Eslam Elawadi

Status of trace metals in surface seawater of the Gulf of Aqaba, Saudi Arabia

The Gulf of Aqaba (GoA) is of significant ecological value with unique ecosystems that host one of the most diverse coral communities in the world. However, these marine environments and biodiversity have been threatened by growing human activities. We investigated the levels and distributions of trace metals in surface seawater across the eastern coast of the Saudi GoA. Zn, Cu, Fe, B and Se in addition to total dissolved solids and seawater temperature exhibited decreasing trends northwards. While Mn, Cd, As and Pb showed higher average levels in the northern GoA. Metal input in waters is dependent on the adjacent geologic materials. The spatial variability of metals in water is also related to wave action, prevailing wind direction, and atmospheric dry deposition from adjacent arid lands. Also, water discharged from thermal desalination plants, mineral dust from fertilizer and cement factories are potential contributors of metals to seawater water, particularly, in the northern GoA.

Hydrochemical Facies and Ionic Ratios of the Coastal Groundwater Aquifer of Saudi Gulf of Aqaba: Implication for Seawater Intrusion

ABSTRACT Batayneh, A.; Zaman, H.; Zumlot, T.; Ghrefat, H.; Mogren, S.; Nazzal, Y.; Elawadi, E.; Qaisy, S.; Bahkaly, I., and Al-Taani, A., 2014. Hydrochemical facies and ionic ratios of the coastal groundwater aquifer of Saudi Gulf of Aqaba: implication for seawater intrusion. It is now fairly documented that major ion chemistry of the groundwater can be used to determine an interaction between the groundwater and saline water in the costal aquifers, and that there exists a relationship between total dissolved solids and Cl−, Na+, Mg2+, and concentrations of groundwater. This hypothesis is tested on an aquifer located along the Saudi Gulf of Aqaba coast (Red Sea). Groundwater samples collected from 23 locations show the abundance of ions in the order of: Ca2+ > Na+ > Mg2+ > K+ = Cl− > > > . The Piper trilinear diagram reveals two dominant clusters, i.e. the Ca2+–Cl−– facies and the Na+–Cl−– facies. Besides the major chemical compositions, ionic ratios ( /Cl−, Na+/Ca2+, Na+/Cl−, Ca2+/Cl−, Mg2+/Cl−, K+/Cl−, /Cl−, Ca2+/Mg2+, Ca2+/ , and Ca2+/ ) are used to evaluate the effects of saline water intrusions. Factor analysis of the studied samples demonstrates that changes in the groundwater composition are primarily controlled by mineral dissolution, human activities, weathering of marine sediments, evaporation/salinization of groundwater, and the residence time of water. An attempt has been made to identify hydrochemical processes accompanied with the current intrusion of seawater through the use of ionic exchanges. Following this procedure, about 7.97% mixing rate of seawater intrusion has been estimated for the month of March 2012. Furthermore, the seawater mixing index has also been applied, which resulted in a range of values from 0.395 to 7.922. These results determine 13 of 23 groundwater samples (57%) as saline, with electrical conductivity > 3000 μS/cm.

Integrated Geophysical Survey for Site Investigation at a New Dwelling Area, Egypt

An integrated geophysical survey was carried out in a new dwelling area at 15-May town, southeast Cairo, Egypt. The buildings in this area are intensively affected by dangerous cracks that cause structural instability. The survey aimed to image the shallow subsurface structures, including karstic features, and evaluate their extent, as they may cause rock instability and lead to cracking of the residential buildings. Resistivity profiling (2-D), using a dipole-dipole array and ground penetrating radar (GPR) surveys were carried out along seven parallel traverses extending about 150 meters between the buildings blocks. Additional measurements using a Schlumbereger array and very low frequency electromagnetic (VLF-EM) methods were conducted. The acquired data were processed and interpreted integrally to elucidate the shallow structural setting of the site. Integrated interpretation led to the delineation of hazard zones rich with karstic features in the area. Most of these karstic features are associated with vertical and sub-vertical linear features such as faults, fracture zones, and geologic contacts. These features are the main reason of the rock instability that resulted in potentially dangerous cracking of residential buildings.

Use of Geoelectrical Technique for Detecting Subsurface Fresh and Saline Water: A Case Study of the Eastern Gulf of Aqaba Coastal Aquifer, Jordan

Abstract Geoelectrical measurements using the vertical electrical sounding method were conducted on the eastern Gulf of Aqaba (GOA) coast in Jordan. The objectives of the study were (i) to map the Quaternary sediments in areas where little is known about the subsurface geology and to infer shallow geological structure, and (ii) to identify formations that may present fresh aquifer waters, and subsequently to estimate the relationship between groundwater resources and geological structures. Data collected at 47 locations were interpreted first with curve-matching techniques, using theoretically calculated master curves. The initial earth models were double-checked and reinterpreted using a one-dimensional inversion program in order to obtain final earth models. Resistivity measurements show three zones with different resistivity values, corresponding to three different bearing formations: (i) a water-bearing formation in the west containing GOA saltwater; (ii) a transition zone of alternate layers of silt, sand, clay, and clayey sand; and (iii) strata saturated with fresh groundwater in the east and disturbed by the presence of clay and clayey sand horizons.

Environmental Assessment of the Gulf of Aqaba Coastal Surface Waters, Saudi Arabia

ABSTRACT Batayneh, A.; Elawade, E.; Zaman, H.; Al-Taani, A.A.; Nazzal, Y., and Ghrefat, H., 2014. Environmental assessment of the Gulf of Aqaba coastal surface waters, Saudi Arabia. A research project on the Saudi Gulf of Aqaba was initiated in January 2012 to evaluate, protect, and develop a proper management plan for sustainable use of water resources in the coastal region. Within the framework of this project, a total of 85 surface water samples was collected and investigated to document the surface distribution of the hydrographical parameters (including water temperature, salinity, density, hydrogen ion concentration, and dissolved oxygen) as well as concentration of the nutrient salts (ammonium, nitrite, nitrate, phosphate, and silicate). The results show no thermocline or thermal pollution in the studied water and that they are mostly well oxygenated. In addition, no significant variations in the pH and salinity values have been observed. Relatively low levels of nitrogen, phosphorus (in the dissolved and total forms), and reactive silicate are observed. Inorganic nitrogen is found in the order of NO3-N > NO2-N > NH4-N. On the basis of the relatively low level of nutrient salts, the Gulf of Aqaba coastal water is classified as oligotrophic to mesotrophic in nature, and the study area is not yet seriously affected by contamination in spite of rapid population growth and fast infrastructural/recreational development during the past decade.

Major ion chemistry and weathering processes in the Midyan Basin, northwestern Saudi Arabia

Chemical characteristics of 72 groundwater samples collected from Midyan Basin have been studied to evaluate major ion chemistry together with the geochemical and weathering processes controlling the water composition. Water chemistry of the study area is mainly dominated by Na, Ca, SO4, and Cl. The molar ratios of (Ca + Mg)/total cations, (Na + K)/total cations, (Ca + Mg)/(Na + K), (Ca + Mg)/(HCO3 + SO4), (Ca + Mg)/HCO3, and Na/Cl reveal that water chemistry of the Midyan Basin is controlled by evaporite dissolution (gypsum and/or anhydrite, and halite), silicate weathering, and minor contribution of carbonate weathering. The studied groundwater samples are largely undersaturated with respect to dolomite, gypsum, and anhydrite. These waters are capable of dissolving more of these minerals under suitable physicochemical conditions.

Structural interpretation of the Ifal Basin in north-western Saudi Arabia from aeromagnetic data: hydrogeological and environmental implications

The Ifal (Midyan) Basin is one of the well defined basins along the Red Sea coast, north-western Saudi Arabia. Location, geometry, thick sedimentary cover and structural framework qualify this basin for groundwater, oil and mineral occurrences. In spite of being studied by two airborne magnetic surveys during 1962 and 1983, structural interpretation of the area from a magnetic perspective, and its uses for hydrogeological and environmental investigations, has not been attempted. This work thus presents interpretation of the aeromagnetic data for basement depth estimation and tectonic framework delineation, which both have a role in controlling groundwater flow and accumulation in the Ifal Basin. A maximum depth of 3.5 km is estimated for the basement surface by this study. In addition, several faulted and tilted blocks, perpendicularly dissected by NE-trending faults, are delineated within the structural framework of the study area. It is also observed that the studied basin is bounded by NW- and NE-trending faults. All these multi-directional faults/fracture systems in the Ifal Basin could be considered as conduits for groundwater accumulation, but with a possibility of environmental contamination from the surrounding soils and rock bodies.

Combined Inversion of Electrical Resistivity and Transient Electromagnetic Soundings for Mapping Groundwater Contamination Plumes in Al Quwy'yia Area, Saudi Arabia

Time-domain electromagnetic (TEM) soundings and vertical electrical soundings (VES) were conducted to assess the subsurface groundwater contamination in Al Quwy’yia area through tracing the conductivity changes caused by leachate contamination of groundwater. Most of the contamination sources are coming from the incomplete sanitary system and the illegal dumping of wastewater along the lowland area outside the town. Contamination of the groundwater poses a major threat because most of the local inhabitants rely on ground water to supply up to 60% of their water needs for various life activities. TEM and VES data sets have been acquired along four longitudinal profiles to cover the most urban area of Al Quwy’yia. The combined inversion of VES and TEM data sets increase the resolving certainty of the subsurface resistivity models. The basement rock has the highest resistivity values, whereas the uncontaminated limestone has moderate resistivity response in comparison with the contaminated zones, which have a lower resistivity response. The constructed cross-sections and resistivity slice maps along the area provide valuable information about the shallow seepage from the septic tanks, as well as the deep infiltration from the dump site at the southern part of the study area.

Utilizing potential field data to support delineation of groundwater aquifers in the southern Red Sea coast, Saudi Arabia

In this paper potential field data are interpreted to map the undulation of the basement surface, which represents the bottom of the water bearing zones, and to delineate the tectonic framework that controls the groundwater flow and accumulation in the southern Red Sea coastal area of Saudi Arabia. The interpretation reveals that the dominant structural trend is a NW (Red Sea) trend that resulted in a series of faulted tilted blocks. These tilted blocks are dissected by another cross-cut NE trend which shapes and forms a series of fault-bounded small basins. These basins and the bounded structural trends control and shape the flow direction of the groundwater in the study area, i.e. they act as groundwater conduits. Furthermore, the present results indicate that volcanic intrusions are present as subsurface flows, which hinder the groundwater exploration and drilling activities in most of the area; in some localities these volcanic flows crop out at the surface and cover the groundwater bearing formations. Furthermore, the gravity and magnetic data interpretation indicates the possible existence of a large structural basin occupying the southeastern side of the study area. This basin is bounded with NW and NE trending faults and is expected to be a good host for groundwater aquifers; thus it is a promising site for hydrogeological investigation.

Statistical analysis of different chemical elements in groundwater of northwestern Saudi Arabia

A total of 72 water samples were collected from the sub-surface aquifer system in the Midyan basin and analyzed for 24 major, minor and trace elements. Histograms and normal quantile plots were used to delineate the sub-populations of the chemical constituents in the studied groundwater samples. Some of the elements such as Al, K, Ca, Mg, Na and Cl have concentrations that could be linked to the weathering of the surface rock strata. On the other hand, the elements like As, Pb and Sb have concentration, that can be linked to agricultural practices in the area. The use of simple statistical analysis, frequency histograms, and Q-Q plots were useful for the detection and evaluation of elemental constituents in the groundwater of the study area.