Comprehensive physicochemical study of dioctahedral palygorskite-rich clay from Marrakech High Atlas (Morocco)

This study is devoted to the physicochemical and mineralogical characterizations of palygorskite from Marrakech High Atlas, Morocco. The raw clay and its Na⁺-saturated <2 μm fraction were characterized using chemical, structural, and thermal analytical techniques. Measurements of specific surface area and porous volume are reported. The clay fraction was found to be made up of 95 % of palygorskite and 5 % of sepiolite. An original feature of this palygorskite is its deficiency in zeolitic H₂O. The half-cell structural formula of its dehydrated form was determined on the basis of 21 oxygens to be (Si_7.92Al_0.08)(Mg_2.15Al_1.4Fe_0.4Ti_0.05 $ \square_{1} $ )(Ca_0.03Na_0.08K_0.04)O₂₁, while the hydrated form could be formulated as (Si_7.97Al_0.03)(Mg_2.17Al_1.46Fe_0.40Ti_0.05)(Ca_0.03Na_0.07K_0,03)O_20.18(OH)_1.94(OH₂)_3.88·2.43 H₂O. These formulas show that the (Al³⁺+Fe³⁺)/Mg²⁺ ratio is around 0.84, revealing a pronounced dioctahedral character. Further, inside its octahedral sheet, it was determined that the inner M₁ sites are occupied by vacancies, whereas the M₂ sites are shared between 90 % of trivalent cations (78 % for Al³⁺ and 22 % for Fe³⁺), 7.5 % of Mg²⁺, and 2.5 % of Ti⁴⁺, all of them linked to 1.94 of structural hydroxyls. The two remaining Mg²⁺ by half-cell occupy edge M₃ sites and are coordinated to 3.88 molecules of OH₂. Channels of this palygorskite are deficient in zeolitic H₂O since they contain only 2.43 H₂O molecules. A correlation was found between these results and the observation of very intense and well-resolved FTIR bands arising from dioctahedral domains (mainly Al₂OH, Fe₂OH, and AlFeOH) along with very small responses from a trioctahedral domain (Mg₃OH). Accordingly, a schematic representation of the composition of the octahedral sheet was proposed. The cation exchange capacity, specific surface area, and total pore volume were also assessed to be ca. 21.2 meq/100 g, 116 m²/g, and 0.458 cm³/g, respectively.     

A priori testing of sparse adaptive polynomial chaos expansions using an ocean general circulation model database

This work explores the implementation of an adaptive strategy to design sparse ensembles of oceanic simulations suitable for constructing polynomial chaos surrogates. We use a recently developed pseudo-spectral algorithm that is based on a direct application of the Smolyak sparse grid formula and that allows the use of arbitrary admissible sparse grids. The adaptive algorithm is tested using an existing simulation database of the oceanic response to Hurricane Ivan in the Gulf of Mexico. The a priori tests demonstrate that sparse and adaptive pseudo-spectral constructions lead to substantial savings over isotropic sparse sampling in the present setting.     

Abu Roash G dolomite reservoir characterization using seismic inversion technique, Horus field, Western Desert, Egypt

The main objective of this paper was the characterization of the reservoir (Abu Roash G dolomite) in terms of acoustic impedance from surface seismic data complemented by available well logs. To reach our target, a two-step procedure was followed: first, identification of the reservoir signatures using synthetic seismogram using Strata program in Hampson–Russell software and second, applying inversion technique to the post-stack seismic data using Strata program in Hampson–Russell software to obtain acoustic impedance profiles and maps. This procedure was applied to 12 3D seismic lines (six cross-lines, and six in-lines) from Horus field in Western Desert in Egypt after converting them from analog state to SEGY format by vectorization. Five wells had been used in this study. The outcome of this paper is an improved subsurface image of seismic data and achieving the reservoir characterization in a good way.     

Multi-label class assignment in land-use modelling

During the last two decades, a variety of models have been applied to understand and predict changes in land use. These models assign a single-attribute label to each spatial unit at any particular time of the simulation. This is not realistic because mixed use of land is quite common. A more detailed classification allowing the modelling of mixed land use would be desirable for better understanding and interpreting the evolution of the use of land. A possible solution is the multi-label (ML) concept where each spatial unit can belong to multiple classes simultaneously. For example, a cluster of summer houses at a lake in a forested area should be classified as water, forest and residential (built-up). The ML concept was introduced recently, and it belongs to the machine learning field. In this article, the ML concept is introduced and applied in land-use modelling. As a novelty, we present a land-use change model that allows ML class assignment using the k nearest neighbour (kNN) method that derives a functional relationship between land use and a set of explanatory variables. A case study with a rich data-set from Luxembourg using biophysical data from aerial photography is described. The model achieves promising results based on the well-known ML evaluation criteria. The application described in this article highlights the value of the multi-label k nearest neighbour method (MLkNN) for land-use modelling.     

The cumulative impacts of reclamation and dredging on the marine ecology and land-use in the Kingdom of Bahrain

This article assesses the ecological and economic impacts of land reclamation and dredging through consulting recent environmental impact assessment reports. Geographic features of Bahrain during 1963-2008 are produced using Geographical Information System. Extensive but inexpensive shallow coastal areas and tidal flats have been reclaimed particularly from 1997 to 2007 at a high rate of 21 km(2)/year. Formal records show the increase in the original land mass by the year 2008 to be 91 km(2). An estimated total cumulative loss of major habitats resulting from 10 reclamation projects was around 153.58 km(2). Also much larger scale impacts should be considered resulting from the borrow areas used for the extraction of sand or infill materials. A number of key habitats and species are affected in the vicinity of these projects. The study attempts to assign a monetary value to the marine ecosystem functions. There is a need for efficient coastal zone management to regulate a sustainable use of the marine resources.     

New methodology for urban seismic risk assessment from a holistic perspective

The seismic risk evaluation usually works with a fragmented concept of risk, which depends on the scientific discipline in charge of the assessment. To achieve an effective performance of the risk management, it is necessary to define risk as the potential economic, social and environmental consequences due to a hazardous phenomenon in a period of time. This article presents a methodology which evaluates the seismic risk from a holistic perspective, which means, it takes into account the expected physical damage and also the conditions related to social fragility and lack of resilience, which favour the second order effects when a hazard event strikes an urban centre. This seeks to obtain results which are useful in the decision making process for risk reduction. The proposed method for urban seismic risk evaluation uses the fuzzy sets theory in order to handle qualitative concepts and variables involved in the assessment, the physical risk level and aggravation level, related to the social fragility and the lack of resilience, are evaluated and finally a total risk level is determinate.     

Degradation and Leaching of Napropamide in BRIS Soil Amended with Chicken Dung and Palm Oil Mill Effluent

The degradation and leaching of napropamide were compared between Beach Ridges Interspersed with Swales (BRIS) soil samples, and the same soil samples amended with 20 mg ha^?1 of either chicken dung (CD) or palm oil mill effluent (POME). The effects of removing dissolved organic carbon (DOC) from the soil samples on napropamide degradation and leaching were also studied. The addition of CD and POME to BRIS soil increased the napropamide half‐life values to 69 and 49.5 days, respectively. Sterilization of the soil samples resulted in partial inhibition of napropamide degradation in all soil samples. The half‐lives of napropamide in BRIS soils receiving 0, 20, 100, and 200 mg kg^?1 of DOC derived from CD were 43, 46.2, 53.4, and 63 days, respectively. The napropamide half‐lives in soil samples treated with 0, 20, 100, and 200 mg kg^?1 of DOC derived from POME were 43, 49.2, 57.7, and 69 days, respectively. However, in the sterilized soil samples, there were no significant effects of adding DOC derived from either CD or POME on napropamide half‐lives. Incorporating either CD or POME decreased napropamide leaching and total amounts of napropamide remained in the soil columns after two pore volumes of water has been leached were higher in the amended than the non‐amended soil. The CD was more effective in decreasing napropamide leaching than the POME. There were no effects of DOC on napropamide leaching in all soil treatments.     

Present stage of recent crustal movements and seismicity within Greater Cairo area, Egypt

Greater Cairo and the Nile Delta are considered very important, high-density population areas. The subject of the research work is dealing with recent crustal movements and its relation to seismicity and tectonics setting. A Global Positioning System (GPS) network consisting of 11 benchmarks covering Greater Cairo and the southern part of the Nile Delta was established in 1996. Different campaigns surveyed the network. In this study, we used ten measurements collected during the period from 2004 to 2010. The data were processed using Bernese 5.0 software to derive velocity vectors and principal components of crustal strains. The horizontal velocity varies in average between 3 and 6 mm per year across the network. Rate of the accumulated strains in the southern part of Greater Cairo varies from low to moderate. The low strain rates and low level of earthquakes occurrence in the present interval in the Nile Delta area indicated that the rate of the deformation in this area is small. The result from coupling GPS and seismic data indicates that the southern part of the area is seismo-active area when compared with the other parts in the network areas. The paper gives information about the present state of the recent crustal movements within Greater Cairo area to understand the geodynamics of that area. This study is an attempt to build a basis for further development of seismic catastrophic risk management models to reduce a risk of large catastrophic losses within the important area.     

Forming Jupiter, Saturn, Uranus and Neptune in few million years by core accretion

Giant planet formation process is still not completely understood. The current most accepted paradigm, the core instability model, explains several observed properties of the Solar System’s giant planets but, to date, has faced difficulties to account for a formation time shorter than the observational estimates of protoplanetary disks’ lifetimes, especially for the cases of Uranus and Neptune. In the context of this model, and considering a recently proposed primordial Solar System orbital structure, we performed numerical calculations of giant planet formation. Our results show that if accreted planetesimals follow a size distribution in which most of the mass lies in 30-100 m sized bodies, Jupiter, Saturn, Uranus and Neptune may have formed according to the nucleated instability scenario. The formation of each planet occurs within the time constraints and they end up with core masses in good agreement with present estimations.