Yousef Nazzal

Assessment of metal pollution in urban road dusts from selected highways of the Greater Toronto Area in Canada

Over the last several decades, there has been increased attention on the heavy metal contamination associated with highways because of the associated health hazards and risks. Here, the results are reported of an analysis of the content of metals in roadside dust samples of selected major highways in the Greater Toronto Area of Ontario, Canada. The metals analysed are lead (Pb), zinc (Zn), cadmium (Cd), nickel (Ni), chromium (Cr), copper (Cu), manganese (Mn), calcium (Ca), potassium (K), magnesium (Mg) and iron (Fe). In the samples collected, the recorded mean concentrations (in parts per million) are as follows: Cd (0.51), Cu (162), Fe (40,052), Cr (197.9), K (9647.6), Mg (577.4), Ca (102,349), Zn (200.3), Mn (1202.2), Pb (182.8) and Ni (58.8). The mean concentrations for the analysed samples in the study area are almost all higher than the average natural background values for the corresponding metals. The geo-accumulation index of these metals in the roadside dust under study indicates that they are not contaminated with Cr, Mn and Ca; moderately contaminate with Cd and K; strongly contaminated with Fe and Mg; strongly to extremely contaminated with Ni and Pb; and extremely contaminated with Cu and Zn. The pollution load index (PLI) is used to relate pollution to highway conditions, and the results show that PLI values are slightly low at different samples collected from Highways 401 and 404 and high in many samples collected from Highway 400 and the Don Valley Parkway. Highway 400 exhibits the highest PLI values.

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.

Reverse ion exchange as a major process controlling the groundwater chemistry in an arid environment: a case study from northwestern Saudi Arabia

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.

Application of multivariate geostatistics in the investigation of heavy metal contamination of roadside dusts from selected highways of the Greater Toronto Area, Canada

A good understanding of roadside soil contamination and the location of pollution sources is important for addressing many environmental problems. The results are reported here of an analysis of the content of metals in roadside dust samples of four major highways in the Greater Toronto area (GTA) in Ontario, Canada. The metals analyzed are Pb, Zn, Cd, Ni, Cr, Cu, Mn, and Fe. Multivariate geostatistical analysis [correlation analysis (CA), principal component analysis (PCA), and hierarchical cluster analysis (HCA)] were used to estimate soil chemical content variability. The correlation coefficient shows a positive correlation between Cr–Cd, Mn–Fe, and Fe–Cu, while negatively between Zn–Cd, Mn–Cd, Zn-Cr, Pb–Zn, and Ni–Zn. PCA shows that the three eigenvalues are less than one, and suggests that the contamination sources are processing industries and traffic. HCA classifies heavy metals in two major groups. The cluster has two larger subgroups: the first contains only the variables Fe, Mn, Cu, Cr, Ni, and Pb, and the second includes Cd and Zn. The geostatistical analysis allows geological and anthropogenic causes of variations in the contents of roadside dust heavy metals to be separated and common pollution sources to be identified. The study shows that the high concentration of traffic flows, the parent material mineralogical and chemical composition, and land use are the main sources for the heavy metal concentration in the analyzed samples.

Hydrogeological vulnerability and pollution risk mapping of the Saq and overlying aquifers using the DRASTIC model and GIS techniques, NW Saudi Arabia

AbstractSaq 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 NO3, SO4 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.

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.

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.

A combined hydrochemical-statistical analysis of Saq aquifer, northwestern part of the Kingdom of Saudi Arabia

The present study includes detailed hydrochemical assessment of groundwater resources of Saq aquifer. The Saq aquifer covers a large area (about 375,000 km2) 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 (Mg2+), and calcium (Ca2+), bicarbonate (HCO3) chloride (Cl−), sulfate (SO42−) and nitrate (NO3). 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; SO4 and EC, TDS, Ca, Cl, Na, Mg. The distribution of major ions in the groundwater is Na+ > Ca++ > Mg++ > K+ and Cl− > SO4−2>HCO3−>NO3−. 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, SO4, and Mg, where the relationship within the group are strong. The second group includes K, HCO3, pH, and NO3. 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.

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.

Risk assessment through evaluation of potentially toxic metals in the surface soils of the Qassim area, Central Saudi Arabia

Metal pollution is an increasing environmental problem worldwide, especially in regions undergoing rapid development. The present work highlights the extent of metal pollution in the central part of Saudi Arabia, which is currently experiencing significant agricultural development. The study determined concentrations of Hg, Cd, Zn, As, Mo, Cu, Pb and Cr in surface soils, assessing the level of pollution and potential ecological risks using soil quality guidelines, the geo-accumulation index (Igeo), the Hakanson potential ecological risk index (RI) and standard statistical analysis methods. Overall, the mean potential ecological risk values of metals in the surveyed soils display the following decreasing trend: Hg>Cd>Pb>As>Cu>Zn>Mo>Cr. The potential ecological risks associated with the eight investigated metals in the study area were high for Hg and Cd, and ranged from considerable too low for the rest of the analysed metals. The results also showed that surface soils in the study area are heavily affected by agricultural activities, municipal waste, local industries and quarries. These anthropogenic activities may, therefore, pose a risk to soil and water resources, and have the potential to change the physiochemical characteristics of the associated ecosystem.