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Chemical Composition Change in TSP Due to Dust Storm at Gosan, Korea: Do the Concentrations of Anthropogenic Species Increase Due to Dust Storm
2009
Kim, Na Kyung | Park, Hye-Jin | Kim, Yong Pyo
Aerosol composition change between dust storm and non-dust storm periods in spring is studied using the total suspended particle data measured at Gosan, a background area in Korea. The concentrations of eight inorganic ions and 12 elements were analyzed for the TSP samples collected from March 1992 to May 2006. Two-step statistical analyses were carried out for the data: F test and t test. The concentrations of anthropogenic ionic species showed increasing trend since 2003. The absolute concentrations of most anthropogenic species such as sulfate or nitrate increased (from 7.33 to 9.25 µg m⁻³ and from 2.04 to 4.84 µg m⁻³, respectively) during the dust storm period. However, the enrichment factors or normalized concentrations based on Al of most anthropogenic species decreased during dust storm period (factor of 0.1-0.5). It suggests that, in general, relative importance of anthropogenic species during dust storm would be not high.
Mostrar más [+] Menos [-]Evaluation of Microbial Community Activity, Abundance and Structure in a Semiarid Soil Under Cadmium Pollution at Laboratory Level
2009
Ros, Margarita | Pascual, José A (José Antonio) | Moreno, José Luis | Hernandez, M Teresa | Garcia, Carlos
Cadmium (Cd) pollution can alter soil flora and fauna, as well as the microbial community associated with the main biogeochemical cycles of a soil. The present study was conducted to investigate the effect of two different concentrations of Cd pollutant, 6.5 mg kg⁻¹ (low level) and 12.5 mg kg⁻¹ (high level) on microbial community activity, abundance, and structure in a semiarid soil after a 60-day incubation period at laboratory level. Available Cd, water soluble carbon (WSC), microbial biomass carbon (Cmic), adenosine triphosphate (ATP) content, and real-time polymerase chain reaction were used to measure the influence of Cd on the abundance and activity of the microbial community. Bacteria and fungi community structure and diversity based on denaturing gradient gel electrophoresis (DGGE) analysis were also analyzed. The percentage of Cd extracted by diethylenetriamine pentaacetic acid increased with the higher total concentration of Cd added to the soil, being 16.9% at low level and 77.9% at the high level. WSC, Cmic, and ATP content decreased significantly as soil Cd concentration increased (WSC 29% and 34%, Cmic 27% and 35%, and ATP 32% and 47%, at low and high levels, respectively). While fungal diversity already decreased with low levels of Cd concentration, and was even more negatively affected by the higher pollution levels, bacterial (acidobacteria, α-proteobacteria, and β proteobacteria) diversity only showed a decline with the higher Cd concentration. The fungi-to-bacteria ratio showed by the different treatments could imply that fungi abundance is less influenced by increased Cd pollution, although fungi diversity as revealed by DGGE analysis diminished as soil Cd concentration increased.
Mostrar más [+] Menos [-]The Simulated Effects of Iron Dust and Acidity During the Early Stages of Establishment of Two Coastal Plant Species
2009
Kuki, K. N. | Oliva, M. A. | Costa, António Carlos (António Carlos Borges Santos da)
In Brazil's littoral, many iron ore industries are located in areas of restinga, a type of coastal ecosystem; such industries represent stationary sources of iron and acid particulates. The industrial sector is under expansion, threatening the already fragile ecosystem. In the present study, the simulated impact of these emissions was studied on the early establishment stages of two native plant species, Sophora tomentosa and Schinus terebinthifolius. The results indicate that S. tomentosa display deficient germination and low root tolerance when exposed to iron dust and acidity. Toxic iron concentrations were found to accumulate only in the roots of S. tomentosa plants exposed to increasing doses of iron dust. In these plants, initial growth was reduced, leading to the conclusion that S. tomentosa was unable to regulate, and, thus, to overcome, the effects of the iron dust in the substrate. In contrast, the germination, root tolerance index, and initial growth of S. terebinthifolius were not affected by iron dust and acidity, revealing the species' resistance to these pollutants. We propose that under similar field conditions, S. tomentosa would be adversely affected, whereas S. terebinthifolius would thrive. On a long-term basis, this imbalance is likely to interfere in the vegetational composition and dynamics of the affected ecosystem.
Mostrar más [+] Menos [-]Assessment of the Critical Load of Trace Elements in Soils Polluted by Pyrite tailings. A Laboratory Experiment
2009
Díez, M. | Simón, M. | García, I. | Martin, F.
Nineteen soil samples (SE Spain) with very different chemical physical properties and developed over different parent materials were contaminated by adding increments of an acidic solution from oxidised pyrite tailings. The quantities of Cu, Zn, Cd and Pb precipitated by the soil samples were directly and significantly related to the pH-buffering capacity. However, when the contamination caused the pH to fall below 3.0 the soil tended to release a fraction of the element adsorbed, which increased as the pH decreased. The quantity of each precipitated element at which the action value for each element is reached, was also directly related to the pH-buffering capacity. Nevertheless, in carbonate-rich soils, the precipitated Cu and Zn maintained a relatively high level of bioavailability, while Cd reached a critical level with a content exceeding 25 mg kg⁻¹, regardless of the pH-buffering capacity.
Mostrar más [+] Menos [-]Inkjet Printing for Silicon Solar Cells
2009
Liu, Han-Chang | Chuang, Chia-Pin | Chen, Yi-Tsun | Du, Chen-Hsun
Inkjet printing of metal nanoparticles is an attractive method for front-side metallization of silicon solar cells. It is owing to noncontact, low-cost, low-waste, and simple process. In this work, we proposed the ink-jet printing and electroless technology to fabricate the seed layer and electrode layer, respectively. Furthermore, we used electroplating method to increase the electrode conductivity. In this way, the energy conversion efficiency up to 12.22% without AR coating can be obtained on 100 × 100 mm c-Si cell.
Mostrar más [+] Menos [-]A Novel Method to Capture and Analyze Flow in a Gross Pollutant Trap Using Image-Based Vector Visualization
2009
Madhani, Jehangir T | Young, Joseph | Kelson, Neil A | Brown, Richard J
A novel method is developed to capture and analyze several experimental flow regimes through a gross pollutant trap (GPT) with fully and partially blocked screens. Typical flow conditions and screen blockages are based on findings from field investigations that show a high content of organic matter in urban areas. Fluid motion of neutral buoyant particles is tracked using a high-speed camera and particle image velocimetry (PIV) software. The recorded fluid motion is visualized through an image-based, line integral convolution (LIC) algorithm, generally suitable for large computational fluid dynamics (CFD) datasets. The LIC method, a dense representation of streamlines, is found to be superior to the point-based flow visualization (e.g., hedgehog or arrow plots) in highlighting main flow features that are important for understanding litter capture and retention in the GPT. Detailed comparisons are made between the flow regimes, and the results are compared with CFD data previously obtained for fully blocked screens. The LIC technique is a useful tool for identifying flow structures in the GPT and areas that are subjected to abnormalities difficult to detect by conventional methods. The novel method is found to be useful both in the laboratory and in the field, with little preparation and cost. The enhancements and pitfalls of the LIC technique along with the experimentally captured flow field are presented and discussed.
Mostrar más [+] Menos [-]Inundation Analysis in the Coastal Area Considering Climate Change Due to Global Warming
2009
Pokharel, Parameshor | Takeda, Makoto | Naoki, Matsuo
This paper describes the possible inundation scenarios under sea level rise conditions due to global climate change with particular reference to Nagoya, Japan. The study was carried out by using a two-dimensional sea model integrated with one-dimensional river flow model and two-dimensional overland flow model. For the connections of models, the upstream discharge or downstream water level in each grid is considered as the boundary conditions. The governing equations used for the analysis have been solved by finite volume method. The analysis results implicate that some parts of densely populated coastal area of Nagoya city will be vulnerable to inundation if the sea level rise due to global warming by 1 m. Moreover, the performances of existing sewer system and inundation scenario under various conditions have been analyzed.
Mostrar más [+] Menos [-]Indoor Air Quality Assessment of Elementary Schools in Curitiba, Brazil
2009
Godoi, R. H. M | Avigo, D Jr | Campos, V. P | Tavares, T. M | de Marchi, M. R. R | Van Grieken, R | Godoi, A. F. L
The promotion of good indoor air quality in schools is of particular public concern for two main reasons: (1) school-age children spend at least 30% of their time inside classrooms and (2) indoor air quality in urban areas is substantially influenced by the outdoor pollutants, exposing tenants to potentially toxic substances. Two schools in Curitiba, Brazil, were selected to characterize the gaseous compounds indoor and outdoor of the classrooms. The concentrations of benzene, toluene, ethylbenzene, and the isomers xylenes (BTEX); NO₂; SO₂; O₃; acetic acid (HAc); and formic acid (HFor) were assessed using passive diffusion tubes. BTEX were analyzed by gas chromatography-ion trap mass spectrometry and other collected gasses by ion chromatography. The concentration of NO₂ varied between 9.5 and 23 µg m⁻³, whereas SO₂ showed an interval from 0.1 to 4.8 µg m⁻³. Within the schools, BTEX concentrations were predominant. Formic and acetic acids inside the classrooms revealed intermediate concentrations of 1.5 µg m⁻³ and 1.2 µg m⁻³, respectively.
Mostrar más [+] Menos [-]Long-Term Soil Reaction Changes in a Temperate Beech Forest Subject to Past Alkaline Pollution
2009
Pichler, Viliam | Homolák, Marián | Capuliak, Jozef
Changes in deposition exert effects on forests. Some evidence for a slow recovery of strongly alkalised forest soils after a reduction in alkaline pollution exists, but the recovery rate is little known. The objective of this study was to estimate temporal soil reaction changes. For this purpose, measurements of soil reaction under a beech forest near magnesite works in Central Slovakia were taken in 1991 and 2006, following the alkaline pollution reduction in 1992. As a result, the mean active soil reaction decreased from pH 7.8 to 6.6. Beyond the range of beech stemflow, which amplifies water and acid pollution inputs into soils locally, soil reaction dropped from pH 7.8 to 6.8. The effect of stemflow on local exchangeable reaction minima was detected even before the pollution reduction. The logarithmic function fitted on the pH data indicates considerable differences between neutralisation rates within and outside the stemflow zone.
Mostrar más [+] Menos [-]Biodegradation of Light Fuel Oils in Water and Soil as Determined by the Manometric Respirometric Method
2009
Karhu, M. | Kaakinen, J. | Kuokkanen, T. | Rämö, J.
In this biological oxygen demand (BOD) study, the manometric respirometric BOD OxiTop® method was used to monitor the biodegradation of two summer grade (SFO 1 and 2) and two winter grade light fuel oils (WFO 1 and 2) in OECD 301 F conditions, in groundwater, and in two different Finnish forest soils (mineral-poor and mineral-rich). The biodegradation measurements in the OECD 301 F conditions were carried out in two nutrient solutions for 28 days. In both solutions WFO 1 reached the highest biodegradation degree, 32% in the solution OECD 301 F, and 70% in a solution containing additional ammonium chloride. In groundwater conditions all the biodegradation degrees of fuel oils remained below 2% within the 28-day period. SFO 1 reached the highest 30 day biodegradability (4%) in mineral-poor soil, 18% in mineral-rich soil. In a 189-day measurement in a mineral-rich soil, the biodegradation degree for the SFO 1 was 94%. The manometric respirometric method proved to be a very suitable and practicable measurement method for the purpose of biodegradation studies of highly volatile light fuel oils, because in this method samples are treated to a lesser degree than in conventional methods, and dilutions are not needed. Results also indicated a considerable effect of conditions on the biodegradability in both water and soil environments. The results of these biodegradation studies could be used when planning in situ treatment methods based on natural biodegradation. In situ treatment methods are eco-efficient, and are especially suitable for sparsely populated sites.
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