http://hdl.handle.net/10092/169 2013-04-20T06:54:26Z http://hdl.handle.net/10092/7626 Title: Non-invasive imaging of hydrocarbon contamination in permafrost soils at Marble Point, McMurdo Sound region, Antarctica Authors: Nobes, D.C.; Pettersson, J.K. Abstract: Summary: Hydrocarbon spills can cause extensive environmental damage and can last a long time in dry permafrost environments like that in Antarctica. Intrusive sampling and attempts at remediation can cause more harm to a site already damaged, particularly in the harsh yet fragile Antarctic environment. Additionally, even carefully planned intrusive sampling programmes can miss the target, in this case the location and extent of contamination. With negligible physical disturbance, non-invasive, non-destructive geophysical methods determined the extent of hydrocarbon contamination in the permafrost soil at Marble Point, in the McMurdo Sound region. Limited sampling was done for calibration, with minimal and highly restricted disturbance. The contamination is 35 to 40 years old; however the electromagnetic response was electrically resistive, the same as relatively young contamination in temperate soils, whereas older temperate spills tend to be electrically conductive. Radar profiles were acquired across the eastern half of the site, crossing two contaminated locations. The radar reflections were enhanced, again as observed for young contamination in temperate soils. Correlation between the radar and electromagnetic responses was excellent. The cold polar climate slows chemical and physical changes to contaminants, so that they respond as if young and relatively fresh. Geophysical imaging provided a viable non-invasive means to map the extent of hydrocarbon contamination in Antarctic permafrost soils with little or no site disturbance. 2012-01-01T00:00:00Z http://hdl.handle.net/10092/7479 Title: Gravitational energy as dark energy: Average observational quantities Authors: Wiltshire, D. Abstract: In the timescape scenario cosmic acceleration is understand as an apparent effect, due to gravitational energy gradients that grow when spatial curvature gradients become significant with the nonlinear growth of cosmic structure. This affects the calibratation of local geometry to the solutions of the volume–average evolution equations corrected by backreaction. In this paper I discuss recent work on defining observational tests for average geometric quantities which can distinguish the timescape model from a cosmological constant or other models of dark energy. 2009-01-01T00:00:00Z http://hdl.handle.net/10092/7387 Title: Recent Travels in kt-Land Authors: Barth, J.; Beuermann, S.; Buback, M.; Russell, G.T.; Siegmann, R. 2012-01-01T00:00:00Z http://hdl.handle.net/10092/7351 Title: Gravitational energy as dark energy: Towards concordance cosmology without Lambda Authors: Wiltshire, D.L. Abstract: I briefly outline a new physical interpretation to the average cosmological parameters for an inhomogeneous universe with backreaction. The variance in local geometry and gravitational energy between ideal isotropic observers in bound structures and isotropic observers at the volume average location in voids plays a crucial role. Fits of a model universe to observational data suggest the possibility of a new concordance cosmology, in which dark energy is revealed as a mis-identification of gravitational energy gradients that become important when voids grow at late epochs. 2009-01-01T00:00:00Z