Chemometric Differentiation of Oil Families and Their Potential Source Rocks in the Gulf of Suez

Natural Resources Research - An oil–oil and oil–source rock correlation study was carried out using chemometric methods applied to geochemical data for 123 Upper Cretaceous—Lower...     

Assessment of persistent organochlorine pollutants in sediments from Lake Manzala, Egypt

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in surface and core sediment samples collected from Manzala Lake, the largest of the Egyptian coastal lakes. Total concentrations of OCPs and ∑7 PCBs (ICES) in sediments ranged from 0.63 to 31.31 ng/g and 0.26 to 31.27 ng/g, respectively. Geographical distribution indicates that levels of contaminants were significantly higher in areas which are mainly influenced by municipal discharge, indicating significant sources of these compounds in urbanised areas. The composition of DDT and its metabolites suggest old input of DDT. The levels of contaminants in Manzala Lake were similar or lower than those observed in comparable areas worldwide. The profiles of ∑OCPs and ∑PCBs in a core from a site heavily impacted by sewage discharge have highest concentrations in the surface core section indicating recent inputs. Assessment of ecotoxicological risk indicated that sediments in two sites were likely to pose potential biological adverse impact.     

Testing the downscaling ability of a one-way nested regional climate model in regions of complex topography

The downscaling ability of a one-way nested regional climate model (RCM) is evaluated over a region subjected to strong surface forcing: the west of North America. The sensitivity of the results to the horizontal resolution jump and updating frequency of the lateral boundary conditions are also evaluated. In order to accomplish this, a perfect-model approach nicknamed the Big-Brother Experiment (BBE) was followed. The experimental protocol consists of first establishing a virtual-reality reference climate over a fairly large area by using the Canadian RCM with grid spacing of 45 km nested within NCEP analyses. The resolution of the simulated climate is then degraded to resemble that of operational general circulation models (GCM) or observation analyses by removing small scales; the filtered fields are then used to drive the same regional model, but over a smaller sub-area. This set-up permits a comparison between two simulations of the same RCM over a common region. The Big-Brother Experiment has been carried out for four winter months over the west coast of North America. The results show that complex topography and coastline have a strong positive impact on the downscaling ability of the one-way nesting technique. These surface forcings, found to be responsible for a large part of small-scale climate features, act primarily locally and yield good climate reproducibility. Precipitation over the Rocky Mountains region is a field in which such effect is found and for which the nesting technique displays significant downscaling ability. The best downscaling ability is obtained when the ratio of spatial resolution between the nested model and the nesting fields is less than 12, and when the update frequency is more than twice a day. Decreasing the spatial resolution jump from a ratio of 12 to six has more benefits on the climate reproducibility than a reduction of spatial resolution jump from two to one. Also, it is found that an update frequency of four times a day leads to a better downscaling than twice a day when a ratio of spatial resolution of one is used. On the other hand, no improvement was found by using high-temporal resolution when the driving fields were degraded in terms of spatial resolution.     

Apport de l'analyse d'images dans l'étude de l'altération d'un basalte alcalin (Moyen Atlas, Maroc)Contribution of image analysis to the study of weathering process in alkaline basalt (Middle Atlas, Morocco)

Quaternary alkaline basalts of Middle Atlas, are weathered into spheroidal volumes organized into weathering cover. In the profile studied, the study of transformations from a fresh core basalt to the most weathered rinds, has been analysed using BESI images (backscattred electron image analysis). A part from the microscopic analysis of each weatherted basalt, proportions of primary minerals, clays and pore space has been quantified in different stages of weathering. Indeed, in fresh core basalt, weathering is characterized by a first dissolution of the glass, followed by feldspar transformations in twinning plans, cleavages and in micropores inherited from the magmatic and cristallographic history of the rock.

In most basaltic weathered rinds, pore spaces given by the dissolution of the glass, were filled by a mixture of clays and iron products. In these samples, feldspars are completely dissolved giving important porosity occupied by small quantity of halloysite and kaolinite. The olivine and pyroxene transformations are accompanied by weak pore space formation. At the bottom of the soil, this porosity decreases in response to filling by later secondary products which come from the upper part of the soil by weathering solutions.     

Sulfur based hazardous waste solidification

Existing uses for sulfur are relatively advanced and offer limited opportunities to consume significant new supplies. Currently, sulfur is in net surplus on a global basis, and with environmental regulations, greater sulfur recovery from petroleum and gas processing is mandated. The outlook is clear: there will be substantial and growing surpluses in global sulfur supply in the foreseeable future. Sulfur prices are likely to be under pressure, and producers could face substantial and growing disposal fees. Therefore, new markets must be found for sulfur to avoid disposal crises. One potential new market is the production of sulfur-solidified concrete. This is a thermoplastic composite of mineral aggregates bound together with chemically modified sulfur. The product is more durable than Portland cement. There may be monetizeable benefits in reducing greenhouse gas emissions that would enhance the attraction of sulfur solidified cement applications. The main objective of this study is to evaluate experimentally the potential use of sulfur as a solidifying agent for hazardous waste. To achieve this objective, the study reviewed the sulfur concrete literature, analyzed locally produced sulfur, evaluated a number of sulfur polymer modifiers and physical stabilizing agents, designed a set of experiments and evaluated the produced product for its hydro-mechanical-chemical properties. The results indicated that the manufactured sulfur polymer cement is an excellent candidate for: waste management practices such as solidification/stabilization of hazardous waste; barrier systems for landfilling of hazardous waste; and waste water treatment plants.     

Modelling flash flood propagation in urban areas using a two-dimensional numerical model

This paper reports on the numerical modelling of flash flood propagation in urban areas after an excessive rainfall event or dam/dyke break wave. A two-dimensional (2-D) depth-averaged shallow-water model is used, with a refined grid of quadrilaterals and triangles for representing the urban area topography. The 2-D shallow-water equations are solved using the explicit second-order scheme that is adapted from MUSCL approach. Four applications are described to demonstrate the potential benefits and limits of 2-D modelling: (i) laboratory experimental dam-break wave in the presence of an isolated building; (ii) flash flood over a physical model of the urbanized Toce river valley in Italy; (iii) flash flood in October 1988 at the city of Nîmes (France) and (iv) dam-break flood in October 1982 at the town of Sumacárcel (Spain). Computed flow depths and velocities compare well with recorded data, although for the experimental study on dam-break wave some discrepancies are observed around buildings, where the flow is strongly 3-D in character. The numerical simulations show that the flow depths and flood wave celerity are significantly affected by the presence of buildings in comparison with the original floodplain. Further, this study confirms the importance of topography and roughness coefficient for flood propagation simulation.     

Impacts of a Ghg-Induced Climate Change on Crop Yields: Effects of Acceleration in Maturation, Moisture Stress and Optimal Temperature

The present study involves using the Canadian Climate Centre (CCC) climate change scenario to evaluate the impacts of a CO₂-induced climate change on agriculture in Québec and vicinity. Climate change using the CCC General Circulation Model (GCM) data are fed into a crop model (FAO) so as to gauge the changes in agroclimatic factors such as growing season length and growing degree days, and subsequently potential yield changes for a variety of cereal (C₃ and C₄), leguminous, oleaginous, vegetable and special crops, for twelve major agricultural regions in southern Québec. Our results show that depending upon the agricultural zone and crop type, yields may increase (ex. corn and sorghum by 20%) or decrease (ex. wheat and soybean by 20 to 30%). Also, these crop yield changes appear to be related to acceleration in maturation rates, mainly to change in moisture stress and to shifts in optimal thermal growth conditions. These possible shifts in agricultural production potentials would solicit the formulation of appropriate adaptation strategies.     

Groundwater vulnerability and risk mapping of the Angad transboundary aquifer using DRASTIC index method in GIS environment

The protection and preservation of groundwater resources are compulsory, particularly in the arid and semiarid countries where the waters are scarce. The effects of increasing urbanization, economic development, and agricultural activities, along with the erratic and scarce rainfall, contribute to the quantitative and qualitative deterioration of these resources. This paper attempts to produce groundwater vulnerability and risk maps for the Angad transboundary aquifer using DRASTIC model. The data which correspond to the seven parameters of the model were collected and converted to thematic maps in Geographic Information System environment. The modified DRASTIC map, which is the summation of the DRASTIC index and the network fractures maps, shows two degreed of vulnerability: medium and high. This map is then integrated with a land use map to assess the potential risk of groundwater to pollution in the Angad transboundary aquifer. There are three risk zones that are identified: moderate, high, and very high.     

浙江花岗岩的工程岩石学研究

对浙江省花岗岩的岩相学特征及力学性质进行了研究以确定它们之间的关系.矿物学研究显示出花岗岩的交代蚀变特征,这可以反映在岩石的力学性质上.岩石材料的物理性质决定其工程学性质,在相关定量参数确定的情况下,可以预测岩石材料的工程学性质.镜下观察、硬度、密度、孔隙度及点负荷强度均可作为所研究花岗岩的定量参数.上述每个因素都可提供岩石工程学的可靠预测.岩石的物理性质受岩石成分及蚀变状态控制,而岩石的工程学性质和力学特征是其物理性质的函数.