The Yanbu industrial city along the Red Sea coast includes industries associated with crude oil and natural gas production and refining and support industries that produce manufactured goods for domestic and/or internal consumption. This study investigates the potential environmental impact and the possible sources of heavy metals (HMs), and it evaluates the quality of coastal surface seawater in the vicinity of Yanbu, along the Red Sea coast of Saudi Arabia. Thirty seawater samples have been collected and analyzed using an inductively coupled plasma mass spectrometer (ICP-MS) in order to determine the concentration values of Fe, Cr, Pb, Sb, Mn, Cu, Zn, Al, Ni, As, Cd, Co, and Hg. Reported HMs averages (μg/L) are in the following sequence: Ni (4.424) > As (4.297) > Cu (2.447) > Zn (1.667) > Al (1.133) > Fe (0.983) > Cr (0.723) > Mn (0.328) > Cd (0.309) > Pb (0.276) > Sb (0.238) > Co (0.144) > Hg (0.058). The contamination index (Cd) showed low contamination levels in all of the analyzed samples, whereas the index of heavy metal pollution (HPI) revealed medium contamination levels in 28 samples and low levels in two samples. Reported high HMs variations within samples are attributed to the multiplication of sources. The statistical analyses indicated anthropogenic sources for Cd, Co, Hg, Zn, and Ni, which may have originated from industrial, farming, or fishing activities around Yanbu city, while the remaining metals might be originated from combined lithogenic and human sources.

The contamination of seawater with anthropogenic factors is a global challenge because of its negative impacts on marine environments and coastal societies. Therefore, assessing water contamination is crucial. The present work uses pollution indices and multivariate statistical analyses to document high-level heavy metal concentrations and identify potential polluters by analyzing 35 seawater samples collected from Al-Uqair coastline, Arabian Gulf, Saudi Arabia. The total content of heavy metals (HMs) (μg/L) ranged from 7109 to 7398 for Sr, 7.00–14.50 for Cr, 3.30–9.90 for Zn, 3.00–8.80 for Fe, 4.40–7.60 for As, 1.20–6.90 for Ni, 2.30–4.70 for V, 1.10–3.80 for Cu, 2.50–3.10 for Se, 0.31–1.43 for Al, 0.18–1.10 for Hg, 0.04–0.08 for Cd, 0.09–0.43 for Pb, and 0.02–0.10 for Sb. The recorded average concentrations of HMs were below the maximal admissible concentration of the World Health Organization (WHO). The heavy-metal pollution index (HPI) indicates that 14.29% of the water samples were below medium pollution, and 85.71% were below high pollution. All seawater samples were categorized under low contamination and good water on the basis of the degree of contamination (Cd) and water pollution index (PIj), respectively. Multivariate analysis indicates mixed anthropogenic and natural sources for the investigated metals, with increasing control of the anthropogenic factors for Cr, Zn, As, V, Ni, Se, Cu, Hg, Pb, Sb, and Cd; and the control of natural factors for Sr, Fe, and Al.

The Sequoia Pliocene channel reservoirs within the West Delta Deep Marine (WDDM) concession, located offshore of the Nile Delta, pose significant challenges due to their complex stratigraphy and variable reservoir properties. This study employs an integrated approach, combining seismic data interpretation with comprehensive petrophysical analysis, to characterize these reservoirs and assess their hydrocarbon potential. Seismic data interpretation revealed a complex depositional environment, characterized by an upward-fining sequence of sandstones and mudstones. High seismic amplitudes were associated with gas sands, while lower amplitudes indicated background shale. The seismic stratigraphy indicates that the Sequoia channel system evolved from an initial high-energy erosional phase to a more subdued depositional environment, leading to significant heterogeneity in the reservoir quality. Petrophysical analysis demonstrated that effective porosity values within the reservoir range from 18 to 30%, with water-saturation levels of between 38 and 68%, reflecting the variability in reservoir properties across different zones. The calculated gas initially in place (GIIP) for the Sequoia channel ranges from 724.1 to 4158.71 Bcf, highlighting the substantial hydrocarbon potential within this complex system. This study underscores the importance of integrating seismic and petrophysical data to develop a comprehensive understanding of the Sequoia channel reservoirs. The results provide a robust framework for optimizing field development strategies, which is crucial for maximizing hydrocarbon recovery. The findings also offer valuable insights into the geological complexities of the WDDM concession, serving as a reference for future exploration and production efforts in similar deep-water environments.

This study investigates the processes leading to karst development in the southeastern part of Riyadh city extending up to Al Kharj. Numerous solution features such as sinkholes, collapsed dolines, and solution caverns are common in the area. The role of water in the development of the karst features was investigated using an integrated geological and hydrochemical approach. Geological investigations included the petrographic analysis of rock samples collected from zones of intense karstification with special emphasis on mineral dissolution. The study showed that the Sulaiy Formation is commonly fractured, brecciated, foliated, and contains numerous cavities, vugs, and openings. These features have formed by mineral dissolution by circulating groundwater, which has removed anhydrite beds from the underlying Arab–Hith sequence. Karstification likely started from the tectonically weak zones when there was more groundwater recharge. Studies show that during the early to mid-Holocene period, the climate in the Arabian Peninsula was humid, promoting groundwater recharge and subsequent mineral dissolution, though the process of karstification must have started much earlier. Hydrochemical findings reveal that mineral dissolution (halite and calcium sulfate) is the main process affecting groundwater chemistry. The Piper plot revealed two main hydrochemical facies: the (Ca²⁺ + Mg²⁺)–(Cl+ SO₄²⁻) Type (Type A) and the (Na⁺ + K⁺)–(SO₄²⁻ + Cl) Type (Type B). Most of the samples belong to Type B, typical of groundwater facies affected by dissolution of halite and anhydrite mineral. The absence of the (Ca²⁺ + Mg²⁺)–(CO₃²⁻ + HCO₃⁻) type of groundwater facies indicates a lack of recent groundwater recharge and the removal of carbonate minerals from the system through precipitation, as evidenced by the saturation indices. Plots of the major ionic pairs (cations vs. anions) in groundwater indicate strong halite and gypsum/anhydrite dissolution. Of the three carbonate minerals, calcite has the highest average saturation index followed by aragonite and dolomite. This suggests significant past rock–water interaction leading to carbonate dissolution. Presently, any additional calcium or carbonate ions introduced into the water lead to calcite precipitation. The study indicates that the process of karst development may not be active today. Currently, groundwater chemistry is mainly influenced by rock–water interaction leading to gypsum/anhydrite dissolution, which has resulted in a high concentration of Na⁺, Ca²⁺, Cl⁻ and SO₄²⁻ ions in groundwater. The dissolution of gypsum and halite from the Hith Formation weakens the structural integrity of the overlying Sulaiy Formation, creating large underground cavities. These cavities increase the risk of roof collapse, leading to cover-collapse sinkholes as the roof becomes too thin to support the weight above.