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Canadian Power Stations and the National Pollutant Release Inventory (NPRI): A Success Story for Pollution Intensity? Texte intégral
2014
Tang, Minmeng | Mudd, Gavin M.
This paper presents a comprehensive analysis of the pollutant emissions and intensity from Canada’s power stations. An analysis of National Pollutant Release Inventory (NPRI) and site generation data shows significant variability with the dominant emissions pathway being point-source air emissions. In general, power stations are a very small fraction of Canada’s direct facility and estimated diffuse emissions, as well as showing significant variability of pollutant intensities per megawatt or megawatt hour of capacity or generation. The evidence also suggests that increased scale does not lead to a lower pollutant intensity, and that transfers and disposal pollutant loads are substantial, often representing most of the total reported pollutants. Overall, this study provides a valuable insight into the current status of pollutant intensities from Canada’s power stations, possible improvements to the NPRI and a valuable benchmark for future studies and international comparisons.
Afficher plus [+] Moins [-]Saltwater Upconing Below a Pumping Well in an Inland Aquifer: a Theoretical Modeling Study on Testing Different Scenarios of Deep Saline-Groundwater Pathways Texte intégral
2014
Cai, Jialiang | Taute, Thomas | Schneider, Michael
To date, studies on the geological conditions in inland aquifers leading to pathways for upwelling deep saline groundwater due to pumping have not been published yet. Therefore, this paper conducted a theoretical modeling study to raise two hypotheses about deep saline-groundwater pathways leading to saltwater upconing below a pumping well in an inland aquifer based on the field situation at the Beelitzhof waterworks in southwestern Berlin (Germany), defined as follows: (1) there are windows in the Rupelian clay caused by glacial erosion, where their locations are uncertain, and (2) there are no windows in the clay, but the clay is partially thinned out but not completely removed by glacial erosion, so salt can merely come through the clay upward by diffusion and eventually accumulate on its top. These hypotheses were tested to demonstrate the impact of the lateral distance between windows in the clay and the well, as well as salt diffusion through the clay depending on its thickness on saltwater intrusion in the pumping well, respectively, using a density-dependent groundwater flow and solute transport model. Hypothesis 1 was validated with four scenarios that windows could occur in the clay at the site, and their locations under some conditions could significantly cause saltwater intrusion, while hypothesis 2 could be excluded, because salt diffusion through the clay with thickness greater than 1 m at the site was not able to cause saltwater intrusion.
Afficher plus [+] Moins [-]Surface Modification of Sediment with Surfactant for Capping Material on Contaminated Coastal Sediment Texte intégral
2014
Song, Young-Chae | Subha, B. | Woo, J. H. | Lim, H. J. | Senthilkumar, P.
A study on the surface modification of uncontaminated sediment dredged for new port development with surfactant was performed, and the effectiveness of surface modified sediment for in-situ capping to control pollutant (N, P) release from the contaminated coastal sediments into seawater was also investigated. From this experiment, the adsorbed amount of surfactants on the surface of sediment particles was increased with the increase in the surfactant concentration. A more feasible method for the sediment modification with surfactants was mechanical shaking for 3 h, compared to sonication for 30 min or microwave radiation for 3 min. The adsorption capacities of the sediments modified with cationic surfactant (hexadecyltrimethylammonium bromide [HDTMA]) were 40 mg g⁻¹ for ammonia-nitrogen, 16 mg g⁻¹ for nitrate-nitrogen, 31 mg g⁻¹ for phosphorus, which are higher those of the sediment modified with anionic (SDS) and nonionic surfactants (TX-100). The capping layer with the sediment modified with HDTMA in column experiment was effective for inhibiting the release of nitrogen and phosphorus from the contaminated sediment into overlying seawater, indicating that the cationic surfactant modified sediment is reusable as a good in-situ capping material for contaminated coastal sediment.
Afficher plus [+] Moins [-]Modeling the Diffusion of Contaminated Site Remediation Technologies Texte intégral
2014
Hou, Deyi | O’Connor, David | Al-Tabbaa, Abir
The present study developed epidemic models to predict the diffusion of remediation technology. Hypotheses were derived from the models and then tested using data collected from a questionnaire survey (n = 223) and a qualitative interview (n = 28) mainly conducted in the USA, UK, and China, as well as data from the US Superfund program. Hypothesis testing results indicate that: (1) tacit knowledge in innovative remedial technologies leads to logistic rather than exponential growth in their adoption, and (2) social-economic and regulatory factors affect the adoption of remediation technologies. For specific remedial technologies adopted in the US Superfund program, it was found that in-situ bioremediation (ISB) has a higher maximum adoption rate than in-situ chemical treatment (ISC), likely due to lower cost and higher social acceptance associated with ISB. The diffusion of ISC was found to be more rapid than that of ISB due to a greater degree of tacit knowledge associated with ISB.
Afficher plus [+] Moins [-]Land Use Specific Ammonia Deposition Velocities: a Review of Recent Studies (2004–2013) Texte intégral
2014
Schrader, Frederik | Brümmer, Christian
Land Use Specific Ammonia Deposition Velocities: a Review of Recent Studies (2004–2013) Texte intégral
2014
Schrader, Frederik | Brümmer, Christian
Land use specific deposition velocities of atmospheric trace gases and aerosols—particularly of reactive nitrogen compounds—are a fundamental input variable for a variety of deposition models. Although the concept is known to have shortcomings—especially with regard to bi-directional exchange—the often limited availability of concentration data and meteorological input variables make it a valuable simplification for regional modeling of deposition fluxes. In order to meet the demand for an up-to-date overview of recent publications on measurements and modeling studies, we compiled a database of ammonia (NH₃) deposition velocities published from 2004 to 2013. Observations from a total of 42 individual studies were averaged using an objective weighing scheme and classified into seven land use categories. Weighted average and median deposition velocities are 2.2 and 2.1 cm s⁻¹for coniferous forests, 1.5 and 1.2 cm s⁻¹for mixed forests, 1.1 and 0.9 cm s⁻¹for deciduous forests, 0.9 and 0.7 cm s⁻¹for semi-natural sites, 0.7 and 0.8 cm s⁻¹for urban sites, 0.7 and 0.6 cm s⁻¹for water surfaces, and 1.0 and 0.4 cm s⁻¹for agricultural sites, respectively. Thus, values presented in this compilation were considerably lower than those found in former studies (e.g., VDI 2006). Reasons for the mismatch were likely due to different land use classification, different averaging methods, choices of measurement locations, and improvements in measurement and in modeling techniques. Both data and code used for processing are made available as supplementary material to this article.
Afficher plus [+] Moins [-]Land use specific ammonia deposition velocities: a review of recent studies (2004-2013) Texte intégral
2014
Schrader, Frederik | Brümmer, Christian
Land use specific deposition velocities of atmospheric trace gases and aerosolsparticularly of reactive nitrogen compoundsare a fundamental input variable for a variety of deposition models. Although the concept is known to have shortcomingsespecially with regard to bi-directional exchangethe often limited availability of concentration data and meteorological input variables make it a valuable simplification for regional modeling of deposition fluxes. In order to meet the demand for an up-to-date overview of recent publications on measurements and modeling studies, we compiled a database of ammonia (NH3) deposition velocities published from 2004 to 2013. Observations from a total of 42 individual studies were averaged using an objective weighing scheme and classified into seven land use categories. Weighted average and median deposition velocities are 2.2 and 2.1 cm s-1 for coniferous forests, 1.5 and 1.2 cm s-1 for mixed forests, 1.1 and 0.9 cm s-1 for deciduous forests, 0.9 and 0.7 cm s-1 for semi-natural sites, 0.7 and 0.8 cm s-1 for urban sites, 0.7 and 0.6 cm s-1 for water surfaces, and 1.0 and 0.4 cm s-1 for agricultural sites, respectively. Thus, values presented in this compilation were considerably lower than those found in former studies (e.g., VDI 2006). Reasons for the mismatch were likely due to different land use classification, different averaging methods, choices of measurement locations, and improvements in measurement and in modeling techniques. Both data and code used for processing are made available as supplementary material to this article.
Afficher plus [+] Moins [-]Bioremediation trial on aged PCB-polluted soils—a bench study in Iceland Texte intégral
2014
Lehtinen, Taru | Mikkonen, Anu | Sigfusson, Bergur | Ólafsdóttir, Kristín | Ragnarsdóttir, Kristín Vala | Guicharnaud, Rannveig
Polychlorinated biphenyls (PCBs) pose a threat to the environment due to their high adsorption capacity to soil organic matter, stability and low reactivity, low water solubility, toxicity and ability to bioaccumulate. With Icelandic soils, research on contamination issues has been very limited and no data has been reported either on PCB degradation potential or rate. The goals of this research were to assess the bioavailability of aged PCBs in the soils of the old North Atlantic Treaty Organization facility in Keflavík, Iceland and to find the best biostimulation method to decrease the pollution. The effectiveness of different biostimulation additives (N fertiliser, white clover and pine needles) at different temperatures (10 and 30 °C) and oxygen levels (aerobic and anaerobic) were tested. PCB bioavailability to soil fauna was assessed with earthworms (Eisenia foetida). PCBs were bioavailable to earthworms (bioaccumulation factor 0.89 and 0.82 for earthworms in 12.5 ppm PCB soil and in 25 ppm PCB soil, respectively), with less chlorinated congeners showing higher bioaccumulation factors than highly chlorinated congeners. Biostimulation with pine needles at 10 °C under aerobic conditions resulted in nearly 38 % degradation of total PCBs after 2 months of incubation. Detection of the aerobic PCB degrading bphA gene supports the indigenous capability of the soils to aerobically degrade PCBs. Further research on field scale biostimulation trials with pine needles in cold environments is recommended in order to optimise the method for onsite remediation.
Afficher plus [+] Moins [-]Spent Potassium Silicate Drilling Fluid Affects Soil and Leachate Properties Texte intégral
2014
Yao, Linjun | Naeth, M Anne | Chanasyk, David S.
Potassium silicate drilling fluid (PSDF) is a relatively new type of drilling waste generated by the oil and gas industry. PSDF effects on soil, vegetation, and ground water must be determined before its land disposal and use in reclamation can be regulated. A laboratory column leachate study was conducted to quantify the response of select soil and leachate properties to PSDF at various depths in soil column profiles. A spent PSDF was applied to two soils (sand and loam textures) at four rates (20, 40, 60, 120 m³ ha⁻¹) with two application methods (incorporated, sprayed). Changes to soil and leachate properties were at values that would not be detrimental to most plant species when PSDF was applied at ≤60 m³ ha⁻¹. Applying PSDF at 120 m³ ha⁻¹had significant effects on soil properties and leachate quality. Hydraulic conductivity and field capacity were significantly reduced, and soil available potassium and sulfate concentrations, pH, and salinity increased with PSDF. Incorporated PSDF in the upper 10 cm of soil accelerated PSDF element transport through soil columns to leachate and increased organic carbon and salinity in leachate. PSDF application rate significantly reduced soil field capacity, available nitrogen, and increased salinity at the highest rates in loam soil, suggesting a threshold beyond which conditions will not be suitable for land spraying PSDF. This research demonstrates that PSDF has potential to improve soil short term water availability, macronutrient potassium and sulfur for disposal on cultivated and uncultivated lands. This potential should be field tested.
Afficher plus [+] Moins [-]Relationship Between Atmospheric Ammonia Concentration and Nitrogen Content in Terricolous Lichen (Cladonia portentosa) Texte intégral
2014
Nielsen, Knud Erik | Andersen, H. V. | Strandberg, M. | Løfstrøm, P. | Degn, H. J. | Damgaard, C.
From April 2006 to April 2007, the geographical and seasonal variation in nitrogen content in terricolous lichen (Cladonia portentosa) and atmospheric ammonia concentrations were measured at five heathland sites. The seasonal variation in the nitrogen content of the lichen was small, even though there was a large seasonal variation in the air concentration of ammonia. A sizable local variation in the nitrogen content of the lichen was found even at the scale of a few kilometres. The nitrogen content in the lichen showed a high correlation to the yearly mean value of the measured ammonia concentration in air at the different locations. This investigation is part of a larger attempt to incorporate effects of nitrogen in the conservation status of terrestrial habitat types.
Afficher plus [+] Moins [-]Enhanced Mineralization of Gaseous Organic Pollutant by Photo-Oxidation Using Au-Doped TiO2/MCM-41 Texte intégral
2014
Tangale, Nilesh P. | Belhekar, Anuja A. | Kale, Kishor B. | Awate, Shobhana V.
The synthesis, characterization, and photocatalytic evaluation of titania-loaded MCM-41 with and without Au doping are reported in the present study. The samples were characterized by powder XRD, TEM, low temperature N₂adsorption/desorption, UV–Vis, and FTIR. UV-induced vapor-phase photo-oxidation of acetone was used as a probe reaction to study the role of Au in mineralization of volatile organic compounds (VOCs), viz. acetone at different concentrations. The doping of Au in titania-loaded MCM-41 resulted in the decrease of BET surface area, total pore volume, and average pore size. UV–Vis diffuse reflectance spectra of Au-doped titania-loaded MCM-41 showed the red shift in their absorption bands compared to titania-loaded MCM-41. The activity of mineralization of acetone by photocatalysis for 2 % Au-doped titania-loaded MCM-41 was found to be ∼1.6 times higher than titania-loaded MCM-41. The presence of cocatalytic nanosized gold might be responsible for their enhanced activity on account of the delayed recombination of electron/hole pair. Although, almost complete mineralization of acetone was observed irrespective of the initial concentration of acetone in air (up to 3.72 mol%) by all the catalysts, 2 wt.% Au-doped titania-loaded MCM-41 has shown the most enhanced activity.
Afficher plus [+] Moins [-]Photodegradation of Neonicotinoid Active Ingredients and Their Commercial Formulations in Water by Different Advanced Oxidation Processes Texte intégral
2014
Banić, Nemanja D. | Šojić, Daniela V. | Krstić, Jugoslav B. | Abramović, Biljana F.
This contribution is concerned with the comparison of the efficiency of the removal of four pure neonicotinoid active ingredients (AIs) and their commercial formulations (CFs) from aqueous solutions by using different advanced oxidation processes at the pH 2.8. The AIs of thiamethoxam and imidacloprid, and their CFs (Actara and Confidor), having a nitroguanidine functional group, exhibited low persistence to photolysis. In contrast to them, thiacloprid and acetamiprid and their CFs (Calypso and Mospilan), containing a cyanoimine functional group, were stable during the UV irradiation period. As expected, the degradation rate of the studied neonicotinoids increased significantly in the combined action of UV radiation and H₂O₂. In the case of thiacloprid and acetamiprid and their CFs, the reaction of the OH radicals formed and molecules of these insecticides was the major destruction pathway. The increased photodegradation efficiency of the UV/7.2Fe/TiO₂/H₂O₂ and vis/7.2Fe/TiO₂/H₂O₂ processes was attributed to the surface photoreduction of Fe³⁺ to Fe²⁺, which produces new OH radicals in the reaction with H₂O₂. In the presence of visible light, the efficiency may be partly due to the formation of the H₂O₂–TiO₂ complexes. For the 7.2Fe/TiO₂/H₂O₂ process in the presence of UV or visible radiation, no significant influence on the efficiency of photodegradation was observed in dependence of the structural differences of selected neonicotinoids. These results strongly suggest that highly reactive hydroxyl radicals, generated on the catalyst’s surface in the reaction involving H₂O₂, are responsible for this oxidation. In order to investigate degree of mineralization for all insecticides, TOC measurements were also conducted. Also, it was observed that the removal of pure AIs and their CFs by dark adsorption was almost negligible.
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