Clay mineralogy of the ocean sediments from the Wilkes Land margin,east Antarctica: implications on the paleoclimate,provenance and sediment dispersal pattern

Core U1359 collected from the continental rise off Wilkes Land, east Antarctica, is analyzed for the clay mineralogy and carbon content. The temporal variation of the clay mineralogical data shows a dominance of illite with chlorite, smectite and kaolinite in decreasing concentration. Clay mineral illite is negatively correlated with smectite which shows enrichment during 6.2–6.8, 5.5–5.8, 4.5 and 2.5 Ma. The mineralogical analyses on the silt size fraction (2–53 μm) of some selected samples were also carried out. The combined result of both the size fractions shows the presence of chlorite and illite in both size fractions, smectite and kaolinite only in clay size fraction (<2 μm) and similarity in the crystallinity and chemistry of illite in both fractions. Similar nature of illite in both fractions suggests negligible role of sorting probably due to the deposition from the waxing ice sheet. During times of ice growth, nearby cratonic east Antarctica shield provided biotite-rich sediments to the depositional site. On the other hand, the presence of smectite, only in the clay size fraction, suggests the effective role of sorting probably due to the deposition from distal source in ice retreat condition. During times of ice retreat, smectite-rich sediment derived from Ross Orogen is transported to the core site through surface or bottom water currents. Poor crystallinity of illite due to degradation further corroborates the ice retreat condition. The ice sheet proximal sediments of U1359 show that in the eastern part of Wilkes Land, the ‘warming’ was initiated during late Miocene.     

Stable isotopic composition of precipitation in the River Bhagirathi Basin and identification of source vapour

River Ganges one of important rivers in the northern part of India receives water from two of its tributaries, Alaknanda and Bhagirathi. In this present study, we have tried to characterise the precipitation in the Bhagirathi River Basin. The study shows that isotopic composition of precipitation shows depleted nature during monsoon period due to moisture source from the oceanic region and from African region of Indian Ocean and enriched isotopic composition during non-monsoon period due to moisture source from westerlies and local evaporation. The study also shows that temperature and amount show expected positive and negative relationship with individual locations. A positive relationship is exhibited by amount for the entire region due to depleted isotopic composition with increase in altitude. The altitude effect shows that there is a depletion of up to ?0.24 to ?0.29 ‰ of isotopic composition with an increase in 100 m of elevation.     

Factors influencing the high fluoride concentration in groundwater of Vellore District,South India

Most of the arid and semi-arid zones of the Indian subcontinent experience serious health problems due to high concentration of fluoride in drinking water. The Vellore District of Tamil Nadu suffers from high concentration of fluoride in water. However, most of the past studies in this region focused on tannery-related pollution and not on fluoride contamination. The present study attempts to identify the factors influencing the origin and spatial distribution of fluoride in the district. From the observed hydrochemical results of 68 well samples in the context of water level, well depth and hydrochemical parameters, F^? concentration showed increasing trend in the presence of Na⁺ and HCO₃ ^?. This is due to the alkaline nature of groundwater that favors the dissolution of F^?-rich minerals. The occurrence of high fluoride in Na–HCO₃ type of water confirmed this hypothesis. However, Ca²⁺ showed an insignificant correlation with F^?. The high Na/Ca ratio (>1) in 73 % of the samples and the result of Na/Na+Cl plot suggest the occurrence of cation exchange in the study area. The major source of F^? was identified as products of the weathering and the dissolution of fluorites, amphiboles and micas present in the geological formations in the study area. The positive relationship between NO₃ ^? and F^? in few wells located in agricultural fields suggest possible source of F^? from the application of fertilizers. More than 25 % of the samples had higher values of fluoride than the permissible limit of drinking water according to Indian standards. Spatial distribution of fluoride showed a higher concentration in the southwest part of the study area, namely, Thirupathur and Vaniyambadi. This study shows that contamination was high in certain parts of Vellore District and the quality of water must be maintained by resorting to appropriate treatment and management strategies.     

Ionospheric disturbances with the time of occurrence, magnitude and location of the earthquake (M6.5) near the Indian subcontinent

The present study purports the analysis of total electron content (TEC, which is one of the major ionosphere anomalies during the earthquake), sea surface temperature (SST) and outgoing long-wave radiation (OLR) during the earthquake event recorded on 10 March 2013 (M = 6.5). Global assimilative ionosphere modelled output TEC values have been used for this present study; the clear signature of TEC during the recorded earthquake has been noticed (i.e. increase in TEC 60–70 TECU during the event). The correlation between the magnitude and location of earthquake with TEC is around 0.9, and the least correlation between SST and OLR is due to concerned atmospheric effects; we tried to study the variations of SST and OLR prior during and after the event from Kalpana satellite image products archived by IMD.     

Earthquake damage identification: a case study using soft classification approach

The October 8, 2005, Kashmir earthquake (M _w 7.6) affected the rough mountainous regions of India and Pakistan with poor accessibility, and thus, no proper comprehensive ground survey was possible. However, due to the ability of remote sensing technology to acquire spectral measurements of damaged areas at various spatial and temporal scales, extraction of damaged areas can be carried out quickly and with great reliability. The fuzzy-based classifiers [Possibilistic c-Means (PCM), noise cluster (NC), and NC with entropy (NCE)] were applied to identify 2005 Kashmir earthquake, induced landslides, as well as built-up damage (BD) areas, as soft computing approaches using supervised classification. Results indicate that for the identification of landslides and BD areas, NCE classifier generated the best outputs, while for the identification of built-up undamaged areas, NC classifier generated the best output. Further, it was found that the proposed Class Based Sensor Independent (CBSI) technique can improve spectral information of specific class for better identification.     

Bootstrap aggregating approach to short-term load forecasting using meteorological parameters for demand side management in the North-Eastern Region of India

Theoretical and Applied Climatology - Electricity is an essential commodity that must be generated in response to demand. Hydroelectric power plants, fossil fuels, nuclear energy, and wind energy...     

Chemometric analysis to infer hydro-geochemical processes in a semi-arid region of India

Groundwater exploitation in Punjab has increased in last few decades due to rapid increase in industrialization, population, crop production, and erratic monsoon. In the present study, groundwater samples from 29 locations were collected and analyzed for almost all major anions, cations, and heavy metals. The analyzed parameters formed the attribute database for statistical analysis. The study approach included multivariate statistical analysis of hydro-chemical data to identify hydro-geochemical processes occurring in the study area and its relation to groundwater quality. The principal component analysis produced seven significant factors that explained nearly 77 % of the cumulative variance. Factor 1 explained nearly 22.05 % of dataset with variables loading indicating mineralization of geological component of soil. Trilinear plot and other graphical methods were also used to identify chemical facies of groundwater and geochemical processes occurring in study area. The water type in the study area is of Na/K–Mg–HCO₃ type. It was found that the general hydro-geochemistry of groundwater in the study area dominated is by the processes such as carbonate/silicate weathering, ion-exchange, and dissolution. Thus, statistical methods can prove to be an effective tool understanding hydro-geochemistry of a region along with conventional graphical methods.     

Observations of intensity oscillations in a prominence-like cool loop system as observed by SDO/AIA: evidence of multiple harmonics of fast magnetoacoustic waves

Using SDO/AIA 304 Å channel, we study the evolution of weak intensity oscillations in a prominence like cool loop system observed at North-West limb on 7 March 2011. We use the standard wavelet tool to produce statistically significant power spectra of AIA 304 Å normalized fluxes derived respectively near the apex and footpoint of the fluxtube. We find periodicities of ≈667 s and ≈305 s respectively near apex and above footpoint with significance level >98 %. Observed statistically significant periodicities in the tube of projected length ≈170 Mm and width ≈10 Mm, are interpreted as most likely signature of evolution of various harmonics of tubular fast magnetoacoustic waves. Sausage modes are unlikely though they are compressive as they need bulky and highly denser loop system for their evolution for sustaining such large periods. We interpret the observed periodicities as multiple harmonics (fundamental and first) of fast magnetoacoustic kink waves that can generate some weak density perturbations (thus intensity oscillations) in the tube and can be observed pertaining to periodic variation in plasma column depth as tube is oblique in projection with respect to line-of-sight. The period ratio P ₁/P ₂=2.18 is observed in the fluxtube, which is the signature of the magnetic field divergence of the cool loop system. We estimate tube expansion factor as 1.27 which is typical of EUV bipolar loops in the solar atmosphere. We estimate the lower bound average magnetic fields ranging from ≈9 to 90 Gauss depending upon typical densities as 10⁹–10¹¹ cm^?3 in the observed prominence-like cool loop system. We also observe the first signature of lowering fundamental mode period by a factor 0.85 due to cooling of this loop system.