2 results
1 - Contamination, regulation, and remediation: an introduction to bioremediation of petroleum hydrocarbons in cold regions
-
- By Ian Snape, Contaminants Geochemist Working for the Australian Antarctic Division in Tasmania, Larry Acomb, Geosphere Inc., 3055 Seawind Drive, Anchorage AK 99516, USA, David L. Barnes, Dept. of Civil and Environmental Engineering, University of Alaska Fairbanks, PO Box 755900, Fairbanks AK 99775, USA, Steve Bainbridge, Contaminated Sites Program, Division of Spill Prevention and Response, Department of Environmental Conservation, 610 University Avenue, Fairbanks AK 99709–3643, USA, Robert Eno, Department of Sustainable Development, Government of Nunavut, PO Box 1000, Stn 1195, Iqaluit NU X0A 0H0, Canada, Dennis M. Filler, Dept. of Civil and Environmental Engineering, University of Alaska Fairbanks, PO Box 755900, Fairbanks AK 99775, USA, Natalie Plato, Department of Sustainable Development, Government of Nunavut, PO Box 1000, Stn 1195, Iqaluit NU X0A 0H0, Canada, John S. Poland, Analytical Services Unit, Queens University, Kingston ON K7L 3N6, Canada, Tania C. Raymond, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, John L. Rayner, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, Martin J. Riddle, Environmental Protection and Change Program, Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia, Anne G. Rike, Dept. of Environmental Technology, Norwegian Geotechnical Institute, PO Box 3930, Ullevaal Stadion, N-0806 Oslo, Norway, Allison Rutter, Analytical Services Unit, Queens University, Kingston ON K7L 3N6, Canada, Alexis N. Schafer, University of Saskatchewan, 51 Campus Drive, Saskatoon, Canada S7N 5A8, Steven D. Siciliano, University of Saskatchewan, 51 Campus Drive, Saskatoon SK S7N 5A8, Canada, James L. Walworth, Dept. of Soil Water and Environmental Science, University of Arizona, 429 Shantz Bldg. #38, Tucson AZ 85721, USA
- Edited by Dennis M. Filler, University of Alaska, Fairbanks, Ian Snape, David L. Barnes, University of Alaska, Fairbanks
-
- Book:
- Bioremediation of Petroleum Hydrocarbons in Cold Regions
- Published online:
- 22 August 2009
- Print publication:
- 21 February 2008, pp 1-37
-
- Chapter
- Export citation
-
Summary
Introduction
Oil and fuel spills are among the most extensive and environmentally damaging pollution problems in cold regions and are recognized as potential threats to human and ecosystem health. It is generally thought that spills are more damaging in cold regions, and that ecosystem recovery is slower than in warmer climates (AMAP 1998; Det Norske Veritas 2003). Slow natural attenuation rates mean that petroleum concentrations remain high for many years, and site managers are therefore often forced to select among a range of more active remediation options, each of which involves a trade-off between cost and treatment time (Figure 11). The acceptable treatment timeline is usually dictated by financial circumstance, perceived risks, regulatory pressure, or transfer of land ownership.
In situations where remediation and site closure are not urgent, natural attenuation is often considered an option. However, for many cold region sites, contaminants rapidly migrate off-site (Gore et al. 1999; Snape et al. 2006a). In seasonally frozen ground, especially in wetlands, a pulse of contamination is often released with each summer thaw (AMAP 1998; Snape et al. 2002). In these circumstances natural attenuation is likely not a satisfactory option. Simply excavating contaminants and removing them for off-site treatment may not be viable either, because the costs are often prohibitive and the environmental consequences of bulk extraction can equal or exceed the damage caused by the initial spill (Filler et al. 2006; Riser-Roberts 1998).
Mechanism Of Ductile Rupture In The AL/Sapphire System Elucidated Using X-Ray Tomographic Microscopy
- Wayne E. King, Geoffrey H. Campbell, David L. Haupt, John H. Kinney, Robert A. Riddle, Walter L. Wien
-
- Journal:
- MRS Online Proceedings Library Archive / Volume 409 / 1995
- Published online by Cambridge University Press:
- 15 February 2011, 147
- Print publication:
- 1995
-
- Article
- Export citation
-
The fracture of a thin metal foil constrained between alumina or sapphire blocks has been studied by a number of investigators. The systems that have been investigated include Al [1,2], Au [3], Nb [4], and Cu [5]. Except for Al/ Al2O3 interfaces, these systems exhibit a common fracture mechanism: pores form at the metal/ceramic interface several foil thicknesses ahead of the crack which, under increasing load, grow and link with the initial crack. This mechanism leaves metal on one side of the fracture surface and clean ceramic on the other. This has not been the observation in Al/ A12O3 bonds where at appropriate thicknesses of Al, the fracture appears to proceed as a ductile rupture through the metal.
The failure of sandwich geometry samples has been considered in several published models, e.g., [6,71. The predictions of these models depend on the micromechanic mechanism of crack extension. For example, Varias et al. proposed four possible fracture mechanisms: (i) near-tip void growth at second phase particles or interfacial pores and coalescence with the main crack, (ii) high-triaxiality cavitation, i.e., nucleation and rapid void growth at highly stressed sites at distances of several layer thicknesses from the crack tip, (iii) interfacial debonding at the site of highest normal interfacial traction, and (iv) cleavage fracture of the ceramic. Competition among the operative mechanisms determines which path will be favored.
This paper addresses the question of why the fracture of the A1/A12O3 system appears to be different from other systems by probing the fracture mechanism using X-ray tomographic microscopy (XTM). We have experimentally duplicated the simplified geometry of the micromechanics models and subjected the specimens to a well defined stress state in bending. The bend tests were interrupted and XTM was performed to reveal the mechanism of crack extension.