Sulfate-enriched water effects on a floodplain forest in Florida

Sulfate-enriched water that was discharged experimentally into a floodplain forest in Florida caused H₂S formation, and trees showed signs of stress within one year. Chloride-enriched water also caused trees to show signs of stress. Trees in this ecosystem may also be sensitive to changes in hydroperiod.     

Evaluating Participatory Modeling: Developing a Framework for Cross-Case Analysis

Participatory modeling is increasingly recognized as an effective way to assist collective decision-making processes in the domain of natural resource management. This article introduces a framework for evaluating projects that have adopted a participatory modeling approach. This evaluation framework—known as the “Protocol of Canberra”—was developed through a collaboration between French and Australian researchers engaged in participatory modeling and evaluation research. The framework seeks to assess the extent to which different participatory modeling initiatives not only modify perceptions among and interactions between participants, but also contribute to collective decision-making. The article discusses the development of the framework and it’s application to three case-studies, two from Australia and one from the Pacific Island of the Republic of Kiribati. The article concludes with some comments for future use of the framework in a range of participatory modeling contexts.     

Metal capital sustaining a North American city: Iron and copper in New Haven, CT

A detailed inventory shows that an average resident of the City of New Haven depends on a per capita capital stock of 9200 kg/c of iron and 144 kg/c of copper in the city infrastructure, buildings, transportation systems, and equipment. Of the iron stock 28% is in items such as rail cars and ships in ocean trade not permanently within the city, and 22% is devoted to receiving and delivering oil fuel to the city and its surrounding communities. Copper is principally used in the distribution of electric power and in water piping within buildings. The city's 9200 kg/c of iron stock-in-use is less than the 13,000 kg/c national average due to New Haven's lack of heavy industry and relatively small number of large buildings. The 144 kg/c of copper stock-in-use is only 58% of the overall value for the United States, but is comparable to that in cities such as Stockholm, Sweden. Attainment of a level of iron and copper services with contemporary technology in less developed countries to the level enjoyed in New Haven would require consumption of the presently identified world copper resources.     

Structure and function of a warm monomictic lake

Construction and simulation of a model of Lake Conway, Florida, U.S.A., provided a framework for defining major characteristics of this ecosystem. The relationships that are formalized in this model comprise a set of hypotheses about the nature of a warm monomictic lake. The data that were used to parameterize the model came primarily from literature estimates, although approximations of biomass levels were available from associated research conducted on the lake.Submersed macrophytes are a major biomass component in Lake Conway; simulation suggested that their role in nutrient recycling overshadows their importance in the grazing food chain. Phytoplankton biomass and degree of fluctuation are considerably lower than are observed in most cool temperate lakes, although simulated respiration and herbivory rates are closer to temperate values than tropical values. Simulated epipelic algae biomass varies an order of magnitude during the year, and this group appears to be a significant part of the food chain. Simulated zooplankton consumption and turnover rates are very high, in part because of the relatively small biomass per individual. Simulation of the model suggests that slightly more carbon is processed through the grazing food chain in Lake Conway than through the detritus food chain.     

Theoretical and Observational Assessments of Flare Efficiencies

ABSTRACT

Flaring of waste gases is a common practice in the processing of hydrocarbon (HC) materials. It is assumed that flaring achieves complete combustion with relatively innocuous byproducts such as CO₂ and H₂O. However, flaring is rarely successful in the attainment of complete combustion, because entrainment of air into the region of combusting gases restricts flame sizes to less than optimum values. The resulting flames are too small to dissipate the amount of heat associated with 100% combustion efficiency.

Equations were employed to estimate flame lengths, areas, and volumes as functions of flare stack exit velocity, stoichiometric mixing ratio, and wind speed. Heats released as part of the combustion process were then estimated from a knowledge of the flame dimensions together with an assumed flame temperature of 1200 K. Combustion efficiencies were subsequently obtained by taking the ratio of estimated actual heat release values to those associated with 100% complete combustion.

Results of the calculations showed that combustion efficiencies decreased rapidly as wind speed increased from 1 to 6 m/sec. As wind speeds increased beyond 6 m/sec,combustion efficiencies tended to level off at values between 10 and 15%. Propane and ethane tend to burn more efficiently than do methane or hydrogen sulfide because of their lower stoichiometric mixing ratios.

Results of theoretical predictions were compared to nine values of local combustion efficiencies obtained as part of an observational study into flaring activity conducted by the Alberta Research Council (ARC). All values were obtained during wind speed conditions of less than 4 m/sec. There was generally good agreement between predicted and observed values. The mean and standard deviation of observed combustion efficiencies were 68 ± 7%. Comparable predicted values were 69 ± 7%.     

The employee as a punching bag: The effect of multiple sources of incivility on employee withdrawal behavior and sales performance

The link between the interpersonal stressor of workplace mistreatment and objective measures of performance is often overlooked in organizational research. In order to fill this research gap, we examined the unique and combined effects of two sources of incivility (customer and coworker) on objective sales performance and withdrawal behaviors (absenteeism and tardiness). We hypothesized that coworker and customer incivility would interact to predict reduced performance and increased withdrawal, using the conservation of resources model to support our hypotheses. We surveyed 120 bank tellers regarding experienced incivility and obtained performance and withdrawal data spanning a period of several months following the survey. The data indicated that coworker and customer incivility did interact to predict decreased sales performance and increased absenteeism, supporting the majority of our proposed hypotheses. Theoretical and practical implications of the findings and future directions are discussed. Copyright © 2011 John Wiley & Sons, Ltd.