Stable isotope systematics and geochemical signatures constraining groundwater hydraulics in the mining environment of the Korba Coalfield,Central India

The present study explores the use of stable isotopes and major ion chemistry of various water sources such as mine water, groundwater, river water, and rainwater to identify the dominant hydrogeochemical process that controls the water quality in the active opencast coal mining area of the Korba Coalfield, India. Different hydrochemical models have revealed that the study area is mostly characterized by two facies alongside a dominance by ion exchange: i.e., a slightly mineralized Ca²⁺–Mg²⁺–Cl^? and a meteorically derived Ca²⁺–HCO₃^? fresh water facies. In the isotope bivariate plot, the samples plot to the right of the LMWL and slopes observed in pre (4.94) and post-monsoon (5.85) seasons are not as steep as the LMWL (7.95) and this warrants the suggestion that meteoric water is the major source that replenishes the dynamic groundwater resource in the study area after being subjected to evaporation. The negative d-excess values (<?0) and enrichment of the δ¹⁸O ratio observed at some locations suggests a non-equilibrium process and a “mechanism of mixing”. A noteworthy fact is that isotopically river water is in tandem with the mine water samples for both seasons and testifies to a hydraulic connectivity between Hasdeo River water and mine water through a major fault. It is substantiated by mine inflows assessed by the sump test for Kusmunda and Gevra, which is two times higher than the predicted values by Darcy’s law. The wide variation in the isotopic composition is attributed to different vapor sources viz., southwest monsoon (SW) that originates in the Arabian Sea and locally driven air moisture from surface water bodies.     

Ocean Model Simulation of Southern Indian Ocean Surface Currents

The dynamic importance of the Southern Indian Ocean (SIO) lies in the fact that it connects the three major world oceans: the Pacific, Atlantic, and Indian Oceans. Modeling study has been used to understand the circulation pattern of this very important region. Simulation of SIO (10°N-60°S and 30°E-120°E) is performed with z-coordinate Ocean General Circulation Model (OGCM) viz; MOM3.0 and the results have been compared with observed ship drift data. It is found that except near coastal boundaries and in equatorial region, the simulated current reproduce most well known current pattern such as Antarctic Circumpolar Current (ACC), South Equatorial Current (SEC) etc. and bears a resemblance to that of the observed data; however the magnitude of the surface current is weaker in model than the observed data, which may be due to deficiency in the forcing field and boundary condition and problem with observed data. The annual mean wind stress curl computed over the oceanic domain reveals about ACC and its similar importance. The way in which the ocean responds to the windstress and vertically integrated transport using model output is fascinating and rather good.     

Tilted Bianchi type I cosmological models filled with disordered radiation in general relativity revisitedD

Tilted Bianchi type I cosmological models filled with disordered radiation in presence of a bulk viscous fluid and heat flow are investigated. The coefficient of bulk viscosity is assumed to be a power function of mass density. Some physical and geometric properties of the models are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evidence of internal gravity waves in the lower ionosphere

Temperature and wind measurements extending up to 95 km have been made with rocket-grenade experiments at Natal, Brasil. On many occasions the temperature and wind speed above 60 km show uniformly spaced maxima and minima. In one series of these experiments four rockets were launched during a period of 18 hr. A comparison of these spaced observations gives an indication of the propagating character of the maxima and minima and also suggests a downward phase propagation. The perturbations in the temperature and the wind speed are similar in form but they appear to differ in phase. The wavelike appearance of the temperature profiles is believed to be caused by the adiabatic heating and cooling associated with propagating gravity waves. The wavelength obtained from these observations is 10–12 km which coincides with the expected vertical wavelength of 12 km for the dominant gravity wave in this altitude range. The observed temperature variations are also in agreement with the computed values for the prevailing conditions.     

Seasonal inhomogeneity of soot particles over the central Indo-Gangetic Plains,India: Influence of meteorology

Black carbon (BC) particles play a unique and important role in earth’s climate system. BC was measured (in-situ) in the central part of the Indo-Gangetic Plains (IGP) at Varanasi, which is a highly populated and polluted region due to its topography and extensive emission sources. The annual mean BC mass concentration was 8.92 ± 7.0 µg m ^-3, with 34% of samples exceeding the average value. Seasonally, BC was highest during the post-monsoon and winter periods (approximately 18 µg m ^-3) and lower in the premonsoon/ monsoon seasons (approximately 6 µg m ^-3). The highest frequency (approximately 46%) observed for BC mass was in the interval from 5 to 10 µg m ^-3. However, during the post-monsoon season, the most common values (approximately 23%) were between 20 and 25 µg m ^-3. The nighttime concentrations of BC were approximately twice as much as the daytime values because of lower boundary layer heights at nighttime. The Ångström exponent was significantly positively correlated (0.55) with ground-level BC concentrations, indicating the impact of BC on the columnar aerosol properties. The estimated mean absorption Ångström exponent was 1.02 ± 0.08 µg m ^-3, indicating that the major source of BC was from fossil fuel combustion. Significant negative correlations between BC mass and meteorological parameters indicate a pronounced effect of atmospheric dynamics on the BC mass in this region. The highest mean BC mass concentration (18.1 ± 6.9 µg m ^-3) as a function of wind speed was under calm wind conditions (38% of the time).     

Spatio-temporal dynamics of sediment transport in lesser Himalayan catchments,India

Sediment transport from mountainous to lowland areas is considered one of the most important geomorphological processes. In the present study, variations in transported sediment loads and dissolved loads have been studied over 3 years (2008–2011) for two forested catchments located in the Lesser Himalayan region of India. Seasonal and annual suspended sediment flux was strongly influenced by amounts of rainfall and streamflow. On average, 93% of annual load was produced during the monsoon, of which 62–78% occurred in only five peak events. Sediment production by the degraded forest catchment (Bansigad) was 1.9-fold (suspended sediment load) to 5.9-fold (bedload) higher than the densely forested catchment (Arnigad). The dissolved organic matter potentially influences total dissolved solids in the stream. Heavy rainfall triggers both stream discharge and landslides, which lead to higher bedload transport. Total denudation rates for Arnigad and Bansigad were estimated at 0.68 and 1.02 mm?year^?1, respectively.     

Dating of Columbite-tantalite and Monazite from Pegmatites of the Kawadgaon–Challanpara Area,Bastar Craton,Central India

The results of geochronological studies on columbite-tantalite and monazite from the rare metal pegmatites of the Kawadgaon–Challanpara area in Bastar craton, central India are presented. Columbite-tantalite yielded U-Pb concordia upper intercept age of 1978±16 Ma (MSWD = 0.18). Radiogenic ²⁰⁷Pb*/²⁰⁶Pb* (T_7/6) ages on 4 out of 5 columbite-tantalite vary in a narrow range of 1903 to 2077 Ma and are similar to U-Pb age, whereas, one sample shows younger ²⁰⁷Pb*/²⁰⁶Pb*(T_7/6) age of 1728 Ma. Younger Pb-Pb age of 1744 ± 250 Ma (MSWD = 150) has also been indicated by these columbite-tantalite samples. Four out of five monazite samples define Pb-Pb errorchron age of 2050±370 Ma (MSWD = 165) and radiogenic ²⁰⁷Pb*/²⁰⁶Pb* (T_7/6) ages on 3 out of 5 monazites show a narrow range of 1983 to 2083 Ma. Other two samples show younger ²⁰⁷Pb*/²⁰⁶Pb*(T_7/6) ages as 1254 Ma and 1592Ma. Both monazite and columbite-tantalite indicate disturbance in Pb and U isotopic systematics as revealed by high MSWD. However, selected samples from both monazite and columbite-tantalite indicate age of their formation as c. 2000 Ma. Younger ages, i.e., 1254 to 1744 Ma are indicative of later geological disturbances. Reported age of c. 2000 Ma is comparable to Rb-Sr date of pegmatitic muscovite (1850-2330 Ma) from this area and is younger to intrusive granites of c. 2500 Ma. By analogy, therefore, it may be inferred that the age of the rare element mineralization may be ~2000 Ma old, and linked with younger granitic activity that spanned over the period from 2300 to 2100 Ma in the Bastar craton.     

Quantifying Four Decades of Changes in Land Use and Land Cover in India’s Kailash Sacred Landscape: Suggested Option for Priority Based Patch Level Future Forest Conservation

Effective quantification of land cover changes remains a challenge in Himalayan hills and mountains, and has a colossal value addition for natural resource management. Here we present a new robust method for classifying land cover vegetation at physiognomic scale along steep elevational gradients from ~?200 to ~?7000 masl in the Kailash Sacred Landscape, Western Himalaya, India along with four decades of land use and land cover changes (1976–2011) using remote sensing techniques coupled with intensive ground surveys. Results show that forest cover loss was minimum ca 7.14% of existing forest in 1976; but, however forest fragmentation is high especially in montane broad-leaved and subtropical needle leaved forests. This change largely impacted the quality of valuable tree species such as Quercus spp. Post 1976, continuous migration forced conversion of high altitude agricultural lands into grasslands and scrublands. Human settlement expansion was high especially in low altitudinal range valleys between 1000 and 2000 masl and has increased 6.76 fold since 1976, leading to high forest fragmentation in spite of reduced agriculture area in the landscape. Our physiognomic level classified land cover map will be a key for forest managers to prioritize conservation zones for protecting this unique forest land.     

Role of organic matter in uranium mineralisation in Vempalle dolostone; Cuddapah basin,India

Dolostone of Vempalle Formation near Tummalapalle hosts large uranium deposit (>100,000 tonnes with an average grade of 0.045%U₃O₈). It is a unique type of uranium deposit because carbonate formations have been considered to be among the least uraniferous of all the rocks of the Earth’s crust due to mobility of uranium in aqueous fluid in the presence of carbonate and bicarbonate ions. Vempalle dolostone hosts syn-sedimentary uranium mineralization in the form of discrete uranium phases (pitchblende and coffinite) associated with collophane, and adsorbed uranium in organic matter. The organic matter has played dual role of concentrating uranium from solution and also chemically reducing it to pitchhblende and coffinite.