The behavior of natural and anthropogenic osmium in the Hudson River-Long Island Sound estuarine system

The extent to which riverine Os is trapped in a temperate estuary was the aim of this study. The behavior of Os through the Hudson River, East River and the Long Island Sound (LIS) system is addressed using both natural Os and anthropogenically mobilized Os. The Os concentration ([Os]) and isotopic composition (¹⁸⁷Os/¹⁸⁸Os) of the Mid-Atlantic Bight as inferred from the analysis of a water sample of 31‰ salinity (S) at Vineyard Sound, MA are 46 fM and 1.070, respectively. In comparison, the Hudson River at Newburgh, NY has [Os] = 68 fM and ¹⁸⁷Os/¹⁸⁸Os = 1.265. The Os concentration of the East River at the Whitestone Bridge is 51 fM and remains essentially constant proceeding eastward in the LIS despite the increase of salinity from 20‰ towards the higher value of the Mid-Atlantic Bight. The ¹⁸⁷Os/¹⁸⁸Os ratio of water at Whitestone Bridge is 0.945 and increases eastward through the Sound to 0.979 at 7 km and then to 1.019 at 39.6 km. The behavior of Os through LIS appears to be conservative at S > 20‰. On the basis of Os concentration and isotopic composition we infer that anthropogenic Os is being added to the East River through sewers with the likely isotopic ratio of ∼0.13 and that about 24% of riverine Os must be removed at S ? 20‰. There is a net transport of about 0.4-1 mole of anthropogenic Os per year from the East River into the LIS. The residence time of Os in the ocean at present must be about 39,000 years, unless an independent source of supply of Os can be identified.     

Electrical analogy for modelling thermal regime and moisture distribution in sandy soils

The soil mass is subjected to temperature variation due to several human activities (viz. tanks storing heated fluids, buried cables and pipelines, air-conditioning ducts, disposal of nuclear and thermal power plant wastes etc.), which result in heat-induced migration of the moisture in it. Though several studies have been conducted in the past to investigate the mechanism of heat migration through the soil mass, a methodology for ‘real-time measurement of the variations in temperature, flux and moving moisture front, in tandem, with respect to space' has rarely been attempted. In this context, extensive laboratory investigations were conducted to measure real-time flux and temperature variations in the sandy soils, and the validation of results has been done by employing an equivalent electrical circuit programme, LTspice. Subsequently, a mathematical model PHITMDS (i.e. Prediction of Heat-Induced Temperature and Moisture Distribution in Soil) has been developed and its utility and efficacy, for predicting the depth-wise temperature and heat-induced moisture migration, due to evaporation, in terms of position of moving moisture front in the sandy soil has been critically discussed and demonstrated.     

Major Element, REE, and Other Trace Element Behavior in Amphibolite Weathering under Semiarid Conditions in Southern India

A body of komatiitic amphibolite, an enclave within the Archean high-grade orthogneisses in southern India, shows mild chemical weathering under semiarid conditions. Along fractures, chemical weathering has advanced (Chemical Index of Alteration &sqbl0;CIA&sqbr0;=53; CIA of fresh rock approximately 26) to the extent that secondary Mg-Fe-Al clay minerals have formed and the rock has turned brownish red, soft, and fine grained. The weathering process has resulted in the mobilization and redistribution of the so-called immobile elements Fe, Al, Ti, and REE effected by the nature of secondary mineral formation (talc vs. aluminous clay minerals) and also possibly by soil microbes. In the initial stages of secondary mineral formation, there is a small loss of Fe, Al, and REE (noticeably Eu). However, in the fracture zone as well as in the incipiently altered zone, there is significant REE enrichment, probably affected by a different precipitation mechanism. Mobilized REE may have come from a minor alteration of clinopyroxene.     

Mapping lithological variations in a river basin of West Bengal,India using electrical resistivity survey: implications for artificial recharge

Groundwater is a treasured earth’s resource and plays an important role in addressing water and environmental sustainability. However, its overexploitation and wide spatial variability within a basin and/or across regions are posing a serious challenge for groundwater sustainability. Some parts of southern West Bengal of India are problematic for groundwater occurrence despite of high rainfall in this region. Characterization of an aquifer in this area is very important for sustainable development of water supply and artificial recharge. Electrical resistivity surveys using 1-D and 2-D arrays were performed at a regular interval from Subarnarekha River at Bhasraghat (south) to Kharagpur (north) to map the lithological variations in this area. Resistivity sounding surveys were carried out at an interval of 2–3 km. Subsurface resistivity variation has been interpreted using very fast simulated annealing (VFSA) global optimization technique. The analysis of the field data indicated that the resistivity variation with depth is suitable in the southern part of the area and corresponds to clayey sand. Interpreted resistivity in the northern part of the area is relatively high and reveals impervious laterite layer. In the southern part of the area resistivity varies between 15 and 40 Ωm at a depth below 30 m. A 2-D resistivity imaging conducted at the most important location in the area is correlated well with the 1-D results. Based on the interpreted resistivity variation with depth at different locations different types of geologic units (laterite, clay, sand, etc.) are classified, and the zone of interests for aquifer has been demarcated. Study reveals that southern part of the area is better for artificial recharge than the northern part. The presence of laterite cover in the northern part of the area restricts the percolation of rainwater to recharge the aquifer at depth. To recharge the aquifer at depth in the northern part of the area, rainwater must be sent artificially at depth by puncturing laterite layers on the top. Such studies in challenging areas will help in understanding the problems and finding its solution.     

Uranium mineralisation associated with felsic volcanism at Mohar,Shivpuri district,Madhya Pradesh

Several small lensoidal bodies of felsic volcanics are exposed in a curvilinear pattern within the brecciated granitoids of Bundelkhand Gneissic Complex (BGC) at Mohar. Sub-surface data reveals extensive presence of these felsic volcanics below the sediment of Vindhyan Supergroup. It occurs like a sheet with thickness varying from 12 m to 134 m. Its lateral extent has been traced upto 4.8 km. Multiple flows of felsic magma are identified based on colour, granularity, cross cutting relations and cyclic distribution of multiple vesicular bands along the entire thickness of felsic magma. The felsic rock contains upto 13.21% K₂O. Chemical composition of these felsic volcanics varies across the column. Petrographically and chemically all these felsic volcanics are identified as rhyolite or rhyolite tuff.     

The role of fluids in the formation of talc deposits of Rema area,Kumaun Lesser Himalaya

Talc deposits of Rema area in the Kumaun Inner Lesser Himalaya are hosted within high magnesium carbonates of the Proterozoic Deoban Formation. These deposits occur as irregular patches or pockets mainly within magnesite bodies, along with impurities of magnesite, dolomite and clinochlore. Textures represent different phases of reactions between magnesite and silica to produce talc. Petrography, XRD and geochemistry reveal that the talc has primarily developed at the expense of magnesite and silica, leaving dolomite largely un-reacted. Early fluid inclusions in magnesite and dolomite associated with talc are filled with H₂O+NaCl+KCl ± MgCl₂ ± CaCl₂ fluids, which represent basin fluid system during diagenesis of carbonates. Their varied degree of re-equilibration was although not pervasive but points to increased burial, and hence requires careful interpretation. H₂O-CO₂ fluid with XCO₂ between 0.06 and 0.12 was equilibrated with talc formation. The reaction dolomite+quartz → talc was not extensive because T-X_CO2 was not favourable, and talc was developed principally after magnesite+quartz.     

Comparative study of MLT mean winds using MF radars located at 16.8°N and 8.7°N

The main aim of the paper is to describe mesosphere and lower thermosphere (MLT) wind field observed between June 2000 and May 2002 by medium frequency (MF) radars at two locations near the equatorial region and at tropical latitude. We have presented and compared observations of mean horizontal winds in the mesosphere and lower thermosphere (MLT) region over Kolhapur (16.8°N, 74.2°E) and Tirunelveli (8.7°N, 77.8°E). Our analysis reveals annual oscillation in the zonal wind and semi-annual oscillation in the meridional wind over Kolhapur. On the other hand, results over Tirunelveli reveal semi-annual oscillation (SAO) in the zonal wind and annual oscillation in the meridional wind. Also we have observed enhanced magnitude of wind speed in spring equinox period of 2002 exhibiting the signatures of the quasi-biennial oscillation (QBO) over Tirunelveli.     

Environmental impact assessment in the Moradabad industrial area (rivers Ramganga-Ganga interfluve), Ganga Plain,India

Sediment samples collected in the Moradabad area, lying in the interfluve of the Ganga and Ramganga Rivers, were analysed for heavy metals, after studying the geomorphology of the area. Geomorphologically, the area can be divided into three terraces - the T₀, T₁ and T₂ surfaces. The rivers on these three surfaces show varying amounts of pollution depending upon the input from industries and urban settlements. The Ramganga River on the T₀ surface shows the highest amount of pollution. However, the pollution levels in all these rivers show a downstream dilution effect. The characteristic feature of the vast interfluve area (T₂ surface) is the presence of several, independent basins which are closed and rarely interact with each other or with any river. The sediments are redistributed and redeposited within the basin itself, and thus these basins serve as sinks. The sediments of one such basin in the study area show significant concentrations of arsenic, chromium, copper, nickel, lead, zinc and organic carbon. The concentrations of heavy metals in such a basin will show exponential increases with time, because there is no activity to funnel out the sediments and dilute the effect of pollution. This increase will pose more threats, as ultimately it will make its way laterally and vertically through the sediments, thereby polluting groundwater.     

Evaluation of seismic events detection algorithms

Identification of seismic events from continuously recorded seismic data in real-time through a Digital Seismic Data Recording system is a difficult task. Despite the vast amount of research in this field, the signal processing and event parameters discrimination algorithms have not yet fully come of age. Presently, we have a wide spectrum of trigger algorithms, ranging from a very simple amplitude threshold type to the sophisticated ones based on pattern recognition approaches. Some of the other approaches use adaptive technique and neural network methods. Researchers are continuously making efforts for the development of algorithms using various techniques, which produce minimum false trigger. Some approaches have been reported which are accurate for detecting first phase of events and take minimum possible computational time. In this paper several approaches for detecting event signals in background noise are presented and their precision evaluation is discussed.     

Nutrient chemistry and salinity mapping of the Delhi aquifer,India: source identification perspective

Present study is an effort to distinguish between the contributions of natural weathering and anthropogenic inputs towards high salinity and nutrient concentrations in the groundwater of National Capital Territory (NCT) Delhi, India. Apart from the source identification, the aquifer of entire territory has been characterized and mapped on the basis of salinity in space and water suitability with its depth. Major element chemistry, conventional graphical plots and specific ionic ratio of Na⁺/Cl⁻, SO₄ ²⁻/Cl⁻, Mg²⁺/Ca²⁺ and Ca²⁺/(HCO₃ ⁻ + SO₄ ²⁻) are conjointly used to distinguish different salinization sources. Results suggest that leaching from the various unlined landfill sites and drains is the prime cause of NO₃ ⁻ contamination while study area is highly affected with inland salinity which is geogenic in origin. The seasonal water level fluctuation and rising water level increases nutrients concentration in groundwater. Mixing with old saline sub-surface groundwater and dissolution of surface salts in the salt affected soil areas were identified as the principle processes controlling groundwater salinity through comparison of ionic ratio. Only minor increase of salinity is the result of evaporation effect and pollution inflows. The entire territory has characterized into four groups as fresh, freshening, near freshening and saline with respect to salinity in groundwater. The salinity mapping suggests that in general, for drinking needs, groundwater in the fresh, freshening and near freshening zone is suitable up to a depth of 45, 20 and 12 m, respectively, while the saline zones are unsuitable for any domestic use. In the consideration of increasing demand of drinking water in the area; present study is vital and recommends further isotopic investigations and highlights the need of immediate management action for landfill sites and unlined drains.