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Groundwater resources in coastal aquifers are commonly subjected to several anthropogenic threats that deteriorate their quality. This study focuses on the key factors influencing groundwater in Tarout Island, Saudi Arabia, including seawater intrusion, heavy metal contamination, and nitrate pollution. A comprehensive sampling and analysis strategy was implemented, incorporating the primary ion chemistry, stable isotopes (Oxygen-18 (δ18O), Deuterium (δ2H), Sulfur-34 (δ34SSO4)), and heavy metals/toxic elements concentrations. Both graphical and statistical tools were used to assess the presence and patterns of seawater intrusion, pollutant sources, and health hazards. According to the hydrochemical facies evolution diagram, stable isotopes and conservative ion mixing tendencies confirmed seawater mixing in 90% of tested samples. The study showed that heavy metals/toxic elements including Fe, Cr, Ni, V, As, and Co have exceeded regulation limits with 79% of groundwater samples tested being unfit for drinking purposes. In addition, nitrate was recorded surpassing the permissible limit in 38% of samples. The potential ecological risk index of the heavy metals/toxic elements varied from moderate to extremely high, with Ni, Cu, V, and As being the most hazardous metals. The results also show that 42% and 100% of tested groundwater showed potential non-carcinogenic and carcinogenic health risks, with total HQ and total CR exceeding the threshold values, respectively. The results show that seawater intrusion, heavy metal pollution, and nitrate contamination have detrimental effects on the island's groundwater quality. To mitigate the health and environmental hazards, groundwater use must be urgently managed alongside implementing suitable pollution control techniques. The study provides a robust scientific foundation for formulating policies that promote the sustainable use of Tarout Island's valuable groundwater resources. Similar anthropogenic pressures on coastal aquifers throughout the world necessitate the scientific understanding and integrated management approaches presented in this study to protect groundwater quality. It is recommended to establish a groundwater monitoring system that constantly monitors critical quality parameters to maintain an in-depth understanding of the complex nature of the vulnerable coastal aquifer. [ABSTRACT FROM AUTHOR]

Global groundwater resources have been threatened by both climate change and anthropogenic activities. Both factors could lead to groundwater depletion that might seriously threaten the living environment and food security. As one of the world's most water-stressed countries, Saudi Arabia has experienced long-term groundwater depletion due to excessive groundwater abstraction to meet the irrigation water demand. Moreover, rainfall and groundwater recharge are considered extremely low in most places in the Kingdom. Hence, a comprehensive assessment of groundwater risk in Saudi Arabia is necessary to avoid a worse scenario. The main objective of this study is to use the composite index to evaluate the groundwater risk in the Arabian Basin in Saudi Arabia. To achieve the objective, multiple variables, such as groundwater storage variations, groundwater reserves, total cropland area, and cropland expansion were integrated. The integration between physical hydrogeological assessment and anthropogenic factors is assumed to be a comprehensive risk measurement. Based on the final score, results demonstrated that Jouf and Najran could be classified as high-risk (17/100) and low-risk areas (71/100), respectively. The groundwater risk status was affected mainly by anthropogenic factors. Results of this study could serve as a diagnostic tool for decision-makers to prioritize and develop sustainable schemes, especially in high-risk areas. [ABSTRACT FROM AUTHOR]

The escalating demand of drinking water, coupled with increasing agricultural and industrial needs, has imposed a significant strain on groundwater sources worldwide, which is further exacerbated by the implications of climate change. The current research aims to identify the groundwater potential zones (GPZs) and the optimal sites for artificial recharge in the Wadi Waj watershed, Taif, Saudi Arabia. An integrated approach using remote sensing (RS), GIS, multi-criteria decision analysis (MCDA), and the analytic hierarchy process (AHP) was utilized. Seven hydrological and geological factors have been weighted and analyzed using AHP and GIS-based weight overlay approaches. Five GPZs have been mapped with the range from very high to very low where the very high, high, moderate, low, and very low GPZs were 0.046, 33.5, 31.3, 35.1, and 0.023 percent of the basin, respectively. The high GPZs were found in the downstream region, while the low GPZs were located in the upstream region with impermeable rock and steep slopes. A total of 27 locations have been identified as optimal sites for constructing artificial recharge facilities. These sites are positioned strategically to both catch and encourage the infiltration of rainwater into the ground. The findings were verified with the agricultural farms and wells demonstrating the alignment with moderate to high GPZs. The GPZs were also verified with the groundwater depth data obtained from the global model “GLOBGM v1.0,” and the findings showed comparable trends. The findings will support water resources management to enhance regional water security and maintain sustainable groundwater resources. [ABSTRACT FROM AUTHOR]

In drilling operations, the fine drilled cutting are mixed with the drilling fluid. As a result, the properties of the drilling fluid, such as density and rheological properties, will change based on the cutting properties. Previous studies investigated the effect of rock type with different loadings on the drilling fluid properties. However, the effect of cutting's mechanical properties variation was not addressed. In this paper, the effect of variation in cutting's mechanical properties on the drilling fluid properties was investigated in sandstone reservoir. Particles of sandstone formation core samples with different compressive strength (UCS) and different Young's modulus (E) were mixed, in different percentages, with the drilling fluid. The mechanical properties of the cuttings were determined in the laboratory using destructive method. The drilling fluid density and rheological properties were measured using mud balance and 900-Viscometer®, respectively. The results of this work showed that, for sand content less than 10 wt%, the mechanical properties of the drilled cutting have no effect on drilling fluid properties. The effect of the mechanical properties of the drilled cutting becomes more significant for sand content greater than 10 wt%. In this range of sand content (> 10 wt%), for a constant UCS, drilled cutting with a smaller Young's modulus have a higher effect on the drilling fluid rheological properties compared to drilled cutting with a larger Young's modulus. On the other hand, for a constant E, drilled cutting with larger UCS showed a higher effect on the drilling fluid rheological properties compared to drilled cutting with smaller UCS values. [ABSTRACT FROM AUTHOR]

Hierarchical structures have recently attracted significant interest due to their exceptional performance in energy storage and catalytic applications. In this study, novel hierarchical Fe2TiO5 nanosheets, fabricated by one-step solvothermal process, for boosted photocatalytic conversion of CO2 with water to fuels, were investigated. The characteristics and properties of these photocatalysts were analyzed using various techniques including XRD, FESEM, TEM, XPS, UV–vis, and PL spectroscopy. The hierarchical Fe2TiO5 nanosheets demonstrated significant performance, yielding 149.5 µmole/g-cat of CH3OH and 61.6 µmole/g-cat of dimethyl ether (DME), respectively. Compared to TiO2 samples, the optimized 2D hierarchical nanosheets of Fe2TiO5 displayed 3.8-fold and 4.1-fold higher efficiency in CH3OH and DME production, highlighting the advantages of their structure. The 2D hierarchical nanosheets of Fe2TiO5 facilitate electron transfer to CO2 due to their unique structure, providing efficient electron pathways and electron storage sites within the nanosheets, thereby enhancing photoactivity. Moreover, the extended stability of Fe2TiO5 in CO2 conversion further confirms the controllable selectivity and stability offered by the 2D hierarchical nanosheets structure. This study suggests that the fabrication of hierarchical structures holds promise for advancing high-performance photocatalysts for solar fuel production through CO2 conversion. [ABSTRACT FROM AUTHOR]