A model for the initial stages following the rupture of a natural gas transmission pipeline

Experience shows that, despite the best efforts of the pipeline industry worldwide, pipelines do fail and release their contents to the atmosphere. In the case of below-ground pipelines transmitting natural gas, there is a chance that the release will be ignited, posing a significant hazard to any people in the vicinity. Mindful of this hazard, an international group of gas companies have collaborated over a period of many years on research projects aimed at developing an understanding of how these releases may arise (failure causes), how often they might occur (failure frequency), what type of releases might be produced (failure modes) and what type of behaviour might be produced for each of these modes of release (consequence analysis). This paper has been prepared to describe the mathematical models that have been developed on behalf of this group to assess the initial transient period following the rupture of a buried natural gas transmission pipeline assuming the release ignites immediately. It gives details of the equations used by the different models and it refers to some of the experimental data that has been used in the development of the models. A comparison of the model with the experimental data is provided. This demonstrates that the early stages could have a significant impact when evaluating the harm that could be caused. This provides a justification for developing the models rather than using a simpler alternative that does not take the initial highly transient period into account.     

Estimating the Density of Honeybee Colonies across Their Natural Range to Fill the Gap in Pollinator Decline Censuses

Abstract: Although pollinator declines are a global biodiversity threat, the demography of the western honeybee (Apis mellifera) has not been considered by conservationists because it is biased by the activity of beekeepers. To fill this gap in pollinator decline censuses and to provide a broad picture of the current status of honeybees across their natural range, we used microsatellite genetic markers to estimate colony densities and genetic diversity at different locations in Europe, Africa, and central Asia that had different patterns of land use. Genetic diversity and colony densities were highest in South Africa and lowest in Northern Europe and were correlated with mean annual temperature. Confounding factors not related to climate, however, are also likely to influence genetic diversity and colony densities in honeybee populations. Land use showed a significantly negative influence over genetic diversity and the density of honeybee colonies over all sampling locations. In Europe honeybees sampled in nature reserves had genetic diversity and colony densities similar to those sampled in agricultural landscapes, which suggests that the former are not wild but may have come from managed hives. Other results also support this idea: putative wild bees were rare in our European samples, and the mean estimated density of honeybee colonies on the continent closely resembled the reported mean number of managed hives. Current densities of European honeybee populations are in the same range as those found in the adverse climatic conditions of the Kalahari and Saharan deserts, which suggests that beekeeping activities do not compensate for the loss of wild colonies. Our findings highlight the importance of reconsidering the conservation status of honeybees in Europe and of regarding beekeeping not only as a profitable business for producing honey, but also as an essential component of biodiversity conservation.     

The sense of snow – Individuals’ perception of fatal avalanche events

This empirical paper aims at examining individuals’ risk perception in the context of an environmental disaster. Risk is defined as probability of dying in a snow avalanche. Risk perception is analyzed from two different perspectives: (i) individuals’ estimate of the average avalanche risk and (ii) the perceived personal avalanche risk. The perception of personal risk is summarized in an ordered categorical variable, average risk perception is captured by a measurement previously used in risk communication that results in a continuous variable. The variation in risk perception observed is examined by using individual leisure activities (skiing) and the timing of the survey (fall vs. winter) as proxies for frequency, familiarity, controllability, voluntariness, and beneficiary of risk exposure and by including several individual specific characteristics such as age, gender, education, income. The results show that risk as well as individual specific characteristics are significant determinants of participants’ perception of risk but their relevance differs depending on whether the focus is on perception of average risk or of personal risk.     

Possible linkages between lignite aquifers, pathogenic microbes, and renal pelvic cancer in northwestern Louisiana, USA

In May and September, 2002, 14 private residential drinking water wells, one dewatering well at a lignite mine, eight surface water sites, and lignite from an active coal mine were sampled in five Parishes of northwestern Louisiana, USA. Using a geographic information system (GIS), wells were selected that were likely to draw water that had been in contact with lignite; control wells were located in areas devoid of lignite deposits. Well water samples were analyzed for pH, conductivity, organic compounds, and nutrient and anion concentrations. All samples were further tested for presence of fungi (cultures maintained for up to 28 days and colonies counted and identified microscopically) and for metal and trace element concentration by inductively-coupled plasma mass spectrometry and atomic emission spectrometry. Surface water samples were tested for dissolved oxygen and presence of pathogenic leptospiral bacteria. The Spearman correlation method was used to assess the association between the endpoints for these field/laboratory analyses and incidence of cancer of the renal pelvis (RPC) based on data obtained from the Louisiana Tumor Registry for the five Parishes included in the study. Significant associations were revealed between the cancer rate and the presence in drinking water of organic compounds, the fungi Zygomycetes, the nutrients PO₄ and NH₃, and 13 chemical elements. Presence of human pathogenic leptospires was detected in four out of eight (50%) of the surface water sites sampled. The present study of a stable rural population examined possible linkages between aquifers containing chemically reactive lignite deposits, hydrologic conditions favorable to the␣leaching and transport of toxic organic compounds from the lignite into the groundwater, possible microbial contamination, and RPC risk.     

Characteristics of Urban Natural Areas Influencing Winter Bird Use in Southern Ontario,Canada

Characteristics of urban natural areas and surrounding landscapes were identified that best explain winter bird use for 28 urban natural areas in southern Ontario, Canada. The research confirms for winter birds the importance of area (size) and natural vegetation, rather than managed, horticultural parkland, within urban natural areas as well as percent urban land use and natural habitat in surrounding landscapes. Alien bird density and percent ground feeding species increased with percent surrounding urban land use. Higher percent forest cover was associated with higher percentages of forest, bark feeding, small (<20 g) and insectivorous species. Natural area size (ha) was related to higher species richness, lower evenness and higher percentages of insectivorous, forest interior, area-sensitive, upper canopy, bark feeding, and non-resident species. Higher number of habitat types within natural areas and percent natural habitat in surrounding landscapes were also associated with higher species richness. Common, resident bird species dominated small areas (<6.5 ha), while less common non-residents increased with area, indicative of a nested distribution. Areas at least 6.5 ha and more generally >20 ha start to support some area-sensitive species. Areas similar to rural forests had >25% insectivores, >25% forest interior species, >25% small species, and <5% alien species. Indicator species separated urban natural areas from rural habitats and ordination placed urban natural areas along a gradient between urban development and undisturbed, rural forests. More attention is needed on issues of winter bird conservation in urban landscapes.     

Chemical composition and antifungal activity of Chelidonium majus extracts – antagonistic action of chelerythrine and sanguinarine against Botrytis cinerea

This study discusses the similarities and differences between the antifungal activity of Chelidonium majus L. extracts and chelerythrine/sanguinarine, the main alkaloids in these extracts, against the plant pathogenic fungus, Botrytis cinerea. The obtained data show that the Ch. majus L. extracts inhibit the growth of B. cinerea very effectively. The extracts activity is significantly greater than that of chelerythrine/sanguinarine standard solutions alone and it does not always reflect the total content of alkaloids in the extracts. It has been proved that B. cinerea exhibits very diverse resistance to chelerythrine and sanguinarine. The IC₅₀ values for chelerythrine and sanguinarine equal 5.41?mg/mL and 1.76?mg/mL, respectively. In the mixture the antifungal activity of chelerythrine and sanguinarine is antagonistic in the concentration dependent way. Based on the presented data it is not clear, however, which alkaloids present in the Ch, majus extracts at significantly lower concentration levels enhance the activity of chelerythrine and sanguinarine so that the extracts activity is considerably greater than that of both main alkaloids mixtures.     

Assessing the natural attenuation of organic contaminants in aquifers using plume-scale electron and carbon balances: model development with analysis of uncertainty and parameter sensitivity

A quantitative methodology is described for the field-scale performance assessment of natural attenuation using plume-scale electron and carbon balances. This provides a practical framework for the calculation of global mass balances for contaminant plumes, using mass inputs from the plume source, background groundwater and plume residuals in a simplified box model. Biodegradation processes and reactions included in the analysis are identified from electron acceptors, electron donors and degradation products present in these inputs. Parameter values used in the model are obtained from data acquired during typical site investigation and groundwater monitoring studies for natural attenuation schemes. The approach is evaluated for a UK Permo-Triassic Sandstone aquifer contaminated with a plume of phenolic compounds. Uncertainty in the model predictions and sensitivity to parameter values was assessed by probabilistic modelling using Monte Carlo methods. Sensitivity analyses were compared for different input parameter probability distributions and a base case using fixed parameter values, using an identical conceptual model and data set. Results show that consumption of oxidants by biodegradation is approximately balanced by the production of CH4 and total dissolved inorganic carbon (TDIC) which is conserved in the plume. Under this condition, either the plume electron or carbon balance can be used to determine contaminant mass loss, which is equivalent to only 4% of the estimated source term. This corresponds to a first order, plume-averaged, half-life of > 800 years. The electron balance is particularly sensitive to uncertainty in the source term and dispersive inputs. Reliable historical information on contaminant spillages and detailed site investigation are necessary to accurately characterise the source term. The dispersive influx is sensitive to variability in the plume mixing zone width. Consumption of aqueous oxidants greatly exceeds that of mineral oxidants in the plume, but electron acceptor supply is insufficient to meet the electron donor demand and the plume will grow. The aquifer potential for degradation of these contaminants is limited by high contaminant concentrations and the supply of bioavailable electron acceptors. Natural attenuation will increase only after increased transport and dilution.     

A Screening Procedure for Prioritizing Riparian Management

A spatially explicit linear, additive model was developed for quantifying site characteristics of riparian areas of the lower Cedar River, Washington, USA. The spatial complexity and distribution of combined habitat and anthropogenic landscape features were used to define habitat indices that indicate the relative quality of riparian habitats. Patches of contiguous grid cells were measured in terms of their locations, sizes, and relative degree of fragmentation. Additionally, intrapatch heterogeneity was measured to identify unique combinations of habitat and anthropogenic factors for individual grid cells within patches. Model verification indicated that existing floodplain riparian habitats received positive indices more than 90% of the time. Mean patch sizes and fragmentation indices were similar for all positive indices throughout the reaches in the valley floor. Among all reaches, reach 7 had the highest number of positive patches due to a higher degree of meandering in this reach. This procedure and model outputs provide unique screening opportunities for prioritizing management of riparian areas (e.g., conservation, restoration and enhancement).     

Success factors in community based natural resources management in northern Botswana: Lessons from practice

The article explores and examines challenges and lessons learned from the implementation of community based natural resources management (CBNRM) programmes in Ngamiland, northern Botswana. The article, based largely on primary data, with some secondary data sources, draws on the CBNRM framework, which promotes rural socio‐economic development and natural resources management. Among the key factors identified as pivotal to the success of CBNRM is broadening the consultation base during the mobilization phase of the programme to facilitate effective community participation and representation. Preparedness by both the implementing institutions and participating communities is also highlighted as key to effective mobilization. This means moving away from a conventional consultative forum, to a more multi‐faceted approach that will facilitate capturing the views of diverse user groups within the community. The article also suggests that feasibility studies are needed to address socio‐economic, political and cultural characteristics inherent in communities to guide programme implementation. To achieve increased community participation and enhance positive conservation attitudes, the article advocates a mobilization approach and practice that will effectively facilitate the process.     

Women and natural resource management: Illustrations from India and Nepal

This article attempts to delineate women's roles in natural resource management by highlighting their roles in management of water, agriculture, livestock, forestry and fishery. The article is based on the findings of case studies in rural areas of India and Nepal done during 2003 and 2004 by the author as well as by other researchers. Taking women as primary respondents, empirical work used participatory techniques, such as in‐depth surveys, focus group discussions and participant observation. Findings suggest that women clearly outdo men in terms of their involvement in use and management of all the studied sectors, i.e., water, agriculture, livestock, forestry and fishery. Yet, they face categorical exclusion and denial of equal sharing of benefits from natural resources. In order to ensure sustainable use of these resources, the article recommends that policy makers, planners and development workers must have a better understanding of the relative and often shifting roles of men and women in natural resource management, including division of labour, access to resources, decision‐making and traditional knowledge and practices. The article concludes with sector‐specific recommendations.