the prevailing low energy environment. Textural parameters of the sediments show a characteristic variation in mean size and sorting in the zones of wave divergence and convergence. At wave divergent zones, sediments are of fine, moderately sorted, negatively skewed and mesokurtic in nature. Coarse sediments of well sorted, negatively skewed and mesokurtic nature are the characteristic of sediments in convergent zones

Landslide Hazard and Risk Mapping Using the Weighted Linear Combination Model Applied to the Tevankarai Stream Watershed, Kodaikkanal, India

<div><p>ABSTRACT</p><p>Natural hazards like landslides, earthquakes, and floods are a major deterrent to the development of mountain regions of the world. Recently, there has been a rise in the number of landslides in Western Ghats, India. Several factors cause landslides and they depend on the local geo-environmental set-up of the region. This study attempts to map the spatial distribution of landslide hazard and analyze the risk for a typical hill town, Kodaikkanal in the Western Ghats, India, facing rapid urbanization and infra-structure growth, using a weighted linear combination model in a geographic information system platform. Landslides in the region are triggered by rainfall and it is fairly uniform throughout the area. Hence, the susceptibility map is used as the hazard map. Validation of the weighted linear combination model using landslide hazard index shows that landslide density increases with the hazard class. The risk assessment matrix (RAM) is used to evaluate risk based on the land use and landslide hazard category. The land use map is reclassified by assigning damage potential for each land use feature. The risk map is classified into low, moderate, and high risk categories. Suitable control measures are suggested for various risk categories.</p></div

Polyphenols from the roots of <i style="">Plumbago rosea</i>

386-389 Two flavonoids and two carboxylic acids have been isolated from the ethyl acetate extract of the roots. The structures of these compounds have been established as myricetin-3,3′,5′,7-tetra methyl ether 1, ampelopsin-3′,4′,5′,7-tetramethyl ether 2, plumbagic acid 3 and roseanoic acid 4 on the basis of UV, IR, 1H and 13 C NMR and mass spectrum studies. The two carboxylic acids 3 and 4 are reported here for the first time. Compounds 1 and 2 are the first report from the genus plumbago. </smarttagtype

Morphometric analysis of sub-watershed in parts of Western Ghats, South India using ASTER DEM

Morphometric analysis is a key to understand the hydrological process and hence is a prerequisite for the assessment of hydrological characteristics of surface water basin. Morphometric analysis to determine the drainage characteristics of Palar sub-watershed, a part of Shanmukha watershed in the Amaravati sub-catchment is done using Advanced Space-borne Thermal Emission and Reflection Global Digital Elevation Model (ASTER GDEM) data, and is supplemented with topographical maps in geographical information systems platform. This study uses ASTER GDEM data to extract morphometric features of a mountain stream at micro-watershed level. The sub-watershed is divided into six micro-watersheds. The sub-watershed includes a sixth-order stream. Lower stream orders, in particular first-order streams, dominate the sub-watershed. Development of stream segments is controlled by slope and local relief. Drainage pattern of the sub-watershed and micro-watersheds is dendritic in general. The mean bifurcation ratio of the sub-watershed is 3.69 but its variation between the various stream orders suggests structural control in the development of stream network. The shape factors reveal the elongation of the sub-watershed and micro-watersheds.The relief ratio reveals the high discharge capability of the sub-watershed and meagre groundwater potential. This study is a useful tool for planning strategies in control of soil erosion and soil conservation

Psycho-emotional stress -A cause of coronary artery disease

ABSTRACT Psycho-emotional stress is one of the risk factors for metabolic syndrome and related diseases. Hence, this study has designed to the effect of psycho-emotional stress in the form of immobilization stress in rabbits. In this study, we used 12 male New Zealand White rabbits (2.5 -3 kg body weight), Six animals for hanging fixation and another six as control. Blood samples were taken before hanging (0 minute) and at 60, 120 minutes. Serum was separated and used for the estimation of various biochemical parameters. Hanging fixation appears to produce significant increase in malondialdehyde and lipid profile levels. The non-enzymatic antioxidants like reduced glutathione, vitamin E and ceruloplasmin were found to be decrease and the level of enzymatic antioxidant like glutathione peroxidase was increased significantly. The results reveal that the hanging fixation may develop coronary artery disease. This is the area, which should be evaluated further by carrying out chronic studies in hung stress and by histopathological studies