Small-scale physical explosions in shock tubes in comparison with condensed high explosive detonations

A series of small-scale experiments involving physical explosions in a 1.6 l pressure vessel was carried out. Explosions were initiated by spontaneous rupture of an aluminium membrane on one side of the vessel at a pressure in the range 1–1.2 MPa. The pressure waves released were measured at different distances along two separate shock tubes, one 10 m long and 200 mm in diameter (closed at one end by the high pressure vessel) and the other 15 m long and 100 mm in diameter.TNT equivalency was used for predicting the blast wave characteristics after vessel rupture. TNT equivalency was used because equations for prediction of peak pressure and impulse of the blast wave in 1-D geometry after detonations of condensed explosives are known. Some experiments with an equivalent amount of real explosive were carried out for comparison with the theoretical and experimental data obtained. The applicability of the TNT equivalency method presented for calculations of maximum pressure and shock wave impulse generated after rupture of the pressure vessel in 1-D geometry is discussed.     

Media surface properties and the development of nitrifying biofilms in mixed cultures for wastewater treatment

Plastic was tested to select biofilm support media that would enhance nitrification in the presence of heterotrophs. Eight different types (acrylonitrile butadiene styrene, nylon, polycarbonate, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinyl chloride and tufnol) were immersed in an aerobic fed-batch reactor receiving domestic settled wastewater. Nitrification rates did not correlate with biomass concentrations, nor surface roughness of the plastics as measured by atomic force microscopy (AFM). The maximum nitrification rate of 1.5 g/m² d^?1 was obtained from biofilms growing on PTFE which had the lowest surface adhesion force (8 nN). Nitrification rates for the biofilms were inversely correlated with the attraction forces as measured by AFM.     

Environmental risk mapping of accidental pollution and its zonal prevention in a city

Accidental releases of pollution can have severe environmental, societal, economic, and institutional consequences. This paper considers the use of risk mapping of accidental pollution events, and zonal prevention measures for alleviating the impact on large urban areas. An Environmental Pollution Accident Risk Mapping (EPARM) model is constructed according to a mapping index system supported by quantitative sub-models dedicated to evaluating the risk arising from different sources of potential accidental pollution. The EPARM approach consists of identifying suitable indexes, assessment of environmental risk at regional and national scales based on information on previous pollution accidents and the prevailing environmental and social conditions, and use of GIS to map the overall risk. A case study of pollution accidents in Minghang District, Shanghai, China is used to demonstrate the effectiveness of the model. The paper also proposes a systemic framework for accidental environmental pollution risk prevention, and detailed countermeasures for specific risk zones.     

Experimental and theoretical investigations for mitigating NaAlH4 reactivity risks during postulated accident scenarios involving exposure to air or water

Experimental and theoretical studies were conducted to investigate the pyrophoricity and water-reactivity risks associated with employing sodium alanate (NaAlH₄) complex metal hydride in on-board vehicular hydrogen (H₂) storage systems. The ignition and explosivity of NaAlH₄ upon exposure to oxidizers in air or water were attributed to the spontaneous formation of stable hydroperoxyl intermediates on the NaAlH₄ surface and/or H₂ production, as well as the large driving force for NaAlH₄ conversion to favorable hydroxide products predicted by atomic and thermodynamic modeling. The major products from NaAlH₄ exposure to air: NaAl(OH)₄, gibbsite and bayerite Al(OH)₃, and Na₂CO₃ observed by XRD, were identified to be formed by surface-controlled reactions. The reactivity risks were significantly minimized, without compromising de-/re-hydrogenation cyclability, by compacting NaAlH₄ powder into wafers to reduce the available surface area. These core findings are of significance to risk mitigation and H₂ safety code and standard development for the safe use of NaAlH₄ for on-board H₂ storage in light-duty vehicles.     

全球沙尘气溶胶源汇分布及其变化特征的模拟分析

根据全球沙尘气溶胶气候模式GEM-AQ/EC模拟的1995~2004年的沙尘起沙量和干湿沉降量,分析了沙尘气溶胶源汇的全球时空变化特征.全球沙尘起沙量集中在各个主要沙漠地区,北非对全球沙尘气溶胶贡献最大为66.6%.沙尘气溶胶沉降的高值区分布在沙漠源区及其紧临的下风地区.最大净沙尘气溶胶接收主要分布在沙漠周围地区并形成净接收量大于10t/(km2×a)的位于0°N~60°N之间的北非、欧亚大陆、西太平洋、北印度洋、北美和大西洋的带状分布.在北非、阿拉伯半岛、中亚、东亚和澳大利亚5个主要沙漠地区中,起沙量和沉降量都存在明显的季节变化,除中亚其他4个区域干湿沉降量和起沙的季节变化基本一致;东亚地区沙尘气溶胶起沙量和总沉降量的季节变化最为明显,而北非沙漠起沙量和总沉降量的季节变化最小,其他3个区域的季节变化幅度基本相同.中亚起沙峰值和阿拉伯半岛起沙次峰值出现在夏季,其他区域的峰值均出现在春季.10年间全球陆地年平均起沙量为(1500±94)Mt,保持略微上升趋势.以北非沙漠起沙量年际变化率最低(6.3%), 而以东亚(28.3%)和澳大利亚(45.0%)起沙量年际变化最为明显;全球陆地的沙尘气溶胶沉降量以约9.9Mt/a的速率递减,全球海洋的沙尘气溶胶沉降递增.     

A matter of approach: the retort's potential to reduce mercury consumption within small-scale gold mining settlements in Tanzania

The mercury-based gold extraction processes prevalent within small-scale mining are both efficient and harmful. While ensuring relatively high levels of gold recovery, they cause environmental and health problems for people living within mining settlements. This mercury consumption can be minimized by using a simple mercury recycling device known as a retort. While mining legislation in Tanzania dictates the use of retorts for gold recovery, virtually no miners use them, indicating the inadequacy of previous introduction attempts. During action research, retorts were introduced in two mining settlements through a thorough and participatory approach. Twenty miners were given retorts and their attitudes and receptiveness to them were studied. Of the recipients, 18 used the retorts over a period of five months, recycling 10 kilos of mercury. Less mercury was spilled into the environment and miners saved money normally spent on purchasing mercury. The findings have implications for the strategies of development interventions targeting mercury-instigated problems within small-scale gold mining.     

Operational decisions in response to a performance-based regulation to reduce organic waste impacts near Atlantic salmon farms in British Columbia,Canada

Nutrient enrichment of the seafloor (benthos) has been a primary subject of investigation since the beginning of commercial salmon farming. Waste feed and feces passing through the containment nets can create zones of organic enrichment to the benthos in the vicinity of the pen cages. Early studies of salmon farming in British Columbia Canada (500–1200 metric ton production farms) showed that these effects varied greatly and were reduced where conditions of adequate water depth and strong tidal currents were present. More recent studies of farms producing in excess of 2000 tons of fish have documented measurable organic benthic impacts.The implementation of a performance-based waste regulation in British Columbia in 2002 has caused operational changes to achieve and maintain compliance. This paper describes field monitoring data for four representative farm operations including the waste impact levels prior to the implementation of regulatory standards and the effect of adaptive management actions taken to reduce organic enrichment such as modified feed delivery, relatively small position changes to the cages or reducing site production to achieve continuing compliance.Monitoring over several full production cycles at selected farms indicated that sediment impacts at maximum production levels have decreased while maintaining, and in some cases increasing overall production of salmon.     

Building institutions based on information disclosure: lessons from GRI's sustainability reporting

Global Reporting Initiative (GRI) is the best-known framework for voluntary reporting of environmental and social performance by business worldwide. Using extensive empirical data, including interviews and documentary analysis, we examine GRI's organizational field and conclude that since its modest beginnings in 1999 GRI has been by several measures a successful institutionalization project. But the institutional logic of this new entity, as an instrument for corporate sustainability management, leaves out one of the central elements of the initial vision for GRI: as a mobilizing agent for many societal actors. This emergent logic reflects GRI's dominant constituency – large global companies and financial institutions and international business management consultancies – and not the less active civil society organizations and organized labor. We attribute these developments to factors such as building GRI within the existing institutional structures; the highly inclusive multistakeholder process; and the underdeveloped base of information users. From the institutional theory perspective, this case shows how the process of institutionalization is deeply affected by initial strategies of the founders, and how it reproduces existing power relations. From the governance perspective, this case leads us to question the power of commodified information to mobilize civil society and to strengthen governance based on partnerships.     

Development of vermicast from sludge and powdered oyster shell

Soil acidification is one of the rising land degradation issues facing world agriculture. The risk of acidification is currently being assessed as part of agriculture productivity and sustainable theme. This study was conducted to produce a new vermicomposting cast as a recycling resource derived from municipal sewage sludge and waste oyster shell. The earthworm, Eisenia Andrei, was fed under different conditions. The most suitable mixture was 77:23 w/w% of sewage sludge and waste oyster shell. Powdered oyster shell (POS) sludge blend provided a stable pH, due to its buffering capacity during vermiculture because of the Ca²⁺ and OH^? release effect. The vermicast products fulfilled the cast standards of Korea Ministry of Environment for all the parameters such as moisture content, pH, salinity, organic carbon, TKN, Phosphate, and heavy metals. Slowly released organic matter when added to soil improves the capacity of the soil to hold nutrients for plants, improve soil aeration for roots, and improves soil drainage. This product will be an addition to already-commercialized sludge vermicast as a higher value product.