Hydraulic characterization for steam enhanced remediation conducted in fractured rock

To explore the viability of Steam Enhanced Remediation (SER) in fractured rock a small-scale steam injection and water/vapour extraction pilot study was conducted at the former Loring Air Force Base in northern Maine, USA. A detailed well testing program was undertaken to assist in the design of the injection and extraction well array, and to assess the possibility of off-site heat and contaminant migration. A structurally complex limestone having low matrix porosity and a sparse distribution of fractures underlies the study site. To characterize the groundwater and steam flow pathways, single-well slug tests and more than 100 pulse interference tests were conducted. The results of the well testing indicate that the study site is dominated by steeply dipping bedding plane fractures that are interconnected only between some wells in the injection/extraction array. The SER system was designed to take advantage of interconnected fractures located at depth in the eastern end of the site. An array of 29 wells located in an area of 60 by 40 m was used for steam injection and water/vapour extraction. The migration of heat was monitored in several wells using thermistor arrays having a 1.5 m vertical spacing. Temperature measurements obtained during and after the 3 month steam injection period showed that heat migration generally occurred along those fracture features identified by the pulse interference testing. Based on these results, it is concluded that the pulse interference tests were valuable in assisting with the design of the injection/extraction well geometry and in predicting the migration pathways of the hot water associated with the steam injection. The pulse interference test method should also prove useful in support of any other remedial method dependant on the fracture network for delivery of remedial fluid or extraction of contaminants.     

Making humanitarian relief networks more effective: operational coordination, trust and sense making

Effective coordination of humanitarian assistance activities remains elusive. This paper briefly addresses some of the reasons for what is widely perceived as a coordination dilemma in humanitarian affairs and argues for a new conceptualisation of the issue. Rather than continue to request that more authority be vested in a single organisation to secure coordination through top-down control, it contends that it may be timely to consider whether relief agencies involved in an emergency should be reconceived as social networks and efforts made to achieve changes in their organizational cultures that encourage operational coordination across institutional lines. Since such labours imply the need to trust, this article explores what forms of trust might be employed to promote improved coordination among relief institutions and how those relationships could themselves be conceptualised. Finally, while acknowledging that coordination is not costless, it suggests that its effective pursuit may be advantageous even in scenarios where aid organisations balk at cooperating to secure it.     

Discarded queen conch (<Emphasis Type="Italic">Strombus gigas</Emphasis>) shells as shelter sites for fish

Within the Caribbean millions of queen conch (Strombus gigas Linnaeus) are harvested each year and shells discarded randomly or as middens. Fish use of discarded conch shells was investigated in four different habitat types: sand, seagrass beds, mangrove forests, and coral reefs. The study was carried out in the waters off South Caicos, Turks and Caicos Islands (TCI), between October 2003 and January 2004. The density of discarded shells was greatest near coral reefs; however, the percentage of shells occupied by adult fish was higher in isolated shells on sand and in mangrove habitats. Juvenile fish also showed a preference for sheltering in conch shells relative to other microhabitat types on sandy plains and in mangrove and seagrass habitats. Differences in use of single shells by fish in different habitats were attributed to differences in piscivore abundance and habitat complexity. Although not all isolated shells were occupied by fish, all conch middens deposited by fishermen had fish inhabitants. Examination of fish use of conch middens in three habitat types and conch piles of one, three, and five shells constructed on sand found both fish diversity and abundance increased on conch middens of increasing size. This study suggests that disposal of conch shells as large middens in habitats of low complexity will increase the amount of shelter present and may enhance fish populations in these habitats.Communicated by J.P. Grassle, New Brunswick     

Soil acidification and foliar nutrient status of Ontario's deciduous forest in 1986 and 2005

To assess the impacts of the decline in sulphur (S) deposition over the past 20 years in Ontario, soil chemistry and sugar maple (Acer saccharum Marsh) foliar chemistry were measured at 17 sites in south and central Ontario in 2005 and compared with archived samples collected in 1986. Foliar S concentrations were lower in 2005, reflecting the decline in S deposition whereas foliar N remained unchanged, reflecting the lack of change in N deposition in Ontario. Mineral soil pH, exchangeable base cations were lower in 2005 whereas total S, N and cation exchange capacity (CEC) were unchanged. Foliar concentrations of Ca were positively related to soil Ca levels in the A-horizon and were lower in 2005. Despite evidence of increasing soil acidity and losses of calcium, foliar base cation concentrations at most sites were adequate for sugar maple and forest health in terms of canopy appearance (Decline Index) improved.