A new shock tube configuration for studying dust-lifting during the initiation of a coal dust explosion

The traditional defence against propagating coal dust explosions is the application of dry stone dust. This proven and effective safety measure is strictly regulated based on extensive international experience. While new products, such as foamed stone dust, offer significant practical benefits, no benchmark tests currently exist to certify their dust lifting performance in comparison to dry stone dust. This paper reviews the coal dust explosion mechanism, and argues that benchmark testing should focus on dust lifting during the initial development of the explosion, prior to arrival of the flame. In a practical context, this requires the generation of shock waves with Mach numbers ranging from 1.05 to 1.4, and test times of the order of 10’s to 100’s of milliseconds. These proposed test times are significantly longer than previous laboratory studies, however, for certification purposes, it is argued that the dust lifting behaviour should be examined over the full timescales of an actual explosion scenario. These conditions can be accurately targeted using a shock tube at length scales of approximately 50 m. It is further proposed that useful test time can be maximised if an appropriately sized orifice plate is fitted to the tube exit, an arrangement which also offers practical advantages for testing. The paper demonstrates this operating capability with proof-of-concept experiments using The University of Queensland’s X3 impulse facility

Conservation status of oyster reef ecosystem of Southern and Eastern Australia

Reef ecosystems all over the world are in decline and managers urgently need information that can assess management interventions and set national conservation targets. We assess the conservation status and risk of ecosystem collapse for the Oyster Reef Ecosystem of Southern and Eastern Australia, which comprises two community sub-types established by Saccostrea glomerata (Sydney rock oyster) and Ostrea angasi (Australian flat oyster), consistent with the IUCN Red List of Ecosystems risk assessment process. We established: (i) key aspects of the ecosystem including: ecological description, biological characteristics, condition and collapse thresholds, natural and threatening processes; (ii) previous and current extent of occurrence and current area of occupancy; and (iii) its likelihood of collapse within the next 50e100 years. The most severe risk rating occurred for Criterion A: Reduction in Extent (since 1750) and Criterion D: Disruption of biotic processes (since 1750), although assessment varied from Least Concern to Critically Endangered amongst the four criteria assessed. Our overall assessment ranks the risk of collapse for the ecosystem (including both community sub-types) as Critically Endangered with a high degree of confidence. Our results suggest the need for rapid intervention to protect remaining reefs and undertake restoration at suitable sites. Several restoration projects have already demonstrated this is feasible, and Australia is well equipped with government policies and regulatory mechanisms to support the future conservation and recovery of temperate oyster ecosystems

Effects of ocean sprawl on ecological connectivity: impacts and solutions

The growing number of artificial structures in estuarine, coastal and marine environments is causing “ocean sprawl”. Artificial structures do not only modify marine and coastal ecosystems at the sites of their placement, but may also produce larger-scale impacts through their alteration of ecological connectivity - the movement of organisms, materials and energy between habitat units within seascapes. Despite the growing awareness of the capacity of ocean sprawl to influence ecological connectivity, we lack a comprehensive understanding of how artificial structures modify ecological connectivity in near- and off-shore environments, and when and where their effects on connectivity are greatest. We review the mechanisms by which ocean sprawl may modify ecological connectivity, including trophic connectivity associated with the flow of nutrients and resources. We also review demonstrated, inferred and likely ecological impacts of such changes to connectivity, at scales from genes to ecosystems, and potential strategies of management for mitigating these effects. Ocean sprawl may alter connectivity by: (1) creating barriers to the movement of some organisms and resources - by adding physical barriers or by modifying and fragmenting habitats; (2) introducing new structural material that acts as a conduit for the movement of other organisms or resources across the landscape; and (3) altering trophic connectivity. Changes to connectivity may, in turn, influence the genetic structure and size of populations, the distribution of species, and community structure and ecological functioning. Two main approaches to the assessment of ecological connectivity have been taken: (1) measurement of structural connectivity - the configuration of the landscape and habitat patches and their dynamics; and (2) measurement of functional connectivity - the response of organisms or particles to the landscape. Our review reveals the paucity of studies directly addressing the effects of artificial structures on ecological connectivity in the marine environment, particularly at large spatial and temporal scales. With the ongoing development of estuarine and marine environments, there is a pressing need for additional studies that quantify the effects of ocean sprawl on ecological connectivity. Understanding the mechanisms by which structures modify connectivity is essential if marine spatial planning and eco-engineering are to be effectively utilised to minimise impacts

Mining Modification of River Systems: A case study from the Australian Gold Rush

Mobilisation of large volumes of bedrock, regolith and soil has long been a characteristic feature of metal mining. Prior to the 20th century this was most efficiently achieved through harnessing the motive power of water. Large-scale water use in mining produced waste sands, gravels and silts that were flushed downstream, triggering changes in stream and floodplain morphology and function. During the 19th century the shift from artisanal to industrialised mining resulted in a rapid increase in the scale and extent of environmental change. This paper presents results from a multi-disciplinary research program investigating the environmental effects of 19th-century gold mining on waterways in south-eastern Australia. Archaeological and geospatial landscape survey are combined with historical data modelling and geomorphological analysis to examine the extractive processes that produced sediment in headwater regions and how this influenced fluvial processes operating on downstream waterways and floodplains. Our case study of the Three Mile-Hodgson Creek system on the Ovens (Beechworth) goldfield in north-east Victoria indicates that miners mobilised up to 7.3 million m3 of sediment in this small catchment alone. Results of the research suggest that tailings dams and sludge channels in this catchment are important archaeological evidence for early attempts to manage industrial waste

Policy Entrepreneurship by International Bureaucracies: The Evolution of Public Information in UN Peacekeeping

The UN Secretariat’s role in the expansion of peacekeeping after the cold war is debated. Different theoretical accounts offer competing interpretations: principal–agent models and sociological institutionalism tend to emphasize the Secretariat’s risk-averse behaviour; organizational learning scholarship and international political sociology find evidence of the Secretariat’s activism; constructivism analyses instances of both. I argue that the UN Secretariat can be both enthusiastic and cautious about new tasks depending on the circumstances and the issue area. For example, UN officials have been the driving force behind the development of public information campaigns by peacekeeping missions aimed at the local population. During the cold war, it was not regarded as necessary for UN missions to communicate with the public in the area of operation: their interlocutors were parties to the conflict and the diplomatic community. With the deployment of the first multidimensional missions in the late 1980s and the early 1990s, UN staff realized the need to explain the organization’s role to the local population and provide information about UN-supported elections. In promoting this innovation, they played the role of policy entrepreneurs. The institutionalization of this innovation, however, was not an automatic process and required continuous advocacy by UN information staff