Characteristics,modification and environmental application of Yemen’s natural bentonite     

Aref Alshameri  Alkhafaji R.Abood  Chunjie Yan  Akhtar Malik Muhammad 《Arabian Journal of Geosciences》2014,7(3):841-853

The bentonite deposit of Lahij Province, Yemen, has very promising commercial applications due to its mineralogy and physical and chemical properties. It was examined to determine its mineralogical composition, chemical and physical properties of the bentonite deposit, purity and sodium-exchanged bentonite. Modified bentonite was synthesized by exchanging cetyltrimethylammonium cations for inorganic ions on the bentonite and its adsorption properties for ammonium were characterized in batch experiments. Analytical methods were carried out to study the bentonite comprising X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy, chemical analysis and kinetic and isotherm models were also tested. The results have shown that the purification of bentonite resulted in a bentonite fractions of the total sample composed of montmorillonite and <5 % quartz. The XRD data showed that the interlayer spacing (d ₀₀₁) of bentonite decreased from 15.3 to 12.5 Å and then increased to 19.7 Å. Moreover, high cation exchange capacity, good water absorption and high swelling capacity were also obtained. The results have shown that the modified bentonite was more effective than the natural bentonite for ammonium removal. In addition to that, pseudo-second-order kinetic model, Freundlich and the Langmuir models described the adsorption kinetics and isotherm well. It was concluded that Yemen (Alaslef) bentonite can be potential adsorbents for ammonium removal.  相似文献   

Microfacies and Depositional Environments of Miocene Isolated Carbonate Platforms from Central Luconia, Offshore Sarawak, Malaysia     

Hammad Tariq JANJUHAH  José Antonio GáMEZ VINTANED  Ahmed Mohamed AhmedSALIM  Ibrahima FAYE  Mumtaz Muhammad SHAH  Deva Prasad GHOSH 《《地质学报》英文版》2017,91(5):1778-1796

The Luconia Province – offshore Sarawak – is a key geological unit for understanding the distribution of hydrocarbon resources in Malaysia. Nevertheless, little effort has been made to address the palaeoenvironmental characteristics of the Tertiary carbonates in the key sector of Central Luconia. We study the sedimentology and petrography of core samples from a well in Central Luconia, for which thirteen microfacies have been identified reflecting different depositional settings. This is the first microfacies scheme elaborated for Luconian carbonates. Lithofacies and microfacies distribution are compatible with deposition in a reef complex, originating around a framework reef, within the euphotic zone. Sediments were deposited in environments of backreef, reef crest, and forereef. The fair weather wave base is marked by the presence of coralline red algae, foraminifera, decreasing degree of bioclast fragmentation and other microfacies features. As a result, a depositional-environmental model is constructed, depicting a reef complex built around a framework reef developed on the margin of an isolated platform. In addition, an innovative, preliminary time series analysis of facies, microfacies and depositional environment data reveal the existence of seasonal cycles in the stacking patterns of facies and microfacies.  相似文献   

Place,identity and stigma: blocks and the ‘blockies’ of Tara,Queensland, Australia     

Muhammad Makki  Kitty van Vuuren 《GeoJournal》2017,82(6):1085-1099

This article explores the role of geographical context in generating a stigmatised identity among residents of Tara rural subdivisions in the coal seam gas fields in Queensland’s Western Downs. The research was based on qualitative interviews with Tara ‘Blockies’, as these residents are commonly referred to, that revealed how their existence in the middle of an agrarian region resulted in the assignation of a stigma that has marked them as different, and subsequently devalued their status. We explain that this distinction and category division of the normals, referring to Tara’s Agrarian residents, from the ‘stigmatised’ led to an antagonistic relationship that prevented successful socio-cultural assimilation. We demonstrate how an immoral place becomes disadvantaged, resulting in poor well-being, and how imposed labels threaten the self-esteem of its occupants.  相似文献   

Disaster risk management in agriculture: tragedies of the smallholders     

Raza Ullah  Ganesh P. Shivakoti  Farhad Zulfiqar  Muhammad Nadeem Iqbal  Ashfaq Ahmad Shah 《Natural Hazards》2017,87(3):1361-1375

Agriculture sector is exposed to a variety of risks and uncertainties which can lead to sizeable losses in crop yields and alter farm incomes. Risk management is, therefore, an essential element of the overall farm management process. Farmers have number of options in managing farm risks; however, smallholders, due to their small operations and limited financial capabilities, find it difficult to adopt sophisticated risk management strategies to overcome yield and income instabilities at farm level. This study is, therefore, designed to investigate the enabling environment for small farmers to manage climatic risks at farm level. A total of 330 sampled respondents from Khyber Pakhtunkhwa Province of Pakistan are randomly selected for the study using multistage sampling technique. Analysis of variance technique is employed to compare the risk management adoption decision of small, medium and large farmers. A post hoc analysis is also performed to highlight the difference in means and the magnitude of differences. The results indicate that smallholders have significantly lower access to credit (both formal and informal), formal information sources along with significantly higher perceptions of pest and diseases. Smallholders are also at the tail end in the adoption of precautionary savings and agricultural credit to manage climatic risk at farm level. The study urges for risk management policies particularly in favor of the small farmers and intervention in the existing information and credit provision programs to facilitate smallholders in managing farm risks.  相似文献   

Petrography,provenance, diaganesis and depositional environment of Murree Formation in Jhelum Valley,Sub Himalayas,Azad Jammu and Kashmir,Pakistan     

Muhammad Zaheer  Muhammad Sabir Khan  Muhammad Saleem Mughal  Noman Abbasi 《Arabian Journal of Geosciences》2017,10(23):514

The clastic sediments of the Murree Formation of Miocene age are exposed in Jhelum valley areas of Azad Jammu and Kashmir Pakistan. Field observations revealed the cyclic deposition in the Murree Formation. The sandstone, siltstone, and shale constitute a single cycle within the formation. This single unit is divided into five different lithofacies which constitute the Bouma sequence in the Murree Formation. The Murree Formation shows faulted contacts with Panjal Formation and Nagri Formation in the study area. The modal mineralogy data obtained from the petrography of sandstone indicates that sandstone is litharenite and lithic greywacke. The mineralogical and textural data suggests that sandstone is compositionally mature and poorly to moderately sorted. The dominantly angular to sub angular quartz grains show nearness of the source area. Fractured and sutured quartz grain reveals tectonodiagentic changes that occurred in Murree Formation. The sandstone experienced diagenetic changes. The pressure solution and cementation reduced the primary porosity of sandstone. However, alteration of feldspar and fractures in grains have produced secondary porosity. The X-ray diffraction (XRD) of the shale samples indicates that shale of the Murree Formation is argillaceous and dominated by illite clay mineral. The illite crystallinity values indicate very low grade metamorphism of Murree Formation in core of Hazara Kashmir Syntaxis. The petrographic data suggests that the provenance of sandstone is recycled orogen. Quartz is of igneous and metamorphic origin. Feldspar (albite and microcline) composition suggests its derivation from acidic igneous rocks. The rock fragments of volcanics, slate, phyllite, and schist suggest igneous and metamorphic provenance. The petrographic data suggests that at the time of deposition of Murree Formation, igneous and low grade metamorphic rocks were exposed. However, presence of some clasts of carbonates indicates that sedimentary rocks were also exposed in the source region. The quartz content and clay minerals in the shale revealed that source region was igneous and metamorphic rocks. Cyclic deposition, lithofacies, and various sedimentary structures like cross bedding, ripple marks, and calcite concretions suggest that deposition of Murree Formation occurred in fluviatile environment by meandering river system having decreasing turbidity current.  相似文献   

Robust approach for optimal positioning and ranking potential rainwater harvesting structure (RWH): a case study of Iraq     

Khamis Naba Sayl  Nur Shazwani Muhammad  Ahmed El-Shafie 《Arabian Journal of Geosciences》2017,10(18):413

Rainwater harvesting (RWH) structure is considered as the best solution to conserve water for arid regions. The selection of RWH location is based on several key determinants such as hydrology, environment, topography, and socio-economic. This study proposed a robust methodology to identify and select the location of RWH using geographical information systems (GIS) and remote sensing (RS) with multi-criteria decision techniques in areas where data are scarce. Several thematic maps were extracted such as vegetation cover, soil group, slope, land use, and digital elevation (DEM). The RWH sites were ranked based on four major indexes: evaporation, cost-benefit, sediment, and hydrological index. Sensitivity analysis shows that the variance inverse (VI) and rank order method (ROM) considered all indices that effect ranking as compared to the analytic hierarchy process (AHP) and fuzzy-AHP. Sensitivity analysis also proved that the proposed method is suitable to be used for RWH site selection in arid regions.  相似文献   

Assessment of sea water inundation along Daboo creek area in Indus Delta Region,Pakistan     

Ibrahim Zia  Hina Zafar  Muhammad I. Shahzad  Mohsin Meraj  Jamil H. Kazmi 《中国海洋大学学报(英文版)》2017,16(6):1055-1060

Indus Deltaic Region (IDR) in Pakistan is an erosion vulnerable coast due to the high deep water wave energy. Livelihood of millions of people depends on the fisheries and mangrove forests in IDR. IDR consists of many creeks where Daboo is a major creek located at southeast of the largest city of Pakistan, Karachi. Unfortunately, there has been no detailed study to analyze the damages of sea water intrusion at a large temporal and spatial scale. Therefore, this study is designed to estimate the effects of sea water inundation based on changing sea water surface salinity and sea surface temperature (SST). Sea surface salinity and SST data from two different surveys in Daboo creek during 1986 and 2010 are analyzed to estimate the damages and extent of sea water intrusion. Mean salinity has increased 33.33% whereas mean SST decreased 13.79% from 1987 to 2010. Spatio-temporal analysis of creek area using LANDSAT 5 Thematic mapper (TM) data for the years 1987 and 2010 shows significant amount of erosion at macro scale. Creek area has increased approximately 9.93% (260.86 m² per year) which is roughly equal to 60 extensive sized shrimp farms. Further Land Use Land Cover (LULC) analyses for years 2001 and 2014 using LANDSAT 7 Enhanced Thematic Mapper Plus (ETM+) has indicated 42.3% decrease in cultivated land. Wet mud flats have spread out at the inner mouth of creek with enormous increase of 123.3%. Significant sea water intrusion has increased the area of barren land by 37.9%. This also resulted in overall decrease of 6.7% in area covered by mangroves. Therefore, this study recorded a significant evidence of sea water intrusion in IDR that has caused serious damages to community living in the area, economical losses. Additionally, it has also changed the environment by reducing creek biological productivity as reported by earlier studies over other regions of the world.  相似文献   

Correction to: A local scale flood vulnerability assessment in the flood‑prone area of Khyber Pakhtunkhwa,Pakistan     

Nazeer  Muhammad  Bork  Hans‑Rudolf 《Natural Hazards》2022,111(1):1103-1103

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影响三大洲的北非强沙尘暴动力机制WRF-chem模拟与分析北大核心          下载免费PDF全文

Altayeb Raga  王坚红  Abdoul Aziz Saidou Chaibou  Muhammad Arsha  Mohammed AbdAllah  Birhanu Asmerom Habtemicheal 《气象科学》2022,42(6):769-780

基于WRF-chem模式对北非2018年3月下旬的典型强沙尘暴过程进行模拟,分析了此次强沙尘发生季节、持续时间、局地特征以及传输路径的关键动力系统与动力机制。鉴于起沙是沙尘暴发生的关键点之一,并且起沙主要取决于风力和下垫面沙源性质,本文测试了三种起沙参数化方案的影响,并将模拟结果与卫星MODIS监测及其再分析资料MERRA-2进行了对比,又经系列统计方法检验。结果显示,宏观思路的起沙方案GOCART比AFWA和UoC两种起沙方案更适合此次大尺度强沙尘暴数值模拟(锋面跨度接近60个经度)。综合沙尘暴关键系统的动力机制分析和数值模拟结果显示,强沙尘暴关键系统为深厚的西风槽、沙尘冷锋锋面和锋后的地面高压反气旋。北非中部深厚的西风槽为后倾槽,该系统稳定,造成沙尘暴持续时间长。沙尘暴锋后反气旋中的下沉气流抑制了扬沙向高层扩散,造成低层能见度恶劣。沙尘锋区结合了动力、热动力以及湿热动力不稳定,因此锋区风力大,地面沙尘驱动力强。而西风槽和强大反气旋依托环流形势,提供了沙尘传输到三大洲的长途输送力。  相似文献