Search Results (15)

The Arabian Gulf, bordered by major energy-producing nations, harbors diverse microalgal communities with strong potential for the bioremediation of environmental pollutants, particularly petroleum hydrocarbons. This review evaluates two key microalgal groups—micro-green algae and dinoflagellates—highlighting their distinct physiological traits and ecological roles in pollution mitigation. Dinoflagellates, including Prorocentrum and Protoperidinium, have demonstrated hydrocarbon-degrading abilities but are frequently linked to harmful algal blooms (HABs), marine toxins, and bioluminescence, posing ecological and health risks. The toxins produced by these algae can be hemolytic or neurotoxic and include compounds such as azaspiracids, brevetoxins, ciguatoxins, okadaic acid, saxitoxins, and yessotoxins. In contrast, micro-green algae such as Oedogonium and Pandorina are generally non-toxic, seldom associated with HABs, and typically found in clean freshwater and brackish environments. Some species, like Chlorogonium, indicate pollution tolerance, while Dunaliella has shown promise in remediating contaminated seawater. Both groups exhibit unique enzymatic pathways and metabolic mechanisms for degrading hydrocarbons and remediating heavy metals. Due to their respective phycoremediation capacities and environmental adaptability, these algae offer sustainable, nature-based solutions for pollution control in coastal, estuarine, and inland freshwater systems, particularly in mainland Qatar. This review compares their remediation efficacy, ecological impacts, and practical limitations to support the selection of effective algal candidates for eco-friendly strategies targeting petroleum-contaminated marine environments. Full article

Diatoms in the Arabian Gulf region could contribute to various biological carbon pumps, playing crucial ecological roles and producing bioactive compounds beneficial to both humans and marine animals. Despite their significance, some diatoms pose risks to human health and the economy; however, research on their roles in Qatar remains limited. This review explores the roles of diatoms in the Arabian Gulf, highlighting their potential for remediating polluted seawater and their applications in pharmacology, biofuel production, and detoxification of chemical waste and hazardous metals. Among the 242 diatom species identified along the coastline of the Gulf and Qatar, several genera represent 50% of the identified species and have demonstrated notable efficiency in phycoremediation and bioactive compounds production. These include antibacterial agents with therapeutic potential, antioxidants to neutralize harmful free radicals, compounds that degrade toxic substances, and agents for remediating heavy metals. Additionally, diatoms contribute to the production of biofuels, nutritional agents, dyes, and extracellular polymeric substances, and some species serve as bioindicators of pollution stress. To fully utilize their potential requires significant efforts and comprehensive research. This review explores the reasons behind the current lack of such initiatives and highlights the importance of conducting targeted studies to address the environmental challenges facing the Arabian Gulf. Full article

Cyanobacteria play a crucial role in marine ecosystems as primary producers of food and oxygen for various organisms while helping remove waste and toxic substances from the environment. They are essential to the carbon cycle and help regulate the climate. These marine autotrophs also aid in the absorption of essential elements and support diverse life forms. They help degrade organic compounds, including petroleum hydrocarbons as well as heavy metals. Fluctuations in cyanobacteria populations can indicate ecosystem health, influencing both human well-being and wildlife. Their significance also extends to potential technological advancements, thus providing valuable resources for fields such as pharmacology, medicine, health care, biofuels, cosmetics, and bioremediation. However, some species produce toxins that pose risks to human health and marine organisms. Consequently, cyanobacteria are a major focus of research aimed at preserving and improving marine ecosystems—especially given the environmental damage caused by past and potential future conflicts. This review highlights their roles in cyanoremediation and other industrial and biotechnological applications with a particular focus on the Arabian Gulf region. Full article

The pearl oyster Pinctada radiata (Leach, 1814), a crucial ecosystem builder in the Arabian Gulf, has experienced a significant decline, mainly attributed to anthropogenic pressures. This study aimed to characterize the reproductive cycle of P. radiata in Qatar and compare the current data with historical records in the region obtained between 1992 and 1993. From May 2020 to April 2022, we found a well-defined seasonal reproductive pattern, with a narrow peak spawning period in April. This observation stands out strongly from the previous recordings of 1992–1993 for the region, where spawning extended from May to August. The observed shift in the reproductive cycle coincides with a notable increase in the maximum sea surface temperature (SST), rising from 34 °C in August (1992–1993) to 37 °C in July (2020–2022), while the minimum SST remained stable at 15–16 °C in January during both periods. Furthermore, a contraction in the duration of the main spawning period was observed, with spawning now confined to an earlier and shorter timeframe. We propose that climate change, in addition to other environmental stressors, must have played a key role in modifying the reproductive cycle of the pearl oyster P. radiata in the Arabian Gulf. These findings highlight the importance of further monitoring reproductive dynamics in the context of climate change. Full article

This paper presents a comparative study that examines the effects of the Dubai Creek extension on its hydrodynamics and water flushing dynamics. Dubai Creek (Khor Dubai) is a 24 km long artificial seawater stream located in the emirate of Dubai. The creek has experienced the impact of the rapid urbanization of Dubai and a major 13 km extension project, which connected the creek to the Arabian Gulf from the other side. In this paper, two-dimensional hydrodynamic and flushing models were created using Delft3D Flexible Mesh (2021.03) to investigate the water circulation and water quality of the creek before and after the extension. The hydrodynamic models were calibrated and validated to accurately simulate water levels and currents with correlation values close to 1 and very small RMSE and bias. Flushing models were created to simulate water renewal along the creek. The results of the flushing models showed a significant improvement in the flushing characteristics of pollutants in terms of the residence times of the extended creek (Existing Creek) model compared to the old one (Old Creek). This improvement emphasized the positive impact of the creek extension project on the local aquatic ecosystem and its overall water quality. Full article

Severe environmental conditions can have a diverse impact on marine microorganisms, including bacteria. This can have an inevitable impact on the biofouling of membrane-based desalination plants. In this work, we have utilized indicator bacteria such as total coliform, fecal coliform, and Pseudomonas aeruginosa, as well as 16S rRNA sequencing, to investigate the impact of environmental conditions and spatial variations on the diversity of bacterial communities in the coastal waters and sediments from selected sites in Qatar. The concentration levels of indicator bacteria were affected by increasing temperatures and pH, and by decreasing salinity of seawater samples. Diversity indices and the molecular phylogeny demonstrated that Proteobacteria, Bacteroidetes, and Cyanobacteria were the dominant phyla in all locations. The most abundant operational taxonomic units (OTUs) at the family level were from Flavobacteriaceae (27.07%, 4.31%) and Rhodobacteraceae (22.51%, 9.86%) in seawater and sediment, respectively. Alphaproteobacteria (33.87%, 16.82%), Flavobacteria (30.68%, 5.84%), and Gammaproteobacteria (20.35%, 12.45%) were abundant at the species level in both seawater and sediment, while Clostridia (13.72%) was abundant in sediment only. The results suggest that sediment can act as a reservoir for indicator bacteria, with higher diversity and lower abundance compared to seawater. Full article

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. Full article

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. Full article

Several Membrane Distillation (MD) technologies have been employed to remove boron from various concentrations. In this study, Vacuum Membrane Distillation (VMD), Permeate Gap Membrane Distillation (PGMD), and Air Gap Membrane Distillation (AGMD) are examined to evaluate their effectiveness when combined with several boron concentrations (1.5, 7 and 30 ppm) and operating parameters (circulation rate from 0.9 L/min to 5 L/min, feed temperature from 40 to 70 °C, and pH from 3–11). Those concentrations of boron are selected on the basis of the concentration of boron in the permeate side of the single-pass reverse osmosis (RO) system, Arabian Gulf, and contaminated brackish water. Moreover, synthetic seawater is treated to assess MD technologies’ effectiveness. A high removal efficiency of boron is accomplished by MD. AGMD, PGMD, and VMD are promising methods for the desalination industry. AGMD shows excellent boron removal, which was above 99% with a wide ranging concentration. In addition, VMD demonstrates good permeate flux compared to the other MD technologies, which were about 5.8 kg/m²·h for synthetic seawater. Furthermore, there is no noteworthy influence of the pH value on the boron removal efficiency. Full article

Pre-treatment of seawater plays a critical role in removing colloidal particles, algae, sediment, and microbes, which could adversely affect the desalination process. This study focused on the utilization of the natural process of infiltration by beach wells to pre-treat the intake water for the desalination process. The scope of the study was achieved by drilling two beach wells at Al-Khobar and Jubail sites at the Arabian Gulf of Saudi Arabia at 50 m depth each. In addition to that, a total of eight monitoring wells were drilled for pump testing. Numerical modeling was conducted using SEEP/W to investigate the properties of well water flux at the beach wells. The comprehensive physio-chemical parameters such as cation, silt density index (SDI), total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), total organic carbon (TOC), salinity, and alkalinity were analyzed for a quality assessment concerning the actual seawater. Preliminary experimental results show a reduction of the targeted parameters and indicate that beach well sand filtration in the Eastern Province would be a valuable pre-filtration step in reverse osmosis (RO)-based drinking water production systems. The water flux values for both sites were 0.0197 and 0.0208 m³/s/m², respectively, which corresponds to 72 m³/h/m² and 1356.48 m³/h/m². In terms of the rate of pumping flow, the model suggests production can be increased by 20 and 53 times the measured production of the Jubail and Al-Khobar sites, respectively. The experimental results of water parameters, such as cation, SDI, TDS, TSS, etc., indicate that beach well sand filtration in the Eastern Province would be a valuable pre-filtration step in reverse osmosis drinking water production systems. Full article

Novel thin film composite (TFC) polyamide (PA) membranes blended with 0.01–0.2 wt.% of Acacia gum (AG) have been prepared using the interfacial polymerization technique. The properties of the prepared membranes were evaluated using contact angle, zeta potential measurements, Raman spectroscopy, scanning electron microscopy, and surface profilometer. It was found that the use of AG as an additive to TFC PA membranes increased the membrane’s hydrophilicity (by 45%), surface charge (by 16%) as well as water flux (by 1.2-fold) compared with plain PA membrane. In addition, the prepared PA/AG membranes possessed reduced surface roughness (by 63%) and improved antifouling behavior while maintaining NaCl rejection above 96%. The TFC PA/AG membranes were tested with seawater collected from the Arabian Gulf and showed higher salt rejection and lower flux decline during filtration when compared to commercial membranes (GE Osmonics and Dow SW30HR). These findings indicate that AG can be used as an efficient additive to enhance the properties of TFC PA membranes. Full article

The application of seawater desalination technology using a reverse osmosis (RO) membrane has been expanding because it requires less energy compared with other distillation methods. Even in Middle Eastern countries where energy costs are lower such as Saudi Arabia, UAE, Qatar, and Kuwait, almost all desalination plants where only water production is required have adopted the RO method. However, large plants in excess of half mega-ton size are required, and Seawater Reverse Osmosis (SWRO) operation lacks reliability due to heavy biofouling and large amounts of briny discharge contaminated with chemicals. For reliable desalination systems with lower environmental impact, membrane-processing technology, including biotechnology (such as marine bacteria), has been examined as national research in Japan in the “Mega-ton Water System” project. We examined the influence of chlorination on marine bacteria using the fluorescence microscopic observation method and found that the effect of chlorination is limited. Chlorination sterilization triggers biofouling and sodium bisulfate (SBS) addition as a de-chlorinating agent also triggers biofouling, so a process with no chlorine or SBS addition would reduce biofouling. As polyamide SWRO membranes have low chlorine resistivity, such a process would enable longer membrane life in real plants. We used a biofouling monitoring technology, the Membrane Biofilm Formation Rate (mBFR), to design a process that involves no chlorine or SBS addition and verified it in the Arabian Gulf Sea, of Saudi Arabia, which is one of the most difficult and challenging seawaters in which to control biofouling. Furthermore, by minimizing the addition of a sterilizer, the desalination system became more environmentally friendly. Full article

Regionally calibrated algorithms for water quality are strongly needed, especially for optically complex waters such as coastal areas in the Arabian Gulf. In this study, a regional qualitative algorithm was proposed to retrieve seawater transparency, with Secchi disk depth (SDD) as a surrogate, in the Arabian Gulf. A two-step process was carried out, first estimating the diffuse attenuation coefficient of downwelling irradiance at 490 nm (K_d_490) from MODIS/Aqua imagery and then SDD based on empirical correlations with K_d_490. Three satellite derived K_d products were tested and assessed against a set of in situ measurements, and one from a semi-analytical algorithm based on inherent optical properties gave the best performance with a R² of 0.62. Comparisons between the performances of SDD models developed in this study and those established in other regions indicated higher accuracy of our proposed model for the Gulf region. The potential factors causing uncertainties of the proposed algorithm were also discussed. Seasonal and inter-annual variations of SDD over the entire Gulf were demonstrated using a 14-year time series of MODIS/Aqua data from 2002 to 2015. High SDD values were generally observed in summer while low values were found in winter. Inter-annual variations of SDD did not shown any significant trend with exceptions during algal bloom outbreaks that resulted in low SDD. Full article

In this paper we report on the corrosion inhibition of cast iron in Arabian Gulf seawater by two different ionic liquids namely, 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) and 1-butyl-1-methylpyrrolidinium chloride ([Py_1,4]Cl). The inhibiting influence of the employed ionic liquids was investigated by weight loss, open circuit potential electrochemical impedance spectroscopy, and cyclic potentiodynamic polarization. The results show the corrosion inhibition impact of the employed ionic liquids (ILs). Compared with [Py_1,4]Cl, [EMIm]Cl shows a higher inhibition efficiency at a short immersion time, for the examined ILs concentrations. However, [Py_1,4]Cl exhibits a higher efficiency upon increasing the immersion time indicating the persistence of the inhibiting influence. The corrosion inhibition of the employed ionic liquids is attributed to the adsorption of the cations of the ionic liquids onto the surface of cast iron forming a corrosion barrier. Full article

In this work, the results obtained from studying the corrosion of cast iron in freely aerated stagnant Arabian Gulf seawater (AGS) at room temperature were reported. The study was carried out using weight-loss (WL), cyclic potentiodynamic polarization (CPP), open-circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) measurements and complemented by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) investigations. WL experiments between two and 10 days’ immersion in the test electrolyte indicated that the weight-loss the cast iron increases with increasing the time of immersion. CPP measurements after 1 h and 24 h exposure period showed that the increase of time decreases the corrosion via decreasing the anodic and cathodic currents, as well as decreasing the corrosion current and corrosion rate and increasing the polarization resistance of the cast iron. EIS data confirmed the ones obtained by WL and CPP that the increase of immersion time decreases the corrosion of cast iron by increasing its polarization resistance. Full article