The kinetics of reductive dehalogenation of a set of halogenated aliphatic hydrocarbons in anaerobic sediment slurries

Disappearance rate constants are reported for the reductive transformation of 17 halogenated aliphatic hydrocarbons in anaerobic sediment-water samples. Statistical experimental design in combination with multivariate chemical characterization of their chemical properties was used to select the compounds. Degradation followed pseudo first-order kinetics through at least two half-lives for 15 of the 17 compounds. Of all the compounds investigated, 1,2,3-trichloropropane and dichloromethane were unique in that they were dehalogenated according to zero-order kinetics. Reductive dehalogenation was the sole transformation reaction taking place.     

Risk measures constituting a risk metrics which enables improved decision making: Value-at-Risk

In this work, a novel approach is proposed for expressing the risks of process plants consisting of a large number of scenarios, in the form of a risk metrics of leading indicators to prevent potential high profile industry accidents. The methodology includes: 1) risk estimation of a portfolio by CPQRA (or QRA), 2) monetization of the tangible risks with the inclusion of the lost time of production, 3) estimation of the maximum portfolio loss using Value-at-Risk approach, 4) inclusion of intangible risks using FN-curve and, 5) generation of F$-curve of tangible risks. The proposed methodology can particularly help in understanding the stakes at risk by performing the overall cost-benefit analysis, for identifying the most risky scenarios and identifying critical equipments to enable better risk-informed decision making in order to adopt appropriate risk mitigation measures. This work establishes the groundwork for developing measures for understanding and comparing the large number of risk values derived from QRA studies for large portfolios. It will aid in less subjective decision making as it enables the decision maker to choose the most preferred portfolio option among alternatives. Decisions made with the accurate understanding of the consequences of risks can significantly reduce potential work-related fatalities, property losses and save millions of dollars.     

Safety challenges in view of the upcoming hydrogen economy: An overview

If produced and arranged in the right way with carbon dioxide as a possible but permanently removed by-product, hydrogen as a new, large scale, applicable energy carrier promises significant reductions of carbon dioxide emissions. It is light, non-toxic, and clean burning. In different parts of the world, viz. United States, Japan, and Europe, programs have started some years ago to investigate hazardous properties of hydrogen in more detail and to develop special safety measures where necessary. Recently, in September 2009, the third International Conference on Hydrogen Safety (3rd ICHS) was held at Corsica, France. CFD tools have been adapted to describe hydrogen dispersion and explosion. Field tests have been carried out, an incident databank has been founded, knowledge gaps were defined, and risk analysis methods reviewed. The latter are required for drafting installation guidelines and measures for safe distances in land-use planning and licensing of hydrogen storage locations, pipelines, and re-fuelling stations. Yet some challenges remain. The paper will summarize present results and will address hydrogen related issues where more knowledge is needed to reduce uncertainty and improve the quality of risk control.     

Behaviour of Rice-Byproducts and Optimizing the Conditions for Production of High Performance Natural Fiber Polymer Composites

This present study deals with evaluating some available rice by-products, such as rice straw and rice husks, as a fiber component in manufacturing of high performance natural fiber polymer composites (NFPC). The utilization of these undesirable wastes will contribute to the reduction of the environmental impact of waste disposal by burning. Two matrices (thermoset and thermoplastic) were used. Optimization of manufacture conditions of polyester-based thermosetting polymer composites was carried out through examine the effects of fibers to polymer ratio, amounts of catalyzed and initiator, fraction size of fibers and substituting one fibers by another, as well as time, temperature and pressure of pressing. The possibility of styrene containing polyester solution on improving the fiber interface via in situ grafting and enhancing the strength and water resistance of the produced NFPC was also evaluated, in comparison with that produced from using thermoplastic matrix (polypropylene) in presence of coupling agent. The production of this valuable product (NFPC) by this simple procedure, which not needs special devices (twin extrusion with heater), and chemicals to improve the compatibility between fibers and polymer matrix, will ensure reasonable profits and direct impacts on the Egyptian economy in general and rice growers in particular.     

Future ocean acidification will be amplified by hypoxia in coastal habitats

Ocean acidification is elicited by anthropogenic carbon dioxide emissions and resulting oceanic uptake of excess CO₂ and might constitute an abiotic stressor powerful enough to alter marine ecosystem structures. For surface waters in gas-exchange equilibrium with the atmosphere, models suggest increases in CO₂ partial pressure (pCO₂) from current values of ca. 390 μatm to ca. 700–1,000 μatm by the end of the century. However, in typically unequilibrated coastal hypoxic regions, much higher pCO₂ values can be expected, as heterotrophic degradation of organic material is necessarily related to the production of CO₂ (i.e., dissolved inorganic carbon). Here, we provide data and estimates that, even under current conditions, maximum pCO₂ values of 1,700–3,200 μatm can easily be reached when all oxygen is consumed at salinities between 35 and 20, respectively. Due to the nonlinear nature of the carbonate system, the approximate doubling of seawater pCO₂ in surface waters due to ocean acidification will most strongly affect coastal hypoxic zones as pCO₂ during hypoxia will increase proportionally: we calculate maximum pCO₂ values of ca. 4,500 μatm at a salinity of 20 (T = 10 °C) and ca. 3,400 μatm at a salinity of 35 (T = 10 °C) when all oxygen is consumed. Upwelling processes can bring these CO₂-enriched waters in contact with shallow water ecosystems and may then affect species performance there as well. We conclude that (1) combined stressor experiments (pCO₂ and pO₂) are largely missing at the moment and that (2) coastal ocean acidification experimental designs need to be closely adjusted to carbonate system variability within the specific habitat. In general, the worldwide spread of coastal hypoxic zones also simultaneously is a spread of CO₂-enriched zones. The magnitude of expected changes in pCO₂ in these regions indicates that coastal systems may be more endangered by future global climate change than previously thought.     

The safety barometer: How safe is my plant today? Is instantaneously measuring safety level utopia or realizable?

During the last decade, serious accidents have continued to occur in the process industry. Apparently the scenarios of various undesired events leading to those accidents are still not sufficiently controlled. The key question is how potentially hazardous situations develop, what processes form the basis for this development, and how to control them? Safety level is not static but depends on many risk factors that change in presence and intensity over location and time. Safety level is dependent not only on technical process parameters that have immediate effects on the ‘frequency’ or probability of catastrophic consequences, but also depends on equipment integrity degradation, operational and management quality, attitudes, and cultural processes which may change over a prolonged time. The time and human interaction aspects make dynamic risk assessment complex. This paper will outline a conceptual approach using in addition to the regular process parameter signals received, also weak and slowly changing signals from various safety indicators, enabling to keep track of the risk factors. In theory this could lead to obtaining an instantaneous safety level ‘measure’ making possible forecast alarming for an imminent event to occur. Such concept could be regarded as a ‘writing’ safety barometer, or barograph. However, there are quite a number of problems to be solved which in the paper will be discussed.     

Meeting Heterogeneity in Consumer Demand for Animal Welfare: A Reflection on Existing Knowledge and Implications for the Meat Sector

The legitimacy of the dominant intensive meat production system with respect to the issue of animal welfare is increasingly being questioned by stakeholders across the meat supply chain. The current meat supply is highly undifferentiated, catering only for the extremes of morality concerns (i.e., conventional vs. organic meat products). However, a latent need for compromise products has been identified. That is, consumer differences exist regarding the trade-offs they make between different aspects associated with meat consumption. The heterogeneity in consumer demand could function as a starting point for market segmentation, targeting and positioning regarding animal welfare concepts that are differentiated in terms of animal welfare and price levels. Despite this, stakeholders in the meat supply chain seem to be trapped in the dominant business model focused on low cost prices. This paper aims to identify conflicting interests that stakeholders in the meat supply chain experience in order to increase understanding of why heterogeneous consumer preferences are not met by a more differentiated supply of meat products produced at different levels of animal welfare standards. In addition, characteristics of the supply chain that contribute to the existence of high exit barriers and difficulty to shift to more animal-friendly production systems are identified. Following the analysis of conflicting interests among stakeholders and factors that contribute to difficulty to transform the existing dominant regime, different routes are discussed that may help and motivate stakeholders to overcome these barriers and stimulate the creation of new markets.     

Contrasting Landscape Influences on Sediment Supply and Stream Restoration Priorities in Northern Fennoscandia (Sweden and Finland) and Coastal British Columbia

Sediment size and supply exert a dominant control on channel structure. We review the role of sediment supply in channel structure, and how regional differences in sediment supply and landuse affect stream restoration priorities. We show how stream restoration goals are best understood within a common fluvial geomorphology framework defined by sediment supply, storage, and transport. Landuse impacts in geologically young landscapes with high sediment yields (e.g., coastal British Columbia) typically result in loss of instream wood and accelerated sediment inputs from bank erosion, logging roads, hillslopes and gullies. In contrast, northern Sweden and Finland are landscapes with naturally low sediment yields caused by low relief, resistant bedrock, and abundant mainstem lakes that act as sediment traps. Landuse impacts involved extensive channel narrowing, removal of obstructions, and bank armouring with boulders to facilitate timber floating, thereby reducing sediment supply from bank erosion while increasing export through higher channel velocities. These contrasting landuse impacts have pushed stream channels in opposite directions (aggradation versus degradation) within a phase-space defined by sediment transport and supply. Restoration in coastal British Columbia has focused on reducing sediment supply (through bank and hillslope stabilization) and restoring wood inputs. In contrast, restoration in northern Fennoscandia (Sweden and Finland) has focused on channel widening and removal of bank-armouring boulders to increase sediment supply and retention. These contrasting restoration priorities illustrate the consequences of divergent regional landuse impacts on sediment supply, and the utility of planning restoration activities within a mechanistic sediment supply-transport framework.