Identification, Quantification, and Toxicity of PCDDs and PCDFs in Soils from Industrial Areas in the Central and Eastern Regions of Saudi Arabia.

This study was conducted to identify and quantify polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in soil samples collected from selected industrial areas in the central and eastern regions of Saudi Arabia. All the investigated compounds of PCDDs/PCDFs were identified in the studied locations. The average concentrations of PCDDs (sum of seven congeners measured) ranged from 11.5 to 59.6 pg g(-1), with a maximum concentration of 125.7 pg g(-1) at an oil refinery station followed by 100.9 pg g(-1) at a cement factory. The average concentrations of PCDFs (sum of 10 congeners measured) accounted for 11.68-19.35 pg g(-1), with a maximum concentration of 38.67 pg g(-1) at the cement factory. It was generally observed that the soil samples collected from industrial areas have substantially high toxicity equivalence (TEQ) values of PCDDs/PCDFs compared to soils of remote areas. Principal component analysis revealed that the cement factories and oil refineries were the primary sources of PCDDs and PCDFs.

Effect of Stabilized nZVI Nanoparticles on the Reduction and Immobilization of Cr in Contaminated Soil: Column Experiment and Transport Modeling.

Batch and transport experiments were used to investigate the remediation of loamy sand soil contaminated with Cr(VI) using zero-valent iron nanoparticles (nZVI) stabilized by carboxymethylcellulose (CMC-nZVI). The effect of pH, ionic strength (IS), and flow rate on the removal efficiency of Cr(VI) were investigated under equilibrium (uniform transport) and non-equilibrium (two-site sorption) transport using the Hydrus-1D model. The overall removal efficiency ranged from 70 to over 90% based on the chemical characteristics of the CMC-nZVI suspension and the transport conditions. The concentration and pH of the CMC-nZVI suspension had the most significant effect on the removal efficiency and transport of Cr(VI) in the soil. The average removal efficiency of Cr(VI) was increased from 24.1 to 75.5% when the concentration of CMC-nZVI nanoparticles was increased from 10 to 250 mg L-1, mainly because of the increased total surface area at a larger particle concentration. Batch experiments showed that the removal efficiency of Cr(VI) was much larger under acidic conditions. The average removal efficiency of Cr(VI) reached 90.1 and 60.5% at pH 5 and 7, respectively. The two-site sorption model described (r2 = 0.96-0.98) the transport of Cr(VI) in soil quite well as compared to the uniform transport model (r2 = 0.81-0.98). The average retardation of Cr(VI) was 3.51 and 1.61 at pH 5 and 7, respectively, indicating earlier arrival for the breakthrough curves and a shorter time to reach maximum relative concentration at lower pH. The methodology presented in this study, combining column experiment and modeling transport using the Hydrus-1D model, successfully assessed the removal of Cr(VI) from polluted soils, offering innovative, cost-effective, and environmentally friendly remediation methodologies.

Stability and Dynamic Aggregation of Bare and Stabilized Zero-Valent Iron Nanoparticles under Variable Solution Chemistry.

Surface modification of nanoscale zero-valent iron (nZVI) using polymer stabilizers (e.g., sodium carboxymethyl cellulose, CMC) is usually used to minimize aggregation, increase stability, and enhance transport of nZVI. We investigated the stability and dynamic aggregation of bare and CMC-nZVI as affected by variations in pH, ionic strength (IS), and nZVI particle concentration. CMC coating of nZVI resulted in smaller hydrodynamic size and larger zeta potential. The largest hydrodynamic size of nZVI was associated with bare nZVI at high IS (100 mM), pH close to the point of zero charge (PZC, 7.3-7.6), and larger particle concentration (1.0 g L-1). The increase in the zeta potential of CMC-nZVI reached one- to four-fold of that for bare nZVI, and was greater at pH values close to PZC, high IS, and larger particle concentration. The stability of CMC-nZVI was increased by 61.8, 93.1, and 57.5% as compared to that of bare nZVI at IS of 1, 50 and 100 mM, respectively. Calculations of Derjaguin, Landau, Verwey and Overbeek (DLVO) interaction energy were in agreement with stability results, and showed the formation of substantial energy barriers at low IS indicating greater nZVI stability. Our results suggest that at IS above 50 mM and nZVI particle concentration larger than 0.1 g L-1, the likelihood of nZVI aggregation is high. Nevertheless, CMC polymer stabilizer would enhance the stability and transport of nZVI even under these unfavorable solution chemistry conditions.

Photolysis degradation of polyaromatic hydrocarbons (PAHs) on surface sandy soil.

Polycyclic aromatic hydrocarbons (PAHs) are potent environmental pollutants, and some of them have been identified as carcinogenic and mutagenic. To advance the knowledge of the environmental fate of PAHs, we systematically investigated the influence of different UV wavelengths irradiation on photolysis of PAHs on sandy soil under tow wavelengths (254 and 306 nm) UV irradiation for six PAHs. In addition, kinetic model and influence of several parameters on PAHs photolysis have been studied. The results obtained indicated that UV radiation with a wavelength of 306 nm was more efficient in the photolysis of the polycyclic aromatic hydrocarbons. Our results showed that fluoranthene (Flt) was the fastest in decomposition, has the greatest value for the coefficient of photolysis (7.4 × 10(-3) h(-1)), and has less half-life, reaching 94 h when using a wavelength of 254 nm. The results indicated that the pyrene (Pyr) was more resistant to photolysis in comparison with indeno(1,2,3-cd) pyrene (IP) and fluoranthene (Flt). The results indicate that photolysis is a successful way to remediate the six studied PAHs compounds.

Clinico-pathological patterns of a rare presentation of abdominal neuroblastoma in children.

BACKGROUND: To study the diagnosis, management, and outcome of abdominal neuroblastoma (NBL) in infants and children and also the behavior of some rare types. PATIENTS AND METHODS: This is a retrospective review of 46 infants and children having abdominal NBL at King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia and Tanta University Hospital, Tanta, Egypt (a joint study) between February 2008 and January 2012. The patients' medical records were reviewed for demographic details, clinical presentations, histopathology, radiological diagnosis, management, and outcome. RESULTS: Of the 46 patients, 5 (10.7%), three males and two females, aged 1.5-6.5 years (mean: 4.5 years) had rare types of NBL (one bilateral NBL, one pelvic NBL, one pelvic-abdominal, and there were two cases of ganglioneuroblastoma). Three patients (two ganglioneuroblastoma and one pelvic) underwent complete surgical removal of the tumor with a good disease survival, whereas the other two patients (two bilateral and one pelviabdominal) had advanced disease and received palliative chemoradiotherapy. The remaining 41 patients, 23 males (56.1%) and 18 females (43.9%), with mean age 3.9 years (range: 1-7 years), had unilateral abdominal NBL. Twelve of them had resectable tumor and underwent primary surgical removal of the tumor, whereas the remaining 29 patients had unresectable tumor and received pre-operative chemotherapy with good response of the tumor in seven patients and no response in the remaining 22 patients. CONCLUSION: Primary complete surgical removal of tumor is advisable in localized NBL with a good outcome, whereas in advanced cases, it is better to start with pre-operative chemotherapy to downsize the tumour mass and safe delayed surgical excision. An increase in patient's age is associated with advanced stage of NBL and poor prognosis except in ganglioneuroblastoma cases due to maturation of tumor cells.

Post-bariatric surgery satisfaction and body-contouring consideration after massive weight loss.

BACKGROUND: Following a bariatric surgery and massive weight-loss, the outcome is usually sullied by consequences on the body's contour and redundant skin. AIMS: We aimed to record the frequency of contour irregularities and quantify patients' satisfaction with appearance and anticipations from body contouring surgery. MATERIALS AND METHODS: The ethical committee at King Abdulaziz University Hospital approved the study, and patients were consented. A cross-sectional study targeting the post-bariatric patients from May 2011 to April 2012 was conducted at our hospital. We used post-massive weight loss Satisfaction Questionnaire. RESULTS: The total numbers of patients were 64 (51 women and 13 men), of which 57 patients (89.2%) developed sagging skin. Most patients were dissatisfied with their appearance after weight loss. The most common zones were the upper arms (50%) and abdomen (45%). Considerably more women (36.2%) than men (24%) were dissatisfied with certain body areas. The most noticeable expectation of patients from body contouring surgery was improved cosmetic appearance (65.6%) and self-confidence (64.1%). More women (70.58%) than men (46.15%) expected a better cosmetic appearance after body contouring (P = 0.003). CONCLUSION: After bariatric surgery, sagging excess skin is an unsatisfactory problem. Therefore, body contouring surgery must be included in morbid obesity management.