Heavy metals’ mobility from phosphate washing effluents discharged in the Gafsa area (southwestern Tunisia)     

Sondes Marzougui  Ali Sdiri  Farhat Rekhiss 《Arabian Journal of Geosciences》2016,9(12):599

Wet processing of natural phosphate to increase the P₂O₅ content and eliminate non-desired fraction (both coarse and fine fractions) took place in various laundries of the Gafsa-phosphatic area. Effluents of those laundries often contain various contaminants that are directly discharged to the receiving waterbody, representing a serious threat to the environment. Physico-chemical characterization of those effluents showed elevated levels of sulfates, fluorine, and metals. The bordering land showed gypseous soils. Those soils are covered by the discharged phosphate-washing sludge. The effect of which on the structure and the permeability of the soils seemed to be significantly harmful. Batch tests were conducted to evaluate the mobility of various metals on the surrounding area of phosphate laundries. Leaching results revealed low cadmium and uranium mobilities. However, Cd concentrations in the studied samples leached from soils exceeded the standards. This suggested the contamination by cadmium.  相似文献   

A three-scale micro-mechanical model for elastic–plastic damage modeling of shale rocks     

Farhat  F.  Shen  W. Q.  Xie  S. Y.  Shao  J. F.  Pourpak  H.  Su  K. 《Acta Geotechnica》2020,15(12):3525-3543

Acta Geotechnica - This paper is devoted to study the elastic–plastic damage behavior of heterogeneous shale rocks. The representative microstructure of this kind of rocks is first studied in...  相似文献   

Impact of Lithofacies and Structures on the Hydrogeochemistry of the Lower Miocene Aquifer at Moghra Oasis,North Western Desert,Egypt     

Abdelazeem  Maha  Salem  Zenhom E.  Fathy  Mohamed S.  Saleh  Maha 《Natural Resources Research》2020,29(6):3789-3817

Natural Resources Research - The Moghra Oasis is one of the major Egyptian desert-reclamation projects. Understanding the hydrochemistry of the Moghra aquifer is an onus to properly plan and manage...  相似文献   

Changes in precipitation extremes over arid to semiarid and subhumid Punjab,Pakistan     

Farhat Abbas  Ashfaq Ahmad  Mohammad Safeeq  Shafaqat Ali  Farhan Saleem  Hafiz Mohkum Hammad  Wajid Farhad 《Theoretical and Applied Climatology》2014,116(3-4):671-680

Asymmetrical monsoons during the recent past have resulted into spatially variable and devastating floods in South Asia. Analysis of historic precipitation extremes record may help in formulating mitigation strategies at local level. Eleven indices of precipitation extremes were evaluated using RClimDex and daily time series data for analysis period of 1981–2010 from five representative cities across Punjab province of Pakistan. The indices include consecutive dry days, consecutive wet days, number of days above daily average precipitation, number of days with precipitation ≥10 mm, number of days with precipitation ≥20 mm, very wet days, extremely wet days, simple daily intensity index, maximum 1-day precipitation quantity, maximum 5 consecutive day precipitation quantity, and annual total wet-day precipitation. Mann-Kendall test and Sen’s slope extremes were used to detect trends in indices. Droughts and excessive precipitation were dictated by elevation from mean sea level with prolonged dry spells in southern Punjab and vice versa confirming spatial trends for precipitation extremes. However, no temporal trend was observed for any of the indices. Summer in the region is the wettest season depicting contribution of monsoons during June through August toward devastating floods in the region.  相似文献   

Modeling of Mrihla anticline (Central Tunisian Atlas), combination fault propagation fold and halokenitic model     

Chawki Khalfi  Riadh Ahmadi  Farhat Rhekiss  Hazem Trigui  Jamel Ouali 《Arabian Journal of Geosciences》2014,7(2):811-818

The modeling study on the Mrihla anticline was carried out using two techniques, i.e., excess area law and balanced cross section. The results show that this structure is likely affected by at least two compressive phases. The interpretation of surface (bedding dips, thickness, lithology, etc.) and subsurface (seismic lines) data along the cross section indicates that the Mrihla structure has a shortening of about 525 m that is evolved above a detachment layer formed by gypsum Triassic formation. The top of this layer is situated at a depth of about 3,890 m from the top of the Aptian dolomitic level, known in Central Tunisian Atlas as Serdj Formation. The kinematic of the investigated structure is a combination of two deformation models. The first is the halokenitic model, defined by the flowing of Triassic ductile material upward toward the surface through the deep Mrihla fault, which is parallel to Mrihla anticline. The second is the fault propagation fold model, characterized by thin-skin deformation mechanics in relation with the movement of the Mrihla fault.  相似文献   

High grade metamorphic zone in the basement of Wadi Araba,Jordan     

J.S. Farhat 《Precambrian Research》1978,6(1):A21-A22

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Treatment of secondary effluents by infiltration-percolation process using sand fortified with activated charcoal     

M. Bali  H. Jridi  S. Farhat  B. Louhichi  R. Boukchina 《International Journal of Environmental Science and Technology》2017,14(6):1209-1216

The main purpose of this study was to investigate the ability of sand/granular activated charcoal mixture medium to treat urban wastewater effluents. Several laboratory experiments were conducted to determine the best combination ratio of sand/activated charcoal which would allow the optimum water purification. A comparative study was undertaken to evaluate the effect of the addition of activated charcoal on infiltration-percolation efficiency. Experiments demonstrated that fortifying sand medium with granular activated charcoal improved the pollutants removal efficiencies. Results showed that a combination ratio of 3:1 (by volume) of sand and granular activated charcoal gave the best depuration efficiency regarding organic matter, nitrogen and orthophosphorous. The mean removal rates of COD, NH₄–N and PO₄–P were 83.29, 95.85 and 65.21%, respectively. Furthermore, experiments demonstrated that a mixture of sand/activated charcoal in a 3:1 ratio resulted in the optimum oxidation capacity.  相似文献   

Prediction of Solar Activity Based on Neuro-Fuzzy Modeling     

Abdel-Fattah?AttiaEmail author  Rabab?Abdel-Hamid  Maha?Quassim 《Solar physics》2005,227(1):177-191

This paper presents an application of the neuro-fuzzy modeling to analyze the time series of solar activity, as measured through the relative Wolf number. The neuro-fuzzy structure is optimized based on the linear adapted genetic algorithm with controlling population size (LAGA-POP). Initially, the dimension of the time series characteristic attractor is obtained based on the smallest regularity criterion (RC) and the neuro-fuzzy model. Then the performance of the proposed approach, in forecasting yearly sunspot numbers, is favorably compared to that of other published methods. Finally, a comparison predictions for the remaining part of the 22nd and the whole 23rd cycle of the solar activity are presented.  相似文献   

Geochronologic investigations of the Sudbury Nickel Irruptive and the Superior Province granites north of Sudbury     

R.W. Hurst  J. Farhat 《Geochimica et cosmochimica acta》1977,41(12):1803-1815

RbSr ($\text{λ}\text{Rb}\text{= 1.39 × 10}{}^{\mathrm{?11}}\text{yr}{}^{\mathrm{?1}}\text{)}$ and U-Pb ($\text{λ 238 = 1.54 × 10}{}^{\mathrm{?10}}\text{yr}{}^{\mathrm{?1}}\text{, λ235 = 9.72 × 10}{}^{\mathrm{?10}}\text{yr}{}^{\mathrm{?1}}$) measurements were undertaken in the Sudbury area, Sudbury, Ontario to determine the ages of the Sudbury Nickel Irruptive, Superior Province granites north of Sudbury, Sudbury Breccia and subsequent metamorphism. The Sudbury Nickel Irruptive norite whole rock Rb-Sr data yield an age of $\text{1883 ± 136}\text{Myr}$ ($\text{I.R}\text{. = 0.7071 ± 0.0005}$; all results quoted at 2π level) while the Nickel Irruptive micropegmatite Rb-Sr system has been disturbed and does not yield an isochron. A plagioclase-whole rock pair from the norite near the norite-micropegmatite transition yields an age of 1866 Myr, which when taken in conjunction with field (Stevenson and Colgrove, 1968) and geochemical (Naldrettet al., 1970, 1972) data does not support the conclusion of gibbins and McNurr (1972) that the micropegmatite is a later intrusion rather than a differentiate of the magma which produced the norite. Rb-Sr studies of the Superior Province granites north of Sudbury yield an age of $\text{2698 ± 162}\text{Myr}$ ($\text{I.R.}\text{= 0.7019 ± 0.0012}$). U-Pb zircon studies of these granites and granitic clasts within the Sudbury Breccia yield an age of $\text{2.71 ± 0.05}$ Byr and suggest the breccia granitic clasts were derived from the Superior Province granites. The granitic rocks ~150 km north of Sudbury have been undisturbed for ~ 2.6 Byr based on Rb-Sr mineral studies, whereas the granites and Sudbury Breccia within ~ 15 km of the Nickel Irruptive, as well as the Sudbury norite at the perimeter of the Irruptive have been disturbed by the Penokean Orogeny 1.7–1.75 Byr ago. The Penokean event appears to have overprinted isotopic evidence of the Sudbury impact event at least in the area studied.  相似文献   

Bartonian orthophragminids with new endemic species from the Pirkoh and Drazinda formations in the Sulaiman Range,Indus Basin,Pakistan     

Nowrad Ali  Ali Osman Yücel  Muhammad Hanif  Syed Irfanullah Hashmi  Farhat Ullah 《Geodinamica Acta》2018,30(1):31-62

The Pirkoh and Drazinda formations in the Sulaiman Range, central Pakistan, yielded assemblages of (early) Bartonian orthophragminids, characterized predominantly by discocyclinids with a significant number of species probably endemic to Indian Subcontinent. The rarity of Asterocyclina and the absence of Orbitoclypeus and Nemkovella are noteworthy. Ten species of Discocyclina Gümbel and two species of Asterocyclina Gümbel, referable to the Shallow Benthics Zone (SBZ) 17 are described for the first time from Pakistan. The discocyclinids, i.e. Discocyclina praeomphalus, D. sulaimanensis, D. kutchensis, along with the new taxa established here, D. zindapirensis sp. nov., D. rakhinalaensis sp. nov., and D. pseudodispansa sp. nov., seem to be confined to the Indo-Pakistani region (Eastern Tethys). The Discocyclina dispansa, D. discus, D. nandori, and D. augustae lineages known from Western Tethys are also common in the Indian Subcontinent, as are asterocyclinids, such as Asterocyclina sireli and A. stellata. The upper part of the Drazinda Formation (‘Pellatispira beds’), referable to latest Bartonian and/or the early Priabonian, is poor in orthophragminids and is characterized by the occurrence of reticulate Nummulites, Heterostegina, Pellatispira and Silvestriella. The records of ‘Lepidocyclina of Caribbean affinity’ with large embryons from the Eocene of the Indian Subcontinent correspond to misidentified Discocyclina discus.  相似文献