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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. [ABSTRACT FROM AUTHOR]

Heavy metals in agricultural soils enter the food chain when taken up by plants. The main purpose of this work is to determine metal contamination in agricultural farms in northwestern Saudi Arabia. Fifty surface soil samples were collected from agricultural areas. The study focuses on the geochemical behavior of As, Cd, Co, Cr, Cu, Hg, Pb and Zn, and determines the enrichment factor and geoaccumulation index. Multivariate statistical analysis, including principle component analysis and cluster analysis, is also applied to the acquired data. The study shows considerable variation in the concentrations of the analyzed metals in the studied soil samples. This variation in concentration is attributed to the intensity of agricultural activities and, possibly, to nearby fossil fuel combustion activities, as well as to traffic flows from highways and local roads. Multivariate analysis suggests that As, Cd, Hg and Pb are associated with anthropogenic activities, whereas Co, Cr, Cu and Zn are mainly controlled by geogenic activities. Hg and Pb show the maximum concentration in the analyzed samples as compared to the background concentration. [ABSTRACT FROM AUTHOR]

Identifying potential groundwater recharge zones is a pre-requisite for any artificial recharge project. The present study focuses on identifying the potential zones of Artificial Groundwater Recharge (AGR) in Northwestern Saudi Arabia. Parameters including slope, soil texture, vadose zone thickness, groundwater quality (TDS) and type of water bearing formation were integrated in a GIS environment using Boolean logic. The results showed that 17.90% of the total studied area is suitable for AGR. The identified zones were integrated with the land use/land cover map to avoid agricultural and inhabited lands which reduced the total potential area to 14.24%. Geomorphologically the wadi beds are the most suitable sites for recharge. On the basis of the potential AGR zones closeness to the available recharge water supply (rain water, desalinated sea water and treated waste water) the potential zones were classified as Category A (high priority) and Category B (low priority). [ABSTRACT FROM AUTHOR]

Assessment of groundwater quality is of utmost significance in arid regions like Saudi Arabia where the lack of present-day recharge and high evaporation rates coupled with increasing groundwater withdrawal may restrict its usage for domestic or agricultural purposes. In the present study, groundwater samples collected from agricultural farms in Hail (15 samples), Al Jawf (15 samples), and Tabuk (30 samples) regions were analyzed for their major ion concentration. The objective of the study was to determine the groundwater facies, the main hydrochemical process governing the groundwater chemistry, the saturation index with respect to the principal mineral phases, and the suitability of the groundwater for irrigational use. The groundwater samples fall within the Ca-Cl type, mixed Ca-Mg-Cl type, and Na-Cl type. Evaporation and reverse ion exchange appear to be the major processes controlling the groundwater chemistry though reverse ion exchange process is the more dominating factor. The various ionic relationships confirmed the reverse ion exchange process where the Ca and Mg in the aquifer matrix have been replaced by Na at favorable exchange sites. This phenomenon has accounted for the dominance of Ca and Mg ions over Na ion at all the sites. The process of reverse ion exchange was further substantiated by the use of modified Piper diagram (Chadha's classification) and the chloro-alkaline indices. Evaporation as a result of extreme aridity has resulted in the groundwater being oversaturated with aragonite/calcite and dolomite as revealed by the saturation indices. The groundwater samples were classified as safe (less than 10) in terms of sodium adsorption ratio (SAR) values, good (less than 1.25) in terms of residual sodium carbonate (RSC) values, and safe to moderate (between 0 and 3) in terms of Mg hazard for irrigation purposes. Though the high salinity groundwater in the three regions coupled with low SAR values are good for the soil structure, it can have a negative impact on the crop production by adversely affecting the crop physiology. Cultivation of high-salinity-resistant varieties of crops is recommended for maximum agricultural productivity. [ABSTRACT FROM AUTHOR]

Saq and overlying aquifers serve as important sources of water supply for agricultural and domestic usage in Saudi Arabia. Due to urbanization and growth in the agricultural sector, groundwater resources are over-exploited and are prone to quality deterioration. The aquifer vulnerability technique helps delineate areas according to the susceptibility to groundwater contamination. Various parameters pertaining to the surface and subsurface environment were synthesized to represent the data variation in the 3D horizon. Estimates of the parameters, such as recharge, soil media, and vadose zone, were obtained based on modified criteria to account for data variability. Statistical analysis indicates that the input parameters are independent and contribute individually to the vulnerability index. For vulnerability assessment, the DRASTIC model was considered due to the large number of data input parameters. Based on the vulnerability index, the study area is classified into low to very high vulnerability classes. To assess the human interaction on the groundwater environment, the land-use pattern was included as an additional input layer. Sensitivity analyses helped to compute the influence of the input layers on the vulnerability index and the model calibration through revised weights. The model validity tests were performed by comparing the NO, SO and Cl concentration with the different vulnerability zones. The aquifer vulnerability maps developed in the present study may serve as an important tool for effective groundwater resource management. [ABSTRACT FROM AUTHOR]

The present study deals with the interpretation of the major processes governing the groundwater chemistry in parts of Qassim and Riyadh province of Saudi Arabia. The study area that is dominated by agricultural activities is represented by a multi-layered aquifer system with sedimentary formations ranging from Cambrian to the Quaternary present as outcrops. Groundwater samples from 97 agricultural bore wells in the area were collected and analyzed for 16 physio-chemical parameters. The evaluation of the main hydrochemical processes affecting the groundwater quality was carried out by interpreting the ionic relationships and hydrochemical facies analysis. The interpretation pointed toward evaporation, gypsum dissolution and ion exchange as main factors controlling the major ion groundwater chemistry. The piper plot showed SO-Cl type of groundwater with majority of the samples falling in the zone of permanent hardness due to the formation of non-carbonate salts. Principal component analysis that helps to understand the underlying natural and anthropogenic factors controlling the groundwater chemistry in an area was used in the present study, based on which four principal components (PCs) were extracted. The first PC as expected was dominated by the major ions and was attributed to natural processes, whereas the extracted components (mainly heavy metals) in PC 2, 3 and 4 pointed toward anthropogenic activities playing an active role in affecting the trace element hydrochemistry. [ABSTRACT FROM AUTHOR]

The present study includes detailed hydrochemical assessment of groundwater resources of Saq aquifer. The Saq aquifer covers a large area (about 375,000 km) and lies in the arid region with low annual rainfall and extremely high evaporation. In the study area, groundwater serves as the major source for agricultural activity and for domestic usages. A total of 295 groundwater samples collected and were analyzed for physico-chemical parameters such as hydrogen ion concentration (pH), total dissolved solids (TDS) and electrical conductivity (EC), sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca), bicarbonate (HCO) chloride (Cl), sulfate (SO) and nitrate (NO). The goal and challenge for the statistical overview was to delineate chemical distributions in a complex, heterogeneous set of data spanning over a large geographic range. After de-clustering to create a uniform spatial sample distribution with 295 samples, histograms and quantile-quantile (Q-Q) plots were employed to delineate subpopulations that have coherent chemical affinities. The elements showing significantly higher positive correlation are: TDS with EC; Ca with EC, TDS; Mg and EC, TDS, Ca, K; Cl and EC, TDS, Mg, Na, Ca; SO and EC, TDS, Ca, Cl, Na, Mg. The distribution of major ions in the groundwater is Na > Ca > Mg > K and Cl > SO>HCO>NO. Ionic abundance plot of alkalis with Ca and Mg is suggestive of mix type trends of concentrations as evident by moderate correlation (r = 0.57). About 60% of the total samples have alkalis abundance and rests have more Ca + Mg concentrations than alkalis. Taking both results of cluster tree and geochemical features of variables into consideration, the authors classify the elements into two major groups, the first includes TDS, Na, EC, Cl, Ca, SO, and Mg, where the relationship within the group are strong. The second group includes K, HCO, pH, and NO. This group has close relationship with group 1 demonstrate that, the increase in the concentration to some elements could be the same. Some of the analyzed parameters approach a normal distribution, as both their skewnesses and kurtoses reach close to '0'. The study revealed that, all of the element pairs exhibit positive relations. [ABSTRACT FROM AUTHOR]

Batayneh, A.T.; Ghrefat, H.; Zumlot, T.; Elawadi, E.; Mogren, S.; Zaman, H.; Al-Taani, A.A.; Nazzal, Y., and Elwahaidi, M., 2015. Assessing of metals and metalloids in surface sediments along the Gulf of Aqaba coast, northwestern Saudi Arabia. The Gulf of Aqaba in northwestern Saudi Arabia is among the world's most important areas in terms of marine diversity and economic potential. Its coastal area witnessed significant anthropogenic changes as a result of rapid economic development and urbanization during recent decades. To document the impacts of these changes on the local environment, the distribution of heavy metal and metalloid pollutants (Fe, Al, As, Cu, B, Zn, Ba, Cr, Pb, Mn, Hg, V, Co, Mo, Se, Sb, Cd, and Be) and their variations in the surface sediments were investigated. Based on average concentrations, the dominance is as follows: Fe > Al > As > Cu > B > Zn > Ba > Cr > Pb > Mn > Hg > V > Co > Mo > Se > Sb > Cd > Be. The results showed a strongly positive linear correlation among Ba, Cr, Pb, and V. The studied sediments' quality was assessed using the geoaccumulation index ( Igeo), an enrichment factor ( EF), and two other sediment testing criteria (China State Bureau of Quality and Technical Supervision, or CSBTS, and Canadian guidelines). Hg is the only element with a moderate-to-strong concentration in terms of the Igeo, exceeding the primary, secondary, and tertiary CSBTS criteria and the threshold and probable effect levels of the Canadian guidelines. As causes moderate pollution, because its presence in the sediments exceeds the threshold effect level of the Canadian guidelines. The EF results showed Hg as a strong pollutant metal in the surface sediments of the study area, followed by As and Cu metals. [ABSTRACT FROM AUTHOR]

The main purpose of this research is to determine the quality of ground water in Wadi AdDawasir by the assessment of 12 chemical parameters: pH, EC, Eh, TDS, TH, Ca2+, Cl–, HCO3–, Mg2+, Na+, NO3–, and SO42–. Statistical analyses were carried out using descriptive statistics, histograms, and normal quantile plots. The SPSS 15 software package (SPSS Inc. 2006) and JMPIN (version 4.0.4) were used as the main statistical software. Many locations within the study area show thatf pH, EC, HCO3– and Na+ values exceed permissible limits. The concentration of anions is in the order SO42–>Cl–>HCO3–. Some of the analyzed parameters approach a normal distribution, as both their skewness and kurtoses are close to zero. However, skewness for some parameters such as Mg2+ and HCO3– is high. Kurtosis for most of the elements varies from moderate to low. Only pH, HCO3– and SO42– have kurtoses. Both the results of cluster tree and geochemical features of variables could be generally classified into three main groups. Group 1 is comprised of Na and SO42–. The relationships within this group are strong. Group 2 consisted of Mg2+, NO3–, pH, HCO3–, and Ca2+. The fact that this group has a close relationship with group 1 demonstrates that the increase in the concentration of some elements could be the same. Group 3 is comprised of TH, Cl–, Eh, and EC. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The present study deals with detailed hydrochemical assessment of groundwater within the Saq aquifer. The Saq aquifer which extends through the NW part of Saudi Arabia is one of the major sources of groundwater supply. Groundwater samples were collected from about 295 groundwater wells and analyzed for various physico-chemical parameters such as electrical conductivity (EC), pH, temperature, total dissolved solids (TDS), Na, K, Ca, Mg, CO, HCO, Cl, SO, and NO. Groundwater in the area is slightly alkaline and hard in nature. Electrical conductivity (EC) varies between 284 and 9,902 μS/cm with an average value of 1,599.4 μS/cm. The groundwater is highly mineralized with approximately 30 % of the samples having major ion concentrations above the WHO permissible limits. The NO concentration varies between 0.4 and 318.2 mg/l. The depth distribution of NO concentration shows higher concentration at shallow depths with a gradual decrease at deeper depths. As far as drinking water quality criteria are concerned, study shows that about 33 % of samples are unfit for use. A detailed assessment of groundwater quality in relation to agriculture use reveals that 21 % samples are unsuitable for irrigation. Using Piper's classification, groundwater was classified into five different groups. Majority of the samples show Mix-Cl-SO- and Na-Cl-types water. The abundances of Ca and Mg over alkalis infer mixed type of groundwater facies and reverse exchange reactions. The groundwater has acquired unique chemical characteristics through prolonged rock-water interactions, percolation of irrigation return water, and reactions at vadose zone. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Water samples for chemical analyses were collected in January 2012. A total of 72 samples of groundwater were collected from 72 boreholes in the Midyan Basin, northwestern Saudi Arabia. Samples were collected in polyethylene bottles and preserved and the used analytical techniques were in accordance with the standard methods from American public health association. Geochemical analyses of the groundwater samples from Midyan Basin reveal the concentration of fluoride (F) between 0.98 and 2.1 mg/l. Other parameters, e.g, pH, EC, TDS, HCO, SO, NO, Cl, K, Na, Mg, and Ca have been found in a variable proportion. Among them, the concentration of EC, HCO, K, Na and Mg is higher than the permissible limits. According to thermodynamical considerations, most of the analysed samples are graded under-saturated with respect to calcite and fluoride, while saturation has been observed in some samples. The under-saturation could probably be attributed to low concentration of calcite and fluoride in the studied wells. Fluoride concentration shows weak positive correlation with EC, TDS, Na, Cl, and SO. Factors controlling the concentration of fluoride (F) in the studied samples are the area climate, water chemistry and the presence of accessory minerals in the rocks through which groundwater is circulating, besides the anthropogenic activities in the area. [ABSTRACT FROM AUTHOR]

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 coastal aquifers, and that there exists a relationship between total dissolved solids and Cl-, Na+, Mg2+ and SO42- 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- > SO42- >HCO3- > NO3-. The Piper trilinear diagram reveals two dominant clusters, i.e. the Ca2+-Cl- -SO42- facies and the Na+-Cl- -SO42- facies. Besides the major chemical compositions, ionic ratios (HCO3-/Cl-, Na+/Ca2+, Na++/Cl-, Ca2+/Cl-, Mg2+2+/Cl-, K+/Cl- SO42-/Cl-, Ca2+/Mg2+, Ca2+/SO42-, and Ca2+/HCO3-) 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. [ABSTRACT FROM AUTHOR]

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, SO, and Cl. The molar ratios of (Ca + Mg)/total cations, (Na + K)/total cations, (Ca + Mg)/(Na + K), (Ca + Mg)/(HCO + SO), (Ca + Mg)/HCO, 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. [ABSTRACT FROM AUTHOR]