Assessment of elemental chemistry, spatial distribution, and potential risks of road-deposited dusts in Sharjah, United Arab Emirates.

Road dust is a major source of pollution in the environment, carrying different pollutants, including heavy metals and metalloids, from one location to another. This study assesses the concentrations of eight heavy metals and one metalloid (Zn, Pb, Mn, Fe, Cr, Cu, Cd, Ni, and As) in dust samples collected from sixty-eight streets of Sharjah, United Arab Emirates using ICP-OES, as well as investigates their effects on both the environment and humans. Mean concentrations of the elements in µg/g across the sites were 392 ± 46 (Zn), 68.28 ± 11.3 (Pb), 1437 ± 67 (Mn), 39,481 ± 4611 (Fe), 460 ± 31 (Cr), 150 ± 44 (Cu), 1.25 ± 0.65 (Cd), 856 ± 72 (Ni), and 0.97 ± 0.28 (As). The Cdeg and ERI calculated from the study were 54.79 and 573, respectively, suggesting varying pollution levels. The highest contributions were from Ni, Cd, Zn, Cu, Cr, and Pb, especially in areas with heavy traffic. The non-carcinogenic risk assessments were generally low for the three routes of exposure, except HQoral that was slightly higher for children. Similarly, none of the elements exhibited any carcinogenic risk except chromium. Overall, the cancer risk is considered low. In view of the limited studies from UAE in relation to the metal content of road-deposited dusts, the current study serves as novel knowledge, especially in the context of geographical areas with a higher occurrence of sandstorms and the presence of particulate matter. The study also adds to the global understanding of the contribution of street dust to environmental pollution and its implications for human health.

Occurrence, spatial and seasonal variations of emerging contaminants in the aquatic environment of Sharjah, United Arab Emirates.

The occurrence, seasonal variations and spatial distribution of emerging contaminants (ECs) in wastewater effluents from wastewater treatment plant (WWTP) and UAE's receiving coastal aquatic environment (seawater and sediments) were evaluated in the present study. A total of 21, 23, and 22 contaminants in the effluents, seawater, and sediments, respectively, at concentrations ranging from low ng L-1 up to 1782 ng L-1 in effluents, from low ng/l up to 236.10 ng L-1 in seawater, and from low ng g-1 up to 60.15 ng g-1 in sediments were recorded. The study revealed that imidacloprid, thiabendazole, and acetaminophen were the most ubiquitous compounds in effluents, seawater, and sediments, respectively, since they were found in all samples collected with a detection frequency of 100%. The study also revealed that the higher concentrations of most contaminants were recorded in autumn. However, thiabendazole in effluents and seawater, acetamiprid in effluents, and sulphapyridine in seawater and sediments showed a higher load in winter. This study highlights the need for proper monitoring and management of ECs in wastewater effluents, seawater, and sediments, especially during the autumn and winter seasons, to minimize their impact on the marine ecosystem and public health.

Human biomonitoring of environmental contaminants in Gulf Countries - current status and future directions.

BACKGROUND: This systematic review aimed to evaluate the status of Human Biomonitoring (HBM) in the Gulf Cooperation Council (GCC) region and provide recommendations for future research, considering the increased environmental contaminants that pose a threat to human health in this rapidly industrializing area. METHODS: A thorough search was performed in PubMed and Web of Science databases up to February 2023 to identify biomonitoring studies on human exposure and levels in the GCC region. Two independent reviewers assessed study eligibility, conducted data extraction and risk of bias assessment. The NIH Quality Assessment Tools and PRISMA guidelines were utilized for quality evaluation and reporting of results. RESULTS: A total of 38 eligible articles were included in this systematic review out of 662 articles screened. The majority of the publications were from Saudi Arabia (n = 24) and Kuwait (n = 10), while limited representation was found from Qatar (n = 3) and the UAE (n = 1). No articles were identified from Oman and Bahrain. The studies focused on metals, organohalogen compounds, pesticides, polycyclic aromatic hydrocarbons, and phthalates. The findings revealed elevated levels of metals and established correlations between metal exposure and adverse health effects, including infant neurodevelopmental issues, vitamin D deficiency, and oxidative stress. The presence of organohalogen compounds and pesticides was prevalent in the GCC region, with significant associations between exposure to these compounds and negative health outcomes. Notably, high levels of perchlorate were observed in the Kuwaiti population, and a study from Saudi Arabia found an association between per- and polyfluorinated substances and increased odds of osteoporosis. CONCLUSIONS: This review emphasizes the need to address environmental health challenges in the GCC region through improved HBM research methods and strategies. Implementing biomonitoring programs, conducting cohort studies, investing in tools and expertise, promoting collaboration, and engaging the community are crucial for reliable HBM data in the GCC.

Detection of bisphenol A in thermal paper receipts and assessment of human exposure: A case study from Sharjah, United Arab Emirates.

Bisphenol A (BPA) is an industrial chemical that is widely used in various industrial applications. It has concerns in its use as a color developer in thermal paper receipts since it is identified as an endocrine disruptor and causes hormonal disturbances. In this study, thirty thermal paper receipt samples were randomly collected from various locations in Sharjah, United Arab Emirates and analyzed using high performance liquid chromatography-mass spectrometry. Sixty percent (60%) of receipt samples showed BPA levels above the acceptable limit (200 ng/mg) set by the European Union (EU) for thermal papers. On the other hand, 40% of the samples reported very low BPA levels (< 0.02 ng/mg). However, estimated weight adjusted daily intakes (EDI) ranged between 8.22 ×10-11 and 0.000812 µg/kg bw/day for the general population, and between 7.89×10-9 and 0.0681 µg/kg bw/day for the occupationally exposed cashiers. Thus, all calculated EDIs were below the European Food Safety Authority Tolerable Daily Intake (4 µg/kg·bw/day) and the provisional Health Canada Tolerable Daily Intake (25 ug/kg bw/day) under varying paper-to-skin transfer coefficients and absorption fractions. Nevertheless, due to its health effects and recent legal restrictions by EU, the occurrence of co-exposure to dietary and non-dietary sources should be considered in the health risk assessment of Bisphenol A, mainly for people with frequent occupational exposure to thermal paper, and especially with the increased use of sanitizers. The current study is a first within the UAE context in relation to BPA in thermal paper receipts, thus its significance especially with the recent EU enforcement of BPA limits in paper receipts. The study highlights that proper policies as well as education and awareness may assist in limiting transdermal BPA exposure for the general and occupationally exposed populations.

A systematic assessment of research trends on polycyclic aromatic hydrocarbons in different environmental compartments using bibliometric parameters.

Polycyclic aromatic hydrocarbons (PAHs) are a large group of diverse hazardous organic compounds that are relatively stable and widely distributed throughout the world's ecosystems due to various anthropogenic activities. They are generally less soluble in water and have a low vapour pressure, but dissolve easily in adipose tissues; and they bioaccumulate into high concentrations in aquatic animals, thereby exerting a variety of hazardous and lethal effects. Despite the plethora of research studies on these pollutants, only few bibliometric reviews on the subject have been documented in the literature. As a result, the present study aimed to assess the research growth on PAHs-related studies across different ecosystems. Science Citation Index-Expanded of Web of Science was explored to obtain the research studies that were conducted between 1991 and 2020, and RStudio was utilized for the data analysis. Annual productivity increased arithmetically over the years, with a 9.2% annual growth rate and a collaboration index of 2.52. Foremost among the trend topics in this field of study include soil, sediments, biodegradation, bioremediation, bioavailability, and source apportionment. China, USA, Spain, France and Germany were the five top-ranked countries in terms of publications and citations over the three decades investigated; however, Korea, Japan, United Kingdom, Germany, and Canada were ranked as the five leading countries in terms of collaboration per published article (MCP ratio). Therefore, efforts to strengthen international collaboration in this field of study especially among the less participating countries and continents are thus encouraged. The findings of this study are expected to provide future direction for the upcoming researchers in identifying the hot spots in this field of study as well as research leaders whom to seek collaboration in their future research plan.

Assessment of Uptake, Accumulation and Degradation of Paracetamol in Spinach (Spinacia oleracea L.) under Controlled Laboratory Conditions.

The occurrence and persistence of pharmaceuticals in the food chain, particularly edible crops, can adversely affect human and environmental health. In this study, the impacts of the absorption, translocation, accumulation, and degradation of paracetamol in different organs of the leafy vegetable crop spinach (Spinacia oleracea) were assessed under controlled laboratory conditions. Spinach plants were exposed to 50 mg/L, 100 mg/L, and 200 mg/L paracetamol in 20% Hoagland solution at the vegetative phase in a hydroponic system. Exposed plants exhibited pronounced phytotoxic effects during the eight days trial period, with highly significant reductions seen in the plants' morphological parameters. The increasing paracetamol stress levels adversely affected the plants' photosynthetic machinery, altering the chlorophyll fluorescence parameters (Fv/Fm and PSII), photosynthetic pigments (Chl a, Chl b and carotenoid contents), and composition of essential nutrients and elements. The LC-MS results indicated that the spinach organs receiving various paracetamol levels on day four exhibited significant uptake and translocation of the drug from roots to aerial parts, while degradation of the drug was observed after eight days. The VITEK® 2 system identified several bacterial strains (e.g., members of Burkhulderia, Sphingomonas, Pseudomonas, Staphylococcus, Stenotrophomonas and Kocuria) isolated from spinach shoots and roots. These microbes have the potential to biodegrade paracetamol and other organic micro-pollutants. Our findings provide novel insights to mitigate the risks associated with pharmaceutical pollution in the environment and explore the bioremediation potential of edible crops and their associated microbial consortium to remove these pollutants effectively.

Occurrence and Risk Assessment of Polybrominated Diphenyl Ethers in Surface Water and Sediment of Nahoon River Estuary, South Africa.

The concentrations, potential sources, and compositional profile of PBDEs in the surface water and sediment of Nahoon Estuary, East London, South Africa, were investigated with solid-phase extraction and ultra-sonication, respectively, followed by gas-chromatography-electron capture detection. The seasonal range of the contaminants' concentrations in water and sediment samples in spring season were ∑PBDE 329 ± 48.3 ng/L (25.32-785 ng/L) and ∑PBDE 4.19 ± 0.35 ng/g dw (1.91-6.57 ng/g), but ∑PBDE 62.1 ± 1.50 ng/L (30.1-110 ng/L) and ∑PBDE 65.4 ± 15.9 ng/g dw (1.98-235 ng/g) in summer, respectively. NH1 (first sampling point) was the most contaminated site with PBDE in the Estuary. The potential source of pollution is attributed to the stormwater runoff from a creek emptying directly into the Estuary. This study's dominant PBDE congener is BDE-17, ranging from below detection limit to 247 ng/L and 0.14-32.1 ng/g in water and sediment samples, respectively. Most detected at all the sites were BDE-17, 47, 66, and 100. Most BDE-153 and 183 are found in sediment in agreement with the fact that higher brominated congeners of PBDE adsorb to solid materials. There was no correlation between the congeners and organic carbon and organic matter. However, the human health risk assessment conducted revealed that the PBDE concentration detected in the estuary poses a low eco-toxicological risk. Nevertheless, constant monitoring should be ensured to see that the river remains safe for the users, as it serves as a form of recreation to the public and a catchment to some neighbourhoods.

Modelling the Potential Risk of Infection Associated with Listeria monocytogenes in Irrigation Water and Agricultural Soil in Two District Municipalities in South Africa.

Listeria monocytogenes (L. monocytogenes) is the etiologic agent of listeriosis which significantly affects immunocompromised individuals. The potential risk of infection attributed to L. monocytogenes in irrigation water and agricultural soil, which are key transmission pathways of microbial hazards to the human population, was evaluated using the quantitative microbial risk assessment modelling. A Monte Carlo simulation with 10,000 iterations was used to characterize the risks. High counts of L. monocytogenes in irrigation water (mean: 11.96 × 102 CFU/100 mL; range: 0.00 to 56.67 × 102 CFU/100 mL) and agricultural soil samples (mean: 19.64 × 102 CFU/g; range: 1.33 × 102 to 62.33 × 102 CFU/g) were documented. Consequently, a high annual infection risk of 5.50 × 10-2 (0.00 to 48.30 × 10-2), 54.50 × 10-2 (9.10 × 10-3 to 1.00) and 70.50 × 10-2 (3.60 × 10-2 to 1.00) was observed for adults exposed to contaminated irrigation water, adults exposed to contaminated agricultural soil and children exposed to agricultural soil, respectively. This study, therefore, documents a huge public health threat attributed to the high probability of infection in humans exposed to L. monocytogenes in irrigation water and agricultural soil in Amathole and Chris Hani District Municipalities in the Eastern Cape province of South Africa.

Assessment of water quality variations from mains to building storage tanks in Sharjah, United Arab Emirates.

Continuous vigilance of water quality is essential throughout water supply and storage systems to ensure safe water quality and safeguard consumer health. In the present study, sixty-three sampling locations in Sharjah, UAE, were assessed for possible water quality variations from water supply through utilized water storage tanks in buildings. All investigated physico-chemical parameters were within national water quality guidelines except for free residual chlorine (< 0.2 mg/L in 30% of samples), mainly in storage tanks. Compliance of metal concentrations varied with metal type, sampling locations, and points. Highest compliance was reported for manganese, copper, nickel, chromium, and least for iron, lead, and cadmium. No major variations in physico-chemical water quality could be statistically observed using analysis of variance when tracing the water from lower tanks to upper tanks, yet significant variations for turbidity (p = 0.006) were observed from mains to lower tanks and for water temperature (p = 0.026), residual chlorine (p = 0.001), turbidity (p = 0.048), chromium (p = 0.019), copper (p = 0.002), manganese (p = 0.012), and zinc and lead (p = 0.000) from mains to upper tanks. As for investigated microbiological parameters, all investigated samples were completely free from total and fecal coliforms and Pseudomonas aeruginosa. Exhibited ranges of yeasts and molds (0-28 CFU/100 mL) and heterotrophic plate counts (0-356 CFU/mL), though non-enforceable parameters, were always lower than recommended water quality guidelines. Furthermore, Pearson correlation tests exhibited significant correlations for water temperature versus yeasts and molds and electrical conductivity versus sodium and potassium. Statistically (using t-tests), mean heterotrophic plate counts were slightly higher in lower tanks compared to other sampling points. Additionally, mean heterotrophic plate counts were significantly higher in larger tanks exceeding 2000 gallons, in square/rectangular shaped tanks, in tanks exceeding 10 years of age, and in concrete tanks with higher water temperatures. Re-chlorination, proper cleaning, as well as maintenance or upgrade of water storage tanks remain advisable to ensure safe water at point of use.

A comparative study of microbial contamination between public institutional and private residential bottled water dispensers.

Bottled water as well as bottled water dispensers is widely used in the United Arab Emirates as a source of drinking water in residential, commercial, and institutional settings. The quality of such waters is of utmost concern as it has the potential to cause waterborne outbreaks, if (re)contaminated. Besides, bottled water dispensers could act as a source of contamination over time, if not cleaned properly on a regular basis. A cross-sectional study was conducted on 40 water samples collected from public and private bottled water dispensers in the emirates of Dubai and Sharjah. Samples were analyzed for heterotrophic plate count bacteria, fecal and total coliforms, and fungal growth. No total and fecal coliforms were detected in any of the samples. Heterotrophic plate counts (HPC) ranged between 0 and 100 CFU/100 ml, with an overall average of 31 CFU/100 ml. There was no significant difference between the HPC bacterial levels of public and private bottled water dispensers. However, a significant association (p < 0.05) was found between fungal growth and the location of the bottled water dispenser within the investigated sites. Survey outcomes also highlighted the need to spread awareness and knowledge amongst general public on basic cleanliness and hygiene practices contributing to safe drinking water and the need for stricter monitoring of public bottled water dispensers cleaning schedules.

Age-dependent effective ingestion dose estimations and lifetime risk assessment for selected radionuclides (40K and 3H) in bottled waters marketed in United Arab Emirates.

Monitoring drinking water, including bottled water, is imperative to safeguarding public health especially where bottled water consumption is high like in the United Arab Emirates (UAE). In this study, radionuclide activity levels of Tritium (3H) and Potassium (40K) were assessed in various brands of bottled water marketed in UAE. Activity level data was used to calculate the annual effective doses (Ed) for different age groups, and the excess lifetime cancer risk (ELCR) for adult males and females in the UAE population. Activity levels for both radionuclides were below the allowable maximum guideline values specified by local and international standards. Calculated total age dependent ingestion doses revealed that adults and lactation age groups received the highest effective ingestion doses. Adult males exhibited a higher ELCR for both isotopes, compared to females. Nonetheless, total radioactive dose for each water brand (0.91-1.47 µSv/yr) as well as for each population group were well below the recommended annual reference dose level of 100 µSv set by World Health Organization. Therefore, bottled water in the UAE is safe from the radiological aspect for investigated radionuclides, and poses no significant radiological exposure and health risk to the public.

Simultaneous Determination of Pharmaceuticals by Solid-phase Extraction and Liquid Chromatography-Tandem Mass Spectrometry: A Case Study from Sharjah Sewage Treatment Plant.

The present work describes the optimization and validation of a highly selective and sensitive analytical method using solid phase extraction and liquid chromatography tandem mass spectrometry (SPE LC-MS/MS) for the determination of some frequently prescribed pharmaceuticals in urban wastewater received and treated by Sharjah sewage treatment plant (STP). The extraction efficiency of different SPE cartridges was tested and the simultaneous extraction of pharmaceuticals was successfully accomplished using hydrophilic-lipophilic-balanced reversed phase Waters® Oasis HLB cartridge (200 mg/ 6 mL) at pH 3. The analytes were separated on an Aquity BEH C18 column (1.7 µm, 2.1 mm × 150 mm) using gradient elution and mass spectrometric analysis were performed in multiple reactions monitoring (MRM) selecting two precursor ions to produce ion transition for each pharmaceutical using positive electrospray ionization (+ESI) mode. The correlation coefficient values in the linear calibration plot for each target compound exceeded 0.99 and the recovery percentages of the investigated pharmaceuticals were more than 84%. Limit of detection (LOD) varied between 0.1⁻1.5 ng/L and limit of quantification (LOQ) was 0.3⁻5 ng/L for all analytes. The precision of the method was calculated as the relative standard deviation (RSD%) of replicate measurements and was found to be in the ranges of 2.2% to 7.7% and 2.2% to 8.6% for inter and intra-day analysis, respectively. All of the obtained validation parameters satisfied the requirements and guidelines of analytical method validation.

ESTIMATE OF UAE COMMERCIAL AIRCREW EFFECTIVE DOSES USING CARI-6, EPCARD AND SIEVERT CODES.

The aim of this study is to calculate total cruising route effective doses using three commonly used algorithm codes CARI-6, EPCARD and SIEVERT. Further, the impact of flight cruising duration, altitude and latitude on the estimated effective doses will also be investigated. A total of 24 commercial UAE flight data were collected and retrospectively analysed. CARI-6, EPCARD and SIEVERT codes were used to estimate the total route effective doses per single trip of different destinations including USA, Europe, South Africa, Asia and Australia. Aircraft crew effective doses were shown to significantly increase with flying altitude. A strong significant correlation (0.6469; p < 0.05) was obtained between flight duration and the estimated effective doses, while a moderate insignificant correlation (0.3899; p > 0.05) was obtained with flying altitude for all 24 flights using CARI-6. For flights with the same latitude and duration, all codes gave total effective doses within experimental uncertainties.

Human health risk assessment of pharmaceuticals in treated wastewater reused for non-potable applications in Sharjah, United Arab Emirates.

Pharmaceuticals and personal care products are an integral part of societal health yet their presence in various environmental compartments, including treated wastewaters, has sparked concerns towards possible human and ecological health effects. The current study aims to characterize human health risks posed by ten pharmaceuticals quantified in wastewater treatment plant effluents where water is reused mainly for landscape irrigation. Receptors were identified as children playing in green areas, adult landscape workers, and adult users of athletic and golf courses irrigated by treated wastewater. The human health risk assessment model exhibited safe exposure (RQ < 1) to all pharmaceuticals for all receptors through both dermal and ingestion exposure pathways. RQs were highest for the landscape worker followed by children playing in green areas and then adult using the athletic fields. RQs were highest to lowest in the following order of pharmaceuticals: acetaminophen, metoprolol, ciprofloxacin, erythromycin, ofloxacin, sulfadiazine, sulfamethoxazole, sulfapyridine, risperidone, and sulfamethazine. Such risk assessment findings aid in supporting decisions to optimize wastewater treatment and reuse strategies, as well as safeguard public and environmental health.

Assessment of the performance of SMFCs in the bioremediation of PAHs in contaminated marine sediments under different redox conditions and analysis of the associated microbial communities.

The biodegradation of naphthalene, 2-methylnaphthalene and phenanthrene was evaluated in marine sediment microbial fuel cells (SMFCs) under different biodegradation conditions, including sulfate reduction as a major biodegradation pathway, employment of anode as terminal electron acceptor (TEA) under inhibited sulfate reducing bacteria activity, and combined sulfate and anode usage as electron acceptors. A significant removal of naphthalene and 2-methylnaphthalene was observed at early stages of incubation in all treatments and was attributed to their high volatility. In the case of phenanthrene, a significant removal (93.83±1.68%) was measured in the closed circuit SMFCs with the anode acting as the main TEA and under combined anode and sulfate reduction conditions (88.51±1.3%). A much lower removal (40.37±3.24%) was achieved in the open circuit SMFCs operating with sulfate reduction as a major biodegradation pathway. Analysis of the anodic bacterial community using 16S rRNA gene pyrosequencing revealed the enrichment of genera with potential exoelectrogenic capability, namely Geoalkalibacter and Desulfuromonas, on the anode of the closed circuit SMFCs under inhibited SRB activity, while they were not detected on the anode of open circuit SMFCs. These results demonstrate the role of the anode in enhancing PAHs biodegradation in contaminated marine sediments and suggest a higher system efficiency in the absence of competition between microbial redox processes (under SRB inhibition), namely due to the anode enrichment with exoelectrogenic bacteria, which is a more energetically favorable mechanism for PAHs oxidation than sulfate.

Comparative study of humic acid removal and floc characteristics by electrocoagulation and chemical coagulation.

The current study aims at investigating the efficiency of electrocoagulation for the removal of humic acid from contaminated waters. In parallel, conventional chemical coagulation was conducted to asses humic acid removal patterns. The effect of varying contributing parameters (matrix pH, humic acid concentration, type of electrode (aluminum vs. iron), current density, solution conductivity, and distance between electrodes) was considered to optimize the electrocoagulation process for the best attainable humic acid removal efficiencies. Optimum removals were recorded at pH of 5.0-5.5, an electrical conductivity of 3000 µS/cm at 25 °C, and an electrode distance of 1 cm for both electrode types. With aluminum electrodes, a current density of 0.05 mA/cm2 outperformed 0.1 mA/cm2 yet not higher densities, whereas a current density of 0.8 mA/cm2 was needed for iron electrodes to exhibit comparable performance. With both electrode types, higher initial humic acid concentrations were removed at a slower rate but ultimately attained almost complete removals. On the other hand, the best humic acid removals (∼90%) by chemical coagulation were achieved at 4 mg/L for both coagulants. Also, higher removals were attained at elevated initial humic acid concentrations. Humic acid removals of 90% or higher at an initial HA concentration of 40 mg/L were exhibited, yet alum performed better at the highest experimented concentration. It was evident that iron flocs were larger, denser, and more geometrical in shape compared to aluminum flocs.

Reactor performance in terms of COD and nitrogen removal and bacterial community structure of a three-stage rotating bioelectrochemical contactor.

Integrating microbial fuel cell (MFC) into rotating biological contactor (RBC) creates an opportunity for enhanced removal of COD and nitrogen coupled with energy generation from wastewater. In this study, a three-stage rotating bioelectrochemical contactor (referred to as RBC-MFC unit) integrating MFC with RBC technology was constructed for simultaneous removal of carbonaceous and nitrogenous compounds and electricity generation from a synthetic medium containing acetate and ammonium. The performance of the RBC-MFC unit was compared to a control reactor (referred to as RBC unit) that was operated under the same conditions but without current generation (i.e. open-circuit mode). The effect of hydraulic loading rate (HLR) and COD/N ratio on the performance of the two units was investigated. At low (3.05 gCOD g⁻¹N) and high COD/N ratio (6.64 gCOD g⁻¹N), both units achieved almost similar COD and ammonia-nitrogen removal. However, the RBC-MFC unit achieved significantly higher denitrification and nitrogen removal compared to the RBC unit indicating improved denitrification at the cathode due to current flow. The average voltage under 1000 Ω external resistance ranged between 0.03 and 0.30 V and between 0.02 and 0.21 V for stages 1 and 2 of the RBC-MFC unit. Pyrosequencing analysis of bacterial 16S rRNA gene revealed high bacterial diversity at the anode and cathode of both units. Genera that play a role in nitrification (Nitrospira; Nitrosomonas), denitrification (Comamonas; Thauera) and electricity generation (Geobacter) were identified at the electrodes. Geobacter was only detected on the anode of the RBC-MFC unit. Nitrifiers and denitrifiers were more abundant in the RBC-MFC unit compared to the RBC unit and were largely present on the cathode of both units suggesting that most of the nitrogen removal occurred at the cathode.

Physicochemical evaluation of the Upper Litani River watershed, Lebanon.

This study aims to determine the extent of groundwater damage in the Upper Litani River Basin (ULRB) after years of water mismanagement and overfertilization in what is considered to be Lebanon's largest fertile area. Physical and chemical samples were collected between 2005 and 2010 and analyzed using "The Standard Methods for the Examination of Water and Wastewater" (APHA, AWWA) in order to determine the extent of this pollution. The parameters included pH, ammonia, nitrate, nitrite, sulfate, phosphate, dissolved oxygen, and total dissolved solids.

Quality assessment of various bottled waters marketed in Lebanon.

Thirty-two domestic bottled water brands were analyzed for various physico-chemical as well as bacterial water quality parameters. Recorded results were compared with the Lebanese Standards Institution standards of quality and standards of identity as well as various international water standards for bottled waters. Results showed a widespread in the characteristics of investigated bottled waters, yet the majority met the different bottled water standards for physico-chemical parameters except for pH (4 brands), hardness (2 brands), and calcium (2 brands). All samples showed negative growth for fecal coliforms, yet 18.8% (N = 6) and 59.4% (N = 19) of the samples revealed positive results for total coliforms and heterotrophic plate count at 37°C, respectively. Generated Piper diagrams revealed that the majority of investigated waters are of calcium-magnesium bicarbonate type; some brands were rich in sodium-potassium chloride, and few were of the mixed type. Comparison of the study results with reported label values indicated good agreement with stated pH values but considerable variation for dry residue, Mg, Na, K, Ca, Mg, HCO3, Cl, and SO4. Identification labels showed varying compliance with the Lebanese Standards Institution standards of identity.

Modeling the formation of trihalomethanes in drinking waters of Lebanon.

The current research aims at developing predictive models for trihalomethane (THM) formation in Lebanon based on field-scale investigations as well as laboratory controlled experimentations. Statistical analysis on field data revealed significant correlations for TTHM with chlorine dose, Specific UV-A, and UV(254) absorbing organics. Simulated distribution system-THM tests showed significant correlations with applied chlorine dose, total organic carbon, bromides, contact time, and temperature. Predictive models, formulated using multiple regression approaches, exhibiting the highest coefficients of determination were quadratic for the directly after chlorination (DAC; r(2) = 0.39, p < 0.036) and network (r(2) = 0.33, p < 0.064) THM databases, and logarithmic for the laboratory simulated THM database (r(2) = 0.70, p < 0.001). Computed r(2) values implied low correlations for the DAC and network THM database, and high correlation for the laboratory simulated THM database. Significance of the models were at the 0.05 level for DAC database, 0.10 level for the network database, and very high (<0.01 level) for the laboratory simulated THM database. It is noteworthy to mention that no previous attempts to assess, monitor, and predict THM concentrations in public drinking water have been reported for the country although a large fraction of the population consumes chlorinated public drinking water.