Northeast Tunisia Research Articles

Paleoenvironmental and ecological changes during the Eocene-Oligocene transition based on foraminifera from the Cap Bon Peninsula in North East Tunisia

Biostratigraphic analysis of the Eocene-Oligocene transition (E-O) at the Menzel Bou Zelfa and Jhaff composite section in the Cap Bon Peninsula (North East Tunisia) allowed us to recognize a continuous planktic foraminiferal biozonation: E14 Globigerinatheka semiinvoluta Zone, E15 Globigerinatheka index Zone, E16 Hantkenina alabamensis Zone and O1 Pseudohastigerina naguewichiensis Zone. A quantitative study of benthic and planktic foraminifera assemblages was carried out and the richness and diversity of foraminifera allowed us to reconstruct the paleoenvironmental evolution from marine to terrestrial environments. From the Eocene E14 Zone, the foraminiferal association characterizes a relatively warm climate with considerable oxygen content and a dominance of keeled and spinose planktic foraminifera, which became extinct at the E/O boundary, possibly due to cooling of the planktic environment. Nevertheless, the small benthic foraminifera do not show an extinction event at the Eocene/Oligocene (E/O) boundary, indicating that the benthic environment was not significantly affected. In the basal Oligocene O1 Zone, the benthic environment changes to a shallower setting due to cooling of the climate. These changes generated a remarkable dominance of globular forms in the planktic environment. Small benthic foraminifera apparently have a gradual extinction event, or more likely a gradual pattern of local disappearances, that could have been caused by the Oi1 glaciation.

GIS-based analysis of the Stream Length-Gradient Index for evaluating effects of active tectonics: a case study of Enfidha (North-East of Tunisia)

Our study aims at calculating morphometric indices through the recourse to the Digital Elevation Model (DEM) and its attributes (hydrographic networks, watersheds, and reliefs). This quantitative measurement is used for the morphotectonical analysis of the Enfidha area (North-East of Tunisia) in the GIS environment and statistical platform. The Enfidha area is selected to analyze and identify neotectonic morphostructures on basis of the morphological evolution of the landscape. The coastal Enfidha plain is part of the Tunisian Sahel that is marked by its instability and frequent earthquakes that prove the presence of the recent deformation and active subsurface faults. This morphometric modeling in the geological investigation area reflects the morphotectonic spatial evolution in the Quaternary basins areas. Stream length (SL) proposed by Hack (1973) and denominated by Etchebehere et al. (2004) Revista do Instituto de Geociencias USP, Serie Cientifica, Sao Paulo 4(2):43–56 as the RDE index (Relation Declivity Extension) was used for application in the studies of neotectonic approach. RDE index is one of the morphotectonical indices that designates the tectonics anomalies in rivers. The variability in (RDE) values can indicate both a lithology resistance towards erosion and major active subsurface faults or low slope. Our geostatistical method is required to obtain RDE index maps based on lithological filtrations and value interpolations which are calculated in a drainage line network. This method calculates, measures, and validates spatial distribution of hack RDE index through a high statistical accuracy in a quantitative anomalies study. The RDE anomaly maps of the study area mirror the concurrence between anomaly zones, major active subsurface E-W faults, and local geological discontinuities related to neotectonical activities that affect the hydrographic network. This study proves that the RDE index can be especially used to detect the influence of active large-scale faults on the landscape evolution.

Style and timing of tectonic deformation across the Bou Arada-El Fahs troughs system, Northeast Tunisia: integration in the structural evolution of Atlas fold and thrust belt

The Bou Arada-El Fahs troughs system is a particularly E-W trending collapsed structure with the manifestation of normal-to-strike-slip faults. A combined multi-source and multi-scalar structural and geophysical investigation provides important insights on the geometry and the kinematics evolution of trough systems in the Atlas of Tunisia. New data, as well as a reappraisal of available data show that the studied troughs system is established during three main successive events: the Oligocene-Miocene, the Tortonian, and the Plio-Quaternary events. The goal of this paper is to present the structural evolution of the study area, on a pre-structured substratum. The structural evolution progressed from an extensional event, manifested by the formation of grabens, passing by an episode of reactivation of faults related troughs in strike-slip motion during the Atlas compression accompanied by an en-echelon folding in foot wall and hanging wall. These results acquired and presented in the following order: We will initially present the geological context by integrating and correlating the lithostratigraphic data. We continue by examining the geometry and kinematics of structure-related troughs via the detailed geological mapping, the interpretation of available 2D seismic data, and the interpretation of processed fault slip data. This integrated geological and geophysical study allows a better understanding of the BETS, and makes it possible to propose a new geometrical and kinetic model of the establishment of trough structure in the Tunisian Atlas.

Biological characterization of two species of Littorinidae: Melarhaphe neritoides (Linnaeus, 1758) and Echinolittorina punctata (Gmelin, 1791) along the rocky coasts of the North and North-East of Tunisia

Biological characterization of two species of Littorinidae: Melarhaphe neritoides (Linnaeus, 1758) and Echinolittorina punctata (Gmelin, 1791) along the rocky coasts of the North and North-East of Tunisia

Hydro-mechanical Properties of Highly porous Limestone Rock used for Historic Monuments in North-East Tunisia

This paper deals with the study of the physical and hydro-mechanical characteristics of a porous limestone rock. It concerns a historic rock located at El-Haouaria artificial caves on the seacoast in the Northeast of Tunisia. The rock, object of study in this work, has undergone serious alterations, thus compromising the safety of the monuments. This paper focuses on the mechanical behavior of a sedimentary rock with a variable porosity; covering a wide range varying from 25% to 55%. This study is interested in identifying the mineralogical composition and the microscopic structure of the main rocks constituting the historic monument. Several tests were carried out and they showed that the rock’s mineralogical composition was calcite and quartz. The grain dimensions constituting the rock are variable. Its porosity is inter-granular and connected. This porosity changes over time due to weather conditions. Unconfined compressive tests and tensile tests were carried out on several samples with various porosities and in some cases in various saturation states. The performed tests showed the effect of both porosity and water content (suction) on strength characteristics. However, despite the rock’s dependency on the water content, the role of porosity remains more emphasized. Then, porosity seems to be the main factor affecting resistance properties due to the increase of the porosity and due to its variation as a source of humidity. A ‘’Li and Aubertin’s Model’’ was applied to predict the compression and tensile strength dependency on porosity. It highlighted a strong concordance between experimental and analytical model results. All strength characteristics evolutions with porosity and suction make up essential results obtained in this study. This will provide us with the required input data for modeling in order to predict cave structure degradation and eventually to monitor crack propagation.

Assessment of organic pollutants (PAH and PCB) in surface water: sediments and shallow groundwater of Grombalia watershed in northeast of Tunisia

Toxic organic compounds in wastewater are serious threats for both human and environment healthy states. This study investigates the potential sources of surface water, sediment and groundwater pollution by polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyl (PCBs) as discharged by wastewater into the River of Oued El bey in northeastern Tunisia. Analysis indicates that the concentration of PAHs and PCBs are high in wastewater and vary from 0.37 to 0.83 mg/L and from 0.28 and 1.18 mg/L, respectively. The spatial distribution of PAHs and PCB in surface water showed a variation between 0.37 to 9.91 mg/L and between 0.1 to 0.47 mg/L, respectively. However, the quality of surface water is changed after wastewater evacuation at Oued Tahouna. The determination of PAH and PCB pollutants in groundwater shows a great interest in the development of water resources. The Concentration of these pollutants varying from 0.0204 to 1.93 mg/L and from 0.0052 to 0.196 mg/L, respectively. For PAH, analysis reveals also that naphtelene, fluorene, anthracene and chrysene are the most detected PAHs compounds in water and sediment samples while benzo[b]fluoranthene and benzo[a]pyrene are less present and in trace level. Higher concentrations of PAHs and PCBs are found in samples taken close to industrial areas of Bouargoub and Soliman, and wastewater discharge locations in Soliman. Analysis of the spatial distribution of PAHs and PCBs clearly link their higher concentration in water and sediments to wastewater and manufacturing discharges in the study area. In surface sediment, the organic pollutants are present. The cluster analysis for organic pollutants in different state and different matrix highlight a relationship between the wastewater evacuation and the water qualities which confirmed the direct response of the pollution sources on the surface water and groundwater organic pollution quality.

Myxosporea (Cnidaria : Myxozoa) infecting the saddled seabream Oblada melanura (L. 1758) (Teleostei : Sparidae) and the painted comber Serranus scriba(L. 1758) (Teleostei : Serranidae) in Tunisia.

First parasitological surveys of Myxozoa are performed on the sparid saddled seabream Oblada melanura (Linnaeus, 1758) and the serranid painted comber Serranus scriba (Linnaeus, 1758) caught from the Bay of Bizerte and the Gulf of Tunis respectively in Northeast Tunisia, Western Mediterranean. In this study, 6 bivalvulid myxosporean species belonging to the 3 genera Ceratomyxa Thélohan, 1892, Myxodavisia Zhao, Zhou, Kent & Whipps, 2008 and Zschokkella Auerbach, 1910, are isolated infecting their hosts. Two species Ceratomyxa sp. 1 ex O. melanura (Prevalence (P) = 36%) and Ceratomyxa sp. 2 ex O. melanura (P = 13%) infected the saddled seabream and four species Ceratomyxa sp. 1 ex S. scriba (P = 11.7%), Ceratomyxa sp. 2 ex S. scriba (P = 6.7%), Myxodavisia sp. (P = 8.3%) and Zschokkella sp. (P = 5.6%) infected the painted comber. These myxosporeans differ, in vegetative stages and/or in mature spores, from all the previously known congeneric species, and are described here on the basis of their morphological and morphometric features, their host and tissue specificities and their biogeographical distribution. This is the first report of myxosporean infections in O. melanura and S. scriba. The occurrence of two ceratomyxid species in each host species supports that the genus Ceratomyxa is host-specific not only in sparids but also in serranids, which agrees with data previously obtained from Sparidae in Mediterranean Sea and from Serranidae in GBR, Australia. A member of the myxosporean genus Myxodavisia is recorded from the Mediterranean Sea for the first time, and Zschokkella spp. infections have not previously been recorded from a host in Serranidae. During the examination, a several cases of Co-infection among myxosporeans, both with two and three species, are provided and statistically studied. Indeed, 5% of the breams and 9.4% of the combers are infected with more than one myxosporean parasite. The relationship between myxosporean infections and some biological parameters are pointed out. A higher prevalence of myxosporean infection is coincided with the peak period of spawning activity in May-June for S. scriba. For both hosts, analysis using Fulton's condition factor (K) has revealed no significant difference between infected and non-infected fishes. Clinically, no external signs of disease have been occurred in infected hosts, but some changes in the bile fluid, colour, and viscosity and in the gall bladder 's tissue are examined in S. scriba.

Effect of soil moisture on trace elements concentrations using portable x-ray fluorescence spectrometer

Portable X-ray fluorescence (PXRF) technology can offer rapid and cost-effective determination of the trace elements concentrations in soils. The aim of this study was to assess the influence of soil moisture content under different condition on PXRF measurement quality. For this purpose, PXRF was used to evaluate the soil elemental concentrations for Ca, Mg, Cd, Cr, Cu, Ni, Zn, P, Fe, Mn and Pb in 60 samples in a perimeter irrigated with treated wastewater (Cebala Borj Touil, North-east Tunisia). Scanning was conducted under four moisture conditions: in-situ , dried soil at 105°C, 40% moisture content soil and saturated soil. All were then compared relatively to dried sample scans. As expected, the relationship between dried vs both in-situ and 40% moisture content elements concentrations were linear. However, PXRF readings from saturated samples were significantly underestimated compared to the measurements on dry samples. Furthermore, soil moisture content caused a significant under-reporting of elemental concentrations compared to the scanning on dry samples. PXRF acted differently for each element following the moisture content of soil. In fact, attenuation coefficient σ of Cr, Fe and Mn were the most affected by saturation of soil samples, whilst Ca, Mg and Ni were more affected for 40% moisture content while Cd, Pb, Zn, Cu and P were affected for in-situ measurements . Correction equations enhanced the error produced by the water influence moisture content and corrected PXRF measurements.

Evaluation of Chlorpyrifos Resistance and Biochemical Mechanisms of Culex pipiens in Five Localities of Grand Tunis Area, Northeast Tunisia

Five Culex pipiens samples were collected at preimaginal stages from breeding sites in 5 localities of Grand Tunis area, Northeast Tunisia, between March 2002 and November 2005. Larvae were used for bioassays using ethanol solutions of chlorpyrifos and propoxur insecticides. All samples were resistant to chlorpyrifos (RR>1, p 1,000-fold) were recorded in samples # 2, 4, and 5. Our synergist study showed that the increased detoxification by EST (and/or GST) had only a minor role in the chlorpyrifos resistance, although several overproduced esterases, known to be involved in the OPs resistance, were detected in all the resistant field samples. The mortality due to propoxur was significantly correlated with the LC50 of chlorpyrifos and indicated an insensitive AChE.

The Tyrrhenian Calcareous Sandstone Quarries In The Eastern Coast Of The Cap Bon Peninsula (Northeast Tunisia)

Activities related to the extraction and exploitation of natural resources are varied in Tunisia. But the most important numerically and spatially are stone quarries, which, once abandoned, are considered as low-value land and, in most cases, become an environmental nuisance, even though they have the potential to be of great natural, scientific, or cultural interest. The abandoned calcareous sandstone quarries that were opened in the Tyrrhenian barrier beach on the eastern coast of the Cap Bon peninsula (northeast Tunisia) illustrate this. The industrial quarrying started in the 1970s, but more detailed observations of the site reveal that the recent quarries often overlap with older ones dating back to antiquity. The site is very rich in archaeological remains and offers the opportunity not only to analyze and understand the variety of the landscape, but also the evolution of extraction techniques over time. This paper is devoted to sharing better knowledge and valuation of the quarries and their heritage, landscape, and environmental assets. It also aims to provide ideas for reintegrating them into their environment and making them useful spaces for the towns of the east coast of the peninsula, which are undergoing very rapid urbanization.

Fuzzy Logic Energy Management Strategy of a Hybrid Renewable Energy System Feeding a Typical Tunisian House

This paper proposes an energy management strategy for hybrid power system HPS which is composed of a photovoltaic generator, wind turbine, fuel cell generator and NaS battery storage device, feeding a type house. This strategy is based on Fuzzy Logic Control technique. The hybrid power system is sized to provide the energy demand of the inhabitants of the house and if there is an extra power generation, it would be sold to the grid. Using Simulink, we develop the different scenarios in order to use the fuel cell or battery during critical periods. The methodology developed was applied under the climatic conditions (wind speed, solar irradiation and temperature) measured at a site located in the northeast of Tunisia.

Structural Interpretation of Lineaments Uses Satellite Images Processing: A Case Study in North-Eastern Tunisia

This paper presents a lineament detection method using multi-band remote sensing images. The main objective of this work is to design an automatic image processing tool for lineament mapping from Landsat-7 ETM + satellite data. Five procedures were involved: 1) The Principal Component Analysis; 2) image enhancement using histogram equalization technique 3) directional Sobel filters of the original data; 4) histogram segmentation and 5) binary image generation. The applied methodology was contributed in identifying several known large-scale faults in the Northeast of Tunisia. The statistical and spatial analyses of lineament map indicate a difference of morphological appearance of lineaments in the satellite image. Indeed, all the lineaments present a specific organization. Five groups were classified based on three orientations: NE-SW, E-W and NW-SE. The overlapping of lineament map with the geologic map confirms that these lineaments of diverse directions can be identified and recognized on the field as a fault. The identified lineaments were linked to a deep faults caused by tectonic movements in Tunisia. This study shows the performance of the satellite image processing in the analysis and mapping of the accidents in the northern Atlas.

Determination the Origin of Mineralization in the Coastal Aquifer Northeast Tunisia by Isotopic Method

A geochemical and isotopic techniques were undertaken to characterize groundwater in Northeast Tunisia. Hydrogeochemical investigations demonstrated that groundwater can be classified into different water facies. The Ras Djebel-RafRaf aquifer showed a (Ca-Cl-SO4) and (Na-Cl-NO3) water type. Data inferred from 18O and deuterium isotopes in groundwater samples indicated recharge with modern rainfall. Water characterized by lower δ18O and δ2H values is interpreted as recharged by non-evaporated rainfall originating from Mediterranean air masses from Mediterranean air masses at higher altitude. However, water with relatively enriched δ18O and δ2H contents is thought to reflect the occurrence of an evaporation process related to the long-term practice of flood irrigation.

Pirimiphos-Methyl Resistance Status of Field Populations of Culex pipiens (Diptera: Culicidae) From Grand Tunis Area, Northeast Tunisia

Mosquito species are responsible for the transmission of many parasitic diseases and their control leads to the phenomenon of resistance to insecticides. Five Culex pipiens samples were collected from various localities of Grand Tunis area, Northeast Tunisia, between June 2003 and November 2005. All the studied samples were resistant to pirimiphos methyl (organophosphorus insecticide). Our results showed the implication of insensitive acetylcholinesterase and overproduced esterases in the resistance of the Tunisian populations of Culex pipiens. Results were discussed in relation to resistance mechanism.

Characterization of Recharge Mechanisms and Sources of Groundwater Salinization in Ras Jbel Coastal Aquifer (Northeast Tunisia) Using Hydrogeochemical Tools, Environmental Isotopes, GIS, and Statistics

Groundwater is among the most available water resources in Tunisia; it is a vital natural resource in arid and semiarid regions. Located in north-eastern Tunisia, the Metline-Ras Jbel-Raf Raf aquifer is a mio-plio-quaternary shallow coastal aquifer, where groundwater is the most important source of water supply. The major ion hydrochemistry and environmental isotope composition (δ18O, δ2H) were investigated to identify the recharge sources and processes that affect the groundwater salinization. The combination of hydrogeochemical, isotopic, statistical, and GIS approaches demonstrates that the salinity and the groundwater composition are largely controlled by the water-rock interaction particularly the dissolution of evaporate minerals and the ion exchange process, the return flow of the irrigation water, agricultural fertilizers, and finally saltwater intrusion which started before 1980 and which is partially mitigated by the artificial recharge since 1993. As for the stable isotope signatures, results showed that groundwater samples lay on and around the local meteoric water line LMWL; hence, this arrangement signifies that the recharge of the Ras Jbel aquifer is ensured by recent recharge from Mediterranean air masses.

Evaluation of Fenitrothion against Culex pipiens (Diptera: Culicidae) Larvae in Grand Tunis Area of Tunisia

Resistance toward 2 insecticides (fenitrothion and propoxur) was analyzed in 5 samples of Culex pipiens populations collected from various localities of Grand Tunis area, Northeast Tunisia. All studied samples were resistant to fenitrothion and propoxur insecticides. The study of esterase’s activities showed the existence of five overproduced esterases: C1, A1, A2-B2, A4-B4 (and/or A5-B5) and B12. One or several esterases were detected in the studied samples. We also showed that the resistance to fenitrothion was correlated with the propoxur resistance indicating that modifications of the target, the AChE 1, can be involved in the OP resistance. These results should be considered in the current mosquitoes control programs in Tunisia.

Quantification of Groundwater - Saline Surface Water Interaction in a Small Coastal Plain in North-East Tunisia using Multivariate Statistical Analysis and Geophysical Method.

Amultivariate statistical analysis used with geophysical investigation enabled the assessment of interaction between saline surface water and groundwater in the coastal plain of Wadi Al Ayn and Daroufa in CapBon peninsula, north-east Tunisia. The application of the Principal Component Analysis (PCA) identified the end members which contribute to groundwater recharge: the wastewater infiltrated from Wadi Al Ayn, the oilfield brine infiltrated to the aquifer through the sandy bed of Wadi Al Ayn, the intruded seawater near Wadi Daroufa in the downstream region and the fresh groundwater flowing from the upstream region. The contribution of wastewater in groundwater recharge varies from 1.4% in the upstream region of Wadi Al Ayn to 77% near its downstream part. The fraction of oilfield brine mixed with groundwater in the alluvial aquifer under Wadi Al Ayn varies from 1% to 13%; whereas the fraction of intruded seawater into the coastal part of the aquifer near Daroufa region varies from 2% to 21%.

A GIS-based soil erosion prediction using the Revised Universal Soil Loss Equation (RUSLE) (Lebna watershed, Cap Bon, Tunisia)

Soil erosion is a natural process causing grave land degradation problems. In Tunisia, soil erosion represents a serious environmental problem. Both man-made and natural phenomenon is reducing acres of agricultural land. The problem of soil erosion by water is very critical in Lebna watershed. In fact, Lebna is a town in the northeast of Tunisia and it seems high time to protect water and ground resources and to prevent the Lebna dam situated in the downstream from silting. In this context, the application of geographic RUSLE model using the techniques of geographic information system (GIS) and remote sensing has made it possible to assess the estimation of the soil erosion risk at the targeted watershed. This model is composed of several factors associated with climate, topography, soil and vegetation. The spatial distribution of annual average rate of soil loss resulting of this methodology shows an average of 24 ton/ha/year. Consequently, this method based on a combination of RUSLE as erosion model gave very similar results with bathymetric measures performed by Institute of Research for Development. It was about 29 ton/ha/year. Accordingly, Lebna watershed belongs to a zone of rather a steep erosive potential knowing that the maximum acceptable limit value of the erosive potential estimated is 12 ton/ha/year (Roose in Introduction a la gestion conservatoire de l’eau, de la biomasse et de la fertilite des sols (GCES). FAORome, 1994). The results have shown that Lebna watershed has a serious risk on soil erosion on sloping land. The highest values are mainly associated with the steep slopes, poor conservation practices, low vegetation cover and high rainfall. The final soil loss map can be thus a base to plan appropriate strategies for decision-makers to avoid soil erosion risks and consequently to lengthen dam life.

Pollen spectrum in Northern Tunis, Tunisia

This study has been focused on airborne pollen concentration in Northern Tunis. Pollen has been detected by a volumetric Hirst-type spore trap. This suction sampler was placed for two hydrologic years in the area of Mornag, northeastof Tunisia (36°40N; 10°17E). Fifty-two taxa were identified with heterogeneous daily pollen concentrations and a dominance of anemophilous plants. The main pollen types detected in the atmosphere were Olea europaea (38.7 and 20.75%), Cupressus (33.57 and 55.4%), Urticaceae (9.22 and 12.24%), Poaceae (3.55 and 3.32%), Mercurialis annua (2.96 and 1.6%) and Amaranthaceae (2.49 and 1.55%). The monthly pollen spectrum indicated a seasonal periodicity of airborne pollen with the main pollen season during spring. Two pollen seasons have been observed during these hydrologic years, due to both Cupressus and Amaranthaceae airborne pollen is represented during winter or spring, and also during autumn and late summer, respectively. Other pollen types represent a long pollen season, i.e., Urticaceae, starting in autumn and following until late spring. Daily pollen concentration showed a different behavior during the flowering season between both years, observing differences related to pollen index. Correlation between daily pollen concentrations of the dominant taxa showed a positive and significant correlation between airborne pollen concentrations of spring-pollinated taxa and mean temperature, but negative with maximum temperature, humidity and rainfall. In the case of minimum temperature, a different response, positive for trees and negative for herbaceous plants, has been observed.

Adsorption of an anionic textile dye from wastewater by bentonitic clay mineral

In this paper, adsorptive performance of natural clay has been investigated as a potential reactive dye adsorbent, on the basis its promising physical-chemical and morphological properties which were compared to several previous works. Sample used in this work, collected from Grombalia (North-East of Tunisia), has been characterized at the first time. Following its physicochemical study, this sample has been employed and tested as an ion exchange medium, for an anionic toxic textile dye removal from textile effluent and watercourse. Physicochemical experiences confirm that the used clay mineral was a clay of bentonite type having the following structure formula Ca0.014Na0.404K0.16(Si7.65Al0.35)(Al2.910Fe0.762Mg0.376)O22. Dye removal from aqueous solution onto raw (GRb) and purified (GRp) bentonite was investigated, using a batch adsorption technique, as a function of various parameters such as initial dye concentration, contact time, temperature and pH medium. Results prove that the amount of dye removed by the raw and the purified bentonite was found to be around 142 and 294 mg/g respectively. According to previous works this quantity of dye removed from aqueous solution (294 mg/g) reach the anionic exchange capacity of bentonitic sample. A contact time (clay/dye solution) of 20 to 30 min was sufficient to reach adsorption equilibrium. Adsorption rate was fast, more than half of the adsorbed dye was removed from the aqueous solution (C = 10–4 M). The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. Experimental data fit well with Freundlich model (the correlation coefficients, R 2, was found to be equal to 0.98).