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21.
Malki Mouna Choukr-Allah Redouane Bouchaou Lhoussaine Ait Brahim Yassine Hirich Abdelaziz Barbara Reichert 《Arabian Journal of Geosciences》2016,9(10):566
The Chtouka-Massa area in Southern Morocco has shown an increase in water scarcity during the last decades, caused mainly by withdrawal of water resources aggravated by agricultural intensification and climate change impacts. To better understand the changes of groundwater quality, a sampling campaign was conducted in many wells during March 2015 and compared to historical chemical data from the hydraulic basin agency, as well as previous studies performed at Ibn Zohr University. All data were used to assess the spatial-temporal evolution of nitrate and salinity relevant to the recent sampling. This paper describes the current state of groundwater quality in the Chtouka-Massa zone with an overview of different sources of water mineralization and the nitrate evolution in an agricultural area. Our results indicate a general increase in mineralization from the north to the south, and from the east to the west. The plain, dominated by farms, shows a relatively high conductivity (up to 2000 μS/cm), while in both costal area and Anti-Atlas Mountain the water salinity shows a gradient increase from the north to the south. However, the highest electrical conductivity is observed along the Massa River. The water type is bicarbonate, chloride, and sodium for farm samples, while from the other parts, it is mostly dominated by chloride and sodium. The spatial-temporal analysis of nitrates generally shows an increasing trend. However, the levels remain overall lower than the limit. The temporal evolution of control points set by the hydraulic agency shows a decreasing trend decline that can be explained by the improvement of agriculture practices, including the conversion towards drip irrigation mode. Different chemical tracers highlighted some processes involving the changes of mineralization of groundwater (e.g., irrigation water return, marine intrusion, and water/rock interaction). The results will be used to improve water management in this area showing water quality degradation. 相似文献
22.
Geotectonics - Tunisia had been the place of various tectonic episodes which have drawn the actual structural map of the country. The Neogene period was the most active period in which the... 相似文献
23.
The former agro-pastoral system which prevailed in the Tunisian Sahara had developed a pastoral resource management which preserved the rather fragile ecological equilibrium. Nowadays in the Tunisian Sahara nearly all former nomads are settled around the villages and irrigated areas which were created with the official aim of utilizing the Sahara. The sedentarization of the nomads has provoked two phenomena: a concentration and an increased density of population around the newly founded oases on the one hand and a depopulation of the more remote steppes on the other hand. Actually this demographic disequilibrium threatens the ecological equilibrium which existed in the past. It has caused a multiplication of the stocking of the actual pastures and increases the risk of degradation of the peripheral and easily accessible grazing-grounds. It exercises an excessive pressure on the environment through the intensive human activities and the satisfaction of new needs. This pressure manifests itself in the enlargement of the circles of degradation around the oases and the intensification of aeolian dynamics. A regeneration of the former organically developed eco-system is impossible without conscious reference into the local traditions and without consideration of the complexity of interelationship of the various factors. 相似文献
24.
International Journal of Earth Sciences - New field observations carried out in northeastern Tunisia (Kechabta Neogene basin) allowed us to clarify and pinpoint the chronology of the folding phases... 相似文献
25.
Groundwater vulnerability and risk mapping of the Angad transboundary aquifer using DRASTIC index method in GIS environment 总被引：1，自引：0，他引：1
Mimoun Boughriba Alae-eddine Barkaoui Yassine Zarhloule Zakariae Lahmer Boubker El Houadi Massimo Verdoya 《Arabian Journal of Geosciences》2010,3(2):207-220
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. 相似文献
26.
Yahia E.-A. Mohamedzein Mohammed Y. Al-Aghbari Ramzi A. Taha 《Geotechnical and Geological Engineering》2006,24(6):1767-1780
This paper presents experimental results on the use of incinerator ash in stabilizing desert sands for possible use in geotechnical
engineering applications. The incinerator ash was added in percentages of 2, 4, 8, 10 and 12%, by dry weight of sand. Laboratory
tests such as compaction, unconfined compression, shear box and hydraulic conductivity were performed to measure the engineering
characteristics of the stabilized material. The results showed substantial improvements in unconfined compressive strength
and shear strength parameters (c and φ). Thus, incinerator ash can be used to improve the shear strength characteristics of desert sands. The permeability of the
sand–incinerator ash mixture was relatively low. 相似文献
27.
May-June precipitation reconstruction of southwestern Anatolia, Turkey during the last 900 years from tree rings 总被引：1，自引：0，他引：1
A May-June precipitation reconstruction (AD 1097-2000) has been developed for southwestern Anatolia in Turkey, the longest reported to date in this region. The reconstruction was derived from a regional Juniperus excelsa chronology that was built from material sampled at four sites in the Antalya and Mersin Districts. The regional tree-ring chronology accounts for 51% of the variance of instrumentally observed May-June precipitation. The years AD 1518 to 1587 are the most humid period in the reconstruction, coinciding with a major shift in European climate. The driest 70-year period in the reconstruction is AD 1195 to 1264. The period AD 1591-1660 represents the third driest and was characterized by instability climatically, politically, and socially in Anatolia. 相似文献
28.
Antimicrobial-resistance of Streptococcus pneumoniae isolated from the Lebanese environment 总被引：4，自引：0，他引：4
The aim of this study was to isolate and molecularly characterize Streptococcus pneumoniae in samples collected from the aquatic environment in Lebanon. For this purpose, 57 samples of ground waters, sea water, sediments and crabs were collected. Biochemical tests as well as PCR were used for further identification and molecular characterization of 46 suspected isolates using specific primers for the lytA-gene and protein 2B-gene. The confirmed isolates were evaluated for their antimicrobial resistance, using the minimum inhibitory concentration method. Crab samples exhibited a high contamination level of an average count of 8.2 x 10(4)CFU/g. In water samples, the highest contamination was recorded near a coastal landfill with a bacterial count of 1.8 x 10(3)CFU/ml whereas the lowest bacterial counts (non detectable) were observed in ground water samples. Twenty out of the 46 suspected isolates came from sea water, and 17 out of those were characterized by PCR as S. pneumoniae. Testing the antimicrobial resistance of the 20 isolates to various antimicrobials showed that all sea water isolates were resistant to vancomycin, gentamicin, and oxacillin (100%), whereas 62.5% were resistant to clindamycin, and only 25% were erythromycin resistant. Resistance rates were higher in the case of fresh water samples, with 57% resistance to erythromycin, and 100% resistance to vancomycin, gentamicin, clindamycin and oxacillin. Alternatively, all tested crab isolates were susceptible to erythromycin. However, they showed a high resistance of 80% against vancomycin, gentamicin, clindamycin and 100% against oxacillin. 相似文献
29.
Ben Ameur W de Lapuente J El Megdiche Y Barhoumi B Trabelsi S Camps L Serret J Ramos-López D Gonzalez-Linares J Driss MR Borràs M 《Marine pollution bulletin》2012,64(2):241-251
The aim of the study was to evaluate the impact of environmental contaminants on oxidative stress, genotoxic and histopathologic biomarkers in liver of mullet (Mugil cephalus) and sea bass (Dicentrarchus labrax) collected from a polluted coastal lagoon (Bizerte Lagoon) in comparison to a reference site (the Mediterranean Sea). Antioxidant enzyme activities were lower in fish from the polluted site compared with fish from the reference site, suggesting deficiency of the antioxidant system to compensate for oxidative stress. DNA damage was higher in both fish species from the contaminated site indicating genotoxic effects. The liver histopathological analysis revealed alterations in fish from Bizerte Lagoon. Hepatocytes from both fish species featured extensive lipid-type vacuolation and membrane disruption. Results suggest that the selected biomarkers in both fish species are useful for the assessment of pollution impacts in coastal environments influenced by multiple pollution sources. 相似文献
30.
Niklas Höhne Christopher Taylor Ramzi Elias Michel Den Elzen Keywan Riahi Claudine Chen 《Climate Policy》2013,13(3):356-377
This article provides further detail on expected global GHG emission levels in 2020, based on the Emissions Gap Report (United Nations Environment Programme, December 2010), assuming the emission reduction proposals in the Copenhagen Accord and Cancun Agreements are met. Large differences are found in the results of individual groups owing to uncertainties in current and projected emission estimates and in the interpretation of the reduction proposals. Regardless of these uncertainties, the pledges for 2020 are expected to deliver emission levels above those that are consistent with a 2°C limit. This emissions gap could be narrowed through implementing the more stringent conditional pledges, minimizing the use of ‘lenient’ credits from forests and surplus emission units, avoiding double-counting of offsets and implementing measures beyond current pledges. Conversely, emission reduction gains from countries moving from their low to high ambition pledges could be more than offset by the use of ‘lenient’ land use, land-use change and forestry (LULUCF) credits and surplus emissions units, if these were used to the maximum. Laying the groundwork for faster emission reduction rates after 2020 appears to be crucial in any case. 相似文献