This study explores an innovative approach to tackle the critical issue of heavy metal ion contamination in aqueous solutions through the utilization of camel dung-derived biochar. In the context of global environmental concerns and the adverse impacts of heavy metal pollution on ecosystems and human health, the investigation focuses on copper(II) and chromium(III) ions, which are among the most pervasive pollutants originating from industrial activities. The research revealed that camel dung-derived biochar exhibits exceptional potential for the removal of copper(II) and chromium(III) ions, with removal efficiencies of more than 90% and adsorption capacities of 23.20 and 23.36 mg/g, respectively. The adsorption processes followed second-order kinetics, and the data fitted both the Langmuir and Freundlich adsorption models. The underlying mechanisms governing this adsorption phenomenon seem to be grounded in complexation reactions, cation exchange, and cation-π interactions, underscoring the multifaceted nature of the interactions between the biochar and heavy metal ions. This research not only advances our understanding of sustainable materials for water purification but also harnesses the underutilized potential of camel dung as a valuable resource for environmental remediation, offering a promising avenue for addressing global water pollution challenges.
Nowadays, people spend most of their time indoors. Despite constantly cleaning these spaces, dust apparition cannot be avoided. Since dust can contain chemical elements that negatively impact people's health, we propose the analysis of the metals from the indoor dust component collected in different locations in Dubai, UAE. Multivariate statistics (correlation matrix, clustering) and quality indicators (QI)-Igeo, PI, EF, PLI, Nemerow-were used to assess the contamination level with different metals in the dust. We proposed two new QIs (CPI and AQI) and compared the results with those provided by the most used indices-PLI and Nemerow. It is shown that high concentrations of some elements (Ca in this case) can significantly increase the values of the Nemerow index, CPI, and AQI. In contrast, the existence of low concentrations leads to the decrement of the PLI.
MAX phases are the parent materials used for the formation of MXenes, and are generally obtained by etching using the highly corrosive acid HF. To develop a more environmentally friendly approach for the synthesis of MXenes, in this work, titanium aluminum carbide MAX phase (Ti2AlC) was fabricated and etched using NaOH. Further, magnetic properties were induced during the etching process in a single-step etching process that led to the formation of a magnetic composite. By carefully controlling etching conditions such as etching agent concentration and time, different structures could be produced (denoted as M.Ti2CTx). Magnetic nanostructures with unique physico-chemical characteristics, including a large number of binding sites, were utilized to adsorb radionuclide Sr2+ and Cs+ cations from different matrices, including deionized, tap, and seawater. The produced adsorbents were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The synthesized materials were found to be very stable in the aqueous phase, compared with corrosive acid-etched MXenes, acquiring a distinctive structure with oxygen-containing functional moieties. Sr2+ and Cs+ removal efficiencies of M.Ti2CTx were assessed via conventional batch adsorption experiments. M.Ti2CTx-AIII showed the highest adsorption performance among other M.Ti2CTx phases, with maximum adsorption capacities of 376.05 and 142.88 mg/g for Sr2+ and Cs+, respectively, which are among the highest adsorption capacities reported for comparable adsorbents such as graphene oxide and MXenes. Moreover, in seawater, the removal efficiencies for Sr2+ and Cs+ were greater than 93% and 31%, respectively. Analysis of the removal mechanism validates the electrostatic interactions between M.Ti2C-AIII and radionuclides.
Prosopis species were introduced to the United Arab Emirates (UAE) region for desert greening. However, the species now pose a great threat to the native plant diversity. This study used high-resolution satellite imagery (1990-2019) to understand the history and current distribution of Prosopis species and their impact on fresh groundwater. The results show that the Prosopis invasion in the study area reached its maximum expansion rate in 2019 and covered an area of about 16 km2 compared to 0.2 km2 in 1990. The areas near Sharjah Airport, Umm Fannan, and Al Talla, located at a lower elevation of the sand dune area, are heavily invaded. Prosopis groundwater requirement derived using evapotranspiration shows that groundwater consumption has changed drastically after 2010 and consumed about 22.22 million m3 of groundwater in 2019, which is about a 7372% increase in groundwater consumption from the year 1990 to 2019. The results can be useful for setting up a management plan for the sustainable use of this species in the UAE region in particular and other similar countries in the arid land regions that are suffering from freshwater depletion because of Prosopis invasion.
In this study, biochar was prepared from Sidr plant leaves and used for the treatment of ciprofloxacin (CIP)-contaminated water. CIP is important class of emerging water pollutants from pharmaceutical industries. The biochar showed 65% adsorption efficiency and 43.48 mg/g adsorption capacity of CIP. Adsorption efficiency as well as adsorption capacity were improved to 91% and 62.50 mg/g, respectively, by phosphoric acid (H3PO4) modified biochar. Removal of CIP by the prepared biochar was due to different surface functional groups of CIP and biochar as revealed from the study of different characterization analyses. The presence of PO43- group in modified biochar led to maximum binding of CIP. Also, the modified biochar showed higher reusability potential and less leaching of ions when compared to the raw biochar. Removal of CIP was affected by concentrations of CIP, the amount of biochar and different pH's; the maximum removal of CIP was achieved at pH 4. The Freundlich and pseudo-first-order models best fitted the removal of CIP by modified biochar. Advanced characterization techniques were applied to investigate surface and physiological characteristics of the biochar and modified biochar. The modification showed high impact on the performance and stability of biochar. The study showed significant impacts of modification on the potential of the biochar for treatment of CIP-contaminated water.
Ciprofloxacin , Water Pollutants, Chemical , Adsorption , Biodegradation, Environmental , Charcoal/chemistry , Ciprofloxacin/analysis , Ciprofloxacin/chemistry , Kinetics , Water/analysis , Water Pollutants, Chemical/chemistry
We herein report a modified methodology for the synthesis of some oxadiazoles linked to amides under mild conditions. The developed protocol using NMI-TfCl has been found to be effective and tolerant for the amide bond formation reaction of a series of electronically deactivating and sterically challenging amines. The antioxidant potential of the newly synthesized compounds has been evaluated at the later stage.
Amines , Oxadiazoles , Amides/chemistry , Amines/chemistry , Oxadiazoles/chemistry
The Liwa area is a primary food production area in the United Arab Emirates (UAE) and has intensively been used for agriculture. This study investigates the pollution levels with heavy metals in agricultural soils from the Liwa area. Thirty-two soil samples were analyzed for Mn, Zn, Cr, Ni, Cu, Pb, Cd, Co, and As. Results revealed that heavy metal levels varied in the ranges 220.02-311.21, 42.39-66.92, 43.43-71.55, 32.86-52.12, 10.29-21.70, 2.83-8.84, 0.46-0.69, 0.03-0.37 mg/kg for Mn, Zn, Cr, Ni, Cu, Pb, Cd, Co, and As, respectively. All samples presented low As concentrations with an average of 0.01 mg/kg. The variations in bulk metal contents in the soil samples were related to multiple sources, including agrochemicals, atmospheric dust containing heavy metals, and traffic-related metals. Enrichment factor analysis indicates that Cd, Ni, Zn, and Cr were highly enriched in soils, and they could originate from non-crustal sources. Based on the geo-accumulation index (Igeo), the soil samples appeared uncontaminated with Mn, Cr, Zn, Pb, Co, As, Cu, uncontaminated to moderately contaminated with Ni and moderately contaminated with Cd. The contamination factors suggest low contamination, except for Ni, which showed moderate contamination. The average pollution load index (PLI) revealed unpolluted to low pollution of all soil samples. The ecological risk assessment (PERI) showed that all heavy metals posed a low risk, except for Cd which exhibited a high ecological risk.
The aim of this study was twofold. Firstly, we performed a land capability class determination of the agricultural soils from the Abu Dhabi Emirate, the United Arab Emirates, based on the concentrations of 17 chemical elements determined in the soil samples collected from 84 locations. Secondly, we assess the soil pollution with different metals, using several pollution indices. The results of Principal Component Analysis (PCA) shows that four principal components (PCs) are responsible for describing the total metals concentrations' variance, the highest contribution on PC1 being that of Mn, and Cr, on PC2 that of Fe, on PC3 that of Cu, and on PC4 that of Al. After determining the optimal number of clusters, we classified the sites into three clusters, while the studied metals were grouped function on their concentrations. Then, we used five indices to assess the pollution level of the soil at the study sites and in the clusters. The geo-accumulation index (Igeo) indicates uncontamination/moderately contamination with Cu in cluster 1, uncontaminated/moderately contaminate soils with Cd, Cu, and Ni in cluster 2, and uncontaminated/moderately contaminated soil with Cu and moderately contaminated with Pb, Zn, and Ni in cluster 3. By comparison, the enrichment factors overestimate the pollution of the studied sites. The pollution load index (PLI) indicates a baseline level of pollution at 14 sites and the deterioration of the soil quality at four sites. The Nemerow pollution index provides similar results as PLI.
Plant hormones are small regulatory molecules that exert pharmacological actions in mammalian cells such as anti-oxidative and pro-metabolic effects. Kinetin belongs to the group of plant hormones cytokinin and has been associated with modulatory functions in mammalian cells. The mammalian adenosine receptor (A2a-R) is known to modulate multiple physiological responses in animal cells. Here, we describe that kinetin binds to the adenosine receptor (A2a-R) through the Asn253 residue in an adenosine dependent manner. To harness the beneficial effects of kinetin for future human use, we assess its acute toxicity by analyzing different biochemical and histological markers in rats. Kinetin at a dose below 1 mg/kg had no adverse effects on the serum level of glucose or on the activity of serum alanine transaminase (ALT) or aspartate aminotransferase (AST) enzymes in the kinetin treated rats. Whereas, creatinine levels increased after a kinetin treatment at a dose of 0.5 mg/kg. Furthermore, 5 mg/kg treated kinetin rats showed normal renal corpuscles, but a mild degeneration was observed in the renal glomeruli and renal tubules, as well as few degenerated hepatocytes were also observed in the liver. Kinetin doses below 5 mg/kg did not show any localized toxicity in the liver and kidney tissues. In addition to unraveling the binding interaction between kinetin and A2a-R, our findings suggest safe dose limits for the future use of kinetin as a therapeutic and modulatory agent against various pathophysiological conditions.
Kinetin/pharmacology , Kinetin/toxicity , Small Molecule Libraries/pharmacology , Small Molecule Libraries/toxicity , Animals , Antioxidants/physiology , Antioxidants/toxicity , Biomarkers/metabolism , Creatinine/metabolism , Cytokinins/metabolism , Glucose/metabolism , Hepatocytes/drug effects , Hepatocytes/metabolism , Humans , Kidney Glomerulus/drug effects , Kidney Glomerulus/metabolism , Kidney Tubules/drug effects , Kidney Tubules/metabolism , Liver/drug effects , Liver/metabolism , Male , Oxidation-Reduction/drug effects , Oxidative Stress/drug effects , Plant Growth Regulators/pharmacology , Plant Growth Regulators/toxicity , Rats , Receptors, Purinergic P1/metabolism
Scattered seashells were observed on the seabed with no marine corals. The baseline studies indicate that biodiversity decreased from the northeast to southwest direction. The dominant groups of phytoplankton were diatoms followed by dinoflagellates, with insignificant vertical variations in species composition and population due to shallow water. The benthic diversity over the majority of the study area was relatively low compared with other nearshore areas in the region. All subtidal habitats showed evidence of disturbance to varying degrees, with no fish species recorded at these locations. The soft sediment habitat was found to cover much of the area footprint, and faunal diversity was very low. Fish diversity and abundance were equally poor with only a few demersal species recorded. No evidence of coral colonization was recorded although the presence of a low-profile, encrusting species was recorded in close proximity, to the east of the study area. Mangrove, coral, and seagrass were absent in the study area and its immediate vicinity. Modelling of waste plume suggested that the harbor water is fairly well-mixed, and the dispersion of ammonia attenuates with distance.
Anthozoa , Biodiversity , Agriculture , Animals , Coral Reefs , Ecosystem , Fishes , United Arab Emirates
This paper presents the most comprehensive datasets of ambient fine particulate matter (PM2.5) for the UAE from 1980 to 2016. The long-term distributions of PM2.5 showed the annual average PM2.5 concentrations constantly exceeded the EPA and WHO guidelines. They varied from 77 to 49 µg/m3 with an overall average of 61.25 µg/m3. While the inter-annual variability in PM2.5 concentrations showed relatively a cyclic pattern, with successive ups and downs, it broadly exhibited an increasing trend, particularly, over the last 14 years. PM2.5 concentrations displayed a strong seasonal pattern, with greatest values observed during warm summer season, a period of high demand of electricity and dust events. The lowest values found in autumn are attributable to reduced demand of energy. Decreased atmospheric temperatures and high relative humidity coinciding with this period are likely to reduce the secondary formation of PM2.5. The spatial changes in PM2.5 concentrations exhibited gradual downward trends to the north and northeast directions. Airborne PM2.5 is prevalent in the southern and western regions, where the majority of oil and gas fields are located. PM2.5/PM10 ratio indicated that ambient aerosols are principally associated with anthropogenic sources. Peaks in PM2.5/CO ratio were frequently observed during June, July, and August, although few were concurrent with March. This indicates that secondary formation plays an important role in PM2.5 levels measured in these months, especially as the photochemical activities become relatively strong in these periods. The lowest PM2.5/CO ratios were found during September, October, and November (autumn) suggesting a considerable contribution of primary combustion emissions, especially vehicular emissions, to PM2.5 concentration. PM2.5 concentrations are positively correlated with sulfate levels. In addition to sea and dust aerosols, sulfate concentration in the coastal region is also related to fossil fuel burning from power plants, oil and gas fields, and oil industries. The population-weighted average of PM2.5 in UAE was 63.9 µg/m3, which is more than three times greater than the global population-weighted mean of 20 µg/m3.
Air Pollutants/analysis , Air Pollution/statistics & numerical data , Environmental Monitoring , Particulate Matter/analysis , Aerosols/analysis , Dust/analysis , Fossil Fuels , Power Plants , Seasons , United Arab Emirates , Vehicle Emissions/analysis
Environmental scientists are currently assessing the ability of hyper-spectral remote sensing to detect, identify, and analyze natural components, including minerals, rocks, vegetation and soil. This paper discusses the use of a nonlinear reflectance model to distinguish multicomponent particulate mixtures. Analysis of the data presented in this paper shows that, although the identity of the components can often be found from diagnostic wavelengths of absorption bands, the quantitative abundance determination requires knowledge of the complex refractive indices and average particle scattering albedo, phase function and size. The present study developed a method for spectrally unmixing halite and gypsum combinations. Using the known refractive indexes of the components, and with the assistance of Hapke theory and Legendre polynomials, the authors develop a method to find the component particle sizes and mixing coefficients for blends of halite and gypsum. Material factors in the method include phase function parameters, bidirectional reflectance, imaginary index, grain sizes, and iterative polynomial fitting. The obtained Hapke parameters from the best-fit approach were comparable to those reported in the literature. After the optical constants (n, the so-called real index of refraction and k, the coefficient of the imaginary index of refraction) are derived, and the geometric parameters are determined, single-scattering albedo (or ω) can be calculated and spectral unmixing becomes possible.
In this article, we present the results of the regional estimation of the evolution of monthly mean aerosol size over the Arabian Gulf Region, based on the data collected during the period July 2002 - September 2016. The dataset used is complete, without missing values. Two methods are introduced for this purpose. The first one is based on the partition of the regional series in sub-series and the selection of the most representative one for fitting the regional trend. The second one is a version of the first method, combined with the k-means clustering algorithm. Comparison of their performances is also provided. The study proves that both methods give a very good estimation of the evolution of the aerosol size in the Arabian Gulf Region in the study period.
Assessment of groundwater quality is of utmost significance in arid regions like Saudi Arabia where the lack of present-day recharge and high evaporation rates coupled with increasing groundwater withdrawal may restrict its usage for domestic or agricultural purposes. In the present study, groundwater samples collected from agricultural farms in Hail (15 samples), Al Jawf (15 samples), and Tabuk (30 samples) regions were analyzed for their major ion concentration. The objective of the study was to determine the groundwater facies, the main hydrochemical process governing the groundwater chemistry, the saturation index with respect to the principal mineral phases, and the suitability of the groundwater for irrigational use. The groundwater samples fall within the Ca-Cl type, mixed Ca-Mg-Cl type, and Na-Cl type. Evaporation and reverse ion exchange appear to be the major processes controlling the groundwater chemistry though reverse ion exchange process is the more dominating factor. The various ionic relationships confirmed the reverse ion exchange process where the Ca and Mg in the aquifer matrix have been replaced by Na at favorable exchange sites. This phenomenon has accounted for the dominance of Ca and Mg ions over Na ion at all the sites. The process of reverse ion exchange was further substantiated by the use of modified Piper diagram (Chadha's classification) and the chloro-alkaline indices. Evaporation as a result of extreme aridity has resulted in the groundwater being oversaturated with aragonite/calcite and dolomite as revealed by the saturation indices. The groundwater samples were classified as safe (less than 10) in terms of sodium adsorption ratio (SAR) values, good (less than 1.25) in terms of residual sodium carbonate (RSC) values, and safe to moderate (between 0 and 3) in terms of Mg hazard for irrigation purposes. Though the high salinity groundwater in the three regions coupled with low SAR values are good for the soil structure, it can have a negative impact on the crop production by adversely affecting the crop physiology. Cultivation of high-salinity-resistant varieties of crops is recommended for maximum agricultural productivity.
Environmental Monitoring/methods , Groundwater/chemistry , Ion Exchange , Water Pollutants, Chemical/analysis , Water Purification/methods , Adsorption , Agricultural Irrigation , Carbonates , Desert Climate , Salinity , Saudi Arabia
The Gulf of Aqaba (GoA) is of significant ecological value with unique ecosystems that host one of the most diverse coral communities in the world. However, these marine environments and biodiversity have been threatened by growing human activities. We investigated the levels and distributions of trace metals in surface seawater across the eastern coast of the Saudi GoA. Zn, Cu, Fe, B and Se in addition to total dissolved solids and seawater temperature exhibited decreasing trends northwards. While Mn, Cd, As and Pb showed higher average levels in the northern GoA. Metal input in waters is dependent on the adjacent geologic materials. The spatial variability of metals in water is also related to wave action, prevailing wind direction, and atmospheric dry deposition from adjacent arid lands. Also, water discharged from thermal desalination plants, mineral dust from fertilizer and cement factories are potential contributors of metals to seawater water, particularly, in the northern GoA.
Metals/analysis , Seawater/analysis , Water Pollutants, Chemical/analysis , Dust , Environmental Monitoring/methods , Saudi Arabia , Seawater/chemistry , Temperature , Wind
The present study deals with detailed hydrochemical assessment of groundwater within the Saq aquifer. The Saq aquifer which extends through the NW part of Saudi Arabia is one of the major sources of groundwater supply. Groundwater samples were collected from about 295 groundwater wells and analyzed for various physico-chemical parameters such as electrical conductivity (EC), pH, temperature, total dissolved solids (TDS), Na(+), K(+), Ca(2+), Mg(2+), CO3 (-), HCO3 (-), Cl(-), SO4 (2-), and NO3 (-). Groundwater in the area is slightly alkaline and hard in nature. Electrical conductivity (EC) varies between 284 and 9,902 µS/cm with an average value of 1,599.4 µS/cm. The groundwater is highly mineralized with approximately 30 % of the samples having major ion concentrations above the WHO permissible limits. The NO3 (-) concentration varies between 0.4 and 318.2 mg/l. The depth distribution of NO3 (-) concentration shows higher concentration at shallow depths with a gradual decrease at deeper depths. As far as drinking water quality criteria are concerned, study shows that about 33 % of samples are unfit for use. A detailed assessment of groundwater quality in relation to agriculture use reveals that 21 % samples are unsuitable for irrigation. Using Piper's classification, groundwater was classified into five different groups. Majority of the samples show Mix-Cl-SO4- and Na-Cl-types water. The abundances of Ca(2+) and Mg(2+) over alkalis infer mixed type of groundwater facies and reverse exchange reactions. The groundwater has acquired unique chemical characteristics through prolonged rock-water interactions, percolation of irrigation return water, and reactions at vadose zone.
Environmental Monitoring/methods , Groundwater/chemistry , Water Supply/standards , Agricultural Irrigation/methods , Saudi Arabia , Water Pollutants, Chemical/analysis , Water Quality/standards , Water Resources/standards
Chemical characteristics of 72 groundwater samples collected from Midyan Basin have been studied to evaluate major ion chemistry together with the geochemical and weathering processes controlling the water composition. Water chemistry of the study area is mainly dominated by Na, Ca, SO4, and Cl. The molar ratios of (Ca + Mg)/total cations, (Na + K)/total cations, (Ca + Mg)/(Na + K), (Ca + Mg)/(HCO3 + SO4), (Ca + Mg)/HCO3, and Na/Cl reveal that water chemistry of the Midyan Basin is controlled by evaporite dissolution (gypsum and/or anhydrite, and halite), silicate weathering, and minor contribution of carbonate weathering. The studied groundwater samples are largely undersaturated with respect to dolomite, gypsum, and anhydrite. These waters are capable of dissolving more of these minerals under suitable physicochemical conditions.
Fresh Water/chemistry , Water Pollutants, Chemical/analysis , Environmental Monitoring , Ions/analysis , Minerals/analysis , Saudi Arabia , Water Supply/analysis , Water Supply/statistics & numerical data , Weather
