Carbonate formation in waste from the steel industry could constitute a nontrivial proportion of the global requirements for removing carbon dioxide from the atmosphere at a potentially low cost. To utilize this potential, we examined atmospheric carbon dioxide sequestration in a >20 million ton legacy slag deposit in northern England, United Kingdom. Carbonates formed from the drainage water of the heap had stable carbon and oxygen isotope values between -12 and -25 ‰ and -5 and -18 ‰ for δC and δO, respectively, suggesting atmospheric carbon dioxide sequestration in high-pH solutions. From the analyses of solution saturation states, we estimate that between 280 and 2900 tons of CO have precipitated from the drainage waters. However, by combining a 37 year long data set of the drainage water chemistry with geospatial analysis, we estimate that <1% of the maximum carbon-capture potential of the deposit may have been realized. This implies that uncontrolled deposition of slag is insufficient to maximize carbon sequestration, and there may be considerable quantities of unreacted legacy deposits available for atmospheric carbon sequestration.

The objectives of this project were to establish the geometry and internal structure of open system pingos in Adventdalen, Svalbard using electrical resistivity tomography. A clear distinction can be made between the electrical properties of the pingos investigated, depending upon whether they are located either above (Innerhytte pingo) or below (Hytte and Longyear pingos) the maximum Holocene marine limit. The resistivity profile at Innerhytte pingo was characterised by high values of resistivity (10,000-30,000 V m), indicating either ice-rich frozen bedrock or a lens of massive ground ice. The electrical resistivity of Hytte and Longyear pingos, both developed within fine-grained, saline marine clays, is exceptionally low (predominantly ,2,000 V m) for permanently frozen ground. This is inconsistent with the presence of a body of massive ground ice, and suggests that the internal structures of Longyear and Hytte pingos do not follow the classic model of a plano-convex pingo-core of massive injection ice. Instead, the internal structure of these landforms may be dominated by segregation ice and localised pockets of massive ice within a matrix of partially frozen, fine-grained marine muds. The high salinity of the pore waters and the fine-grained nature of the sediment cause high unfrozen pore water contents, even at temperatures well below 0uC, enabling electrolytic conduction and resulting in apparently anomalously low resistivity measurements. It is therefore concluded that electrical resistivity tomography must be interpreted with care when applied to the characterisation of permafrost in areas of saline marine sediments. Future field monitoring of permafrost landforms and laboratory testing of ice-rich sediments are recommended to improve geophysical interpretation of permanently frozen materials.

No abstract

No abstract

Glaciotectonic deformation of the Late Devensian sediments exposed at St Bees, Cumbria is represented by minor extensional faults resulting from ice-sheet loading of the unconsolidated sediments accompanied by thrusting and folding. The highly deformed northern part of the section has numerous thrust faults associated with fold structures that verge predominantly to the SE, but with some NW-vergent (backthrust) structures. A high-resolution seismic reflection survey confirms that the thrust structures form a linked fault system that detaches at, or slightly above bed rock, which is here composed of Triassic, St Bees sandstones. In the less deformed southern part of the section, the seismic survey has imaged bedding with a southerly component of dip in the St Bees sandstone cut by steep north-dipping extensional faults which, to some extent, control rockhead topography. An integrated approach combining structural geology and high-resolution seismic reflection surveying has enabled the construction of a balanced cross-section which estimates a minimum of 115 m (22%) cumulative shortening due to glaciotectonic processes. Minor structures observed in the St Bees cliffs and larger structures interpreted from the seismic profile are compatible with a critical wedge model for deformation caused by an overlying thick ice wedge with a SE-dipping surface slope.