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1.
Surface complexation modeling of Cu(II) adsorption on mixtures of hydrous ferric oxide and kaolinite
Tracy J Lund Carla M Koretsky Christopher J Landry Melinda S Schaller Soumya Das 《Geochemical transactions》2008,9(1):9
Background
The application of surface complexation models (SCMs) to natural sediments and soils is hindered by a lack of consistent models and data for large suites of metals and minerals of interest. Furthermore, the surface complexation approach has mostly been developed and tested for single solid systems. Few studies have extended the SCM approach to systems containing multiple solids. 相似文献2.
The Hassi R’Mel field, which is the largest gas field in Algeria, produces principally gas condensate. The produced gas and oil comes from four reservoirs of Triassic age (reservoir A, reservoir B, reservoir C, and the Lower Series). All the previous studies in this field focused only on the upper reservoirs (A, B, and C), which have shown an excellent petrophysical properties. However, due to the presence of shale facies as well as volcanic intrusions, the Lower Series reservoir has been less explored. Thus, our study is mainly focused on this Lower Series in order to find the best sandy levels. The aim of this paper was to determine the facies types in the area, their distribution in the southern area of the Hassi R’Mel gas field, and their depositional environment. The Triassic rocks in this field are divided into four formations. From the youngest to oldest, these are S4, Lower Shale, Horizon A, and the Lower Series. The Lower Series formation can be further divided into three members (shaly sandstone, andesite, and lower shale). The shaly sandstone member within the Lower Series is composed of four units that are present all over the study area with an important pinch-out toward the northern part. The depositional environment within the defined units is a braided fluvial system in the southern part that evolves into a meandering fluvial system toward the north. Thus, the study area is considered to be a transitional zone between two depositional systems. 相似文献
3.
Spatio‐temporal prediction and forecasting of land surface temperature (LST) are relevant. However, several factors limit their usage, such as missing pixels, line drops, and cloud cover in satellite images. Being measured close to the Earth's surface, LST is mainly influenced by the land use/land cover (LULC) distribution of the terrain. This article presents a spatio‐temporal interpolation method which semantically models LULC information for the analysis of LST. The proposed spatio‐temporal semantic kriging (ST‐SemK) approach is presented in two variants: non‐separable ST‐SemK (ST‐SemKNSep) and separable ST‐SemK (ST‐SemKSep). Empirical studies have been carried out with derived Landsat 7 ETM+ satellite images of LST for two spatial regions: Kolkata, India and Dallas, Texas, U.S. It has been observed that semantically enhanced spatio‐temporal modeling by ST‐SemK yields more accurate prediction results than spatio‐temporal ordinary kriging and other existing methods. 相似文献
4.
B. Siva Soumya M. Sekhar J. Riotte Amlan Banerjee Jean-Jacques Braun 《Environmental Earth Sciences》2013,69(7):2311-2335
Hydrogeological and climatic effect on chemical behavior of groundwater along a climatic gradient is studied along a river basin. ‘Semi-arid’ (500–800 mm of mean annual rainfall), ‘sub-humid’ (800–1,200 mm/year) and ‘humid’ (1,200–1,500 mm/year) are the climatic zones chosen along the granito-gneissic plains of Kabini basin in South India for the present analysis. Data on groundwater chemistry is initially checked for its quality using NICB ratio (<±5 %), EC versus TZ+ (~0.85 correlation), EC versus TDS and EC versus TH analysis. Groundwater in the three climatic zones is ‘hard’ to ‘very hard’ in terms of Ca–Mg hardness. Polluted wells are identified (>40 % of pollution) and eliminated for the characterization. Piper’s diagram with mean concentrations indicates the evolution of CaNaHCO3 (semi-arid) from CaHCO3 (humid zone) along the climatic gradient. Carbonates dominate other anions and strong acids exceeded weak acids in the region. Mule Hole SEW, an experimental watershed in sub-humid zone, is characterized initially using hydrogeochemistry and is observed to be a replica of entire sub-humid zone (with 25 wells). Extension of the studies for the entire basin (120 wells) showed a chemical gradient along the climatic gradient with sub-humid zone bridging semi-arid and humid zones. Ca/Na molar ratio varies by more than 100 times from semi-arid to humid zones. Semi-arid zone is more silicaceous than sub-humid while humid zone is more carbonaceous (Ca/Cl ~14). Along the climatic gradient, groundwater is undersaturated (humid), saturated (sub-humid) and slightly supersaturated (semi-arid) with calcite and dolomite. Concentration–depth profiles are in support of the geological stratification i.e., ~18 m of saprolite and ~25 m of fracture rock with parent gneiss beneath. All the wells are classified into four groups based on groundwater fluctuations and further into ‘deep’ and ‘shallow’ based on the depth to groundwater. Higher the fluctuations, larger is its impact on groundwater chemistry. Actual seasonal patterns are identified using ‘recharge–discharge’ concept based on rainfall intensity instead of traditional monsoon–non-monsoon concept. Non-pumped wells have low Na/Cl and Ca/Cl ratios in recharge period than in discharge period (Dilution). Few other wells, which are subjected to pumping, still exhibit dilution chemistry though water level fluctuations are high due to annual recharge. Other wells which do not receive sufficient rainfall and are constantly pumped showed high concentrations in recharge period rather than in discharge period (Anti-dilution). In summary, recharge–discharge concept demarcates the pumped wells from natural deep wells thus, characterizing the basin. 相似文献
5.
Soumya Mazumdar Ludovico Pinzari Nasser Bagheri Paul Konings Federico Girosi Ian McRae 《Transactions in GIS》2017,21(6):1379-1390
Primary Care is fundamental to a well‐functioning health system. Various geographical small areas including specialized geographies such as Primary Care Service Areas (PCSAs) are used to measure primary care relevant outcomes and services, or to target interventions. PCSAs are small areas, the majority of patients resident in which obtain their primary care services from within the geography. The extent of this self‐sufficiency of use is measured by the Localization Index (LI). PCSAs have been built in the US, Australia and Switzerland using an allocation algorithm, which, while simple and easy to implement, may require the use of various ad‐hoc parameters. In this article we propose an optimization based approach to creating PCSAs, ‐ an approach which has previously been used to generate labour flow regions in Ireland. The approach is data driven, thus requiring a minimal number of ad‐hoc parameters. We compared the resulting PCSAs (or `rPCSAs') with PCSAs generated using the traditional allocation algorithm. We found that rPCSAs were generally larger, offered greater LIs and reflected patient travel patterns better than traditional PCSAs. Accounting for the larger size of rPCSAs showed that rPCSAs offered better LIs than similar sized traditional PCSAs. 相似文献
6.
We perform a realistic evaluation of the potential of IceCube, a kilometer-scale neutrino detector under construction at the South Pole, to detect neutrinos in the direction of the potential accelerators of the Galactic cosmic rays. We take fully account of the fact that the measurement of the energy of the secondary muons at the detector can be used to further discriminate between the signal and the background of atmospheric neutrinos. A PeVatron is defined as the accelerator of cosmic rays with energies of several PeV, the knee in the spectrum; it has a hard energy spectrum and produces secondary photons of hundreds of GeV on the interstellar medium. Assuming that the Milagro sources are PeVatrons, an IceCube analysis combining the information from the different sources can reveal them as such at the 3σ level in one year and at the 5σ level in three years. We discuss the dependence of these expectations on the considerable ambiguities associated with the source spectra. 相似文献
7.
Prasad Amrita Roy Soumya Ghosh Koushik Panja Subhash Chandra Patra Sankar Narayan 《Solar System Research》2021,55(2):169-182
Solar System Research - In the current investigation we have studied the distribution as well as the asymmetry of solar X-ray flares during the period 1976–2017 which corresponds to solar... 相似文献
8.
Soumya Benayad Young-Soo Park Rabah Chaouchi Naima Kherfi 《Arabian Journal of Geosciences》2014,7(4):1541-1557
Petrographic and geochemical analysis of the Hamra Quartzite reservoir in the southern periphery of the Hassi Messaoud field has been undertaken. The aim is to identify the quality of these sandstones as well as their tectonic setting and possible provenance. Petrographic analysis reveals that the studied reservoir is constituted of fine- to coarse-grained sandstones in which quartz forms the principal framework mineral. The main cement phases identified in this reservoir are quartz, illite, and carbonate, precipitated in that order. The principal diagenetic factors controlling the reservoir quality are quartz overgrowths, formation of authigenic clays, and the precipitation of carbonate cement. The Hamra Quartzite reservoir is considered mature from a compositional point of view as it consists predominantly of quartz arenites. Geochemically, these sandstones have a high SiO2 content (93.28–98.79 wt%). The Hamra Quartzite deposits appear to be derived from deeply weathered (under warm–humid climate conditions) granitic–gneissic terrains or recycled sedimentary source areas. A passive margin origin is the most likely tectonic setting for the depositional environment of these arenites. The reservoir quality is strongly influenced by the relationship between the clay content and mineralogy. The combined effect of quartz overgrowth and the plugging of pores by illite have reduced both porosity and permeability. As a result, economically viable oil production in this area will depend most strongly on the combination of matrix and fracture porosity. 相似文献
9.
Ground-motion predictions in Shillong region, northeast India 总被引：1，自引：0，他引：1
Sankar Kumar Nath Kiran Kumar Singh Thingbaijam Soumya Kanti Maiti Avinash Nayak 《Journal of Seismology》2012,16(3):475-488
We deliver ground-motion prediction equations for Shillong region, northeast India, based on a database generated by finite-fault stochastic simulations. An examination of the regional seismic source characteristics is carried out beforehand. Micro/minor earthquakes (M W?<?5.0) nucleating at hypocentral depth <21?km in the region recorded at broadband seismic stations are observed to have Brune stress-drop ranging between 2.8 and 99.9?bars. Likewise, macroseismic intensity data for the 1897 Shillong Earthquake that nucleated at a hypocentral depth of ~35?km places the associated stress-drop at 100?200?bars. The apparent variation of the stress-drop parameter with depth is considered with two source zones namely lower-crust and upper-crust. Equations for the lower-crust predict higher ground-motion levels and exhibit affinity to those developed for stable continental region of Eastern North America. The ground-motion levels predicted by the equations for the upper-crust are relatively lower but are still higher compared with those predicted for tectonically active regions, viz., the Himalayas and Western North America. 相似文献
10.
Soumya Roy Prasad Amrita Ghosh Koushik Panja Subhash Chandra Patra Sankar Narayan 《Geomagnetism and Aeronomy》2021,61(1):128-137
Geomagnetism and Aeronomy - The Mg II core-to-wing ratio (c/w ratio) data is used to derive the solar extreme UV emission which brings a vital role in the creation of the Earth’s ionosphere... 相似文献