Interspecific association of heavy minerals in late Paleozoic Gondwana sandstones of Singrauli sub-basin,central India: Implications for provenance

Heavy mineral analysis of the late Paleozoic Barakar and Raniganj sandstones from the Singrauli Gondwana sub-basin shows relative abundance of garnet, epidote, zircon, tourmaline and muscovite in the Raniganj Sandstone and epidote, garnet, rutile and tourmaline in the Barakar sandstones. Stratigraphically, the heavy mineral crops donot exhibit marked variation in their relative abundance, though garnet, epidote and muscovite form the bulk of the heavy minerals. Significant interspecific association among heavy minerals and provenance of the Barakar and Raniganj sandstones are evaluated by using σ-M multivariate model. Quantitative result suggests that the Barakar Sandstone are characterized by the basic pair match significantly more than expected due to chance alone (p value <<0.05) are garnet-tourmaline and epidote-rutile, whereas, the succeeding Raniganj sandstone are characterized by zircon-rutile and epidote-garnet. These basic pairs may be regarded as interspecific association among the heavy minerals. The basic pairs deduced from heavy mineral suites suggest that the source rocks of late Paleozoic Barakar and Raniganj sandstones have been principally derived from the acid plutonic rocks and low to high grade metasediments lying to the south and southeast of the Singrauli Gondwana sub-basin.     

The impact of intensive groundwater abstraction on recharge to a shallow regional aquifer system: evidence from Bangladesh

Quantitative evaluations of the impact of groundwater abstraction on recharge are rare. Over a period (1975??007) during which groundwater abstraction increased dramatically in the Bengal Basin, changes in net groundwater recharge in Bangladesh are assessed using the water-table fluctuation method. Mean annual groundwater recharge is shown to be higher (300??00?mm) in northwestern and southwestern areas of Bangladesh than in southeastern and northeastern regions (<100?mm) where rainfall and potential recharge are greater. Net recharge in many parts of Bangladesh has increased substantially (5??5?mm/year between 1985 and 2007) in response to increased groundwater abstraction for irrigation and urban water supplies. In contrast, net recharge has slightly decreased (??.5 to ???mm/year) in areas where groundwater-fed irrigation is low (<30% of total irrigation) and where abstraction has either decreased or remained unchanged over the period of 1985??007. The spatio-temporal dynamics of recharge in Bangladesh illustrate the fundamental flaw in definitions of “safe yield??based on recharge estimated under static (non-pumping) conditions and reveal the areas where (1) further groundwater abstraction may increase actual recharge to the shallow aquifer, and (2) current groundwater abstraction for irrigation and urban water supplies is unsustainable.     

Re-appraisal of earthquake catalog in the Pamir―Hindu Kush region,emphasizing the early and modern instrumental earthquake events

Journal of Seismology - The Pamir-Hindu Kush region is seismically the most dynamic and active zone that went through many devastating earthquakes. While much research is ongoing to produce seismic...     

Seasonal variations in the isotopic composition of leaf and stem water from an arid region of Southeast Asia

Abstract

Stable isotopes are powerful research tools in environmental sciences and their use in ecosystem research is increasing. Stable isotope measurements allow the study of evapotranspiration fluxes, soil evaporation and leaf transpiration phenomena. Soil water and leaf water are the sources of the evapotranspiration that transfers large quantities of water from land to the atmosphere; as a result the isotopic composition of water left in the leaves is modified towards enrichment. Evaporation also changes the isotopic composition of water bodies creating a natural isotopic signal. The isotopic identity of soil water affects the oxygen isotopic signature of leaf and stem water. In this paper we present the isotopic data of bulk leaf water, showing the enrichment in isotopic value of oxygen due to evapotranspiration from leaves in conjunction with the isotopic signal of rainwater and other environmental factors such as humidity and temperature. Results suggest that the variation in the values of δ¹⁸O of Eucalyptus citriodora, Dalbergia sissoo, Melia azedarach and Pinus roxburghii is due to the seasonal changes in the δ¹⁸O of the source water for plants, i. e. rain. It is further observed that leaf water δ¹⁸O values are depleted during the months of July, August and September. This occurs due to the following reasons: (a) the sampling areas receive about 50% of the average annual rain during these months, and (b) rainfalls during these months are isotopically depleted compared with winter rains.

Citation Butt, S., Ali, M., Fazil, M. & Latif, Z. (2010) Seasonal variations in the isotopic composition of leaf and stem water from an arid region of Southeast Asia. Hydrol. Sci. J. 55(5), 844–848.     

Sedimentological synthesis of permian fluviatile sediments of East Bokaro basin,Bihar, India

The early Permian Karharbari and Barakar formations of East Bokaro basin comprise the following lithofacies:Lithofacies A, consisting of monomictic cobble- and pebble-conglomerate including pebbly sandstone, with faint crossbeds; deposited mainly by high-velocity aqueous currents as channel-lag deposit or longitudinal bars.Lithofacies B, coarse to medium sandstone, profusely crossbedded; interpreted as channel facies formed by downcurrent migration of sand bars in low-sinuosity streams.Lithofacies C, mainly fine sandstone with interbedded siltstone, characterised by small-scale ripple-lamination; formed in a low-energy environment such as swale-fill and/or overbank deposits.Lithofacies D, including carbonaceous shale and coal, with lack-of-current structures, indicating quiet-water deposition; interpreted as backswamp and lacustrine deposits.The overall context of the Karharbari and Barakar assemblage with relative abundance of pebbly coarse sandstone in the former and fine clastics in the latter, the presence of fining-upward cycles, widespread development of tabular and trough crossbedding and sample to sample variation of foreset azimuths, all suggest a generally alluvial environment. Analysis of crossbedding dip azimuth and dimensional fabric suggest that the sediment milieu in either case consisted of streams flowing persistently from the south-southeast to north-northwest direction. It is inferred that the unidirectional system of streams flowing across the East Bokaro basin changes systematically in channel sinuosity through time.     

Palaeoclimate,stratigraphy and prehistory in north and west Rajasthan

Quaternary formations in western Rajasthan are of fluvial, locustrinal and aeolian origins. Fossil gravel ridge of Jayal in Nagaur District is one of the earliest quaternary formations so far recorded in the region. A rich lower palaeolithic habitation-cum-workshop site has been discovered in association with the gravel ridge. Multiple evidence for climatic change in the area during the quaternary period is discussed.     

Evaluation of aquifer environment under Hazaribagh leather processing zone of Dhaka city

Hazaribagh is a densely populated area of Dhaka city where about 185 leather processing industries have been operating and discharging solid and liquid wastes directly to the low-lying areas, river and natural canals without proper treatment. The area is covered by alluvial deposits of Holocene age and is underlain by Pleistocene Madhupur clay. The Dupi Tila Formation of Mio-Pliocene age underlain by this yellowish gray to brick red clay bed serves as the main water-bearing aquifer of Dhaka city. To assess the environmental degradation as well as the groundwater environment, major anions, cations and heavy metals of water samples, heavy metals and organic carbon content of sediment samples were analyzed in this study. Analyses of tannery effluent detect high concentration of Na⁺, Mg²⁺, Cl⁻ and SO ₄ ²⁻ followed by Ca²⁺, NH ₄ ⁺ and K⁺ with remarkable contents of some trace elements, mainly Cr, Fe, Mn, S, Ni and Pb. Higher accumulations of Cr, Al and Fe are observed in topsoil samples with significant amounts of Mn, Zn, Ni and Cu. Concentrations of ions and all the investigated trace elements of sampled groundwater were within the maximum allowable limit for drinking water of the Department of Environment, Bangladesh (DoE), and World Health Organization (WHO). However, excessive concentrations of Cr, Pb, etc., have already been reported in the shallow groundwater (10–20 m) of the area. Due to excessive withdrawal the vulnerability of groundwater contamination in deeper parts cannot be avoided for the future.     

A study of groundwater irrigation water quality in south-central Bangladesh: a geo-statistical model approach using GIS and multivariate statistics

Southern Bangladesh’s irrigation and drinking water is threatened by saline intrusion. This study aimed to establish an irrigation water quality index (IWQI) using a geostatistical model and multivariate indices in Gopalganj district, south-central Bangladesh. Groundwater samples were taken randomly (different depths) in two seasons (wet-monsoon and dry-monsoon). Hydrochemical analysis revealed groundwater in this area was neutral to slightly alkaline and dominating cations were Na⁺, Mg²⁺, and Ca²⁺ along with major anions Cl^? and HCO₃ ^?. Principal component analysis and Gibbs plot helped explain possible geochemical processes in the aquifer. The irrigation water evaluation indices showed: electrical conductivity (EC) >750 µS/cm, moderate to extreme saline; sodium adsorption ratio (SAR), excellent to doubtful; total hardness (TH), moderate to very hard; residual sodium bicarbonate, safe to marginal; Kelly’s ratio >1; soluble sodium percentage (SSP), fair to poor; magnesium adsorption ratio, harmful for soil; and IWQI, moderate to suitable. In addition, the best fitted semivariogram for IWQI, EC, SAR, SSP, and TH confirmed that most parameters had strong spatial dependence and others had moderate to weak spatial dependence. This variation might be due to the different origin/sources of major contributing ions along with the influence of variable river flow and small anthropogenic contributions. Furthermore, the spatial distribution maps for IWQI, EC, SSP, and TH during both seasons confirmed the influence of salinity from the sea; low-flow in the major river system was the driving factor of overall groundwater quality in the study area. These findings may contribute to management of irrigation and/or drinking water in regions with similar groundwater problems.