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Sequential extraction and single-step cold-acid extraction: A feasibility study for use with freshwater-canal sediments Full text
2006
Cook, S.R. | Parker, A.
Sequential extraction and single-step cold-acid extraction: A feasibility study for use with freshwater-canal sediments Full text
2006
Cook, S.R. | Parker, A.
This investigation examines metal release from freshwater sediment using sequential extraction and single-step cold-acid leaching. The concentrations of Cd, Cr, Cu, Fe, Ni, Pb and Zn released using a standard 3-step sequential extraction (Rauret et al., 1999) are compared to those released using a 0.5 M HCl; leach. The results show that the three sediments behave in very different ways when subject to the same leaching experiments: the cold-acid extraction appears to remove higher relative concentrations of metals from the iron-rich sediment than from the other two sediments. Cold-acid extraction appears to be more effective at removing metals from sediments with crystalline iron oxides than the “reducible” step of the sequential extraction. The results show that a single-step acid leach can be just as effective as sequential extractions at removing metals from sediment and are a great deal less time-consuming.
Show more [+] Less [-]Sequential extraction and single-step cold-acid extraction: A feasibility study for use with freshwater-canal sediments Full text
2006
Cook, S. R. | Parker, A.
This investigation examines metal release from freshwater sediment using sequential extraction and single-step cold-acid leaching. The concentrations of Cd, Cr, Cu, Fe, Ni, Pb and Zn released using a standard 3-step sequential extraction (Rauret et al., 1999) are compared to those released using a 0.5 M HCl; leach. The results show that the three sediments behave in very different ways when subject to the same leaching experiments: the cold-acid extraction appears to remove higher relative concentrations of metals from the iron-rich sediment than from the other two sediments. Cold-acid extraction appears to be more effective at removing metals from sediments with crystalline iron oxides than the "reducible" step of the sequential extraction. The results show that a single-step acid leach can be just as effective as sequential extractions at removing metals from sediment and are a great deal less time-consuming.
Show more [+] Less [-]Trace Elements in Coalbed Methane Produced Water Interacting with Semi-Arid Ephemeral Stream Channels Full text
2006
Patz, M.J. | Reddy, K.J. | Skinner, Q.D.
The objective of this study was to examine the chemistry of trace elements in coalbed methane (CBM) discharge water reacting with semi-arid ephemeral stream channels in Powder River Basin, Wyoming. The study area consisted of two ephemeral streams, Burger Draw and Sue Draw. These streams are tributaries to the perennial Powder River, Wyoming. Samples were collected bimonthly from three CBM discharge points and seven channel locations in Burger Draw and Sue Draw. Samples were also collected bimonthly from the Powder River above and below the confluence of Burger Draw. Before sample collection, pH, temperature, dissolved oxygen (DO), and turbidity were measured in the field. Samples were transported to the laboratory and analyzed for dissolved trace elements including iron (Fe), manganese (Mn), boron (B), arsenic (As), selenium (Se), and fluoride (F). Results suggest pH of discharge water was 7.1 and increased significantly in the downstream channel of Burger Draw to 8.84 before joined with the Powder River. Temperature of CBM produced water at discharge points ranged between 20.3 and 22.7 [composite function (small circle)]C. Before discharge, DO concentrations of CBM produced water were between 1.42 and 1.5 mg/L. No significant differences in temperature, DO, and turbidity were found between Burger Draw flow and Powder River flow. However, significant differences were found within the sampling period in temperature and turbidity in flow of Burger Draw. The temperature, DO, and turbidity were all significantly different in Powder River within the sampling period. The CBM discharge water consisted of higher concentrations of F, Fe and B compared to other components. Significant changes were observed for Fe, Mn, and As; and seasonally for B. Dissolved Fe and Mn decreased, while As and Se increased in downstream channel flow. These findings will be useful in proper management of CBM produced water in semi-arid environments.
Show more [+] Less [-]Microbial Removal of Arsenic Full text
2006
Jahan, Kauser | Mosto, Patricia | Mattson, Crystal | Frey, Erin | Derchak, Lara
Bangladesh is currently the subject of the world's largest mass arsenic poisoning in history. Groundwater throughout Bangladesh and West Bengal is contaminated with naturally occurring arsenic from the alluvial and deltaic sediments that form the region's aquifers. It has been estimated that 75 million people are at risk of developing health effects associated with the ingestion of arsenic. This project focuses on the use of microorganisms such as bacteria and algae to remove arsenic from water. Arsenic in the arsenite form was used in the studies. Experiments were conducted with a common alga and wastewater bacteria. A common green algae Scenedesmus abundans was used for determining arsenic uptake in batch experiments. Results of the experiments indicated that the algae biosorption could be modeled by the conventional Langmuir isotherm model. Algae morphology studies indicated that the algae cells were impacted due to the presence of arsenic as evidenced by clumping or loss of cell clusters. The wastewater bacteria also were capable of high percent of arsenic removal. Results indicate that microbial uptake of arsenic may be a viable method of pretreatment of arsenic contaminated water. However algae and sludge disposal would pose a problem and will have to be dealt with accordingly.
Show more [+] Less [-]Root Exudates Impact on Phenanthrene Availability Full text
2006
Ouvrard, S | Lapole, D | Morel, J. L
In order to improve and optimize phytoremediation of PAH we propose to focus on the rhizospheric processes controlling PAH degradation. In this paper the effect of root exudates on PAH availability is studied. Model organic compounds (malic acid, malonic acid and EDTA) representing root exudates have been tested for their effect on phenanthrene sorption on a reference non polluted agricultural soil material. Phenanthrene adsorption isotherms were first obtained with batch experiments. Results showed linear isotherms and phenanthrene sorption was enhanced as the concentration of organic compounds in the solution increased. Column leaching experiments were then used to simulate the effect of root exudation following the soil pollution. Inlet solutions containing the different organic acids used were flowed through the column containing the artificially polluted soil material. Elution curves showed that the phenanthrene was less easily eluted when the solution injected contained the organic acids. However, magnitude of the phenomena did not fit with adsorption constants obtained in batch experiments. Phenanthrene desorption appeared limited by sequestration but organic acids seemed able to partially disturb the soil material structure to limit the sequestration effect.
Show more [+] Less [-]Groundwater pollution and contamination in India: the emerging challenge
2006
Kumar, M. Dinesh | Shah, Tushaar
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.
Show more [+] Less [-]New source review for stationary sources of air pollution Full text
2006
Physiological and biochemical stress responses in grassland species are influenced by both early-season ozone exposure and interspecific competition Full text
2006
Scebba, Francesca | Canaccini, Francesca | Castagna, Antonella | Bender, Jürgen | Weigel, Hans-Joachim | Ranieri, Annamaria
Growth and nutritive quality ofPoa pratensisas influenced by ozone and competition Full text
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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