Numerical simulation on pollutant dispersion from vehicle exhaust in street configurations

The impact of the street configurations on pollutants dispersion from vehicles exhausts within urban canyons was numerically investigated using a computational fluid dynamics (CFD) model. Three-dimensional flow and dispersion of gaseous pollutants were modeled using standard kappa - epsilon turbulence model, which was numerically solved based on Reynolds-averaged Navier-Stokes equations by the commercial CFD code FLUENT. The concentration fields in the urban canyons were examined in three cases of street configurations: (1) a regular-shaped intersection, (2) a T-shaped intersection and (3) a Skew-shaped crossing intersection. Vehicle emissions were simulated as double line sources along the street. The numerical model was validated against wind tunnel results in order to optimize the turbulence model. Numerical predictions agreed reasonably well with wind tunnel results. The results obtained indicate that the mean horizontal velocity was very small in the center near the lower region of street canyon. The lowest turbulent kinetic energy was found at the separation and reattachment points associated with the corner of the down part of the upwind and downwind buildings in the street canyon. The pollutant concentration at the upwind side in the regular-shaped street intersection was higher than that in the T-shaped and Skew-shaped street intersections. Moreover, the results reveal that the street intersections are important factors to predict the flow patterns and pollutant dispersion in street canyon.     

Silica glass modified with flavonoid derivatives for preconcentration of some toxic metal ions in water samples and their determination with ICP-MS

Quercetin (3,3^′,4^′,5,7-pentahydroxyflavone) chemically bonded through pyran rearrangement on modified controlled pore silica glass (QCPSG) with a capacity 0.213 mmol/g was used for solid phase extraction of some toxic metal and metalloid ions. The newly designed QCPSG quantitatively sorbs As(V), Cd(II), Hg(II), and Pb(II) at the pH range 7.5–8.5 after 10 min of stirring. HCl (1 mol L^???1) instantaneously elutes all the metal ions. The sorption capacity of the ion collector is 0.42, 0.46, 0.53, and 0.49 mmol g^???1 for As(V), Cd(II), Hg(II), and Pb(II), respectively, whereas the preconcentration factor is 200. The effect of NaCl, Na₂SO₄, NaF, NaBr, Na₃PO₄, and other interfering salts on the sorption of metal ions (50 μg L^???1) was reported. Analytical detection limits of As(V), Cd(II), Hg(II), and Pb(II) were 4.18, 2.44, 15.86, and 25.00 pg mL^???1, respectively. QCPSG was used in the separation of the investigated metal ions from some natural water samples collected from diverse origins followed by determination by inductively coupled plasma–mass spectrometry. The data were compared with those obtained by the standard methods of determination using atomic absorption (hydride generation, HGAAS and after solvent extraction with ammonium pyrolidine dithiocarbamate/methyl isobutyl ketone). The suggested solid phase extraction method was found accurate with no random error.     

Multimarker approach analysis in common carp Cyprinus carpio sampled from three freshwater sites

The aim of this study is to assess the response of a multimarker approach in common carp Cyprinus carpio sampled from three Tunisian dam lakes selected according to different environmental and ecological characteristics. Glutathione-S-transferase (GST) activity was analyzed in carp liver and used as a phase II detoxification enzyme, hepatic metallothionein content (MTs) was used as a metallic stress indicator, and cholinesterase activities were analyzed in muscle and brain and used as neurotoxicity biomarker. Micronucleus frequency test (MN) as a genotoxicity marker. GST and MT levels showed an increase in fish from the Bir Mcherga site and a decrease in Sidi Saâd site with respect to fish from Nebhana site. Results showed a strong inhibition of cholinesterase activities in fish from Bir Mcherga and Sidi Saâd sites compared to Nebhana site. Relatively high level of MN is reported specially in fish blood from the Bir Mcherga site.     

Novel materials for environmental remediation of tailing pond waters containing naphthenic acids

A nanofiltration strategy for tailing pond waters (TPWs) that utilizes cyclodextrin (CD)-based polymeric materials as supramolecular sorbents is proposed. Naphthenic acids (NAs) from the Athabasca TPWs are investigated as the target sorbate molecules.The sorption properties of several supramolecular porous materials were characterized using equilibrium sorption isotherms in aqueous solution wherein electrospray ionization mass spectrometry was used to monitor the concentration of NAs in aqueous solution. The characterization of the supramolecular sorbents was performed using ¹³C NMR and IR spectroscopy, while nitrogen porosimetry was used to estimate their surface area and pore structure properties. Independent estimates of surface area were obtained using a chromophore dye adsorption method in aqueous solution.The sorption results for NAs in solution were compared between a commercially available standard; granular activated carbon (GAC) and three types of synthetic materials. The sorption capacities for GAC ranged from 100 to 160 mg NAs/g of material whereas the polymeric materials ranged from 20 to 30 mg NAs/g of material over the experimental conditions investigated. In general, differences in the sorption properties between GAC and the CD-based sorbents were observed and related to differences in the surface areas of the materials and the chemical nature of the sorbents. The CD-based supramolecular materials displayed sorption capacities ranging from 36.2 to 657 m²/g as compared to that for GAC (795 m²/g).     

A Critical Review on Natural Fibers Modifications by Graft Copolymerization for Wastewater Treatment

Graft copolymerization is a distinctive approach to modify the inherently cheap natural fibers (NFs) using different initiators to incorporate synthetic polymer side chains allowing development of novel types of hybrid materials. This method has been widely applied to develop a variety of NFs based adsorbents for decontamination of toxic pollutants from the aqueous environment. However, the development of high-performance adsorbents from NFs is steady challenged by the need to preserve the sustainability during graft modifications and applications. This article critically reviews the progress on modifications of NFs by graft copolymerization of polar monomers on NFs using various initiating methods and their applications in wastewater treatment. Particularly, the applications of the grafted NFs in removal of heavy metal ions, synthetic dyes, oil spills and extraction of precious metals from wastewater are elaborated. The critical challenges to the viability and sustainability of NFs-based adsorbents with respect to functionalization by graft copolymerization and environmental impacts are discussed and the future research directions are also outlined.

     

Analysis of multi-temporal landsat satellite images for monitoring land surface temperature of municipal solid waste disposal sites

This studypresents a remote sensing application of using time series Landsat satellite images for monitoring the Trail Road and Nepean municipal solid waste (MSW) disposal sites in Ottawa, Ontario, Canada. Currently, the Trail Road landfill is in operation; however, during the 1960s and 1980s, the city relied heavily on the Nepean landfill. More than 400 Landsat satellite images were acquired from the US Geological Survey (USGS) data archive between 1984 and 2011. Atmospheric correction was conducted on the Landsat images in order to derive the landfill sites’ land surface temperature (LST). The findings unveil that the average LST of the landfill was always higher than the immediate surrounding vegetation and air temperature by 4 to 10 °C and 5 to 11.5 °C, respectively. During the summer, higher differences of LST between the landfill and its immediate surrounding vegetation were apparent, while minima were mostly found in fall. Furthermore, there was no significant temperature difference between the Nepean landfill (closed) and the Trail Road landfill (active) from 1984 to 2007. Nevertheless, the LST of the Trail Road landfill was much higher than the Nepean by 15 to 20 °C after 2007. This is mainly due to the construction and dumping activities (which were found to be active within the past few years) associated with the expansion of the Trail Road landfill. The study demonstrates that the use of the Landsat data archive can provide additional and viable information for the aid of MSW disposal site monitoring.     

Acute toxicities of cadmium and permethrin on the pre-spawning and post-spawning phases of Hexaplex trunculus from Bizerta Lagoon, Tunisia

Marine gastropods, exposed to anthropogenic pollution, accumulate high chemical concentrations in their tissues, especially in the digestive glands. An evaluation of the impacts of cadmium (Cd) and permethrin (Perm), coupled with reproductive events (pre-spawning and post-spawning phase) throughout the year, was attempted by measuring catalase (CAT), a biomarker of defence, on Hexaplex trunculus experimentally exposed for 48 or 96 h. Specimens of gastropods were sampled from Bizerta Lagoon (Tunisia). The results show that CAT activity increased in gastropods exposed to the three cadmium concentrations (C1 Cd, 100 μg L(-1); C2 Cd, 200 μg L(-1); and C3 Cd, 300 μg L(-1)) and to the three permethrin doses (C1 Perm, 100 μg L(-1); C2 Perm, 150 μg L(-1); and C3 Perm, 200 μg L(-1)) tested. A decrease in CAT was noted in the digestive gland of the H. trunculus exposed to permethrin at the concentration of 200 μg L(-1) during the pre-spawning and post-spawning phases. H. trunculus in post-spawning was more sensitive to cadmium and permethrin than in the pre-spawning phase. The biochemical responses to pollutants (cadmium and permethrin) represented by CAT may act as a biomarker of exposure in this species.     

Organic matter content of sediments in continental shelf area of southeast coast of India

Total organic matter (TOM) content of sediment samples collected from various depths of continental shelf region of the southeast coast of India varied from 0.19% to 7.73%. Higher TOM content and lower median particle diameter could be attributed to the influence of higher riverine flow. Higher values were observed at 100?m depth and above (average 5.29%) and lower values in shallower depths below 100?m (average 3.07%). In the Principal Coordinate Analysis (PCO), the first two axes explained about 83.1% of the total variability. The direction of the vector representing total organic matter was towards 150?m depth. In the Canonical Analysis of Principal Coordinates (CAP) done to confirm the above pattern, the canonical correlation value obtained for the first axis was high (0.9999). The same for the second axis was 0.9995. The direction of the axis representing TOM in this analysis was towards the 100?m depth truly reflecting higher TOM level recorded here (average TOM at 100?m depth—5.81% and at 150?m depth—5.33%). The percentage of samples allocated to the correct group in CAP was 91.67% (33 out of the 36 samples). As the allocation success of samples is substantially greater around 92%, the CAP is explaining greater percentage of variability of TOM than PCO and was found to be quite useful for studies of this nature.     

Toxicity assessment for petroleum-contaminated soil using terrestrial invertebrates and plant bioassays

The assessment of soil quality after a chemical or oil spill and/or remediation effort may be measured by evaluating the toxicity of soil organisms. To enhance our understanding of the soil quality resulting from laboratory and oil field spill remediation, we assessed toxicity levels by using earthworms and springtails testing and plant growth experiments. Total petroleum hydrocarbons (TPH)-contaminated soil samples were collected from an oilfield in Sfax, Tunisia. Two types of bioassays were performed. The first assessed the toxicity of spiked crude oil (API gravity 32) in Organization for Economic Co-operation and Development artificial soil. The second evaluated the habitat function through the avoidance responses of earthworms and springtails and the ability of Avena sativa to grow in TPH-contaminated soils diluted with farmland soil. The EC₅₀ of petroleum-contaminated soil for earthworms was 644 mg of TPH/kg of soil at 14 days, with 67 % of the earthworms dying after 14 days when the TPH content reached 1,000 mg/kg. The average germination rate, calculated 8 days after sowing, varied between 64 and 74 % in low contaminated soils and less than 50 % in highly contaminated soils.     

The performance of biological and tertiary wastewater treatment procedures for rotaviruses A removal

Environmental Science and Pollution Research - Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading...