خيارات البحث
النتائج 121 - 130 من 175
In-Situ Phytoremediation of Pahs Contaminated Soils Following a Bioremediation Treatment النص الكامل
2006
Denys, Sébastien | Rollin, Claire | Guillot, Francis | Baroudi, Hafid
Phytoremediation of pollutants in soils is an emerging technology, using different soil-plant interaction properties. For organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), phytodegradation seems to be the most promising approach. It occurs mostly through an increase of the microbial activity in the plant rhizosphere, allowing the degradation of organic substances, a source of carbon for soil microbes. Despite a large amount of available data in the literature concerning laboratory and short term PAH phytodegradation experiments, no actual field application of such technique was previously carried out. In the present study, a soil from a former coking plant was used to evaluate the feasibility and the efficiency of PAH phytodegradation in the field during a three years trial and following a bioremediation treatment. Before the phytoremediation treatment, the soil was homogenized and split into six independent plots with no hydrological connections. On four of these plots, different types of common plant species were sowed: mixture of herbaceous species, short cut (P1), long cut (P2), ornamental plants (P3) and trees (P4). Natural vegetation was allowed to grow on the fifth plot (P5), and the last plot was weeded (P6). Each year, representative sampling of two soil horizons (0-50 and 50-100 cm) was carried out in each plot to characterize the evolution of PAHs concentration in soils and in soils solution obtained by lixiviation. Possible impact of the phytoremediation technique on ecosystems was evaluated using different eco- and genotoxicity tests both on the soil solid matrix and on the soil solution. For each soil horizon, comparable decrease of soil total PAHs concentrations were obtained for three plots, reaching a maximum value of 26% of the initial PAHs concentration. The decrease mostly concerned the 3 rings PAHs. The overall low decrease in PAHs content was linked to a drastic decrease in PAHs availability likely due to the bioremediation treatment. However, soil solutions concentration showed low values and no signficant toxicity was characterized. The mixture of the herbaceous species seemed to be the most promising plants to be used in such procedure.
اظهر المزيد [+] اقل [-]Use of an In Situ Erosion Flume for Measuring Stability of Sediment Deposits in Hamilton Harbour, Canada النص الكامل
2006
Krishnappan, Bommanna G | Droppo, Ian G
An in situ erosion flume was used to measure the stability of sediment deposits in Hamilton Harbour, Ontario, Canada. The flume consists of a rectangular duct with an opening at the bottom. A submerged pump attached to the downstream end of the flume circulates the ambient water through the flume, thereby generating turbulent shear flows inside the flume. When the flume rests on a sediment deposit, the exposed part of the sediment deposit is subjected to the flow shear stress. By applying a continually increasing flow shear stress on the sediment deposit and by measuring the amount of sediment erosion, it is possible to assess the erosional stability of the sediment deposits. An under water video camera was mounted on the flume to get visual images of the sediment erosion process. The flume was used at two sites in the Harbour. The erosional resistances measured by the flume for the two sites were different. Measurement of dry density of the sediment deposits using an ultrasonic device was carried out to explain the differences in the stability of sediment deposits from the two sites.
اظهر المزيد [+] اقل [-]Performance of Trickle-Bed Air Biofilter: A Comparative Study of a Hydrophilic and a Hydrophobic Voc النص الكامل
2006
Cai, Z | Kim D. | Sorial, G. A
Two lab-scale trickle-bed air biofilters were operated for investigating the difference in performance between a hydrophilic and a hydrophobic volatile organic compound (VOC). Methyl isobutyl ketone (MIBK) and styrene were selected as a model hydrophilic and hydrophobic VOCs, respectively. Effects of loading rates, biofilter re-acclimation, removal profile along biofilter depth, nitrogen consumption, and CO₂ production were compared under three operating conditions, namely, backwashing and two non-use periods (starvation and stagnant). Consistent over 99% removal efficiency up to loading rates of 3.26 kg COD/m³-day was obtained for the MIBK biofilter at 0.76 min empty bed retention time (EBRT) and 1.5 L/d nutrient flow. A similar performance for the styrene biofilter was obtained for loading rates up to 1.9kg COD/m³-day at 2.02 min EBRT and 2.4 L/d nutrient flow. The MIBK biofilter required only an initial acclimation period of 16 days while styrene biofilter required 46 days. Non-use periods can be used as another means of biomass control for both biofilters when the employed loading rate did not exceed 1.27 and 2.17 kg COD/m³-day for styrene and MIBK biofilters, respectively. The re-acclimation of both biofilter was delayed with increase of loading rate. MIBK biofilter re-acclimated in 90 min, while styrene biofilter re-acclimated in more than 600 min. Under similar loading rates, MIBK biofilter utilized less biofilter depth than styrene biofilter. Nitrogen consumption behaviors were apparently different between the two biofilters. Styrene biofilter had higher CO₂ production than MIBK biofilter and its CO₂ production was closely related to the theoretical complete chemical oxidation.
اظهر المزيد [+] اقل [-]Genetic erosion and pollution assessment methodologies: Proceedings of PGR Forum Workshop 5, Terceira Island, Autonomous Region of the Azores, Portugal, 8-11 September 2004 النص الكامل
2006
Ford-Lloyd, B.V. | Dias, S.R. | Bettencourt, E. | Bioversity International
Climate change, ozone depletion and air pollution | Climate change, ozone depletion and air pollution : legal commentaries with policy and science considerations
2006
Gillespie, Alexander
"This book offers a principle collection of all of the material necessary to understand the legal debates on climate change, ozone depletion and air pollution within their scientific and policy contexts. | The mountain of information coming out of the respective regimes on climate change, ozone depletion and air pollution is monumental. | This work attempts to assembly all of the important documents and resolutions generated by the various regimes, analyze them and provide enough background information to understand the issue and its context." | "The book provides guidance to those actively involved or interested in the negotiations to come to better regimes for climate change, ozone depletion and air pollution."--Jacket.
اظهر المزيد [+] اقل [-]Groundwater pollution and contamination in India: the emerging challenge
2006
Kumar, M. Dinesh | Shah, Tushaar
New source review for stationary sources of air pollution النص الكامل
2006
Growth and nutritive quality ofPoa pratensisas influenced by ozone and competition النص الكامل
2006
Bender, Jürgen | Muntifering, Russell B. | Lin, J. C. | Weigel, Hans-Joachim
Protecting the marine environment from land-based sources of pollution
2006
Hassan, Daud
"Global findings estimate that 80 per cent of marine pollution originates from land-based sources and is trans-boundary in nature. These problems persist in spite of a number of legal and policy initiatives taken to protect the marine environment. This volume explores the applications and shortcomings of current international regimes in addressing these issues. The book identifies the sources and effects of land-based marine pollution and analyses the problems of controlling them. Management principles, policy and regulation are examined at both regional and international level. The author discusses the strengths and weaknesses of existing regimes and advances a more effective international legal framework. The text provides a valuable insight into an important area of international environmental law. It will be of interest to researchers and policy-makers working in this area"--Unedited summary from book cover.
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