Weathering of phlogopite in simulated bioleaching solutions     

Tariq M. Bhatti  Jerry M. Bigham  Antti Vuorinen  Olli H. Tuovinen 《International Journal of Mineral Processing》2011,98(1-2):30-34

The purpose of this study was to examine structural alterations of finely ground phlogopite, a trioctahedral mica, when exposed to acid, iron- and sulfate-rich solutions typical of bioleaching systems. Phlogopite suspensions were supplemented with ferrous sulfate and incubated with iron- and sulfur-oxidizing bacteria (Acidithiobacillus ferrooxidans) at 22 °C. As bacteria oxidized ferrous iron, ferric iron thus formed partially precipitated as K-jarosite. K-jarosite precipitation was contingent on the preceding ferrous iron oxidation by bacteria and the release of interlayer-K from phlogopite. This chemically and microbially induced weathering involved alteration of phlogopite to a mixed layer structure that included expansible vermiculite. The extent of phlogopite weathering and structure expansion varied with duration of the contact, concentration of ferrous iron and phlogopite, and the presence of monovalent cations (NH₄⁺, K⁺, or Na⁺) in the culture solution. NH₄⁺ and K⁺ ions (100 mM) added to culture suspensions precipitated as jarosite and thereby effectively prevented the loss of interlayer-K and structural alteration of phlogopite. Additional Na⁺ (100 mM) was insufficient to precipitate ferric iron as natrojarosite and therefore the precipitation was coupled with interlayer-K released from phlogopite. When ferrous iron was replaced with elemental sulfur as the substrate for A. ferrooxidans, the weathering of phlogopite was based on chemical dissolution without structural interstratification. The results demonstrate that iron oxidation and the concentration and composition of monovalent ions can have an effect on mineral weathering in leaching systems that involve contact of phlogopite and other mica minerals with acid leach solutions.  相似文献   

Simulation of equatorial wind field patterns with TAPM during the 1997 haze episode in Peninsular Malaysia     

Mastura Mahmud 《Singapore journal of tropical geography》2009,30(3):312-326

The large‐scale forest fires that occurred during the major El Niño event in 1997 can be counted among the worst environmental disasters in Southeast Asia. This study investigates atmospheric mesoscale features over Sumatra and the Klang Valley in Peninsular Malaysia during the resultant haze episode of September 1997 utilizing a limited area mesoscale three‐dimensional meteorological and dispersion model, The Air Pollution Model (TAPM). Mesoscale features that would not be highlighted by global numerical prediction models, such as the daily land and sea breeze conditions at the selected air pollution stations located near the west coast of Peninsular Malaysia, were predicted with an Index of Agreement of 0.3, which implied a moderate conformity between the predicted and observed values. Tracer analysis of air particles at a selected location in the Straits of Malacca verified the existence of the landward and shoreward movement of the air during the simulation of the low‐level wind field. Air pollutants from the burning areas of neighbouring Sumatra just across the straits were transported towards the Klang valley during the daytime and seawards during the nighttime, highlighting the recirculation features of aged and newer air particles over the seven days (13–18 September) of the model simulation. The presence of the central Main Range east of the Klang valley to a certain extent limited further eastward movement of the air particles. Near calm conditions at low levels were simulated from midnight to midday on 14 September, where the movement of the polluted air particles from the uncontrolled burning in Sumatra was confined within the Straits of Malacca. Turbulence within the planetary boundary layer in terms of the total kinetic energy was found to be weak from 14 to 15 September, congruent with the weak strength of low level winds that reduced the ability of the air to transport the pollutants during the period of severe smoke haze. Statistical evaluation showed that parameters such as the systematic RMSE (root mean square error) and unsystematic RMSE for the zonal wind component were slightly higher than for the meridional one, indicating higher errors between the observed and simulated zonal values. Otherwise, the equatorial meteorological parameters such as wind speed and temperature were successfully simulated by the model with comparatively high correlation coefficients, lower RMSEs and moderately high indices of agreement with observed values.  相似文献   

Rock mass rating and Kinematic analysis for slope stability investigation of Utari dam,Lalitpur district,Uttar Pradesh     

M. E. A. Mondal  Tariq Siddique  Mohammad Alam  M. Masroor Alam 《Journal of the Geological Society of India》2016,87(4):463-468

Rock mass characterization of Utari dam in Lalitpur district of Uttar Pradesh was done to identify different stability classes of rock mass. For better stability of Utari dam, foundation conditions were carefully studied by detailed field investigations of the site supplemented by laboratory tests. During feasibility and preliminary stages, rock mass characterization of slopes was conducted to identify the vulnerable zones of failure. Rock mass characterization was done by compilation of information obtained from intact rock as well as from rock mass to determine its grade and long term slope stability of the site. On the basis of Rock Mass Rating (RMR) and Geological Strength Index (GSI) slope stability is identified which lies under good quality rock mass. Kinematic analysis was conducted to find out the probability for different types of structurally controlled slope failure. Microscopic analyses were conducted to identify the degree of chemical alteration of feldspar. Clay formation by sericitization along joint planes is harmful for the stability of dam structure. Remedial measures must be taken to reduce the extent of chemical alteration. Granitoids at dam site forms a compact and stable foundation consisting of four sets of joints in which two sets were prominent which are dipping on the upstream side of the dam which reveals good condition on the dam site as leakage from reservoir will be minimum and least up-thrust on the dam structure.  相似文献   

SMR geomechanics and kinematic analysis near Rasulpur,Fatehpur Sikri,Uttar Pradesh   总被引：1，自引：0，他引：1  

M. E. A. Mondal  Tariq Siddique  Bulbul Mondal  M. Masroor Alam 《Journal of the Geological Society of India》2016,87(5):623-627

Slope stability of mine slopes is often associated with safety and economics during excavation. Sandstone is excavated from Rasulpur area of Fatehpur Sikri in Uttar Pradesh for the purpose of crushed, decorative and dimension stones. In the present paper an attempt has been made to characterize the rock slope faces into different stability classes. Characterization is based on geological and geotechnical parameters recorded on the outcrop during field investigation and supplemented by geomechanical properties by the laboratory test for strength of the rock intact. SMR Geomechanics classification is used to identify the stability class and remedial measures are also suggested to reduce any possible hazard. Kinematic analysis of slope was also investigated to determine the probability of any possible structurally controlled failure. On the basis of SMR Geomechanics calculations slope under investigation lies under good stability class i.e. 2a and 2b. Installation of nets during excavation can be done and for better safety spot and systematic rock bolting can be done. Kinematic study reveals that toppling failures may occur, special care must be given to the joint set which can trigger toppling failure.  相似文献   

Role of early warning systems for sustainable agriculture in Iran     

Saeed Sharafi  Mahmud Ramroudi  Mehdi Nasiri  Mohammad Galavi  Gholam Ali Kamali 《Arabian Journal of Geosciences》2016,9(19):734

Drought is a complex phenomenon in meteorology and can affect agriculture. Its impacts vary greatly since they depend not only on the magnitude, timing, duration, and frequency of rainfall deficits but also on the differing responses of various plants to water stress. The essence of good drought management is to use this range of responses to the best advantage. Iran is one of the world’s largest and most productive suppliers of food and fiber. The objective of this study was, therefore, to gather and analyze standardized information on the Role of Early Warning Systems for Sustainable Agriculture for cereals and leguminous and industrial crops in Iran environmental zones. Annual average rainfall (mm year^?1) and ET_O (mm year^?1) are 76.56 and 3001, respectively, in stations with very dry climate; 195.41 and 2249, respectively, in stations with dry climate; 343.9 and 1351, respectively, in stations with semi-dry climate; 583.8 and 1153, respectively, in stations with semi-humid climate; and 1272 and 949, respectively, in stations with humid climate. The maximum and minimum of annual average rainfall happened in Rasht (1337 mm year^?1) and Zabol (57 mm year^?1) stations, and the maximum and minimum for annual average ET_O happened in Chabahar (3909.15 mm year^?1) and Anzali harbor (890.6 mm year^?1), respectively. Therefore, 13.63 % of stations have suitable conditions for crop productions and 86.37 % are in critical conditions.  相似文献   

Litter pollution on the Jordanian shores of the Gulf of Aqaba (Red Sea)   总被引：1，自引：0，他引：1  

Abu-Hilal AH  Al-Najjar T 《Marine environmental research》2004,58(1):39-63

Litter was assessed on three beaches along the Jordanian coast of the Gulf of Aqaba, south of the town Aqaba, monthly during 1994 and 1995, in order to determine its nature, extent and possible sources. The overall mean was about 5 and 3 items/m(2) in 1994 and 1995, respectively. Approximately a total of 14,000 m(2) were examined and a total of 101,000 items were noted, 67,000 during 1994 and 34,000 in 1995. More than 50% of the litter was plastic and the remainder wood, glass, cardboard, Styrofoam, metal and other materials. Most litter appears to be from local land-based or near shore sources, although there are some regional influences as well. The main local sources are the passenger port, the cargo port and the beach goers. The findings are compared with other regions of the world. The amount of litter is related to distance of the beach from the main sources, and shape, physiography and orientation of the beach. Spatial and seasonal variations are examined and discussed, and actions and measures to combat the problem on local and regional levels are suggested.  相似文献   

Development of Statistical Models to Predict the Mechanical Properties of Some Metamorphic Rocks from P-Wave Velocity and Certain Physical Properties     

Singh  Hari Om  Ansari  Tariq Anwar  Singh  T. N.  Singh  K. H. 《Geotechnical and Geological Engineering》2022,40(8):4247-4268

Geotechnical and Geological Engineering - Strength and elastic properties of rocks have vital importance for the design of structures in several rock engineering projects. Additionally, these...  相似文献   

The space–time domain: theory and modelling for anisotropic media     

Tariq Alkhalifah  Sergey Fomel  Biondo Biondi 《Geophysical Journal International》2001,144(1):105-113

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Implementing the fast marching eikonal solver: spherical versus Cartesian coordinates   总被引：8，自引：0，他引：8  

Tariq Alkhalifah  Sergey Fomel† 《Geophysical Prospecting》2001,49(2):165-178

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