Groundwater Contamination in Arid Coastal Areas: Qatar as a Case Study.

The Arab region is located in an arid environment and suffers from water scarcity and poor water quality which are expected to become more severe in coming years due to global warming. In this study, the groundwater quality of 205 wells in Qatar was investigated. The physical parameters of pH, electrical conductivity (EC), total dissolved solids (TDS), salinity, inorganic carbon (IC), and organic carbon (OC) were determined. The study characterized the concentrations of major anions of Cl, F, Br, NO3, PO4, and SO4, and major cations of Ca, K, Mg, and Na. Importantly, metals and metalloids including V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, Ba, Pb, and U were determined. The results revealed that the groundwater of all wells is not drinkable due to high salinity (average TDS 4598 mg/L and salinity 0.4%, respectively). Additionally, average concentrations of major anions Cl, SO4, and F were 1472, 1064, and 1.9 mg/L, respectively, and all exceed the World Health Organization (WHO) guidelines for drinking water. However, NO3 concentration in 11 out of 205 wells was above the WHO guidelines of 50 mg/L due to intensive agriculture and fertilizer applications. Major cations of Ca, K, Mg, and Na were higher than WHO guidelines with average concentrations of 345, 63, 127, and 923 mg/L, respectively. All trace metals were much lower than the WHO guidelines for drinking water; however, the vanadium (V) average concentration in groundwater of all wells was 31 µg/L, which is five times higher than the Dutch guidelines (whereas the WHO has no guidelines for V). The groundwater of Qatar is dominated by Ca and Mg sulfates in Sabkha environments and dominated by NaCl in the coastal zones from evaporate environments consisting of coastal salt flats, salt pans, estuaries, and lagoons supersaturated by salts and the influence of sea water intrusion.

Human health risk assessment associated with the reuse of treated wastewater in arid areas.

Qatar produces more than 850,000 m3/day of highly treated wastewater. The present study aims at characterizing the effluents coming out of three central wastewater treatment plants (WWTPs) of chemical pollutants including metals, metalloids and antibiotics commonly used in the country. Additionally, the study is assessing human health risks associated with the exposure to the treated wastewater (TWW) via dermal and ingestion routes. Although the origin of domestic wastewater is desalinated water (the only source of fresh water), the results show that the targeted parameters in TWW were within the international standards. Concentrations of Cl, F, Br, NO3, NO2, SO4 and PO4, were 389, <0.1, 1.2, 25, <0.1, 346, and 2.8 mg/L, respectively. On the other hand, among all cations, metals and metalloids, only boron (B) was 2.1 mg/L which is higher than the Qatari guidelines for TWW reuse in irrigation of 1.5 mg/L. Additionally, strontium (Sr) and thallium (Tl) were detected with relatively high concentrations of 30 mg/L and 12.5 µg/L, respectively, due to their natural and anthropogenic sources. The study found that the low concentrations of all tested metals and metalloids do not pose any risk to human health. However, Tl presents exposure levels above the 10 % of oral reference dose (HQ = 0.4) for accidental oral ingestion of TWW. The results for antibiotics show that exposure for adults and children to TWW are far below the admissible daily intakes set using minimum therapeutic dose and considering uncertainty factors. Treated wastewater of Qatar can be used safely for irrigation. However, further investigations are still needed to assess microbiological quality.

Removal of heavy metals from wastewater by aerogel derived from date palm waste.

Cellulose that has been sourced from date palm leaves as a primary component was utilised. This cellulose served as the foundational material for the development of an aerogel composite. During this process, MXene (Ti3C2Tx) played a pivotal role in enhancing the overall composition of the aerogel. To ensure the stability and durability of the resulting aerogel structure, calcium ions were introduced to the mix. These ions facilitated the cross-linking process of sodium alginate molecules, ultimately leading to the formation of calcium alginate. This cross-linking step is crucial for the enhanced mechanical and chemical stability of the aerogel. Incorporating alginate and Ti3C2Tx into the cellulose aerogel enhanced its structural integrity in aqueous conditions and increased its adsorption capacity. When evaluated with synthetic wastewater, this composite exhibited remarkable adsorption capacities of 72.9, 114.4, 92.9, and 123.9 mg/g for As, Cd, Ni, and Zn ions, respectively. A systematic study was carried out to see the effect of various parameters, including contact time, MXene concentration, pH, and temperature on the adsorption of these elements. Peak adsorption was achieved at 60 min, favoring a pH range between 6 and 8 and exhibited optimal sorption efficiency at lower temperatures. The adsorption kinetics adhered closely to a pseudo-second-order, while the Freundlich model adeptly described the adsorption isotherms. An interesting result of this research was the aerogel's regenerative potential. After undergoing a basic acid treatment, the MXene/cellulose/alginate aerogel composite could be restored and reused for up to three cycles, all while maintaining its core performance capabilities even after the rigorous cross-linking processes. In three consecutive cycles, the removal percentages for As, Cd, Ni, and Zn were 48.15%, 80.38%, 56.51%, and 86.12% in cycle 1; 37.35%, 65.63%, 45.97%, and 78.42% in cycle 2; and 28.60%, 56.22%, 34.70%, and 65.83% in cycle 3, respectively. The composite was tested in conditions resembling seawater salinity. Impressively, the aerogel continued to demonstrate a significant ability to adsorb metals, reinforcing its potential utility in real-world aquatic scenarios. These findings suggest that the composite aerogel, integrating MXene, cellulose, and alginate, is an effective medium for the targeted removal of heavy metals from aquatic environments.

Human health risks associated with the consumption of groundwater in the Gaza Strip.

Groundwater of the Gaza Strip, the main source of drinking water for the Gazans, is highly contaminated by several chemicals of natural and anthropogenic origins. The results of this study confirm the findings of several studies conducted over the past two decades. Over those two decades, the population of Gaza has doubled, resulting in heavy demand for the limited reserves of groundwater. After 20 years since the first comprehensive study, it was found that groundwater salinity increased by 30 %, due to seawater intrusion. On the other hand, nitrate (NO3) decreased by 30 %, due to expansion of the sewer network and decrease in the number and distribution of septic tanks. Salinity, chloride (Cl), NO3 and fluoride (F) distribution maps for the year 2022 are very similar to those of the year 2002. This indicates that sources and loads of such contaminants are still the same. Metals and metalloids are still within the permissible limits set by the World Health Organization (WHO). Strontium (Sr) only showed concentrations of 12 mg/L across the Gaza Strip, which calls for further investigations. Maximum concentrations of the NO3 and F were 365 and 2.6 mg/L, respectively. The results of probabilistic risk assessment using Monte Carlo simulation showed that NO3 and F consumption through drinking water were above the reference dose for 35 % and 5 % of the trials performed, respectively. Consequently, the hazard quotient (HQ) is larger than 1 for 35 % and 5 % of the exposure scenarios simulated for these ions. For all metals and metalloids analyzed, HQ were below one (HQ1) indicating no risk; however, Sr presented an HQ 95th percentile equal to 0.19. Exposure routes such as dietary intake and soil ingestion, among others, should be further investigated to ensure that cumulative exposure does not surpass the safety limit. Recent advances in desalination technology should put an end to this truly regrettable situation.

Synthesis of nanostructured novel ion-imprinted polymer for selective removal of Cu2+ and Sr2+ ions from reverse osmosis concentrated brine.

This study aims to prepare an ion-imprinted polymer (IIP) using copper sulfate as a template and potassium persulfate as an initiator to selectively adsorb copper ions (Cu2+) from aqueous solutions and in an attempt to also test its applicability for removing strontium ions (Sr2+). The prepared polymer was denoted by IIP-Cu. Various physical and chemical characterizations were performed for the prepared IIP-Cu. The scanning electron microscopy and transmission electron microscopy analyses confirmed the cavities formed after the removal of the template. It also indicated that the IIP-Cu had a rough and porous topology. The X-ray photoelectron spectroscopy confirmed the successful removal of the Cu template from IIP-Cu. The Brunauer-Emmet-Teller revealed that the surface area of IIP-Cu is as high as 152.3 m2/g while the pore radius is 8.51 nm. The effect of pH indicated that the maximum adsorption of Cu2+ was achieved at pH 8 with 98.7%. Isotherm studies revealed that the adsorption of Cu2+ was best explained using Langmuir models with a maximum adsorption capacity of 159 mg/g. The effect of temperature revealed that an increase in temperature had an adverse impact on Cu2+ removal from the aqueous solution, which was further confirmed by thermodynamic studies. The negative value of standard enthalpy change (-4.641 kJ/mol) revealed that the adsorption of Cu2+ onto IIP-Cu was exothermic. While the continuous increase in Gibbs free energy from -6776 kJ/mol to -8385 kJ/mol with the increase in temperature indicated that the adsorption process was spontaneous and feasible. Lastly, the positive value of the standard entropy change (0.023 J/mol.K) suggested that the Cu2+ adsorption onto IIP-Cu had a good affinity at the solid-liquid surface. The efficiency of the prepared IIP-Cu was also tested by studying the adsorption capacity using Sr2+ and real brine water. The results revealed that IIP-Cu was able to remove 63.57% of Sr2+ at pH 8. While the adsorption studies revealed that the experiment was best described using the Langmuir model with a maximum adsorption capacity of 76.92 mg/g. Additionally, IIP-Cu was applied in a real brine sample, which consisted of various metal ions. The highest percentage of Cu2+ removal was 90.6% and the lowest was 65.63% in 1:4 and 1:1 brine ratios, respectively. However, this study indicates the successful application of IIP-Cu in a real sample when it comes to the effective and efficient removal of Cu2+ in a solution consisting of various competing ions.

Mapping of trace elements in topsoil of arid areas and assessment of ecological and human health risks in Qatar.

Soil is the incubator of human activities. Mapping of soil contaminants needs to be constantly updated. It is fragile in arid regions, especially if it accompanies dramatic and successive industrial and urban activities in addition to the climate change. Contaminants affecting soil are changing due to natural and anthropogenic influences. Sources, transport and impacts of trace elements including toxic heavy metals need continuous investigations. We sampled soil in accessible sites in the State of Qatar. An inductively coupled plasma-optical emission spectrometry (ICP-OES) and an inductively coupled plasma-mass spectrometry (ICP-MS) were used to determine the concentrations of Ag, Al, As, Ba, C, Ca, Ce, Cd, Co, Cr, Cu, Dy, Er, Eu, Fe, Gd, Ho, K, La, Lu, Mg, Mn, Mo, Na, Nd, Ni, Pb, Pr, S, Se, Sm, Sr, Tb, Tm, U, V, Yb and Zn. The study also presents new maps for the spatial distribution of these elements using the World Geodetic System 1984 (projected on UTM Zone 39N) which is based on socio-economic development and land use planning. The study assessed the ecological risks and human health risks of these elements in soil. The calculations showed no ecological risks associated with the tested elements in soil. However, the contamination factor (CF) for Sr (CF > 6) in two sampling locations calls for further investigations. More important, human health risks were not detected for population living in Qatar and the results were within the acceptable range of the international standards (hazard quotient HQ < 1 and Cancer risk between 10-5 and 10-6). Soil remains a critical component with water and food nexus. In Qatar and arid regions, fresh water is absent and soil is very poor. Our findings enhance the establishment of scientific strategies for investigating soil pollution and potential risks to achieve food security.

Probabilistic human health risk assessment of trace elements in ballast water treated by reverse osmosis desalination plants.

Very few studies have paid attention to the transport of heavy and toxic metals via ballast water coming from different countries of the world. In the present study, ballast water samples (n = 83) were collected from ships, tankers and vessels of 21 different origins arriving at the two main ports of Qatar. Besides the basic physical parameters of pH, electrical conductivity (EC), and total organic carbon (TOC), concentrations of 24 elements (As, Sb, Al, Cd, Pb, Si, V, Ag, Zn, Cr, Mn, Ba, Co, Ni, Sr, Be, Cu, Tl, B, Fe, Se, Sn, Mo and U) were determined. In addition, the potential human health risks of drinking water treated by reverse osmosis (RO) were assessed using Monte Carlo simulations. Two scenarios were used to assess the risks to the general population, namely, seawater (baseline) and ballast water (worst-case scenario). Our results show significant differences among the tested elements, depending on the origin of the ballast water. The human health assessment showed that all hazardous quotients (HQs) were below the safety limits. However, for the ballast water scenario, thallium (Tl) HQs were 10 % above the safety level. Ballast water in Qatar does not pose risks for human health through drinking water, but ballast water discharges should take into consideration seawater catchments and potential toxic elements, especially Tl. Regular monitoring campaigns need to be performed.

Substantiation of propitious "Enzybiotic" from two novel bacteriophages isolated from a wastewater treatment plant in Qatar.

Lysin of bacteriophages isolated from a particular ecosystem could be inducted as a bio-controlling tool against the inhabiting pathogenic bacterial strains. Our study aims at both experimental and computational characterization of the identical lysin gene product inherent in the genomes of two novel Myoviridae bacteriophages, Escherichia Phage C600M2 (GenBank accession number OK040807, Protein ID: UCJ01465) and Escherichia Phage CL1 (GenBank Genome accession number OK040806.1, Protein ID: UCJ01321) isolated from wastewater collected from the main water treatment plant in Qatar. The lysin protein, evinced to be a globular N-acetyl-muramidase with intrinsic "cd00737: endolysin_autolysin" domain, was further expressed and purified to be experimentally validated by turbidimetric assay for its utility as an anti-bacterial agent. Comprehensive computational analysis revealed that the scrutinized lysin protein shared 85-98% sequence identity with 61 bacteriophages, all native to wastewater allied environments. Despite varied Host Recognition Components encoded in their genomes, the similitude of lysins, suggests its apparent significance in host-pathogen interactions endemic to wastewater environment. The present study substantiates the identical lysin from Escherichia Phage C600M2 and Escherichia Phage CL1 as propitious "enzybiotic", a hybrid term to describe enzymes analogous to anti-biotics to combat antibiotic-resistant bacteria by in silico analysis and subsequent experimental validation.

Genomic Characterization and Annotation of Two Novel Bacteriophages Isolated from a Wastewater Treatment Plant in Qatar.

We report the genome sequences of Escherichia phage C600M2 (length, 88,162 bp; G+C content, 38.98%) and Escherichia phage CL1 (length, 87,820 bp; G+C content, 41.32%), which were isolated from a wastewater treatment plant in Qatar. Both Escherichia phage C600M2 and Escherichia phage CL1 genomes contain 128 protein-coding genes and 26 tRNAs.

A comprehensive risk assessment of toxic elements in international brands of face foundation powders.

Despite the COVID-19 pandemic and wearing masks in many countries, women are keen on elegance, beauty and the use of face foundations. Assessment of health risks associated with the regular use of face foundation by females is dynamic due to the emerging products. The most common international 14 brands of face foundation powders were collected and the concentrations of different elements (Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, P, Pb, Sb, Se, Sn, V and Zn) in each sample were determined. A combined approach merging the conventional and computational tools was used for investigating the risk of exposure to toxic elements. Monte Carlo simulations were applied to calculate risks associated with twenty elements. We attempted different probability distribution functions for concentrations because the actual distribution functions are not known, and the only data available are the mean value and standard deviation of concentrations obtained from experiment. Our results indicate that the total non-carcinogenic health risk through exposure to different elements (Hazardous Index, HI) does not strongly depend on the choice of the probability distribution function for the concentrations. We also show that taking into account probability distributions of other variables and parameters such as body weight, exposed skin area, skin adhesion, etc. does not significantly change the main result rather just slightly broadening the final Hazardous Index distribution function. We found that calculated HI is well below unity for all considered samples, i.e., the dermal exposure to toxic elements in the considered facial powders is negligible and the considered face foundation powders are quite safe to use.

Smart Synthesis of Trimethyl Ethoxysilane (TMS) Functionalized Core-Shell Magnetic Nanosorbents Fe3O4@SiO2: Process Optimization and Application for Extraction of Pesticides.

In the current study, a smart approach for synthesizing trimethyl ethoxysilane-decorated magnetic-core silica-nanoparticles (TMS-mcSNPs) and its effectiveness as nanosorbents have been exploited. While the magnetite core was synthesized using the modified Mössbauer method, Stöber method was employed to coat the magnetic particles. The objective of this work is to maximize the magnetic properties and to minimize both particle size (PS) and particle size distribution (PSD). Using a full factorial design (2k-FFD), the influences of four factors on the coating process was assessed by optimizing the three responses (magnetic properties, PS, and PSD). These four factors were: (1) concentration of tetraethyl-orthosilicate (TEOS); (2) concentration of ammonia; (3) dose of magnetite (Fe3O4); and (4) addition mode. Magnetic properties were calculated as the attraction weight. Scanning electron microscopy (SEM) was used to determine PS, and standard deviation (±SD) was calculated to determine the PSD. Composite desirability function (D) was used to consolidate the multiple responses into a single performance characteristic. Pareto chart of standardized effects together with analysis of variance (ANOVA) at 95.0 confidence interval (CI) were used to determine statistically significant variable(s). Trimethyl ethoxysilane-functionalized mcSNPs were further applied as nanosorbents for magnetic solid phase extraction (TMS-MSPE) of organophosphorus and carbamate pesticides.

A simple reaction-diffusion model for initial stages of biofouling in reverse osmosis membranes.

Biofouling is a critical issue in membrane water and wastewater treatment as it greatly compromises the efficiency of the treatment processes and consequently increases operational and maintenance costs. It is difficult to control this operational challenge, so the development of effective biofouling monitoring and control methods and strategies is a critical issue for membrane technology and applications. In this work, we develop a simulation approach for evaluating the operational time of reverse osmosis (RO) membranes based on a reaction-diffusion (RD) type of model. This approach would help to understand different factors involved in the formation of biofilms including microbial population dynamics (replication and death rates of microbial cells) and nutrient consumption. The model is focused on the initial stages of the membrane biofouling that is initiated by attachment of microbial species to the membrane leading to pore blocking followed by the formation of thick cake layer. We applied this approach to study the RO membrane biofouling by Picochlorum algae, the most common biofouling agent in the seawater of the Arabian Gulf, at known contents of total organic carbon and essential nutrients. We found that the biofilm growth dynamics on an RO membrane is mainly defined by the ratio of the replication and death rates of microbial cells. The proposed approach should be useful for fast evaluation of the RO membrane performance in different environmental conditions without using significant computational resources. This methodology allows generalization for multi-microbial and multi-nutrient systems. The establishment of effective fouling control strategies should decrease operational and maintenance costs of RO membrane systems.

Recycling of Date Pits Into a Green Adsorbent for Removal of Heavy Metals: A Fractional Factorial Design-Based Approach.

Date pits (DPs) have been recycled into a low-cost adsorbent for removing of selected heavy metals (HMs) from artificially contaminated aqueous solutions. Adsorption of targeted HMs, both by raw date pits (RDP) and burnt date pits (BDP) was tested. Results showed that BDP is more efficient as an adsorbent and mostly adsorbing Cu(II). A novel approach; fractional factorial design (2 k-p - FrFD) was used to build the experimental pattern of this study. The effects of four factors on the maximum percentage (%) of removal (Y) were considered; pH, adsorbent dose (AD), heavy metal concentration (HMC), and contact time (CT). Statistically significant variables were detected using Pareto chart of standardized effects, normal and half-normal plots together with analysis of variance (ANOVA) at 95.0 confidence intervals (CI). Optimizing (maximizing) the percentage (%) removal of Cu(II) by BDP, was performed using optimization plots. Results showed that the factors: pH and adsorbent dose (AD) affect the response positively. Scanning electron microscopy (SEM) was used to study the surface morphology of both adsorbents while fourier-transform infrared spectroscopy (FTIR) was employed to get an idea on the functional groups on the surface and hence the adsorption mechanism. Raman spectroscopy was used to characterize the prepared adsorbents before and after adsorption of Cu(II). Equilibrium studies show that the adsorption behavior differs according to the equilibrium concentration. In general, it follows Langmuir isotherm up to 155 ppm, then Freundlich isotherm. Free energy of adsorption (ΔG ad) is -28.07 kJ/mole, when equilibrium concentration is below 155 ppm, so the adsorption process is spontaneous, while (ΔG ad) equals +17.89 kJ/mole above 155 ppm, implying that the process is non-spontaneous. Furthermore, the adsorption process is a mixture of physisorption and chemisorption processes, which could be endothermic or exothermic reactions. The adsorption kinetics were described using a second order model.

Influence of Household Water Filters on Bacteria Growth and Trace Metals in Tap Water of Doha, Qatar.

Deteriorating water quality from aging infrastructure, growing threat of pollution from industrialization and urbanization, and increasing awareness about waterborne diseases are among the factors driving the surge in worldwide use of point-of-entry (POE) and point-of-use (POU) filters. Any adverse influence of such consumer point-of-use systems on quality of water at the tap remains poorly understood, however. We determined the chemical and microbiological changes in municipal water from the point of entry into the household plumbing system until it leaves from the tap in houses equipped with filters. We show that POE/POU devices can induce significant deterioration of the quality of tap water by functioning as traps and reservoirs for sludge, scale, rust, algae or slime deposits which promote microbial growth and biofilm formation in the household water distribution system. With changes in water pressure and physical or chemical disturbance of the plumbing system, the microorganisms and contaminants may be flushed into the tap water. Such changes in quality of household water carry a potential health risk which calls for some introspection in widespread deployment of POE/POU filters in water distribution systems.

Desalinated drinking water in the GCC countries - The need to address consumer perceptions.

The Gulf Cooperation Council (GCC) countries consist of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates. These countries depend mainly on seawater desalination to meet their water needs. Although great emphasis is given to characterize desalinated water for its physicochemical and microbial properties, e.g. presence of metals, other organic contaminants and for bacteria, sensorial characteristics including smell, taste and color have not received the same attention. This is possibly attributed to the fact that inhabitants of GCC States do not use desalinated tap water for drinking consumption, rather they depend on locally produced or imported bottled water where color, taste and odor are not problematic. To address the consumer needs and perceptions of drinking desalinated water in GCC countries, water quality standards and guidelines, should respond to the public concern about other sensorial characteristics (organoleptic properties) including taste, odor, and trigeminal sensations. Often the root causes of color and smell in water are attributed to the presence of organic and inorganic contaminants and to bacterial growth which is frequently accompanied by the production of metabolites and byproducts that are obnoxious. The unpleasant sensorial problems associated with desalinated drinking tap water may constitute the driving force for most people in GCC countries to depend on bottled water. To encourage people in the GCC countries to consume desalinated tap water, it is essential that water testing include measurements of physicochemical properties, biofilm presence and organoleptic parameters to improve overall water quality. This review highlights the contribution of organoleptics for consumers of desalinated tap water. It extends water quality research to be addressed by standards for organoleptic parameters in desalinated drinking water. Accordingly, consumer awareness and outreach campaigns should be implemented to encourage people to drink tap water in the GCC countries.

Health effects of desalinated water: Role of electrolyte disturbance in cancer development.

This review contends that "healthy" water in terms of electrolyte balance is as important as "pure" water in promoting public health. It considers the growing use of desalination (demineralization) technologies in drinking water treatment which often results in tap water with very low concentrations of sodium, potassium, magnesium and calcium. Ingestion of such water can lead to electrolyte abnormalities marked by hyponatremia, hypokalemia, hypomagnesemia and hypocalcemia which are among the most common and recognizable features in cancer patients. The causal relationships between exposure to demineralized water and malignancies are poorly understood. This review highlights some of the epidemiological and in vivo evidence that link dysregulated electrolyte metabolism with carcinogenesis and the development of cancer hallmarks. It discusses how ingestion of demineralized water can have a procarcinogenic effect through mediating some of the critical pathways and processes in the cancer microenvironment such as angiogenesis, genomic instability, resistance to programmed cell death, sustained proliferative signaling, cell immortalization and tumorigenic inflammation. Evidence that hypoosmotic stress-response processes can upregulate a number of potential oncogenes is well supported by a number studies. In view of the rising production and consumption of demineralized water in most parts of the world, there is a strong need for further research on the biological importance and protean roles of electrolyte abnormalities in promoting, antagonizing or otherwise enabling the development of cancer. The countries of the Gulf Cooperative Council (GCC) where most people consume desalinated water would be a logical place to start this research.

Assessment of toxic metals in groundwater and saliva in an arsenic affected area of West Bengal, India: A pilot scale study.

Communities in many parts of the world are unintentionally exposed to arsenic (As) and other toxic metals through ingestion of local drinking water and foods. The concentrations of individual toxic metals often exceed their guidelines in drinking water but the health risks associated with such multiple-metal exposures have yet to receive much attention. This study examines the co-occurrence of toxic metals in groundwater samples collected from As-rich areas of Nadia district, West Bengal, India. Arsenic in groundwater (range: 12-1064 µg L(-1); mean ± S.D: 329±294 µg L(-1)) was the most important contaminant with concentrations well above the WHO guideline of 10 µg L(-1). Another important toxic metal in the study area was manganese (Mn) with average concentration of 202±153 µg L(-1), range of 18-604 µg L(-1). The average concentrations (µg L(-1)) of other elements in groundwater were: Cr (5.6±5.9), Mo (3.5±2.1), Ni (8.3±8.7), Pb (2.9±1.3), Ba (119±43), Zn (56±40), Se (0.60±0.33), U (0.50±0.74). Saliva collected from the male participants of the area had mean concentrations of 6.3±7.0 µg As L(-1) (0.70-29 µg L(-1)), 5.4±5.5 µg Mn L(-1) (0.69-22 µg L(-1)), 2.6±3.1 µg Ni L(-1) (0.15-13 µg L(-1)), 0.78±1.0µg Cr L(-1) (

Potential health impacts of consuming desalinated bottled water.

This study compared physicochemical properties, anion and carbon content and major and trace elements in desalinated and non-desalinated bottled water available in Qatar, and assessed the potential health risks associated with prolonged consumption of desalinated water. Results indicate that Qatar's population is not at elevated risk of dietary exposure to As (mean = 666 ng/L), Ba (48.0 µg/L), Be (9.27 ng/L), Cd (20.1 ng/L), Cr (874 ng/L), Pb (258 ng/L), Sb (475 ng/L) and U (533 ng/L) from consumption of both desalinated and non-desalinated bottled water types available in the country. Consumers who primarily consume desalinated water brands further minimize risk of exposure to heavy metals as levels were significantly lower than in non-desalinated bottled water. Desalinated bottled water was not a significant contributor to recommended daily intakes for Ca, Mg and F(-) for adults and children and may increase risk of deficiencies. Desalinated bottled water accounted for only 3% of the Institute of Medicine (IOM) adequate intake (AI) for Ca, 5-6% of the recommended daily allowance for Mg and 4% of the AI for F among adults. For children desalinated water contributed 2-3% of the IOM AICa, 3-10% of the RDA(Mg) and 3-9% of the AIF.

Ten key research issues for integrated and sustainable wastewater reuse in the Middle East.

Wastewater management is not limited to the technology used to collect and treat wastewater. It begins with the early planning phase of building a society and includes considerations of how that society will grow. Therefore, history, culture, religion, and socioeconomy are important components to include in any relevant and integrated studies of wastewater management and reuse. Engineering, health, chemistry, biology, food production, cultural heritage, and the needs of people of all ages should be considered together when making management decisions regarding issues so intimately tied with humanity as water and sanitation. Other escalating challenges such as poverty, food, and water scarcity, migration and instability, flooding and catastrophes, diseases and mortality, etc. should also be considered as part of wastewater management and reuse planning. Emerging contaminants could be associated with the urbanization, modernization, and industrialization of several countries. Several arid countries have developed water security strategies where wastewater reuse is a major component. The existing wastewater treatment technologies in these countries are, in most cases, unable to remove such contaminants which may affect irrigation waters, industrial products, groundwater, etc. People would have to accept that the food on their tables could be irrigated with treated wastewater that they generated a few months ago, even if very advanced technologies were used to treat it. The purpose of this review is to highlight multidisciplinary areas of research on wastewater and to propose applicable and affordable mechanisms by which we may consider wastewater as a legitimate resource.