Surface controls on the characteristics of natural CO2 seeps: implications for engineered CO2 stores

CO₂ injected into rock formations for deep geological storage must not leak to surface, since this would be economically and environmentally unfavourable, and could present a human health hazard. In Italy natural CO₂ degassing to the surface via seeps is widespread, providing an insight into the various styles of subsurface ‘plumbing’ as well as surface expression of CO₂ fluids. Here we investigate surface controls on the distribution of CO₂ seep characteristics (type, flux and temperature) using a large geographical and historical data set. When the locations of documented seeps are compared to a synthetic statistically random data set, we find that the nature of the CO₂ seeps is most strongly governed by the flow properties of the outcropping rocks, and local topography. Where low‐permeability rocks outcrop, numerous dry seeps occur and have a range of fluxes. Aqueous fluid flow will be limited in these low‐permeability rocks, and so relative permeability effects may enable preferential CO₂ flow. CO₂ vents typically occur along faults in rocks that are located above the water table or are low permeability. Diffuse seeps develop where CO₂ (laterally supplied by these faults) emerges from the vadose zone and where CO₂ degassing from groundwater follows a different flow path due to flow differences for water and CO₂ gas. Bubbling water seeps (characterized by water bubbling with CO₂) arise where CO₂ supply enters the phreatic zone or an aquifer. CO₂‐rich springs often emerge where valleys erode into CO₂ aquifers, and these are typically high flux seeps. Seep type is known to influence human health risk at CO₂ seeps in Italy, as well as the topography surrounding the seep which affects the rate of gas dispersion by wind. Identifying the physical controls on potential seep locations and seep type above engineered CO₂ storage operations is therefore crucial to targeted site monitoring strategy and risk assessment. The surface geology and topography above a CO₂ store must therefore be characterized in order to design the most effective monitoring strategy.     

'The last frontier': rationalizing the spread of farming into the boreal woods of Canada, c. 1910–1940

As the twentieth century opened, there were rumours that the cheap land underpinning the dramatic spread of settlement in the previous century might be running out. There were strong motivations, generated particularly by the large body of land seekers with a passion for farming, to hold off the demise of the famous agricultural frontier. Also wedded to the continuation of a frontier were politicians and civil servants across the country. Whether it was a subconscious expectation that the frontier would simply continue or a fear that its disappearance would lead to unpredictable social disturbance, politicians encouraged expansion beyond what was known to be good farmland. The major source of new land, from c . 1910, was the boreal forest. There was a steady accumulation of information about the North that was readily available to government officials but only indirectly to ordinary land seekers. Although the news about farming conditions in the boreal margin was unpromising except for a few pockets, independent and assisted farm settlements continued into the 1930s. The typical two-thirds of farm failure within one generation in most of the new boreal settlements caused a great deal of settler grief and forced reluctant officials to respond to the negative scientific evidence and to reassess frontier nostalgia. The Second World War provided both a denouement of the northern farm settlement and a reason for many people to depart the 'last frontier'.     

Kamula Accounts of Rambo and the State of Papua New Guinea

This paper contributes to the ethnography of masculinity and the media in PNG. I outline some changes in Kamula men's understandings of masculinity as they are registered in accounts of conflicts between state security services, the Kamula, Rambo and other actors. Outlining this history shows how Kamula men are increasingly entangled in forms of state power and violence that are partially defined by new myths of masculinity expressed in Melanesian readings of Rambo. The paper describes how some of the power effects linked to Rambo are transferred to Kamula men. I argue that in their accounts of Rambo the Kamula are also exploring different models of sovereignty and state power.     

Moving Towards Transformative Democratic Action Through Archaeology

Archaeologists have explored how politics affect the way we see the past. They have investigated how constructions of the past naturalize present political conditions, and have explored uses of the past in current politics. Few have examined how politics in archaeology can relate to the future. In this article I develop ideas on a transformational politics in archaeology that focuses on critiquing oppressive relations in the past and present, and works towards building more just relations for the future. I examine how we can achieve this through building more democratic relations in the places we work.