Temporal and Spatial Variations of Potentially Toxic Elements in PM10 Collected in Jeddah City, Saudi Arabia.

Air pollution causes environmental and health problems around the world. In this study, ambient particulate matter with an aerodynamic diameter equal to or less than 10 microns (PM10) has been collected at three different locations in Jeddah city, Saudi Arabia. The locations are characterized by differences in terms of traffic, residential intensity, industrial, and non-road mobile machinery activities. The monthly and annual mass concentration of the PM10 exceeds the recommended annual limit of the World Health Organization (15 µg/m3) and the European air quality standard (40 µg/m3) at the three locations. The collected PM10 samples as well as a certified reference material of atmospheric particulates (NIST 1678a) were digested in aqua regia using microwave digestion. The quantitative elemental analysis was carried out using inductively coupled plasma mass spectrometry. The variations of the elemental concentration in terms of workdays, weekends, seasons, and annual were determined at the three locations. The spatial and temporal elemental variations were found to be different between the three sites, pointing to local influences that should be further evaluated. The concentration of Cd was found to be high and may cause health problems.

A novel test device and quantitative colorimetric method for the detection of human chorionic gonadotropin (hCG) based on Au@Zn-salen MOF for POCT applications.

The human chorionic gonadotropin (hCG) hormone is a biomarker that can predict tumors and early pregnancy; however, it is challenging to develop sensitive qualitative-quantitative procedures that are also effective, inventive, and unique. In this study, we used a novel easy in situ reaction of an organic nano-linker with Zn(NO3)2·6H2O and HAuCl4·3H2O to produce a gold-zinc-salen metal-organic framework composite known as Au-Zn-Sln-MOF. A wide variety of micro-analytical instruments and spectroscopic techniques were used in order to characterize the newly synthesized Au-Zn-Sln-MOF composite. Disclosure is provided for a novel swab test instrument and a straightforward colorimetric approach for detecting hCG hormone based on an Au-Zn-Sln-MOF composite. Both of these methods are easy. In order to validate a natural enzyme-free immunoassay, an Au-Zn-Sln-MOF composite was utilized in the role of an enzyme; a woman can use this gadget to determine whether or not she is pregnant in the early stages of the pregnancy or whether or not her hCG levels are excessively high, which is a symptom that she may have a tumor. This cotton swab test device is compatible with testing of various biological fluids, such as serum, plasma, or urine, and it can be easily transferred to the market to commercialize it as a costless kit, which will be 20-30% cheaper than what is available on the market. Additionally, it can be used easily at home and for near-patient testing (applications of point-of-care testing (POCT)).

The effects of salinity, temperature, and UV irradiation on leaching and adsorption of phthalate esters from polyethylene in seawater.

In this study, the leaching of six phthalic acid esters (PAEs) from three common consumer plastics was investigated: low and high density polyethylene (LDPE, HDPE) and recycled polyethylene (RP). The effects of salinity, temperature, and ultraviolet irradiation (UVR) on leaching were investigated. The study of leaching of phthalates in aqueous environments in batch experiments is challenging due to their readsorption by the high hydrophobicity of PAEs, and there are no standard methods to study release processes. Here with the experiments, leaching (A) and spiking (B) using six PAEs to study the readsorption in the leaching process. PAEs were identified and quantified using GC-MS. Dibutyl phthalate (DBP) and benzyl butyl phthalate (DEHP) showed considerable leaching during the 5-day incubation: 14 ±â€¯1 to 128 ±â€¯14 and 25 ±â€¯2 to 79 ±â€¯5 ng/cm2, respectively, under UVR, corresponding approximately to (1.9-13%) and (12.4-22.4%) of the solvent extracted mass. The highest Kd values were measured for RP polymers (0.3-9.4), followed by LDPE (0.5-5.4) and HDPE (0.2-2.2) polymers. Thus, readsorption of PAEs at the surface removed 30-80% of the leached PAEs in the dissolved phase. For example in LDPE, the calculated total release of DBP was up to 54 ±â€¯4 ng/cm2, while the dissolved amount was 8.5 ±â€¯1 ng/cm2 during the 5-day incubation under freshwater conditions. Increasing salinity negatively affected the leaching rate, which decreased for DBP from 54 ±â€¯4 ng/cm2 in freshwater to 44 ±â€¯3 and 38 ±â€¯3 ng/cm2 at salinity of 20 and 40 g/L, respectively, from LDPE during the 5-day incubation. Temperature and UVR had a positive effect on the leaching rate, with the release of DBP from LDPE increasing from 44 ±â€¯3 ng/cm2 at room temperature (25 °C) to 60 ±â€¯6 and 128 ±â€¯14 ng/cm2 at high temperature (40 °C) and UVR, respectively. Overall, this study highlights the positive relationship between temperatures, UVR on the extent of leaching and surface adsorption on the leaching measurements.

SrSnO3-Assembled MWCNT Heterojunctions for Superior Hydrogen Production under Visible Light.

A one-step sol-gel method for SrSnO3 nanoparticle synthesis and the incorporation of multi-walled carbon nanotubes (MWCNTs) to produce a SrSnO3@MWCNT photocatalyst is presented. The incorporation of MWCNTs results in enhancement of structural, optical, and optoelectrical properties of SrSnO3. The optimized 3.0% addition of MWCNTs results in light absorption enhancement and a reduction of the band gap from 3.68 to 2.85 eV. Upon application of the photocatalyst in the photocatalytic hydrogen production reaction, SrSnO3@MWCNT-3.0% yields 4200 µmol g-1 of H2 in just 9 h with the use of 1.6 g L-1 of the photocatalyst. SrSnO3@MWCNT exhibits remarkable chemical and photocatalytic stability upon regeneration. Enhanced photocatalytic ability is attributed to improved surface properties and charge-carrier recombination suppression induced by the MWCNT addition. This study highlights the remarkable improvements in chemical and physical properties of semiconductors with MWCNT incorporation.

Semi-Volatile Organic Compounds in Car Dust: A Pilot Study in Jeddah, Saudi Arabia.

People may spend a significant amount of their daily time in cars and thus be exposed to chemicals present in car dust. Various chemicals are emitted from during car use, contaminating the car dust. In this study, we compiled published and unpublished data on the occurrence of phthalates, flame retardants (FRs), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) in Saudi car dust. Phthalates, a class of chemical commonly used as plasticizers in different car parts, were the major pollutants found in car dust, with a median value of ∑phthalates 1,279,000 ng/g. Among other chemicals, organophosphate flame retardants (OPFRs) were found to be between 1500-90,500 ng/g, which indicates their use as alternative FRs in the car industry. The daily exposure to Saudi drivers (regular and taxi drivers) was below the respective reference dose (RfD) values of the individual chemicals. However, the estimated incremental lifetime cancer risk (ILCR) values due to chronic exposure to these chemicals was >1 × 10-5 for taxi drivers for phthalates and PAHs, indicating that the long-term exposure to these chemicals is a cause of concern for drivers who spend considerable time in cars. The study has some limitations, due to the small number of samples, lack of updated RfD values, and missing cancer slope factors for many studied chemicals. Despite these limitations, this study indicates the possible range of exposure to drivers from chemicals in car dust and warrants further extensive studies to confirm these patterns.

Fabrication of Mesoporous PtO-ZnO Nanocomposites with Promoted Photocatalytic Performance for Degradation of Tetracycline.

Herein, we report a simple incorporation of PtO NPs at diverse percentages (0.2-0.8 wt %) onto a highly crystalline and mesoporous ZnO matrix by the wet-impregnation approach for degradation of tetracycline (TC) upon visible light exposure. These well-dispersed and small-sized PtO NPs provide the mesoporous PtO-ZnO nanocomposites with outstanding photocatalytic performance for complete TC degradation. The optimized 0.6% PtO-ZnO photocatalyst exhibits excellent TC degradation, and its degradation efficiency reached ∼99% within 120 min. The photocatalytic performance of the 0.6% PtO-ZnO nanocomposite is 20 and 10 times higher than that of pristine ZnO and commercial P-25, respectively. The photodegradation rate of TC over the 0.6% PtO-ZnO nanocomposite is 34 and 12.5 times greater than that of pristine ZnO and commercial P-25, respectively. This is because of the large surface area, unique porous structure, synergistic effect, and broad visible light absorption of the PtO-ZnO nanocomposite. Moreover, mesoporous PtO-ZnO nanocomposites showed a high stability and recyclability over five iterations. This work demonstrates the remarkable role of combining PtO and ZnO photocatalysts in providing nanocomposites with significant potential for the preservation of human health through wastewater remediation.

Generation of Hydrogen Gas Using CuCr2O4-g-C3N4 Nanocomposites under Illumination by Visible Light.

In this research, nanocomposites made of CuCr2O4-g-C3N4 accommodating distinct contents of CuCr2O4 (1-4 wt %) nanoparticles (NPs) were endorsed for hydrogen gas production after illumination by visible light in the presence of aqueous glycerol solution. The ultrasonication-mixture method was applied to assure the homogeneous distribution of CuCr2O4 NPs over synthesized mesoporous g-C3N4. Such nanocomposites possess suppressed recombination between the photoinduced charges. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy examinations affirmed the formation of CuCr2O4-g-C3N4 heterojunctions. The separation between the induced charges and the photocatalytic performance with the CuCr2O4 NP amount were investigated. The CuCr2O4-g-C3N4 heterojunction of 3 wt % CuCr2O4 content was documented as the optimal heterojunction. Upgraded hydrogen gas generation was attained over the optimal heterojunction with the extent of ten and thirty times as those registered for pure CuCr2O4 and g-C3N4 specimens, respectively, under illumination by visible light. The photocatalytic performance acquired by the diverse synthesized specimens was assessed not only by their effectiveness to absorb light in the visible region but also by their potential to separate the photoinduced charges.

Soft and hard templates assisted synthesis mesoporous CuO/g-C3N4 heterostructures for highly enhanced and accelerated Hg(II) photoreduction under visible light.

Herein, triblock copolymer surfactant (F127) and mesoporous silica (MCM-41) as soft and hard templates were employed to synthesize of mesoporous CuO/g-C3N4 heterostructures with large surface areas for Hg(II) photoreduction in existence of formic acid as a holes sacrificial. TEM image for mesoporous CuO/g-C3N4 indicated that CuO NPs are homogeneously distributed with spherical shape in particle size ~5 nm onto the surface of g-C3N4. Mesoporous 2%CuO/g-C3N4 heterostructure was achieved a high Hg(II) photoreduction rate of 628.74 µmolg-1h-1 and high photoreduction efficiency of ~100% within 50 min compared with the pure either mesoporous CuO NPs (130.11 µmolg-1h-1, 21%) and g-C3N4 (88.54 µmolg-1h-1, 14%). The highest Hg(II) photoreduction rate achieved was 628.74 µmolg-1h-1, which is 4.83 and 7.1 magnitudes stronger than mesoporous CuO NPs and g-C3N4. The excellent photocatalytic performance of mesoporous CuO/g-C3N4 heterostructures for Hg(II) photoreduction is referred to highly dispersed mesoporous CuO NPs with small particle size onto g-C3N4, narrow bandgap, large surface area, a rapid transfer of Hg(II) ions and HCOOH to easily reach the active sites due to the facile penetration through the mesostructure, thus promoting the utilization of porous structure of CuO/g-C3N4 heterostructures for efficient diffusion of Hg(II) ions. The intense interaction between mesoporous CuO NPs and porous g-C3N4 confirms the durability of the CuO/g-C3N4 heterostructures during recyclability for five times.

Spectroscopic Assessment of Platinum Group Elements of PM10 Particles Sampled in Three Different Areas in Jeddah, Saudi Arabia.

Platinum group elements (PGE) including Ru, Rh, Pt and Pd have been quantified in air particulate matter with an aerodynamic diameter equal or less than 10 microns (PM10) using inductively coupled plasma mass spectrometry (ICP-MS). PM10 aerosols have been collected from three sites representing various activities in Jeddah city, Saudi Arabia. These locations are residential site with heavy traffic, industrial site and heavy traffic and a light traffic site outside the city. To obtain reasonable data of the PGE concentrations, a group from 10 to 15 PM10 samples were collected every month. The annual and seasonal variation of the mass concentration of the PGE were demonstrated. In all locations, Pt and Pd were relatively higher than Ru and Rh possibly because their main use is in automobile catalytic converters. Concentrations of observed PGE in PM10 could be arranged in ascending order as: Rh < Ru < Pd < Pt. In case of Ru and Pt, there are clear similarities in terms of the overall mean concentrations at the sampling locations. Due to the high concentration of Ru, Rh and Pd at low traffic site, there are certainly other sources of these elements rather than vehicle catalytic converters. However, at the industrial/heavy traffic location, high concentrations of Ru were detected during February 2015. In addition, high Pt concentrations were also detected at the light traffic site during May 2015. Results indicate that Pt source in PM10 is mainly the automobile catalytic converters.

Facile Synthesis of Mesoporous Ag2O-ZnO Heterojunctions for Efficient Promotion of Visible Light Photodegradation of Tetracycline.

Fabrication of 3D mesoporous Ag2O-ZnO heterojunctions at varying Ag2O contents has been achieved through poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic F-108) as the structure-directing agent for the first time. The mesoporous Ag2O-ZnO nanocomposites exhibited a mesoporous structure, which revealed a large pore volume and high surface area. The photocatalytic efficiency over mesoporous Ag2O-ZnO nanocomposites for tetracycline (TC) compared with that over commercial P-25 and pristine ZnO NPs through the visible light exposure was studied. Mesoporous 1.5% Ag2O-ZnO nanocomposites indicated the highest degradation efficiency of 100% of TC during 120 min of the visible light exposure compared with 5% and 10% for pristine ZnO NPs and commercial P-25, respectively. The TC degradation rate took place much rapidly over 1.5% Ag2O-ZnO nanocomposites (0.798 µmol L-1 min-1) as compared to either commercial P-25 (0.097 µmol L-1 min-1) or ZnO NPs (0.035 µmol L-1 min-1). The mesoporous 1.5% Ag2O-ZnO nanocomposite revealed the highest degradation rate among all synthesized samples, and it was 23 and 8 orders of magnitudes greater than those of pristine ZnO NPs and P-25, respectively. The photoluminescence and transient photocurrent intensity behaviors have been discussed to explore photocatalysis mechanisms. It is anticipated that the present work will contribute some suggestions for understanding other heterojunctions with outstanding behaviors.

Currently used organophosphate flame retardants determined in the settled dust of masjids and hotels of Saudi Arabia, a new insight into human health implications of dust exposure.

Indoor settled dust particles are considered as an important source of human exposure to chemicals such as organophosphate flame retardants (PFRs). In recent decades the Kingdom of Saudi Arabia (KSA) has experienced tremendous growth in population, as a result the number of masjids has also increased significantly to provide sufficient space for the public to offer prayers. The hospitality industry in KSA is also expanding to cater for the ever-increasing number of pilgrims visiting the two holy cities of the kingdom. However, limited data are available on the indoor pollution of masjids and hotels. In this study, PFRs were analyzed in the settled dust collected from various hotels and masjids of Jeddah, KSA. Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) and tris(1-chloro-2-propyl) phosphate (TCPP) were the major PFRs in masjid (median = 2490 and 2055 ngg-1) and hotel (median = 2360 and 3315 ngg-1) dust, respectively. A public health risk assessment was carried out by determining the incremental lifetime cancer risk (ILCR), and daily exposure via dust ingestion, inhalation, and dermal contact of PFRs. The calculated daily exposure via dust ingestion was well below the reference dose (RfD) values, and also the calculated hazardous quotient (HQ) and carcinogenic risk were well below the risk mark. However, the ILCR for PFRs was below the reference values of USEPA, which suggested that long-term exposure to these chemicals has a limited cause for concern. The study showed that the general public is exposed to PFRs in the studied microenvironments and the major exposure routes are dermal contact and ingestion.

Phthalates and polycyclic aromatic hydrocarbons (PAHs) in the indoor settled carpet dust of mosques, health risk assessment for public.

A number of studies have reported the occurrence of phthalates and polycyclic aromatic hydrocarbons (PAHs) in indoor settled dust from different occupational and residential settings around the world but limited studies are available from public and religious places. In recent decades Kingdom of Saudi Arabia (KSA) has experienced tremendous industrial growth especially in the petroleum industries, and as result environmental issues related with such industries have also increased but scientific data is still scarce to understand the impact on public health. Therefore, the main objective of this study was to report the phthalates and PAHs profile in the settled dust collected from various mosques of Jeddah, an important part of people living in the region, and to evaluate the health risk associated with these chemicals via dust ingestion, inhalation and dermal contact for the general public who attend mosques for prayers. Phenanthrene (500-3000 ng/g), pyrene (40-1220 ng/g), and chrysene (95-4590 ng/g) were the major PAHs and ∑12PAHs concentrations ranged from 2550 to 9150 ng/g. Whereas, DEHP (

Brominated and organophosphate flame retardants in indoor dust of Jeddah, Kingdom of Saudi Arabia: Implications for human exposure.

Different flame retardants (FRs) namely polybrominated diphenyl ethers (PBDEs), emerging brominated/chlorinated flame retardants (Br/Cl FRs), and organophosphate FRs (OPFRs) were analyzed in cars, air conditioner (AC) filters and floor dust of different households from Jeddah, Kingdom of Saudi Arabia (KSA). To the best of our knowledge, this is first study in literature reporting emerging Br/Cl FRs and OPFRs in AC filter dust and also first to report on their occurrence in dust from KSA. Chlorinated alkyl phosphate, penta-BDEs, BDE-209, and decabromodiphenylethane (DBDPE) were the major chemicals in dust samples from all microenvironments. ΣOPFRs occurred at median concentrations (ng/g dust) of 15,400, 10,500, and 3750 in AC filter, car and house floor dust, respectively. For all analyzed chemicals, relatively lower levels were observed in floor dust than car and AC filter dust. The profiles of FRs in car dust were different from AC filter and floor dust, which reflected their wider application as FR and plasticizer in variety of household and commercial products. For toddlers, assuming high dust intake and 95th percentile concentrations, the computed exposure estimation for BDE-99 was higher than RfD values.

Organohalogenated contaminants in sediments and bivalves from the Northern Arabian Gulf.

Several classes of Organohalogenated contaminants (OHCs) were determined in sediments and bivalves collected from Kuwait coast. The levels and profile of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) were compared in both sediments and bivalves. PCB-153 and -138 were the major contributors towards total OHCs followed by DDT and its metabolites (DDTs). The higher contribution of DDTs (~40%) and BDE-47 (~15%) in bivalves as compared to that in associated sediments indicated high biota-sediment accumulation factors (BSAF). Higher BSAF (values for heavier PCBs, DDTs and PBDEs) also indicated their high accumulation potential from sediment into associated biota at most of the studied locations. Overall, OHCs in sediments and bivalves measured in current study were lower than those reported in the literature worldwide. Most of the sediment concentrations of OHCs (ng/g, dry weight) were in the range of permissible guideline values proposed by Canadian Sediment Quality Guidelines (CSQGs), with few exceptions for DDTs (5 ng/g) and PCBs (22.7 ng/g). Similarly, 10% of bivalve samples contained high levels (ng/g, lipid weight) of PCBs (300) and DDTs (150) and were above the set safety benchmarks. This study establishes baseline for future monitoring programs.

Elemental spatiotemporal variations of total suspended particles in Jeddah city.

Elements associated with total suspended particulate matter (TSP) in Jeddah city were determined. Using high-volume samplers, TSP samples were simultaneously collected over a one-year period from seven sampling sites. Samples were analyzed for Al, Ba, Ca, Cu, Mg, Fe, Mn, Zn, Ti, V, Cr, Co, Ni, As, and Sr. Results revealed great dependence of element contents on spatial and temporal variations. Two sites characterized by busy roads, workshops, heavy population, and heavy trucking have high levels of all measured elements. Concentrations of most elements at the two sites exhibit strong spatial gradients and concentrations of elements at these sites are higher than other locations. The highest concentrations of elements were observed during June-August because of dust storms, significant increase in energy consumption, and active surface winds. Enrichment factors of elements at the high-level sites have values in the range >10~60 while for Cu and Zn the enrichment factors are much higher (~0->700) indicating that greater percentage of TSP composition for these three elements in air comes from anthropogenic activities.

"Soil Pollution Hazardous to Environment": a case study on the chemical composition and correlation to automobile traffic of the roadside soil of Jeddah city, Saudi Arabia.

Soil samples from different roads in Jeddah city were collected and analyzed for their elemental composition. The effects of traffic conditions were critically investigated to reflect the effect of the heavy and light traffic on the soil composition. Samples were analyzed for K, As, Co, Cr, Ni, Pb, Sb, V, and Zn. The results revealed great dependence of lead and zinc contents on traffic conditions. The lead content lies in the range 0.3-104.8+/-0.003 mg/kg for the samples of high traffic conditions and 0.3+/-0.0mg/kg being for the sample with no traffic activity, whereas 104.8+/-0.003 mg/kg was for the one of the most used highways area in Jeddah city. Zinc level lies in the range 56.59+/-0.003-456.93+/-0.06 mg/kg which is quite close to lead pattern. The high zinc concentration was found along the main turn roads. The high zinc content in tested soil samples may come from traffic sources, especially vehicle tires. Concentrations of other elements showed little dependence on traffic conditions.