Simultaneous mobilization of heavy metals and polychlorinated biphenyl (PCB) compounds from soil with cyclodextrin and EDTA in admixture

This study evaluated the efficacy of a washing process with cyclodextrin in combination with ethylenediaminetetraacetate (EDTA) for the simultaneous mobilization of heavy metals and PCBs from a field contaminated soil. Ultrasonically aided mixing of the field contaminated soil with a combination of cyclodextrin solution (10%, w/v) and a sparing quantity (2 mmol) of EDTA, simultaneously mobilized appreciable quantities of PCBs and much of the analyte metal (Cd, Cr, Cu, Mn, Ni, Pb, Zn) burdens. Relative to the action of individual reagents, a combination of randomly methylated (RAMEB) or hydroxypropyl beta-cyclodextrin (HPCD) with EDTA did not alter the PCB extraction efficiency nor did the presence of cyclodextrin change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe, Mn, Ni, and Zn) but did increase the recovery of Cu and Pb modestly. Three sonication-washes with the same charge of reagents mobilized appreciable quantities of PCBs (40-76%) and quantitatively extracted the labile fraction of Cd, Cu, Mn, and Pb. RAMEB proved to be more efficient than HPCD for PCB extractions. Three successive extractions with a single charge of cyclodextrin mobilized almost as much PCB (RAMEB, 76%; HPCD, 40%) as did the companion extractions that used fresh reagents each time (RAMEB, 78%; HPCD, 42%). Collectively, these studies demonstrated that PCB compounds and selected heavy metals can be co-extracted efficiently from soil with three successive washes with the same washing suspension containing EDTA and cyclodextrin.     

A systematic indoor air quality audit approach for public buildings

Good indoor air quality (IAQ) in buildings provides a comfortable and healthy environment for the occupants to work, learn, study, etc. Therefore, it is important to ascertain the IAQ status in the buildings. This study is aimed to establish and demonstrate the comprehensive IAQ audit approach for public buildings, based on Portugal national laws. Four public buildings in Portugal are used to demonstrate the IAQ audit application. The systematic approach involves the measurement of physical parameters (temperature, relative humidity, and concentration of the suspended particulate matter), monitoring of the concentrations of selected chemical indicators [carbon dioxide (CO₂), carbon monoxide, formaldehyde, ozone, and total volatile organic compounds], and the measurements of biological indicators (bacteria and fungi). In addition, air exchange rates are measured by the concentration decay method using metabolic CO₂ as the tracer gas. The comprehensive audits indicated some situations of common IAQ problems in buildings, namely: (1) insufficient ventilation rate, (2) too high particle concentration; and (3) poor filtration effectiveness and hygienic conditions in most of the air handling units. Accordingly, a set of recommendations for the improvement of IAQ conditions were advised to the building owner/managers.     

A new catalytic oxidation method for sensitive quantification of bromate in flours and bottled water using AgNPs

In this paper, a simple and sensitive spectrophotometric method for the determination of nanomolar level of bromate, based on the catalytic effect of silver nanoparticles on the oxidation of acid red 14 by potassium bromate, is described. The reaction rate was monitored spectrophotometrically by measuring the decrease in absorbance of acid red 14 at 516 nm. The detection limit of the method was 8 ng/mL, and the linear range was between 15 and 130 ng/mL. The effects of acidity, concentration of reactants and reaction time, and external ions were also discussed. The optimum reaction conditions were fixed, and some kinetic parameters determined. The relative standard deviation for the determination of bromate at the concentration of 50 ng/mL was calculated to be 0.996 % (n?=?10). The method has been successfully applied to the determination of bromate in flours and bottled waters.     

Assessment of soil screening levels due to ingestion and dermal absorption of chrysene and benzo[k]fluoranthene and appropriate remediation method for Dorson Abad

For years, the Dorson Abad region has been extremely polluted by Tehran Oil Refinery due to leaking from its underground pipelines, storage tanks, and evaporation ponds. To assess the concentrations of hazardous polycyclic aromatic hydrocarbon (PAH) compounds, soil samples were collected from the grounds at and adjacent to a polluted stream located in the study area. The samples were then analyzed, and the results revealed that 12 of the 16 USEPA PAHs were noticeably present in the soil, which, among them, benzo[k]fluoranthene and chrysene had the highest concentrations with averages of 357.17 and 173.38 mg/kg, respectively. A comparison of the obtained concentrations with the soil screening levels indicated that both benzo[k]fluoranthene and chrysene concentrations were substantially higher than EPA screening level values, signifying the necessity of soil remediation for these contaminants in the area. Techniques such as soil washing/flushing, high temperature thermal desorption, and solidification/stabilization were investigated for treatment of the contaminated soil; solidification/stabilization is recommended as an applicable and cost-effective remediation method for Dorson Abad due to the size of the region, relatively low cost of the binder (cement), and low volatility of benzo[k]fluoranthene and chrysene.     

Russia-EU gas game analysis: evidence from a new proposed trade model

Environmental Science and Pollution Research - This paper represents a new proposed trade model of “Intercountries Trade Force (ITF)” which is inspired by Intermolecular Interaction...     

Resilience to heat in public space: a case study of Adelaide,South Australia

During summer heatwaves, heat load exacerbates in urban heat islands (especially in hot climates) and threatens public life in cities. This paper examines the links between urban microclimates, outdoor thermal discomfort and public life through an exploratory case study. Heat resilience is highlighted as the ability of the space to support its normal activities when experiencing out-of-comfort temperatures. It also reports on the correlations between heat sensitive outdoor activities and urban greenery in three disparate case studies in Adelaide. Results indicate that necessary and optional activities start to decline after the apparent temperature reaches the threshold of 28?°C–32 °C, while activities in public spaces with more urban greenery show higher resilience to heat stress. Research findings propose heat resilience as a quality indicator in public space and support the application of urban greenery to make urban settings more resilient to heat stress.     

Governance of water supply systems in the Palestinian Territories: A data envelopment analysis approach to the management of water resources

This study demonstrates that data envelopment analysis (DEA) can be a useful tool to assess the relative efficiencies of water supply systems and to establish benchmarks with which to measure progress in the management of water resources. Frontier efficiency models measure the efficiency of water use in the Palestinian Territories (West Bank and the Gaza Strip). At the municipality level, sufficient data for the years 1999-2002 were available to estimate efficiency and stability scores. The Gaza Strip efficiency scores were considerably lower than those of the West Bank. Water losses were the major source of the inefficiency as indicated by the large slacks of this input. The relative sizes of the municipalities affect efficiency scores little. Palestinian policy makers should focus on rebuilding the infrastructure of the water networks, beginning with the most DEA inefficient municipalities in order to minimize water losses.     

A washing procedure to mobilize mixed contaminants from soil: I. Polychlorinated biphenyl compounds

We conducted a laboratory study to assess the feasibility of a washing process with nonionic and anionic surfactants in combination with ethylenediaminetetraacetate (EDTA) for the simultaneous mobilization of heavy metals and polychlorinated biphenyls (PCBs) from a field-contaminated soil. Unit processes consisting of complexometric extraction and surfactant-assisted mobilization were combined with reagent regeneration and detoxification steps to generate innocuous products. Ten minutes of ultrasonic mixing of the soil with a combination of 30 mL L(-1) surfactant suspension and a sparing quantity (2 mmol) of EDTA mobilized appreciable quantities of PCBs, virtually all of the available Cd, Cu, Mn, and Pb, and lesser amounts of the Zn, Ni, and Cr but only small quantities of Al and Fe. Relative to individual reagents, combinations of surfactant (Brij 98, Triton X-301, or Triton XQS-20) with EDTA did not influence PCB extraction efficiencies perceptibly. Of the three surfactants, the Brij 98 proved to be the most efficient for three successive extractions with a single charge, mobilizing 83% of the PCBs, whereas companion extractions that used fresh reagent each time mobilized 87% of the soil PCB content. The decreased PCB mobilization with the same quantity of anionic surfactant (71 or 68%) resulted from losses during the EDTA regeneration process with zero-valent Mg. In toto, these studies demonstrate that PCB compounds and selected heavy metals can be coextracted efficiently from soil with three successive washes with the same washing suspension containing EDTA and a nonionic surfactant.     

A washing procedure to mobilize mixed contaminants from soil: II. Heavy metals

We conducted a laboratory study to assess the efficiency of nonionic and anionic surfactants in combination with a sparing quantity of ethylenediaminetetraacetate (EDTA) to simultaneously extract heavy metals (HMs) and polychlorinated biphenyl (PCB) compounds from a field-contaminated soil. A soil wash that mobilized both HMs and PCBs was combined with back-extraction with hexane to remove PCBs from the aqueous wash. The aqueous washing suspension was then regenerated by precipitation of the HMs induced by corrosion and hydrolysis of zero-valent Mg to provide a cleaned soil and innocuous extract. Finally, the washing suspension was recycled twice to mobilize more contaminants from the soil particulate fraction. After ultrasonic equilibration, EDTA in admixture with a nonionic surfactant did not appreciably change the efficiency of mobilization of most heavy metals (Al, Cd, Cr, Fe Mn, Ni, and Zn), but did increase the recovery of Cu and Pb. The release of EDTA from HM complexes was efficient for most metals (99%) but was influenced by the chemical characteristics of the surfactant. The EDTA recovery (62-65%) after three cycles of soil washing, hexane back-extraction, and Mg(0) treatment was similar for all reagent combinations. In toto, these studies demonstrate that after treatment with ultrasound, selected heavy metals can be coextracted efficiently from soil with a single washing suspension containing EDTA and a nonionic surfactant.     

Monitoring,mapping and health risk assessment of fluoride in drinking water supplies in rural areas of Maku and Poldasht,Iran

The aim of this study was to investigate and determine fluoride concentrations in drinking water supplies in rural areas of Maku and Poldasht in West Azerbaijan Province, the northwest of Iran. Fluorosis risk assessment and characterization was also investigated. Fluoride concentrations mapping was accomplished by using the GIS system. Totally, 356 water samples, including one sample in each season, were collected from 89 water supplies providing water for 95 and 61 rural areas of Maku and Poldasht, respectively. According to the results, in Maku and Poldasht, 25 and 30 rural areas had contaminated water sources, respectively. Average annual fluoride concentrations ranged from 3.04 to 7.31 mg/l in the contaminated villages of Maku, which is about 2–4.8 times higher than the maximum standard level of the Iranian drinking water standard, and 4.52–8.21 mg/l in the contaminated areas of Poldasht, which is about 3–5.47 times higher than the maximum standard level. The maximum fluoride level was determined 11.12 mg/l and 10.98 mg/l in one of villages of Maku and Poldasht Counties in summer, respectively. Neither in Maku nor in Poldasht, water resources showed dental cavity risk, while dental fluorosis risk and skeletal fluorosis risk were very significant in some villages of both cities. Children were at most risk of fluorosis. New alternative water supplies for the contaminated villages if possible, consumption of bottled water and application of reverse osmosis are recommended as remedial actions in the contaminated areas.