Influence of seawater intrusion and heavy metals contamination on groundwater quality, Red Sea coast, Saudi Arabia.

Groundwater samples were collected from 115 boreholes and dugwells to document the influence of seawater intrusion and heavy metals contamination on groundwater quality of the Al Qunfudhah region along the Red Sea coast, Saudi Arabia. The groundwater quality index (GWQI), metal index (MI), and heavy metal pollution index (HPI) were calculated and multivariate analyses were conducted. pH, EC, TDS, Cl-, HCO3-, SO42-, NO3-, NO2-, PO43-, SiO2, F-, NH4+, Ca2+, Mg2+, Na+, K+, B, Ba, Cd, Cr, As, Ni, Pb, Se, Sb, Hg, Cu, and Zn were analyzed and interpreted. The average values for TDS, Ca2+, Mg2+, Na+, K+, Cl-, HCO3-, SO42-, B, and Se were greater than the permissible limit of WHO standards for drinking water. Piper plots indicated three types of groundwater facies, Na-K-SO4-Cl (72.50%), Ca-Mg-So4-Cl (25.50%), and Na-K-CO3-HCO3 (2%). Based on GWQI, MI, and HPI, approximately 37-70% of the groundwater samples fell under poor quality to unsuitable waters (strongly to severely affected), especially in the western part along the Red Sea coast. This proven the role of seawater intrusion through the NE-SW fault system, dissolution/precipitation of carbonates, silicates, fluorite, and gypsum, as well as anthropogenic factors in increasing the concentrations of heavy metals and controlling the chemistry and quality of the groundwater in the study area. These findings provide an important information on heavy metals pollution in coastal aquifer with seawater intrusion along the Red Sea.

Evaluation of heavy metal contamination and groundwater quality along the Red Sea coast, southern Saudi Arabia.

To evaluate the heavy metal contamination and groundwater quality in southern Saudi Arabia, 105 groundwater samples were analyzed for EC, pH, TDS, major ions (NO3-, Cl-, HCO3-, SO42-, F-, Ca2+, Mg2+, Na+, and K+), and heavy metals (Fe, Li, As, B, Al, Cr, Cu, Mo, Ni, Se, Sr, V, Zn, and Mn). Groundwater quality index (GWQI), degree of contamination (Cd), heavy metal pollution index (HPI), ecological risks of heavy metals (ERI), salinity hazard (EC), sodium adsorption ratio (SAR), sodium percentage (Na%), and Kelly's ratio (KR) were calculated and compared, and multivariate statistical techniques were applied. The results revealed that the major cations and anions followed the orders of Na+ > Ca2+ > Mg2+ > K+ and Cl- > SO42- > HCO3- > NO3- > F-, respectively. The maximum values of As, Mn, Cr, Ni, Se, and Zn were above the permissible limits for drinking water purposes. Pollution indices indicated that 20 to 52% of the groundwater samples were suitable for agricultural and domestic purposes. The unsuitable samples were distributed mostly in the western part along the Red Sea coast. Multivariate statistical analyses revealed that the dissolution of halite and gypsum (in sabkha deposits), carbonates, and the agricultural activities were the possible sources of the major cations and anions, and heavy metals in the study area.

Assessment of hydrological processes operating in a multi-layered sedimentary aquifer system in Saudi Arabia using integrated chemical and statistical approach.

Hydrochemical processes have a great influence on the groundwater quality especially in arid regions where groundwater is the single most important source of water supply. The present study was carried out in the Wadi Ad Dawasir region of Saudi Arabia. The objective of this study was to determine the processes influencing the groundwater composition in the region by integrated hydrochemical and statistical assessment. Hydrochemical data from 140 groundwater samples were interpreted using hydrochemical and statistical techniques. Evaporation, mineral dissolution, reverse ion exchange, and chloride/nitrate contamination from irrigation return flows were the main geogenic and anthropogenic sources influencing the groundwater composition. Principal component analysis was carried out to determine the component showing the maximum variability in the data. Two principal components were extracted. The first principal component representing gypsum dissolution and anthropogenic pollution (chloride and nitrate pollution from agricultural farms) was more pronounced in the western part of the study area whereas the second principal component representing silicate weathering process was more dominant in the eastern part. Total dissolved solid was found to be the single most important hydrochemical parameter showing the maximum variation in the analyzed data set. This study demonstrates that the loadings of the individual hydrochemical parameters in the extracted principal component and the component scores of the individual samples for each extracted principal component can be effectively used for determining the hydrochemical processes influencing the groundwater chemistry in an area.

Spatial distribution and ecological risk assessment of the coastal surface sediments from the Red Sea, northwest Saudi Arabia.

To assess the spatial distribution and ecological risk assessment along the Red Sea coast, Saudi Arabia, 30 samples were collected for aluminum, chromium, copper, zinc, cadmium, lead, mercury, iron, cobalt, nickel and organic matter analysis. The descending order of metal concentrations was Al > Fe > Cr > Cu > Zn > Ni > Co > Pb > Hg > Cd. Average values of enrichment factor of Hg, Cd, Cu, Co, Cr, Ni, Pb and Zn were higher than 2 (209.50, 25.52, 20.36, 9.62, 7.28, 6.52, 6.21 and 6.07 respectively), which means anthropogenic sources of these metals. The average levels most of the studied metals were lower than those of the background shale and the earth crust and those recorded along most worldwide coasts, while the average values of zinc, copper, cobalt and nickel were higher than the values recorded from the Red Sea coast, the Gulf of Aqaba and some Caspian Sea coasts. The Duba bulk plant-Saudi Aramco, Duba refinery station and the tourist resort were the possible anthropogenic sources of pollutants in the southern part of the study area; and the landfilling, cement factory and Duba port and shipment operations in the central part, while the landfilling resulting from construction of the green Duba power plant and crowded fish boats were the possible sources in the northern part.

Assessment of sediment quality using different pollution indicators and statistical analyses, Hurghada area, Red Sea coast, Egypt.

Thirty bottom sediment samples were collected from northern Hurghada coast, Red Sea, Egypt to evaluate the level of anthropogenic pollutants, using enrichment factor (EF), potential ecological risk index (PERI), soil pollution index (SPI), potential contamination index (Cp) and multivariate statistical analysis (correlation analysis, principal component analysis, and hierarchical cluster analysis). Fe, Mn, Zn, Pb, Ni, Cu, Co and Cd were analyzed by Atomic Absorption Spectrophotometer. Results indicated that the average values of Pb and Cd were greater than the ones recorded from many other worldwide coastal areas. The studied sediments are extremely severe enrichment with Pb and Cd (EF > 50), severe enrichment with Zn (EF = 10-25), very high risk with Cd (PERI ≥ 320), high risk with Pb (160 ≤ PERI ˂ 320), highly contaminated with Pb (SPI > 3), a severe contamination with Pb (Cp > 3). The accumulation of pollutants is associated with the muddy and fine sediment; especially the studied area is a semi-closed bay, characterized by long time of water retention. Possible sources of metals pollution in the studied area are shipment operations and anticorrosive and antifouling paints, dredging and land filling, municipal wastewater from tourist centers and fishermen cargo boats.

Spatial distribution and metal contamination in the coastal sediments of Al-Khafji area, Arabian Gulf, Saudi Arabia.

To document the spatial distribution and metal contamination in the coastal sediments of the Al-Khafji area in the northern part of the Saudi Arabian Gulf, 27 samples were collected for Al, V, Cr, Mn, Cu, Zn, Cd, Pb, Hg, Sr, As, Fe, Co, and Ni analysis using inductively coupled plasma-mass spectrometer (ICP-MS). The results revealed the following descending order of the metal concentrations: Sr > Fe > Al > As > Mn > Ni > V > Zn > Cr > Cu > Pb > Co > Hg > Cd. Average levels of enrichment factor of Sr, As, Hg, Cd, Ni, V, Cu, Co, and Pb were higher than 2 (218.10, 128.50, 80.94, 41.50, 12.31, 5.66, 2.95, 2.90, and 2.85, respectively) and that means the anthropogenic sources of these metals, while Al, Zn, Cr and Mn have enrichment factor less than 2, which implies natural sources. Average values of Sr, Hg, Cd, Cr, Ni, and As in the coastal sediments of Al-Khafji area were mostly higher than the values recorded from the background shale and earth crust and from those results along coasts of the Caspian Sea and the Mediterranean Sea. The highest levels of Cu in the northern part of the studied coastline might be due to Al-Khafji desalination plant, while levels of Al, Ni, Cr, Fe, Mn, Pb, and Zn in the central part may be a result of landfilling and industrial sewage. The highest levels of As, Cd, Co, Cu, Hg, and V in the southern part seem to be due to oil pollutants from Khafji Joint Operations (KJO). The higher values of Sr in the studied sediments in general and particularly in locality 7 could relate to the hypersalinity and aragonitic composition of the scleractinian corals abundant in that area.

Metal pollution in Al-Khobar seawater, Arabian Gulf, Saudi Arabia.

In order to assess heavy metals pollution along the Al-Khobar coastline, 30 seawater samples and 15 sediment ones were collected for Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Hg and Pb analysis by Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The analysis indicated a southward decreasing pattern in most heavy metal concentrations and the average values of Zn, Fe, Mn, Cu, As and Cr were higher than the ones reported from some worldwide seas and gulfs. Most of the highest levels were recorded within the bays and were related with in situ under sediments especially that composed of clays and very fine sands, and in localities characterized with anthropogenic activities like landfilling, desalination plants, fishing boats, oil spills and solid rubbish. The results of the present study provide useful background for further marine investigation and management in the Arabian Gulf region.