Assessing the ecological and health risks associated with heavy metal pollution levels in sediments of Big Giftun and Abu Minqar Islands, East Hurghada, Red Sea, Egypt.

This study assessed pollution levels, ecological and health risk, and spatial distribution of eight heavy metals in sediments of Big Giftun and Abu Minqar Islands, Red Sea, Egypt. Iron (Fe) and manganese (Mn) had the highest contents in both island sediments, while cobalt (Co) in Big Giftun and cadmium (Cd) in Abu Mingar had the lowest values. The obtained PCA data exhibited positively significant loadings of Cd, Co, copper (Cu), nickel (Ni), and zinc (Zn) with 51.03 % of data variance in Big Giftun, and lead (Pb), Cu, Mn, Ni, Zn, and Fe (37.7 %) in Abu Minqar sediments. The contamination factor (CF) showed low contamination for all metals, except cadmium; Cd (moderate). The geo-accumulation index (Igeo) values showed uncontaminated (Cd, Co), moderately (Cu), extremely contaminated (Fe, Mn) (Igeo > 5) in Big Giftun, and uncontaminated (Cd), moderately to strongly contaminated (Cu, Ni), and extremely contaminated (Fe, Mn, and Zn) in Abu Minqar sediments. The pollution load index (PLI) values indicated baseline level of contamination (PLI <1), and degree of contamination (DC) indicated low degree of contamination (DC < n) in all sediments. Nemerow pollution index (NPI) showed unpolluted sediments in Abu Minqar (NPI ≤1) and slight pollution (1 < NPI ≤2) in Big Giftun. Cd showed moderate potential ecological risk (40 ≤ Eri < 80) in Big Giftun sediments. Potential ecological risk index (PERI) indicated low risk sediments (PERI <150). Mean effects range median quotient (MERMQ) indicated low-priority risk of toxicity (MERMQ ≤0.1), and toxic risk index (TRI) showed no toxic risk in all sediments (TRI <5). The modified hazard quotient (mHQ) indicated very low severity of contamination (mHQ <0.5). The hazard quotient (HQ) levels of all metals were below the safe value (HQ <1). The hazard index (HI) levels indicated that no chronic risks occur (HI <1). The total cancer risk (TCR) for all metals were below the safe level (1 × 10-4) of the United States Environmental Protection Agency (U.S. EPA) guidelines.

Design of a New Phthalocyanine-Based Ion-Imprinted Polymer for Selective Lithium Recovery from Desalination Plant Reverse Osmosis Waste.

In this study, a novel technique is introduced that involves the combination of an ion-imprinted polymer and solid-phase extraction to selectively adsorb lithium ions from reverse osmosis brine. In the process of synthesizing ion-imprinted polymers, phthalocyanine acrylate acted as the functional monomer responsible for lithium chelation. The structural and morphological characteristics of the molecularly imprinted polymers and non-imprinted polymers were assessed using Fourier transform infrared spectroscopy and scanning electron microscopy. The adsorption data for Li on an ion-imprinted polymer showed an excellent fit to the Langmuir isotherm, with a maximum adsorption capacity (Qm) of 3.2 mg·g-1. Comprehensive chemical analyses revealed a significant Li concentration with a higher value of 45.36 mg/L. Through the implementation of a central composite design approach, the adsorption and desorption procedures were systematically optimized by varying the pH, temperature, sorbent mass, and elution volume. This systematic approach allowed the identification of the most efficient operating conditions for extracting lithium from seawater reverse osmosis brine using ion-imprinted polymer-solid-phase extraction. The optimum operating conditions for the highest efficiency of adsorbing Li+ were determined to be a pH of 8.49 and a temperature of 45.5 °C. The efficiency of ion-imprinted polymer regeneration was evaluated through a cycle of the adsorption-desorption process, which resulted in Li recoveries of up to 80%. The recovery of Li from the spiked brine sample obtained from the desalination plant reverse osmosis waste through the ion-imprinted polymer ranged from 62.8% to 71.53%.

Synthesis of a New Molecularly Imprinted Polymer and Optimisation of Phenylglyoxylic Acid Extraction from Human Urine Samples Using a Central Composite Design within the Response Surface Methodology.

Styrene, a chemical widely used in various industries, undergoes metabolic breakdown in the human body, resulting in the production of phenylglyoxylic acid (PGA). A novel molecularly imprinted polymer (MIP) was synthesised for selective extraction and enrichment of PGA in urine samples prior to high-performance liquid chromatography. The MIP employed in this research was a 4-vinylpyridine molecularly imprinted polymer (4-VPMIP) prepared via mass polymerisation using a noncovalent method. The structural and morphological characteristics of the molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were evaluated using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The efficiency of the molecularly imprinted solid-phase extraction (MISPE) process was optimised by investigating critical variables such as sample pH, sorbent mass, sample flow rate, and volume of the elution solvent. A central composite design (CCD) within the response surface methodology was utilised to develop separate models for the adsorption and desorption steps. Analysis of variance (ANOVA) confirmed the excellent fit of the experimental data to the proposed response models. Under the optimised conditions, the molecularly imprinted polymers exhibited a higher degree of selectivity and affinity for PGA, with a relative selectivity coefficient (α) of 2.79 against hippuric acid. The limits of detection (LOD) and quantification (LOQ) for PGA were determined to be 0.5 mg/L and 1.6 mg/L, respectively. The recoveries of PGA ranged from 97.32% to 99.06%, with a relative standard deviation (RSD) lower than 4.6%. Furthermore, MIP(4VP)SPE demonstrated the potential for recycling up to three times without significant loss in analyte recovery.

Dolphin-shaped island: Exploring the natural resources and radiological hazards of Wadi El Gemal Island.

The objective of this study is to assess the natural resources and radiological risks of Wadi El Gemal Island by examining its topography, mineralogy, geochemistry, and radioactive distributions. This island, which is situated at the outlet of Wadi El Gemal in Egypt's southeastern Desert, has a unique shape resembling a dolphin based on Landsat imagery. It's a part of the Wadi El Gemal-Hamata Protectorate and is notable for its diverse environmental, geological, economic, and archeological features, including recent reefs, sandy deposits, Quaternary carbonate sediments, and mangroves. The main natural resources on the island are fauna, mangrove forests, and flora. Samples collected from the island were analyzed using a NaI detector to measure the concentrations of radionuclides such as 238U, 232Th, 226Ra, and 40K, which were found to be within acceptable levels according to UNSCAR guidelines. The radionuclide 238U, 232Th, 226Ra, and 40K activity concentrations of the collected samples were 32.55 ± 9, 12.63 ± 4, 12.49 ± 4, and 325 ± 34 Bq/kg, respectively. Regarding radiological hazard indices, the values of absorbed gamma dose rate (36.06 ± 5.42 nGy/h), radium equivalent activity (73.88 ± 14.4 Bq/kg), annual effective dose indoor (0.18 ± 0.03 mSv/y) and outdoor (0.04 ± 0.01 mSv/y), internal (0.29 ± 0.05) and external (0.2 ± 0.03) indices, and excess lifetime cancer index (0.15 ± 0.05 × 10-3).This is suggest that there is no significant risk associated with these sediments.

Assessment of heavy metals contamination of sediments and surface waters of Bitter lake, Suez Canal, Egypt: Ecological risks and human health.

The concentrations of heavy metals in the surface waters and sediments of Bitter Lake were investigated to assess the level, distribution, and source of pollution and the associated ecological and human health risks. The ecological indices of the lake water indicate low contamination degrees by heavy metals. A dermal exposure-based health risk evaluation revealed no carcinogenic or non-carcinogenic impact on human health. The contamination factor (CF) for Cu, Ni, Pb, Mn, Fe, and Zn (CF < 1) indicate low contamination levels, while Cd reaches very high contamination in most sediment sites (CF ranges from 6.2 to 72.4). Furthermore, the potential ecological risk factor (Eri) and modified hazard quotient (mHQ) indicate low ecological risk for all metals except Cd, revealing high to very high-level ecological risk in most sites (Eri ranges from 185 to 2173 and mHQ from 1.8 to 6.3). This emphasizes the urgency of prompt actions to improve the environment in Bitter Lake.

Biohydrogen production coupled with wastewater treatment using selected microalgae.

Microalgae such as Chlorella pyrenoidosa, Scenedesmus obliquus and Chlorella sorokiniana were cultivated in domestic wastewater for biohydrogen production. The comparison between the microalgae was executed based on biomass productions, biochemical yields and nutrient removal efficiencies. S. obliquus showed the possibility of growing in domestic wastewater reaching maximum biomass production, lipid, protein, carbohydrate yield and nutrient removal efficiency. All the three microalgae reached high biomass production of 0.90, 0.76 and, 0.71 g/L, respectively for S. obliquus, C. sorokiniana and C. pyrenoidosa. A higher protein content (35.76%) was obtained in S. obliquus. A similar pattern of lipid yield (25.34-26.23%) and carbohydrate yield (30.32-33.21%) was recorded in all selected microalgae. Chlorophyll-a content was higher in synthetic media-grown algae compared algae grown in wastewater. The maximum nutrient removal efficiencies achieved were 85.54% of nitrate by C. sorokiniana, 95.43% of nitrite by C. pyrenoidosa, ∼100% of ammonia and 89.34% of phosphorus by C. sorokiniana. An acid pre-treatment was applied to disintegrate the biomass of microalgae, followed by dark fermentation in batch mode to produce hydrogen. During fermentation process, polysaccharides, protein and lipids were consumed. Maximum hydrogen production of 45.50 ± 0.32 mLH2/gVS, 38.43 ± 0.42 mLH2/gVS and 34.83 ± 1.82 mL/H2/gVS was achieved by C. pyrenoidosa, S. obliquus and C. sorokiniana respectively. Overall, the results revealed the potential of microalgal cultivation in wastewater coupled with maximum biomass production lead to biohydrogen generation for environmental sustainability.

Silver Anchored Polyaniline@Molybdenum Disulfide Nanocomposite (Ag/Pani@MoS2) for Highly Efficient Ammonia and Methanol Sensing under Ambient Conditions: A Mechanistic Approach.

We report the synthesis of silver anchored and para toluene sulfonic acid (pTSA) doped polyaniline/molybdenum disulfide nanocomposite (pTSA/Ag-Pani@MoS2) for highly reproducible room temperature detection of ammonia and methanol. Pani@MoS2 was synthesized by in situ polymerization of aniline in the presence of MoS2 nanosheets. The chemical reduction of AgNO3 in the presence of Pani@MoS2 led to the anchoring of Ag to Pani@MoS2 and finally doping with pTSA produced highly conductive pTSA/Ag-Pani@MoS2. Morphological analysis showed Pani-coated MoS2 along with the observation of Ag spheres and tubes well anchored to the surface. Structural characterization by X-ray diffraction and X-ray photon spectroscopy showed peaks corresponding to Pani, MoS2, and Ag. The DC electrical conductivity of annealed Pani was 11.2 and it increased to 14.4 in Pani@MoS2 and finally to 16.1 S/cm with the loading of Ag. The high conductivity of ternary pTSA/Ag-Pani@MoS2 is due to Pani and MoS2 π-π* interactions, conductive Ag, as well as the anionic dopant. The pTSA/Ag-Pani@MoS2 also showed better cyclic and isothermal electrical conductivity retention than Pani and Pani@MoS2, owing to the higher conductivity and stability of its constituents. The ammonia and methanol sensing response of pTSA/Ag-Pani@MoS2 showed better sensitivity and reproducibility than Pani@MoS2 owing to the higher conductivity and surface area of the former. Finally, a sensing mechanism involving chemisorption/desorption and electrical compensation is proposed.

Biosorption kinetics of cerium(III) and cobalt(II) from liquid wastes using individual bacterial species isolated from low-level liquid radioactive wastes.

The existence of toxic heavy metals in the aquatic environment has emphasized a considerable exigency to develop several multifunctional biosorbents for their removal. Herein, three individual bacterial species of Cellulosimicrobium cellulans, Bacillus coagulans, and Microbacterium testaceum were successfully isolated from low-level liquid radioactive wastes. Their loading capacities towards cerium and cobalt metal ions were inclusivity inspected under variable operational parameters of pH, primary pollutant concentration, interaction time, temperature, stirring speed, and biosorbent dosage. By analyzing the influence of solution pH, concentration, temperature, biosorbent mass, and agitation speed on the biosorption kinetics, the biosorption process confirms pseudo-second-order kinetic, intraparticle diffusion, and Elovich equation. Remarkably, the isolated Microbacterium testaceum exhibited high loading capacities reaching 68.1 mg g-1, and 49.6 mg g-1 towards Ce(III), and Co(II) ions, respectively, at the initial concentration of 2.8 mM, pH 4.5, and 25 °C. Overall, the isolated bacterial species can potentially be offered up as a promising scavenger for Ce(III) and Co(II) from liquid waste effluents.

A novel conversion of marine macroalgal biomass to biofuel (biohydrogen) via calcium hypochlorite induced dispersion.

Environmental pollution due to the consumption of non-renewable energy lead the search for alternative eco-friendly renewable fuel. The study details the biohydrogen production efficiency by potential macroalgal (Ulva reticulata) biomass improved by a disperser combined with calcium hypochlorite pretreatment technology. Calcium hypochlorite was added to decrease the surface energy of the medium induced by sole disperser pretreatment. Optimum condition for algal disperser treatment was 10,000 rpm with 30 min as dispersion time. The specific energy spent for the disintegration of the macroalgal biomass was 1231.58 kJ/kg TS. COD solubilization rate of 11.79% was attained with mechanical pretreatment whereas increased to 20.23% with combined pretreatment. Combination of disperser with calcium hypochlorite significantly reduced the specific energy input spent to 500 kJ/kg TS. The amount of organic materials such as carbohydrates, proteins and lipids released were 680 mg/L, 283 mg/L and 136 mg/L respectively. Thus, the combinative pretreatment with disperser rotor speed (10,000 rpm) for pretreatment time (12 min) and calcium hypochlorite dosage (0.1 g/g) derived as optimum condition for effective solubilization of macroalgal biomass. Biohydrogen production potential was maximum in the macroalgae pretreated with both disperser and calcium hypochlorite recorded highest yield (54.6 mL H2/g COD) compared to the macroalgae pretreated with disperser alone (31.7 mL H2/g COD) and untreated macroalgae (11.5 mL H2/g COD).

Effect of foliar application of nano-nutrients solution on growth and biochemical attributes of tomato (Solanum lycopersicum) under drought stress.

Introduction: Drought stress has drastically hampered the growth and yield of many crops. Therefore, environmentally safe agricultural techniques are needed to mitigate drought stress impact. To this end, foliar spray of nano-nutrients solution to (NNS) alleviate harmful aspects of drought stress. Methods: In a completely randomized design (CRD) experiment, seedlings were transplanted into pots at 2-3 leaf stage, each filled with loam-compost- organic manure soil (3:1:1). Plants were divided into two groups. (a) control group (b) applied stress group. Plants at vegetative stage were treated with 100% FC for control group and 60% FC for drought group, and these levels were maintained until harvesting. Three treatments of NNS with four levels i.e., 0%, 1%, 3% and 5% were given to all the pots after two weeks of drought stress treatment with a gap of 5 days at vegetative stage. Results and discussion: Application of 1% of nano-nutrient solution displayed an improvement in shoot length, shoot fresh and dry weight, number of leaves and flowers. Leaf chlorophylls and carotenoids and total phenolics contents were found maximum while minimum electrolyte leakage was observed at 3% application compared to control. Further, 1% application of NNS increased the Leaf RWC%, total soluble sugars, flavonoids contents. 5% NNS application exhibited higher total free amino acids with minimum lipid peroxidation rate in leaves of tomato under drought. Antioxidant enzyme activities increased in a concentration dependent manner as gradual increase was observed at 1%, 3% and 5%, respectively. Overall, this study introduced a new insights on using nano-nutrient solutions to maintain natural resources and ensure agricultural sustainability.

Bioaugmentation of electrogenic halophiles in the treatment of pharmaceutical industrial wastewater and energy production in microbial fuel cell under saline condition.

Pharmaceutical wastewater with different toxic recalcitrant materials and high salinity requires a novel treatment technology before released into the environment. The present research details the treatment of pharmaceutical wastewater along with energy production using bioaugmentation of halophilic consortium in air cathode microbial fuel cell (ACMFC) under saline condition (4%). Organic load (OL) varied from 1.04 to 3.51 gCOD/L was studied in ACMFC. TCOD (Total Chemical Oxygen Demand) removal exhibited 65%, 72%, 84% and 89% at 1.04, 1.52, 2.01 and 2.52 gCOD/L OL respectively. SCOD (Soluble Chemical Oxygen Demand) removal of 60%, 66%, 76% and 82% was recorded during the operation of identical OL (1.04-2.52 gCOD/L). Prominent TCOD (92%), SCOD (90%), TSS (Total Suspended Solids) removal of 73% was attained at 3.02 gCOD/L OL with corresponding energy production of 896 mV (Current density (CD) - 554 mA/m2, Power density (PD)-505 mW/m2). CE (Columbic Efficiency) was 43%, 38%, 33%, 30%, 28% and 22% at different OL ranged between 1.04 and 3.51 gCOD/L. Increase in OL to 3.51 gCOD/L revealed decrement in TCOD (68%), SCOD (62%), TSS (52%) removal and energy production (CD-234 mA/m2, PD-165 mW/m2). Complete removal of phenol was accomplished at different OL in 6 (1.04, 1.52 gCOD/L) and 8 (2.01, 2.52 and 3.02 gCOD/L) days respectively. Ochrobactrum, Marinobacter, Bacillus and Rhodococcus were the dominant halophilic electrogenic strain in ACMFC at different OL.

Macroalgae (Ulva reticulata) derived biohydrogen recovery through mild surfactant induced energy and cost efficient dispersion pretreatment technology.

Currently identification of alternate fuel is the key area of research under progress to overcome the depletion of fossil fuels, meet the domestic and industrial requirements. Generation of hydrogen, which is a clean fuel gas can solve various environmental related problems. Extensive research is being carried out to increase production of hydrogen through different substrates. This study aims to increase the production of hydrogen from Ulva reticulata (a macroalgal biomass). Initially, the biomass is pretreated mechanically with disperser and a biosurfactant, namely rhamnolipid in order to increase the solubilization of the biomass. The rate of COD liquefaction increased from 14% to 25% with the addition of biosurfactant to the macroalgal biomass, which is further treated mechanically using a disperser. The disperser rotor speed of 12,000 rpm and the specific energy input of 1175 kJ/kg TS (Total Solids) with the disintegration time of 30 min and biosurfactant dosage of 0.075 g/g TS were considered as the optimum parameters for the effective liquefaction of the macroalgal biomass. Approximately 3500 mg/L of the biopolymers were released after the combinative pretreatment (using disperser and biosurfactant). About 80 mL biohydrogen/g COD (Chemical Oxygen Demand) was generated when the biomass was pretreated with both the disperser and biosurfactant while the biomass pretreated with the disperser alone generated just 30 mL biohydrogen/g COD and the untreated biomass generated 5 mL biohydrogen/g COD. Thus, it can be concluded that Ulva reticulata can be utilized effectively to generate biohydrogen.

Application of integrated extremophilic (halo-alkalo-thermophilic) bacterial consortium in the degradation of petroleum hydrocarbons and treatment of petroleum refinery wastewater under extreme condition.

Degradation of petroleum hydrocarbon under extreme conditions such as high salinity, temperature and pH was difficult due to unavailability of potential bacterial strains. The present study details the efficiency of extremophilic bacterial consortium in biodegradation of different petroleum hydrocarbons and treatment of petroleum refinery wastewater under extreme condition. Extreme condition for the degradation of petroleum hydrocarbons was optimized at 8% salinity, pH-10 and temperature-60 °C. The consortium recorded complete degradation of low molecular weight (LMW) petroleum hydrocarbons (200 ppm) such as anthracene, phenanthrene, fluorene and naphthalene in 8 days under optimized extreme condition. High molecular weight (HMW) hydrocarbons such as pyrene (100 ppm), benzo(e)pyrene (20 ppm), benzo(k)fluoranthene (20 ppm) and benzo(a)pyrene (20 ppm), revealed 93%, 60%, 55% and 51% degradation by the extremophilic consortium under optimized extreme condition. The extremophilic consortium mineralized fluorene (61%) at high saline condition up to 24%. Addition of yeast extract potently accelerated the biodegradation under extreme condition. Treatment of petroleum refinery wastewater in continuous stirred tank reactor recorded 92% COD removal with complete removal of LMW hydrocarbons in 16 days and 91% of HMW hydrocarbons in 32 days under extreme condition. The hydrocarbons degrading extremophilic consortium possessed Ochrobactrum, Bacillus, Marinobacter, Pseudomonas, Martelella, Stenotrophomonas and Rhodococcus.

Assessing nutrient salts and trace metals distributions in the coastal water of Jeddah, Red Sea.

In this study, eighteen sites at Jeddah coastal area, Red Sea, have been assessed for water quality status, depending on nutrients, metals, Chlorophyll-a (Chl-a) and physical variables during 2018 and 2019. The investigated parameters of the Water Quality Index (WQI) are temperature, pH, salinity, dissolved oxygen (DO), DO saturation, oxidizable organic matter (OOM), suspended particulate matter (SPM), Chl-a, ammonium, nitrite, nitrate, total nitrogen, reactive phosphate, total phosphorus, silicate, Zn, Fe, Mn Cu, Cd, Pb, and Ni. The results revealed that the pH values were slightly alkaline with a range of 7.85-8.20. The results of other parameters were as follow: salinity (36.95-42.61PSU), DO (5.22-6.67 mg/L), OOM (0.40-1.23 mg/L), SPM (12.39-21.5 mg/L), Chl-a (0.10-0.83 µg/L). The range of nutrients (µM) were 0.07-0.22, 0.45-1.47, 9.62-18.64, 23.31-57.65, 0.05-0.15, 0.55-2.78 and 2.54-5.51 for NH4/N, NO2/N, NO3/N, TN, PO4/P, TP and SiO4/Si, respectively. Cluster analysis was used to classify the stations studied. From the current study, five clusters were found, indicating the need to perform cluster analysis in the water quality assessment process to confirm the durability and consistency of the data discovered in the current application.

Experimental design and data on the adsorption and photocatalytic properties of boron nitride/cadmium aluminate composite for Cr(VI) and cefoxitin sodium antibiotic.

This article reports the experimental data on the adsorption and photocatalytic degradation-reduction properties of pure boron nitride (BN), cadmium aluminate (CdAl2O4) and boron nitride/cadmium aluminate (BN/CdAl2O4) composite for the hexavalent chromium (Cr(VI)) and cefoxitin sodium (CFT) in aqueous solution under the ultraviolet (UV) and visible light irradiation. This work evaluates the adsorption and photocatalytic efficiency of the 0.2g BN coupled with the CdAl2O4 in BN-0.2/CdAl2O4 composite for Cr(VI) and CFT. The experiments were performed by mixing the 0.025 material with 50 mL solution of known concentration (15 mg/L) at pH 3 for Cr(VI) and pH 7 for CFT. The obtained data can be valuable to select the proper light source (UV or visible) and pollutant to investigate the application of BN-0.2/CdAl2O4 composite. Moreover, presented data can help identify the equilibrium time for the adsorption process and to recognize the best process for the removal of the pollutants from wastewaters. A comparison of the obtained data with previously reported works has been conducted for the understanding of the adsorption and photocatalysis of Cr(VI) and CFT using various materials under the different experimental conditions.

Biofloc Technology: Emerging Microbial Biotechnology for the Improvement of Aquaculture Productivity.

With the significant increases in the human population, global aquaculture has undergone a great increase during the last decade. The management of optimum conditions for fish production, which are entirely based on the physicochemical and biological qualities of water, plays a vital role in the prompt aquaculture growth. Therefore, focusing on research that highlights the understanding of water quality and breeding systems' stability is very important. The biofloc technology (BFT) is a system that maximizes aquaculture productivity by using microbial biotechnology to increase the efficacy and utilization of fish feeds, where toxic materials such as nitrogen components are treated and converted to a useful product, like a protein for using as supplementary feeds to the fish and crustaceans. Thus, biofloc is an excellent technology used to develop the aquaculture system under limited or zero water exchange with high fish stocking density, strong aeration, and biota. This review is highlighted on biofloc composition and mechanism of system work, especially the optimization of water quality and treatment of ammonium wastes. In addition, the advantages and disadvantages of the BFT system have been explained. Finally, the importance of contemporary research on biofloc systems as a figure of microbial biotechnology has been emphasized with arguments for developing this system for better production of aquaculture with limited natural resources of water.

Assessing the ecological risks from hydrocarbons in the marine coastal sediments of Jeddah, Red Sea.

The Red Sea is a unique aquatic environment, and it is host to highly biodiverse marine organisms. This body of water occurs along the western side of Saudi Arabia, which is one of the largest producers of crude oil in the world. Thus, the sea's contamination by oil pollutants could pose a large problem and is a major concern in the region. The samples were analyzed to determine their polycyclic aromatic hydrocarbon (PAH) speciation and assess the associated ecological risk to the coastal environment of the Red Sea. The geographical distribution of the 16 total PAHs by concentration (range and average values in ng g-1 dry wt.) occurred in the following order: the northern region (1169.8 to 2742.0; 2083) < the southern region (1971.4 to 3003.4; 2493) < the middle region (2222.0 to 2930.6; 2599). The PAHs with two, three, four, five, and six rings make up 7.0%, 13.0%, 70.0%, and 10.0% of the total PAHs, respectively. The diagnostic ratio results showed that the PAHs may be attributed to petrogenic and pyrogenic sources. The PAH concentrations were considered toxic when their levels ranged from 119 to 491 ng toxic equivalent g-1 dry wt. According to the mean range of PAH effects (the mean effect range median quotient values), the ecological risk posted by the investigated sediments was lower than 0.1, denoting a toxicity effect with a probability of 11%. The analysis of PAHs highlighted that the sampling sites were low priority sites, and their PAHs may not cause acute biological damage.

Determination of sedimentation, diffusion, and mixing rates in coastal sediments of the eastern Red Sea via natural and anthropogenic fallout radionuclides.

The Red Sea is a unique ecosystem with high biodiversity in one of the warmest regions of the world. In the last five decades, Red Sea coastal development has rapidly increased. Sediments from continental margins are delivered to depths by advection and diffusion-like processes which are difficult to quantify yet provide invaluable data to researchers. Beryllium-7, lead-210 and ceseium-137 were analyzed from sediment cores from the near-coast Red Sea near Jeddah, Saudi Arabia. The results of this work are the first estimates of diffusion, mixing, and sedimentation rates of the Red Sea coastal sediments. Maximum chemical diffusion and particle mixing rates range from 69.1 to 380cm-2y-1 and 2.54 to 6.80cm-2y-1, respectively. Sedimentation rate is constrained to approximately 0.6cm/yr via multiple methods. These data provide baselines for tracking changes in various environmental problems including erosion, marine benthic ecosystem silting, and particle-bound contaminant delivery to the seafloor.