Experimental measurement and numerical analysis of binary hydrocarbon mixture flammability limits

The flammability limits of binary hydrocarbon mixtures in air were measured in a combustion apparatus using an innovative method developed for this apparatus. The experimental results were obtained at standard conditions (room temperature and ambient atmospheric pressure) with upward flame propagation. The experimentally determined flammability limits for pure hydrocarbons (methane and ethylene) were compared with existing data reported in the literature. Le Chatelier's Law was fit to all experimental data to obtain LFLs and UFLs for various two-component combinations of saturated and unsaturated hydrocarbons (methane, ethylene, acetylene, propane, propylene, and n-butane). A modification of this law was used if experimental observations showed large deviations from Le Chatelier's predictions. Also, experimentally measured flammability limit data of the binary hydrocarbon mixtures were analytically related to the stoichiometric concentrations.     

Integrated modelling of climate control and air pollution: Methodology and results from one-way coupling of an energy–environment–economy (E3MG) and atmospheric chemistry model (p-TOMCAT) in decarbonising scenarios for Mexico to 2050

This paper reports the methodology and results of an one-way coupling of the E3 Model at the Global level (E3MG) model to the global atmospheric chemistry model, p-TOMCAT, to assess the effects on the concentrations of atmospheric gases over Mexico of a low-GHG scenario compared to an alternative reference case with higher use of fossil fuels. The paper covers the data and methods, changes in atmospheric gas concentrations, the macroeconomic effects of the policies, and the outcome for pollution. The results suggest that in the conditions of underemployment in Mexico, substantial investment in low-carbon technologies, such as electric vehicles, heat pumps and geo-thermal power, could improve employment prospects, maintain growth, as well as reduce some of the risks associated with prospective falls in oil revenues. The concentrations of low-level ozone, both for Mexico-only and global decarbonisation scenarios relative to the original reference case, show appreciable reductions, sufficient to bring concentrations close to the WHO guideline levels. An indication is given of the potential scale of the benefits on human health in Mexico City.     

How to consolidate Trevor’s experience and knowledge? Impossibilities,reflections on possibilities,and call to action

Looking back, significant progress in process safety and the knowledge to achieve a safe level has been made. Professor Kletz with his wise and concise maxims has shown us in many respects the way to go, yet more direction is needed for transfer of this knowledge to new generations. After a brief problem analysis, a sketch is given of various developments in the field of process safety, such as our knowledge on hazardous properties, hazard and risk analysis tools, human aspects, trends and developments in industry, and future perspectives. Subsequently, an analysis is made of the knowledge infrastructure required to maintain and to improve a knowledge base. In particular, scenario identification and modeling is mentioned. To that end the ‘lessons learned’ in the past should be better used. This has proven not to be easy. A way to go is indicated that in the longer term may reap success. However, in the present climate, funds for research are scarce and that for safety research are scant. Research is not only to develop new knowledge but is also of crucial importance to maintain quality academic education and the formation of ‘teacher of teachers’. A recent initiative is reported to bring this problem to the attention of policy makers worldwide.     

Social preferences for the design of biodiversity offsets for shorebirds in Australia

Understanding the social acceptability of biodiversity offsets is important to the design of offset policy. We used a discrete choice experiment to quantify preferences of Australians for a migratory shorebird offset in the context of an oil and gas development project. We surveyed a nationally representative sample of 1371 respondents on their preferences for current and prospective offset‐policy characteristics via an online questionnaire to inform policy design of the social dimensions related to offset acceptability. The majority of respondents accepted offsetting as a means to allow economic development; the option to reject development (and an offset) was selected in 13% of possible offset scenarios. Substituting protection of a species affected by the development with protection of a more endangered species was a desirable policy characteristic, as was having the offset implemented by a third party or the government rather than the company responsible for the development. Direct offset activities (e.g., improving degraded habitat) were preferred over indirect activities (e.g., a research program), and respondents were strongly against locating the offset at a site other than where the impact occurred. Positive and negative characteristics of offsets could be traded off by changing the number of birds protected by the offset. Our results show that Australians are likely to support increased flexibility in biodiversity‐offset policies, particularly when undesirable policy characteristics are compensated for.     

Small-scale medical waste incinerators--experiences and trials in South Africa

Formal waste management services are not accessible for the majority of primary healthcare clinics on the African continent, and affordable and practicable technology solutions are required in the developing country context. In response, a protocol was established for the first quantitative and qualitative evaluation of relatively low cost small-scale incinerators for use at rural primary healthcare clinics. The protocol comprised the first phase of four, which defined the comprehensive trials of three incineration units. The trials showed that all of the units could be used to render medical waste non-infectious, and to destroy syringes or render needles unsuitable for reuse. Emission loads from the incinerators are higher than large-scale commercial incinerators, but a panel of experts considered the incinerators to be more acceptable compared to the other waste treatment and disposal options available in under-serviced rural areas. However, the incinerators must be used within a safe waste management programme that provides the necessary resources in the form of collection containers, maintenance support, acceptable energy sources, and understandable operational instructions for the incinerators, whilst minimising the exposure risks to emissions through the correct placement of the units in relation to the clinic and the surrounding communities. On-going training and awareness building are essential in order to ensure that the incinerators are correctly used as a sustainable waste treatment option.     

Woodlot management and livelihoods in a tropical conservation landscape

In biodiversity hotspots, there is often tension between human needs and conservation, exacerbated when protected areas prevent access to natural resources. Forest-dependent people may compensate for exclusion by managing unprotected forests or cultivating planted woodlots. Outside Bwindi Impenetrable National Park in Uganda, household wood product needs are high and population growth puts pressure on the environment. We investigated the role of privately and collectively managed woodlots in provisioning wood products and supporting local livelihoods. We found that households relied heavily on woodlots for daily needs and as resources during time of need. We also found that locally relevant social institutions, called stretcher groups, played a role in the management of woodlots, providing shared community resources. Privately and collectively owned woodlots support local livelihoods and wood product needs in the region. Long-term management of forests in Uganda should consider the value of woodlots and the mechanisms required to support them.     

Wind Tunnel Testing of Open Top Field Chambers for Plant Effects Assessment

ABSTRACT

This study reports the first field measurements of airborne exavalent chromium (Cr(vi)) in southwestern Ontario. Hexavalent chromium was identified as an inhalation carcinogen and an air toxic of concern during the 1991-93 Windsor Air Quality Study. The results of that study indicated that approximately 20% of the routinely monitored ambient airborne chromium (Cr) was in the hexavalent form. In addition, the range of carcinogenic health risks attributable to airborne Cr(vi) was determined to be between 1.4 x IO⁶ and 3.0 x 10^-4 for people living in the Windsor area. During the summer of 1993, analyses of concurrent indoor and outdoor 24-hour air quality samples taken at 33 residences in Hamilton resulted in geometric mean Cr(vi) concentrations of 0.20 r|g/m³ and 0.55 r|g/m³, respectively, and little or no relationship between the indoor and outdoor sample sets. During the summer of 1994, an airborne Cr(vi) size-fractionation study was conducted in Hamilton, the results of which suggested that the majority of the Cr(vi) was in the inhalable fraction.     

DISSOLVED HEAVY METALS IN SHALLOW GROUND WATER IN A SOUTHEASTERN MICHIGAN URBAN WATERSHED1

ABSTRACT: The occurrence of dissolved heavy metal concentrations in shallow ground water were measured at 126 sites within an urban watershed in southeastern Michigan. A total of 1,140 samples were collected from the first saturated zone, and the mean concentrations of 11 heavy metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc) were obtained and compared to their corresponding mean concentrations within surface soil. The results suggest that former and current land use processes have resulted in significant adverse impacts on the study region. Levels of Cr 20 to 30 times the maximum contaminant level (MCL) have been detected in the ground water beneath industrial sites. In addition, Cd and Pb have been found at levels exceeding their MCLs where surface soils are clay‐rich, and in sandy soils at more than 10 times their MCLs. The high levels of Cr in ground water strongly suggest that the chromium is in a hexavalent form, and this likelihood is supported by current studies. Given the hydraulic connection between the watershed's surface waters and the Great Lakes, these findings raise significant ecological and public health concerns.     

Structural marsh management effects on coastal fishes and crustaceans

Structural marsh management, using levees and water-control structures, is used in the coastal zone for many objectives, for example, to reduce marsh loss, to enhance waterfowl habitat, to revegetate open-water areas, and to reduce saltwater intrusion. The literature was evaluated to categorize structural marsh management and to determine some of its effects on fishes and crustaceans. Structural marsh management had positive effects on standing stock of most resident organisms and negative effects on marine-transient organisms. Emigration was negatively affected for both resident and marine-transient organisms. Techniques such as opening structures at critical migration times, designing structures that offer the greatest management flexibility, and using structures to create a flow-through system could reduce these impacts. More effort should be put into monitoring managed areas to determine if the objectives are being met and to evaluate the effects on fishes and crustaceans. Although frequent manipulation could reduce these impacts, the costs and problems incurred may outweigh the anticipated benefits.     

EMERGY-based environmental systems assessment of a multi-purpose temperate mixed-forest watershed of the southern Appalachian Mountains, USA

Emergy (with an 'm') synthesis was used to assess the balance between nature and humanity and the equity among forest outcomes of a US Forest Service ecosystem management demonstration project on the Wine Spring Creek watershed, a high-elevation (1600 m), temperate forest located in the southern Appalachian mountains of North Carolina, USA. EM embraces a holistic perspective, accounting for the multiple temporal and spatial scales of forest processes and public interactions, to balance the ecological, economic, and social demands placed on land resources. Emergy synthesis is a modeling tool that allows the structure and function of forest ecosystems to be quantified in common units (solar emergy-joules, sej) for easy and meaningful comparison, determining 'system-value' for forcing factors, components, and processes based on the amount of resources required to develop and sustain them, whether they are money, material, energy, or information. The Environmental Loading Ratio (ELR), the units of solar emergy imported into the watershed via human control per unit of indigenous, natural solar emergy, was determined to be 0.42, indicating that the load on the natural environment was not ecologically damaging and that excess ecological capacity existed for increasing non-ecological activities (e.g. timbering, recreation) to achieve an ELR of 1.0 (perfect ecological-economic balance). Three forest outcomes selected to represent the three categories of desired sustainability (ecological, economic, and social) were evaluated in terms of their solar emergy flow to measure outcome equity. Direct economic contribution was an order of magnitude less (224 x 10(12)solar emergy-joules (sej) ha(-1)) than the ecological and social contributions, which were provided at annual rates of 3083 and 2102 x 10(12)sejha(-1), respectively. Emergy synthesis was demonstrated to holistically integrate and quantify the interconnections of a coupled nature-human system allowing the goals of ecological balance and outcome equity to be measured quantitatively.