Northwest Libya Research Articles

Groundwater Overexploitation and Seawater Intrusion in Coastal Areas of Arid and Semi-Arid Regions

The exploitation of groundwater resources is of high importance and has become very crucial in the last decades, especially in coastal areas of arid and semi-arid regions. The coastal aquifers in these regions are particularly at risk due to intrusion of salty marine water. One example is the case of Tripoli city at the Mediterranean coast of Jifarah Plain, North West Libya. Libya has experienced progressive seawater intrusion in the coastal aquifers since the 1930s because of its ever increasing water demand from underground water resources. Tripoli city is a typical area where the contamination of the aquifer in the form of saltwater intrusion is very developed. Sixty-four groundwater samples were collected from the study area and analyzed for certain parameters that indicate salinization and pollution of the aquifer. The results demonstrate high values of the parameters Electrical Conductivity, Na+, K+, Mg2+, Cl− and SO42−, which can be attributed to seawater intrusion, where Cl− is the major pollutant of the aquifer. The water types according to the Stuyfzand groundwater classification are mostly CaCl, NaCl and Ca/MgMix. These water types indicate that groundwater chemistry is changed by cation exchange reactions during the mixing process between freshwater and seawater. The intensive extraction of groundwater from the aquifer reduces freshwater outflow to the sea, creates drawdown cones and lowering of the water table to as much as 25 m below mean sea level. Irrigation with nitrogen fertilizers and domestic sewage and movement of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for the high NO3− concentration in the region.

Mechanical interaction between volcanic systems in Libya

The spatial distributions of monogenetic volcanoes, primarily volcanic craters, within the four principal volcanic provinces of Libya are examined and presented on a volcano-density map. Six main volcanic clusters have been identified, referred to as volcanic systems. Remarkably, the Al Haruj (AHVP) and Nuqay (NVP) volcanic provinces have double-peak volcano-density distributions, while the Gharyan (GVP) and As Sawda (SVP) volcanic provinces have single-peak volcano-density distributions. We interpret each volcano-density peak as corresponding to a separate volcanic system, so that there is a total of six systems in these four provinces. There was an overlap in volcanic activity in these provinces with at least three simultaneously active. We propose that each of the 6 volcanic systems was/is supplied with magma from a large sill-like reservoir – similar in lateral dimensions to the systems/clusters themselves. Numerical results show zones of high tensile and shear stresses between the reservoirs that coincide roughly with the main swarms of extension (dykes and volcanic fissures) and shear (faults) fractures in the areas. The most recent volcanic eruptions in Libya fall within the modelled high-stress concentration zones, primarily eruptions in the volcano Waw an Namus and the Holocene Al Mashaqaq lava flow. There are no known eruptions in Libya in historical time, but some or all the volcanic systems may have had one or more arrested historical dyke injections. In particular, part of the recurrent seismic events in the Hun Graben in the northwest Libya may be related to dyke propagation and arrest. If some of the inferred magma reservoirs are still fluid, as is likely, they pose earthquake and volcanic hazards to parts of Libya, particularly to the city of Gharyan and Zallah town, as well as to many oil-field operations.

Degradation of groundwater quality in coastal aquifer of Sabratah area, NW Libya

Overextraction of groundwater is widely occurring along the coast where good quality groundwater is at risk, due to urbanization, tourist development and intensive agriculture. The Sabratah area at the northern central part of Jifarah Plain, Northwest Libya, is a typical area where the contamination of the aquifer in the form of saltwater intrusion, gypsum/anhydrite dissolution and high nitrate concentrations is very developed. Fifty groundwater samples were collected from the study area and analysed for certain parameters that indicate salinization and pollution of the aquifer. The results demonstrate high values of the parameters electrical conductivity, sodium, potassium, magnesium, chloride and sulphate which can be attributed to seawater intrusion. The intensive extraction of groundwater from the aquifer reduces freshwater outflow to the sea, creates drawdown cones and lowering of the water table to as much as 30 m below mean sea level. Irrigation with nitrogen fertilizers and domestic sewage and movement of contaminants in areas of high hydraulic gradients within the drawdown cones probably are responsible for the high nitrate concentration towards the south of the region. Seawater intrusion and deep salt water upconing result in general high SO4 2− concentrations in groundwater near the shoreline, where localized SO4 2− anomalies are also due to the dissolution of sebkha deposits for few wells in the nearby sebkhas. Upstream, the increase in SO4 2− concentrations in the south is ascribed to the dissolution of gypsum at depth in the upper aquifer.

Evidence of ongoing brucellosis in livestock animals in North West Libya

Animal brucellosis is thought to be present in small ruminants, cattle, and camels in Libya, particularly in the west coastal strip. Before the system collapsed due to political unrest in 2011, prevalence of the disease did not exceed 0.2% in cattle, 0.1% in camels, 8.3% in sheep, and 14.8% in goats. The aim of this study was to highlight outbreaks of disease that took place during the 18-month period from November 2014 to April 2016. A total of 1612 serum samples, collected opportunistically from 29 herds in 12 different localities in the northwest region of Libya, were investigated for brucellosis. The samples were screened for Brucella antibodies using the Rose Bengal test, and confirmed with either indirect enzyme linked immunosorbent assay in the case of sheep, and/or a serum agglutination test, followed with a complement fixation test, in the case of cattle and camels. Our results showed the highest rates of brucellosis seropositivity in goats (33.4%) and sheep (9.2%). The overall percentage of brucellosis seropositivity was 21%. The high level of brucellosis identified by this study, particularly in small ruminants, strongly suggests re-emergence of the disease in the region. Re-evaluation of intervention measures applied to the control of brucellosis is highly recommended.

Haematological Parameters in Pregnant Women Attended Antenatal Care at Sabratha Teaching Hospital in Northwest, Libya

The aim of this study was to evaluate the values of hematological parameters at different trimesters of pregnancy in pregnant women who attended antenatal care at Sabratha Teaching Hospital, Northwest Libya. This cross-sectional survey included consecutive pregnant women who attended the obstetrical department in Sabratha Teaching Hospital for prenatal booking. This study was carried out over period of 6 month from April 2016 to September 2016. The study involved 120 pregnant women as the study group and 40 non-pregnant women as control. The study pregnant women were between the ages of 18 to 45 years. 5 ml of venous blood samples were taken from each pregnant woman in K₃-EDTA tubes for the haematological examinations. The analysis of haematological indices was done using automated hematological analyzer. The obtained results showed that the mean age of pregnant women was 30 years ± 5.8 SD, 48.4% of pregnant women were between 21-30 years old, 40.8% were at age between 31-40 years. The most prevalent blood group in pregnant women was group O, 47.5%; followed by blood group A, 28.3%; blood group B, 17.5% and blood group AB, 6.7%. 15.8% of the pregnant women were observed to lack Rh antigen in their blood. Highly significance decrease in Hb, Hct, MCH, MCHC, lymphocytes%, RBCs and blood platelets count and significant decrease in MCV as compared with non pregnant women. On the other hand, highly significance increased in WBCs count, and neutrophils % of pregnant women compared with non pregnant women. A progressive decline in Hb concentration and haematocrite values from the first to third trimester was observed. The mean corpuscular volume was significantly decreased in the second trimester. The values of MCH showed highly significant decrease in the second and third trimester, and MCHC decreased significantly in the first trimester. WBC count and neutrophils % showed highly significant increase from the first to the third trimester. Lymphocytes % were highly significant decreased from the first to the third trimester. Mixed percentage of leukocytes (eosinophil, basophil and monocytes) decreased significantly in the third trimester. Platelets count exhibited a highly significant decrease in the second and third trimesters, and a significantly decrease in the first trimester. It can be concluded that a significant changes in the haematological parameters at different trimesters of pregnancy in pregnant women. So it is essential to monitor and manage these parameters during pregnancy.

Wind Energy Assessment of the Zawiya Region, in Northwest Libya

The objective of this paper is to evaluate the annual, monthly and the seasonal performance of the wind resource at the Zawiya region in northwest of Libya. In this study, the wind data are obtained from the coastal site located in the northwest of Libya at height of 50 meters above the ground level. The results show that the annual average speed is 6.14 m/s, and the annual Weibull parameters are shape factor K = 3.2, scale factor C = 6.9 m/s, and the annual energy production of 750 kw wind turbine is 2.70 Gwh/year.

Carbon and oxygen isotope variations of the Middle–Late Triassic Al Aziziyah Formation, northwest Libya

This study presents the δ13C and δ18O records from whole rock samples of the Middle-Late Triassic (Ladinian-Carnian) Al Aziziyah Formation that were deposited on a gently sloping carbonate ramp within the Jifarah Basin of Northwest Libya. The Al Aziziyah Formation consists of gray limestone, dolomite, and dolomitic limestone interbedded with shale. The Ghryan Dome and Kaf Bates sections were sampled and analyzed for carbon and oxygen isotope chemostratigraphy to integrate high-resolution carbon isotope data with an outcrop-based stratigraphy, to provide better age control of the Al Aziziyah Formation. This study also discusses the relation between the facies architecture of the Al Aziziyah Formation and the carbon isotope values. Seven stages of relative sea level rise and fall within the Ghryan Dome were identified based on facies stacking patterns, field observations and carbon stable isotopes. The Al Aziziyah Formation δ13C chemostratigraphic curve can be partially correlated with the Triassic global δ13C curve. This correlation indicates that the Al Aziziyah Formation was deposited during the Ladinian and early Carnian. No straight-forward relationship is seen between δ13C and relative sea level probably because local influences complicated systematic environmental and diagenetic isotopic effects associated with sea level change.

The introduction of Neolithic resources to North Africa: A discussion in light of the Holocene research between Egypt and Libya

The dynamics affecting coastal areas of North Africa, especially the rise of Neolithic economies, remained largely unexplored until a few years ago. There are no definitive answers for questions about how groups belonging to a very well-documented late Palaeolithic tradition developed locally, and if and how these changes resulted from outside influences that may have affected the region during the middle and late Holocene. This is especially true of the provenance and success of the main domesticates, in other words the plant (wheat, barley, pulses) and animal species (sheep/goat, cattle, pigs) which constitute the North African Neolithic complex. The obvious intrusion of the domesticates from outside has prompted various authors to seek their exotic locations, but reasons and circumstances that led to the displacement of groups were rarely discussed in trying to reconstruct modalities and routes of diffusion. To understand and study these problems, a trans-regional perspective including North Africa and the Levant seems necessary, but is very rarely adopted. This paper tries to answer these questions, starting from the data on the central-eastern portion of Mediterranean North Africa–Egypt and Libya – which are closer to the Levantine territories. In particular, it focuses on what has recently emerged from important investigations in Egypt (Western Desert) and northwest Libya (Jebel Gharbi and Jefara plain). Through a comparative approach combining chronology, the characteristics of plant and animal resources used, and technology, both of these areas may help to understand the ways and paths followed in the introduction and propagation of food production towards northeastern Africa. In an attempt to trace the routes followed in the transfer from the Levantine towards the western regions, the paper deals also with the main theoretical and problematic issues related to the domestication of plants and animals in the Near East. It shows that, contrary to past claims, the domestication of plants and animals does not seem to have taken a short time and that instead a protracted process of domestication seems to be the more realistic model. Therefore, the search for a core area where everything must have begun seems really complicated. Finally it reconsiders some specific comparisons between Levant and North Africa, chronologically and geographically plausible, that have been suggested for some time. They concern the material culture repertoires, within which the importance of the main component, lithic production, is obvious.

Environmental Geological Studies on Bicess Island Area, Northwest Libya

Due to the few number of islands encountered in the States of the continent of Africa bordering the Mediterranean Sea, Bicess Island may be considered as one of the most important geological features in Libya. The study represents an attempt to identify the threatening of wild birds on Bicess Island through the studying of the various geomorphologic and structural features as well as the stratigraphic sequence. Bicess Island is located west of the Alkhoms City at the mouth of Wadi Bicess which marks the junction of the Nafusa Mountain base with Mediterranean coast. The genesis of Bicess Island is mostly due to the breaking down caused by wave action with the help of the structural effects in the region. The length of the island reaches 240 m, while the width is varying between 40 m and 160 m. The depth of water at the southern part of Bicess Island reaches about 4 m and varies between 7 m and 12 m at the northwestern part and the northeastern part respectively. Bicess Island posses a rocky beach occupied by algae and characterized by highly steeped and irregular cliffs as well as coasts associated with bays and peaks. The presence of dense plant cover on Bicess Island as well as its separation of being surrounded by sea water caused the human activities to be very limited and the occupation of the island by a great number of wild birds build their nests within the holes existing in rocks belonging to Alkhoms Formation. Caves were found at the base of cliffs. The shape of the caves appears as long cylinders extend along zones of weakness with radius become less to the interior of the rocks. On the roof of the caves there were a lot of joints which became wider forming explosive holes. Land destructions by waves and landslides are the most important factors threatening wild bird lives. In order to protect wild bird populations as well as the unique morphological and geological features, the present study recommends Bicess Island to become a natural reserve.

A new structural interpretation relating NW Libya to the Hun Graben, western Sirt Basin based on a new paleostress inversion

The present study is based on fault-slip data (striated fault planes with known sense of slip) measured in outcrops in two structural domains located along the Hun Graben, western Sirt Basin (150 fault-slip data) and the Jifarah Basin and Nafusah Uplift, northwest Libya (200 fault-slip data). Pre-existing field data collected in two previous studies were reprocessed using standard inversion methods in MyFaultTM(v. 1.03) stereonet software, produced by Pangaea Scientific Ltd.The aim of this study was to use paleostress orientations and relative paleostress magnitudes (stress ratios), determined using the reduced stress concept, to test a new understanding of the kinematic characteristics, the relationship between the two areas and the paleostress fields that controlled the evolution of the fault systems responsible for the observed deformation.Various types of faults (normal faults, sinistral normal faults, dextral normal faults and strike-slip faults) were recorded from outcrops comprised of Mesozoic and Cenozoic sedimentary sequences in which a lineation rake is present on minor structures with displacement ranging from several centimetres to several metres.Two different domains of a NNE–SSW directed extension regime ranging from N12 ∘E to 25 ∘E and minor ENE–WSW and WNW–ESE compression were identified in the analysis. The results are remarkably homogeneous at all sites and consistent with progressive collisional coupling of Africa and Europe, being under approximately WNW–ESE reactivated compressional stresses during the Late Eocene-age. The new kinematic and structural conceptual model that has been proposed is a test of the prevailing tectonic models describing the Cenozoic kinematic evolution of the areas. The results show the remarkable influence of basement fabrics of different ages on the subsequent structural development of NW Libya.

Eneration of Electrical Power Using Thermal Energy of Sea Water Off the Libyan Shores

Transformation of thermal energy of ocean/sea into power, a procedure referred to as OTEC or on the other hand STEC, utilizes the regular temperature contrast between the upper water layers’ temperature and close sea bed layers’ temperature to work through a thermodynamic cycle. This paper displays a study on a conceivable use of Mediterranean waters off the shores of Zliten city in northwest Libya utilizing this innovation. This study concerns to design and simulation of a thermodynamic cycle operating at steady-state conditions based on actual climatic data by using Aspen-Hysysv7.3. Results indicated that a closed loop thermodynamic cycle can offer a potential source of renewable energy, and the resulting design data of heat engines used to transform thermal energy into electricity is a feasible, and efficient approach to generate about 25 MW of electrical power at negligible ecological risks.

Weathering of Calcarenite Monuments at Roman and Byzantine Archaeological Sites at Sabratha, Northwestern Libya: A Pilot Study

The Roman and Byzantine monuments at Sabratha in northwest Libya represent cultural heritage of remarkable global significance. This report describes the weathering damage of calcarenites, the most dominant stone type used in the construction of monuments in the ancient city of Sabratha. Stone loss, particularly alveolar weathering, notching and breakout of compact stone fragments, dominates deterioration phenomena. Other weathering forms include stone detachment (granular disintegration into sand) and fractures. Most of the studied monuments are also severely affected by biodeterioration, due to microorganism colonization that appears as biofilm. Both the low durability of the calcarenites and the marine environment with characteristic humidity and salt-rich marine spray are the important factors contributing to stone weathering. The results obtained in this pilot study may be used as a guideline for future restoration works.

Northwest Libya from the early to late Holocene: New data on environment and subsistence from the Jebel Gharbi

The area of Jebel Gharbi, west of Cyrenaica province and the research area of the Italian–Libyan Joint Project (Sapienza University of Rome and Cassino), showed a continuity of occupation even during the most difficult periods of the Last Glaciation, marked by the abandonment of much of North Africa. One of the main research subjects of the project concerns the transformation of hunting societies during the Holocene, with the gradual transition to a food production economy, and the type of Neolithic organization on the coastal Libyan territory.This paper emphasizes this theme and takes into account especially the areas that have allowed for palaeoclimatic and geo-archaeological reconstruction in a broader perspective, including changes in the settlement pattern and the economic system. These conditions were recognized in the Jefara, the plain which begins at the slopes of the Jebel Gharbi plateau and reaches the coast.I describe the principal characteristics of the sites investigated along a belt that runs from Shakshūk to El Jawsh, where a long period of climate stability in the mid-Holocene and particularly between 6.7 and 5.4 ka cal BP, was recognized through the presence of large ponds and marshes that became an important focus for human occupation. Taking into account the palaeoenvironmental context, the paper suggests a model of economic change in the Jebel Gharbi/Jefara region through three different phases of development (Jefara A, B, C), that can be compared with the most recent results of research in other areas of Libya and the Maghreb.

Ecological Effect of Mergheb Cement Emissions on the Vegetation in the Northwest Libya Here

Ecological Effect of Mergheb Cement Emissions on the Vegetation in the Northwest Libya Here

First Molecular Epidemiological Study of Cutaneous Leishmaniasis in Libya

BackgroundCutaneous leishmaniasis (CL) is a major public health problem in Libya. The objective of this study was to investigate, for the first time, epidemiological features of CL outbreaks in Libya including molecular identification of parasites, the geographical distribution of cases and possible scenarios of parasite transmission.Methodology/Principal FindingsWe studied 450 patients that came from 49 areas distributed in 12 districts in north-west Libya. The patients' ages ranged from 9 months to 87 years (median age 25 years); 54% of the cases were males. Skin scrapings spotted on glass slides were collected for molecular identification of causative agent. The ribosomal internal transcribed spacer 1 (ITS1) was amplified and subsequently characterized by restriction fragment length polymorphism (RFLP) analysis. In total, 195 samples were successfully identified of which 148 (75.9%) were Leishmania major, and 47 (24.1%) Leishmania tropica. CL cases infected with L. major were found in all CL areas whereas L. tropica cases came mainly from Al Jabal Al Gharbi (46.4%), Misrata (17.8%) and Tarhuna districts (10.7%). A trend of seasonality was noticed for the infections with L. major which showed a clear peak between November and January, but was less pronounced for infections by L. tropica.ConclusionThe first molecular study on CL in Libya revealed that the disease is caused by L. major and L. tropica and the epidemiological patterns in the different foci were the same as in other Mediterranean foci of CL.

Integrated remote sensing data utilization for investigating structural and tectonic history of the Ghadames Basin, Libya

This study was initiated to constrain the geological structure of the Ghadames Basin in northwest Libya. Detailed analysis was based on digital integration of surface data, including SRTM DEM, ETM+ and geologic maps with subsurface data, including well logs and potential field data. Integrated analysis of remotely sensed data of the SRTM and ETM+ were utilized to identify geologic lineaments in the area. Ground-based verification of the remote sensing data was achieved with field work. Interpretation and analysis of the lineaments indicate that the Ghadames Basin is controlled by four main fault systems that trend WNW, NNW, NW and ENE. Well logs and potential field data were used to delineate a detailed picture of the subsurface structure. The potential field data reveal two NE and NNE trending sedimentary basins. The depth of the basement inside the main basin ranges from 2 to 6km. A two-dimensional (2-D) schematic model shows that the basin gradually deepens towards the southwest. The applied data integration gave new insight into the tectonic and structure patterns of the Ghadames Basin and the adjacent areas of northwest Libya.

Sedimentological Significance and Brine Chemistry of Recent Coastal Sabkha, Northwest Libya

Sedimentological Significance and Brine Chemistry of Recent Coastal Sabkha, Northwest Libya

Integration of DEM, ETM+, Geologic, and Magnetic Data for Geological Investigations in the Jifara Plain, Libya

We used an integrated approach to constrain the geological structure of the Jifara Plain in northwest Libya. The analysis of surface data, including a digital elevation model (DEM), Landsat Enhanced Thematic Mapper Plus images, and geologic maps, was combined with subsurface data, including well logs and magnetic data. The DEM data were used for the identification of geological lineaments in the study area. The interpretation and analysis of the lineaments indicate that the Jifara Plain is controlled by three main fault systems, trending northwest-southeast, east-west, and northeast-southwest. The three trends represent the remnants of reactivated structures that formed under the stress regimes generated during the tectonic evolution of North Africa. The magnetic data reveal three northwest- and northeast-trending sedimentary basins in the study area. The depth of the basement inside the main basin ranges from 1 to 5 km. The results indicate that the Jifara Basin is shallower than the surrounding basins. The integration of the results reflects different periods of tectonic activity in the Jifara Plain and the adjacent Jabal Nafusah.

Assessing image processing techniques for geological mapping: a case study in Eljufra, Libya

Various image processing techniques were experimented with in this study to evaluate their efficiency for geological mapping in the Eljufra area of northwest Libya. Remote sensing data including multi-spectral optical Landsat Enhanced Thematic Mapper (ETM+), Synthetic Aperture Radar (ERS-2 SAR) and Digital Elevation Models (DEMs) extracted from the Shuttle Radar Topography Mission (SRTM) data were used to trace different lithological units as well as extracting geological lineaments in the study area. The study area is located in an arid environment mostly devoid of any vegetation. Most lithological and structural units are distinguishable based on their topographic form and spectral properties. Fusion of ETM+ and ERS-2 images was experimented with to further identify lithological units. Shaded relief techniques were implemented to enhance terrain perspective views and to extract geological lineaments. The results discriminated different rock units and modified formation boundaries and revealed new geological lineaments. Nine rock units were identified and plotted in the new geological map defined by the new boundaries. The dominant lineaments tend to run in the NNW-SSE and NNE-SSW directions. Analysis and interpretation of the lineaments provided information about the tectonic evolution of the study area.

Integrating data from remote sensing, geology and gravity for geological investigation in the Tarhunah area, Northwest Libya

The present work deals with the integration of remote-sensing, surface-geology and gravity-survey data to improve the structural knowledge of the Tarhunah area, northwest Libya. Geological information and remote-sensing data provided information about the surface structure. A gravity survey was conducted to decipher the subsurface structure. The results revealed that a basin having a width of 39 to 48 km trends NE. A two-dimensional (2-D) schematic model shows that the basin gradually deepens toward the southwest. Faults determined from a horizontal gradient, tilt derivative, and Euler deconvolution show a depth range of 2.5 to 7.5 km. The integration and interpretation of the results indicate that volcanic activity was related to the tectonic activity of an anticlinal structure called the Jabal Uplift.