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Résumé Cette étude est basée sur l'analyse des données gravimétriques; elle a pour but d'améliorer la connaissance de la structure de la plaine de Mornag. La carte de l'anomalie résiduelle a d'abord été calculée à partir de la carte de l'anomalie de Bouguer en enlevant un gradient régional. La résiduelle calculée fournit des informations sur la variation de la densité dans le bassin de Mornag. Afin de mettre en évidence les différentes structures dans le bassin, nous avons calculé la magnitude du gradient horizontal (MGH). Cette technique a permis de déterminer des linéaments gravimétriques représentant l'emplacement des contrastes de densité, et de déduire une carte structurale de la zone d'étude. Cette carte constitue un document très utile pour orienter l'exploration des ressources en eau dans la plaine de Mornag. Citation Farhat, B., Benassi, R., Jallouli, C. & Ben Mammou, A. (2010) Contribution de la gravimétrie à l'étude de la structure de la plaine de Mornag (nord est de la Tunisie): implications hydrogéologiques. Hydrol. Sci. J. 55(8), 1396–1404. 相似文献
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ASHRAF Sobia ABBAS Farhat IBRAHIM Muhammad RASHID Umer KHALID Shoaib Raza AHMAD Hammad Rehman HAKEEM Khalid MAJEED Tahir 《地理学报(英文版)》2015,25(2):225-235
Groundwater is the most appropriate and widely used source of drinking water, which is increasingly threatened by pollution from industrial and agricultural activities. To check the severity of the problem, 156 groundwater samples were collected from various depths (60-110 ft) of 52 different localities in Faisalabad city, the third largest metropolis in Pakistan, and analyzed for the metals (Zn, Cu, Cd, Ni, Pb, Mn and Fe) concentration in 2009. Quantification was done by using Flame Atomic Absorption Spectrophotometer technique and the results were compared with WHO standards for drinking water quality. Results showed that the levels of Cu, Mn and Fe were below the WHO standards while the concentrations of Zn, Cd, Ni and Pb were above the recommended levels of safe drinking water. Correlation analysis among the occurrence of these heavy metals revealed a highly significant and positive correlation of Mn with Zn and Fe. A significant and positive correlation of Cd was also found with Cu and groundwater depth showing that there is strong association between Cu-Cd pair and that the Cd concentration varies with depth of groundwater in the study area. Regional patterns of heavy metals occurrence were mapped using Geographical Information System (GIS) for the identification and demarcation of risk areas. The concentration maps may be used by policymakers of the city to mitigate groundwater pollution. 相似文献
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H. Ferchichi M. F. Ben Hamouda B. Farhat A. Ben Mammou 《International Journal of Environmental Science and Technology》2018,15(11):2473-2492
The integration of the statistical approaches and GIS tools with the hydrogeological and geological contexts allowed the assessment of the processes that cause groundwater quality deterioration in the great important deltaic aquifer in the northeastern Tunisia (Medjerda Lower Valley Aquifer). The spatial variation of the groundwater parameters and the molar ratio (Cl?/Br?) were also used to determine the possible impacts from seawater intrusion and from the septic tank leachate. Sixty shallow groundwater samples were collected in 2014 and analyzed for major and trace ions over an area of about 1090 km2 to determine the suitability for drinking or agricultural purposes. The total dissolved solids (TDS) content ranges from 1005 to 19,254 mgl?1 with a mean value of 3477.18 mgl?1. The chemistry is dominated by the sodium–chloride waters (55%). Mapping of TDS, Cl?, Na+, SO42? and NO3? using kriging method shows a clear increase in salinity toward the coastline accompanied by Na+ and Cl? increase which may be related to seawater intrusion and halite dissolution. Locally, higher nitrate concentration is related to the agricultural activities inducing contribution of chemical fertilizers and irrigation with treated wastewater. The saturation indices indicate that all carbonate minerals tend to reach saturation equilibrium confirming water–rock interactions, while evaporitic minerals are still in sub-saturation state and may increase the salinity of the groundwater. The principal component analysis proves the occurrence of groundwater contamination principally by seawater intrusion in the factor I (74.15%) and secondary by an anthropogenic source in the factor II (10.35%). 相似文献
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The Lower Carboniferous sediments at Wadi Abu El Mogheirat consist of four stratigraphic formations, from base upwards: Um Bogma, El Hashash, Magharet El Maiah and Abu Zarab formations. The most-concentrated radioactive anomalies at Wadi Abu El Mogheirat are in the middle member of the Um Bogma Formation. The gibbsitic marl in this formation shows the highest uranium contents (around 710 ppm). Gibbsitic marl and black gibbsite of the middle Um Bogma Formation show higher enrichment in Co, Cu, Mn, Ni, Pb, Zn, U, V, Ce and Th. Black gibbsite contains the highest total rare earth elements concentration, especially in terms of LREEs, while gibbsitic marl contains the highest content of HREEs. Anomalous contents of gold at Wadi Abu El Mogheirat are recorded for the first time in the gibbsitic marl (content: 10.4 ppm), black gibbsite (2.8 ppm) of the middle member of the Um Bogma Formation and in the siltstones of the El Hashash Formation (0.6 ppm). Gibbsitic marl shows the presence of uranothorite, celestite, zircon, atacamite, barite, xenotime and rutile. These characteristic demonstrate that the middle member of the Um Bogma Formation constitutes a potential source for gold. This conclusion is reinforced by the potential to exploit other metals such as Co, Cu, Mn, Ni, Pb, Zn, U, V, Th and Ce as by-products. 相似文献
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Farhat?AbbasEmail author Iqra?Rehman Muhammad?Adrees Muhammad?Ibrahim Farhan?Saleem Shafaqat?Ali Muhammad?Rizwan Muhammad?Raza?Salik 《Theoretical and Applied Climatology》2018,131(3-4):1101-1117
This study examines the variability and change in the patterns of climatic extremes experienced in Indus-Delta of Sindh province of Pakistan, comprising regions of Karachi, Badin, Mohenjodaro, and Rohri. The homogenized daily minimum and maximum temperature and precipitation data for a 36-year period were used to calculate 13 and 11 indices of temperature and precipitation extremes with the help of RClimDex, a program written in the statistical software package R. A non-parametric Mann–Kendall test and Sen’s slope estimates were used to determine the statistical significance and magnitude of the calculated trend. Temperatures of summer days and tropical nights increased in the region with overall significant warming trends for monthly maximum temperature as well as for warm days and nights reflecting dry conditions in the study area. The warm extremes and nighttime temperature indices showed greater trends than cold extremes and daytime indices depicting an overall warming trends in the Delta. Historic decrease in the acreage of major crops and over 33% decrease in agriculture credit for Sindh are the indicators of adverse impacts of warmer and drier weather on Sindh agriculture. Trends reported for Karachi and Badin are expected to decrease rice cultivation, hatching of fisheries, and mangroves forest surrounding these cities. Increase in the prevailing temperature trends will lead to increasingly hotter and drier summers resulting to constraints on cotton, wheat, and rice yield in Rohri and Mohenjodaro areas due to increased crop water requirements that may be met with additional groundwater pumping; nonetheless, the depleted groundwater resources would have a direct impact on the region’s economy. 相似文献
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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
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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
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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
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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