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Результаты 401-410 из 773
Mobility and Bioavailability of Trace Metals in the Water-Sediment System of the Highly Urbanized Brunette Watershed
2009
Li, Loretta Y. | Hall, Ken | Yuan, Yi | Mattu, Gevan | McCallum, Don | Chen, Min
Selected trace metals were determined in stormwater runoff and sediments of the highly urbanized Brunette watershed in Metro-Vancouver. Surface sediment samples from three tributaries and a lake between 1974 and 1998 were analyzed for total and acid-extractable trace metals. Metal bioavailability was also investigated using Chelex-100 resin. Sediment geochemistry was determined by sequential extraction. Total trace metal concentrations decreased as stormwater moved through the hydrologic gradient of stormwater runoff, headwater stream to outflow river. The percentage of dissolved metals increased downstream largely due to disposition. Higher concentrations of particle-associated trace metals were flushed in stormwater runoff as the rainfall and total suspended solids transport increased. The highest trace metal levels were found in the lower reaches of a creek before entering the lake and in the lake where organic matter accumulated. Copper was associated with the organic/sulphur sediment components, whereas iron and manganese were mainly mineral-bound. Zinc concentrated in the easily acid reducible phase, augmented by increasing traffic and development. At least half of the sediment-bound lead was associated with the easily acid reducible and organic/sulphur-bound phases with an overall decrease as lead has been phased out as a gasoline additive.
Показать больше [+] Меньше [-]Inorganic Pollutants in Wet Atmospheric Deposition and the Trajectories of Their Possible Transport
2009
Vach, Marek | Skřivan, Petr | Rohovec, Jan | Fišák, Jaroslav | Kubínová, Petra | Burian, Miloš
This work is concerned with analysis of the transport trajectories and identification of the probable emission sources of a set of chemical elements monitored in samples of atmospheric precipitation collected in the area of Central Bohemia, Czech Republic. This is based on evaluation of the significance of transport trajectories obtained using the HYSPLIT model for specific periods of duration of the sampled precipitation episodes in dependence on the values of the corrected concentrations of the monitored elements in the individual samples. The proposed method of correction of the measured concentrations of the elements is concerned with elimination of meteorological effects that are unspecific from with respect to the direction of the transport trajectories. The results for the group of elements with higher concentration levels in the sampled precipitation agree with the assumptions on their probable most important sources. The common main source of Na, Mg and Ca is marine aerosol, while K, P and Mn are probably of biogenic origin. The common main sources of Al and Fe--probably terrigenic dust--also correspond to the assumptions. Sulfur does not exhibit a significant predominant direction to the sampling site. Zinc, Cd, Cu and also Si are transported to the greatest degree from the north-westerly direction, indicating the probable effect of large energy-production sources in the area under the Krušné Mountains in the CR or the effect of traffic in the Capital City of Prague. The predominant direction of dispersion of Pb and As is a north-easterly to easterly direction of transport.
Показать больше [+] Меньше [-]The Environmental Impact of the Platinum Group Elements (Pt, Pd, Rh) Emitted by the Automobile Catalyst Converters
2009
Kalavrouziotis, I. K. | Koukoulakis, P. H.
The present paper deals with an extensive review of literature concerning the platinum group elements (PGEs), and their impact on the environment. The increased number of cars and vehicles fitted with catalytic converters, has been linked with the wide spread in the environment of the PGEs, i.e. Pt, Pd and Rh. Numerous studies present compelling evidence that the catalytic converters, do not only minimize the pollution caused by the car exhaust fumes, but also they release in the environment particulate matter containing the above noble elements, which accumulate in the soil, and plants, or remain suspended in the air, being transported to large distances. Indeed, the concentration of these noble elements in the soil and plants has increased significantly during the last 10-15 years, especially along the road side of high ways. Assessment of the PGEs health risk was originally based on measuring the body fluid in Pt, Pd and Rh content of occupationally involved people, as well as of the general population. Recent results based on cellular studies show that the PGEs are related to respiratory sensitization, allergic reactions, dermatitis, urticaria, damage of the epithelial lung cells, asthma, rhinoconjuctivitis, lymphocyte proliferation and cytokine release and possibly to cancer. In spite of the progress attained, more work is necessary for an accurate health risk assessment.
Показать больше [+] Меньше [-]Textile Effluents Affected Seed Germination and Early Growth of Some Winter Vegetable Crops: A Case Study
2009
Rehman, Abida | Bhatti, Haq Nawaz | Athar, Habib-ur-Rehman
In order to assess as to whether treated textile effluent could be safely used to irrigate some winter vegetables, growth room experiments were conducted. Varying levels of treated and untreated textile effluents were applied to germinating seeds of some winter vegetables and their effect was evaluated on germination and early growth stage using seed germination, growth, and biochemical attributes. From the results, it was obvious that textile effluent reduced seed germination and early growth of all vegetables. However, this effect was more pronounced at the highest concentration of textile effluent. Furthermore, treated textile effluent did not show any inhibitory effect on seed germination of all vegetables. Photosynthetic pigments such as chlorophyll a and b, and protein contents were higher in the leaves of all vegetable plants irrigated with treated textile effluent than those of supplied with untreated textile effluents. It has been observed that heavy metals were lower in concentration in treated textile effluent as compared with untreated textile effluent. However, germination and growth responses of all three vegetables were different to treated or untreated textile effluents. Furthermore, the Raphanus sativus ranked as tolerant followed by Brassica campastris and Brassica napus based on germination and growth responses. In conclusion, in view of shortage of water, textile effluent could safely be used for irrigation to vegetables after proper processing.
Показать больше [+] Меньше [-]Developing Measures for Assessing the Causality of Safety Culture in a Petrochemical Industry
2009
Wu, Tsung-Chih | Lin, Chia-Hung | Shiau, Sen-Yu
This paper discusses safety culture in the petrochemical sector and the causes and consequences of safety culture. A sample of 520 responses selected by simple random sampling completed questionnaires for this survey, the return rate was 86.75%. The research instrument comprises four sections: basic information, the safety leadership scale (SLS), the safety climate scale (SCS), and the safety performance scale (SPS). SPSS 12.0, a statistical software package, was used for item analysis, validity analysis, and reliability analysis. Exploratory factor analysis indicated that (1) SLS abstracted three factors such as safety caring, safety controlling, and safety coaching; (2) SCS comprised three factors such as emergency response, safety commitment, and risk perception; and (3) SPS was composed of accident investigation, safety training, safety inspections, and safety motivation. We conclude that the SLS, SCS, and SPS developed in this paper have good construct validity and internal consistency and can serve as the basis for future research.
Показать больше [+] Меньше [-]Precious Metals in Municipal Solid Waste Incineration Bottom Ash
2009
Muchova, Lenka | Bakker, Erwin | Rem, Peter
Municipal solid waste incineration (MSWI) bottom ash contains economically significant levels of silver and gold. Bottom ashes from incinerators at Amsterdam and Ludwigshafen were sampled, processed, and analyzed to determine the composition, size, and mass distribution of the precious metals. In order to establish accurate statistics of the gold particles, a sample of heavy non-ferrous metals produced from 15 tons of wet processed Amsterdam ash was analyzed by a new technology called magnetic density separation (MDS). Amsterdam's bottom ash contains approximately 10 ppm of silver and 0.4 ppm of gold, which was found in particulate form in all size fractions below 20 mm. The sample from Ludwigshafen was too small to give accurate values on the gold content, but the silver content was found to be identical to the value measured for the Amsterdam ash. Precious metal value in particles smaller than 2 mm seems to derive mainly from waste of electrical and electronic equipment (WEEE), whereas larger precious metal particles are from jewelry and constitute the major part of the economic value. Economical analysis shows that separation of precious metals from the ash may be viable with the presently high prices of non-ferrous metals. In order to recover the precious metals, bottom ash must first be classified into different size fractions. Then, the heavy non-ferrous (HNF) metals should be concentrated by physical separation (eddy current separation, density separation, etc.). Finally, MDS can separate gold from the other HNF metals (copper, zinc). Gold-enriched concentrates can be sold to the precious metal smelter and the copper-zinc fraction to a brass or copper smelter.
Показать больше [+] Меньше [-]The Emergent Science of Engineering a Sustainable Urban Environment
2009
Goudie, Douglas
Engineering is taking a lead role in sustainability implementation, despite problems linking institutional decision-makers with such things as water purification and cleansing wetlands. An emerging science may help speed an all-system approach to implementing sustainable urban planning. The many innovative approaches to engineering and planning will lead to cities and suburbs where water, urban travel, energy chains and food provision infrastructures are bound together by ESD values, flow-on principles and a workable process of sustainability achievement. JCU Townsville is developing such a process of Sustainability Implementation Planning (SIP) and Engineering, aspiring to become a tropics sustainability exemplar. This article reports on a 90-strong workshop: Paths to Sustainability held in August 2008, with strong regional leadership support. An integrated intellectual frame and ‘futures oriented' blueprint is provided to achieve the myriad cultural, social, economic, energy, water, food, engineering and environmental needs to ‘go sustainable' in an urban setting, where most of us live. The workshop results show SIP water management begins with local raindrops, local capture, local ground penetration, use and reuse, entering local nutrient flows to local urban food gardens and then used as a source to grow aquatic protein and fuel oils. Energy engineering becomes a local mix of renewables and innovative storage, appropriate building design, transport systems and industry; including embodied and life-cycle energy analysis and careful considerations in all built structure and use. Urban planning, people movement, housing location and travel mode will increasingly be judged by energy costs, as will food production.
Показать больше [+] Меньше [-]Trace Metal Availability in Soils Amended with Metal-Fixing Inorganic Materials
2009
Madrid, F. | Florido, M. C. | Madrid, L.
Immobilization of metals by two materials (zeolite, AZ, and a synthetic, carbonate-rich material, “slovakite”, SL) was tested in a pot experiment with two soils from urban areas of Sevilla and two soils affected by a mine spill. Barley (Hordeum vulgare L. Hispanic) was grown in the pots, and metal contents were measured after 31 days in shoots and roots. Available metal was estimated by extraction with CaCl₂ (readily soluble), ethylenediaminetetraacetic acid (EDTA; plant available), a mixture of organic acids (soluble by root exudates), and glycine (bioaccessible by ingestion). Neither treatment caused significant differences on plant growth or metal contents of shoots, whereas roots contained more Cu in the SL treatments. Root Zn uptake was reduced in all cases, but reduction of Pb in roots was observed only in AZ treatments of the mine-spill soils. The effects on metal availability were often method-dependent. Decrease of CaCl₂ data were observed only in the mine-spill soils. EDTA-soluble metals were clearly decreased by both materials. Bioaccessible Zn were decreased by either material in several cases (but not in the most heavily polluted soil), whereas Cu or Pb data were less conclusive.
Показать больше [+] Меньше [-]Environmental Impact of Mining Activities in the Southern Sector of the Guadiana Basin (SW of the Iberian Peninsula)
2009
Delgado, J. | Sarmiento, A. M. | Condesso de Melo, M. T. | Nieto, J. M.
The southern sector of the Guadiana River basin (GRB) drains the central-western part of the Iberian Pyrite Belt, an area with many polymetallic sulfide deposits and residues of mining activities that under oxidizing conditions generate an acidic leachate with large quantities of sulfates, metals, and metalloids in solution. These acidic leachates seep into the fluvial system contaminating the surface water bodies and increasing the contamination risk for local populations and riparian habitats. The present study was carried out both in Portugal and Spain with the main aim of identifying the principal contamination sources that produce acid mine drainage (AMD) in the southern part of the GRB and to evaluate the seasonal variations of water quality affected by AMD. The physicochemical parameters determined in the field (temperature, electrical conductivity, pH, redox potential, and dissolved oxygen) are discussed and interpreted together with the hydrochemical analysis of surface water samples collected at 79 points of observation. The data show a strong seasonal variation of surface water quality with poorer water quality standards during the dry season. It is also possible to observe that there is a natural decrease in pollution levels with increasing distance from the pollution source (mining areas). Acidic leachates are gradually neutralized as they drain away from the mining areas depositing Fe-(Cu-Al) bearing secondary minerals. There is also an important contaminant load reduction in the estuary area as a result of the mixing process with seawater. This contributes to a loss of the metals in solution due to both dilution and precipitation, as a result of pH increase.
Показать больше [+] Меньше [-]Evaluation of Poultry Litter Amendment to Agricultural Soils: Leaching Losses and Partitioning of Trace Elements in Collard Greens
2009
Paramacivam, Aru (Aruṇakiri) | Richards, Karen A. | Alva, A. K. | Richards, Asha M. | Sajwan, K. S. | Jayaraman, K. | Heanacho, A. | Afolabi, J.
Leaching of trace metals and greenhouse plant growth (Collard greens; Brassica oleracea var. acephala) response studies were conducted in two types of soils with contrasting characteristics amended with varying rates (0 to 24.70 Mg ha⁻¹) of poultry litter (PL) or 1:1 mixture of PL and fly ash (FA). Leaching of Cr, Zn, Cd, Cu, and Pb from soils amended with PL or PL + FA (1:1) increased with increasing rates of amendment. Leaching losses were greater from coarse-textured soil compared to that from medium-textured soil. Crop performance study indicated that growth as well as trace elements concentrations increased with increasing rates of amendments only up to 12.35 Mg ha⁻¹. Trace element concentrations in plant parts were greater in plants grown in Candler fine sand (CFS) compared to that grown in Ogeechee loamy sand (OLS). Trace element concentrations were greater in the above ground plant parts (leaf and stem) than those in roots. This study demonstrated beneficial effects of PL or mixture of PL + FA amendments to soils at rates not exceeding 4.94 Mg ha⁻¹. Further field studies are recommended to evaluate the long-term impact of using poultry litter and fly ash on plant growth and tissue trace metal concentration as well as environmental impact.
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