Methodology and model for performance and cost comparison of innovative treatment technologies at wood preserving sites

Wood preserving facilities have used a variety of compounds, including pentachlorophenol (PCP), creosote, and certain metals, to extend the useful life of wood products. Past operations and waste management practices resulted in soil and water contamination at a portion of the more than 700 wood preserving sites in the United States (EPA, 1997). Many of these sites are currently being addressed under federal, state, or voluntary cleanup programs. The U.S. Environmental Protection Agency (EPA) National Risk Management Research Laboratory (NRMRL) has responded to the need for information aimed at facilitating remediation of wood preserving sites by conducting treatability studies, issuing guidance, and preparing reports. This article presents a practical methodology and computer model for screening the performances and comparing the costs of seven innovative technologies that could be used for the treatment of contaminated soils at user‐specified wood preserving sites. The model incorporates a technology screening function and a cost‐estimating function developed from literature searches and vendor information solicited for this study. This article also provides background information on the derivation of various assumptions and default values used in the model, common contaminants at wood preserving sites, and recent trends in the cleanup of such sites. © 2001 John Wiley & Sons, Inc.     

Is there a common metals demand curve?

Previous studies have identified a single, stable and strong correlation between the price of metals and their consumption, such that low priced metals are always used in large amounts and visa versa. Some have interpreted this as evidence that metals share a common demand curve so that a single price elasticity of demand exists. This paper reviews and tests this hypothesis against a number of other possible explanations, including the idea that the relationship is an empirical curiosity. Modifications to the demand curve were tested by allowing metals to have different intercepts and price elasticities. The results from this analysis suggest that metals do not share a common demand curve and that the correlation identified between the price of metals and their level of consumption is an empirical curiosity. As such, the singular price elasticities published in past papers should not be used for assessing future rates of metals substitution.     

Long‐Term Trends of Specific Conductance in Waters Discharged by Coal‐Mine Valley Fills in Central Appalachia,USA

Anthropogenic salinization of freshwaters is a global concern. Coal surface mining causes release of dissolved sulfate, bicarbonate, calcium, magnesium, and other ions to surface waters in central Appalachia, USA, through practices that include mine rock disposal in valley fills (VFs). This region's surface waters naturally have low salinity, with specific conductance (SC, a salinity indicator) generally <200 μS/cm, and aquatic impacts have been found when SC exceeds the 300 to 500 μS/cm range. We analyzed SC in waters emerging from 137 VFs over periods of 1 to 23 years. Mean SCs for these VFs ranged from 227 to 2,866 μS/cm, generally rose during and immediately following construction, but often declined during latter portions of longer monitoring records. Seventy‐four of 103 VFs with postconstruction data had SC trends that fit negative quadratic forms. Of the 16 revegetated VFs with at least five years of SC data past the quadratic maximum, the mean quadratic maximum was 1,464 (±696) μS/cm and the model projected time required to approach natural conditions (by declining to <500 μS/cm) was 19.6 (±6.6) years after VF construction initiation, indicating long‐lasting but not permanent aquatic impacts due to elevated (>500 μS/cm) SC.     

Strategic directions for agent-based modeling: avoiding the YAAWN syndrome

In this short communication, we examine how agent-based modeling has become common in land change science and is increasingly used to develop case studies for particular times and places. There is a danger that the research community is missing a prime opportunity to learn broader lessons from the use of agent-based modeling (ABM), or at the very least not sharing these lessons more widely. How do we find an appropriate balance between empirically rich, realistic models and simpler theoretically grounded models? What are appropriate and effective approaches to model evaluation in light of uncertainties not only in model parameters but also in model structure? How can we best explore hybrid model structures that enable us to better understand the dynamics of the systems under study, recognizing that no single approach is best suited to this task? Under what circumstances – in terms of model complexity, model evaluation, and model structure – can ABMs be used most effectively to lead to new insight for stakeholders? We explore these questions in the hope of helping the growing community of land change scientists using models in their research to move from ‘yet another model’ to doing better science with models.     

Physiological changes associated with aging result in lower internal doses of toluene and perchloroethylene in simulations using pharmacokinetic modeling

Physiologically based pharmacokinetic (PBPK) models were developed in order to translate external concentrations into internal dose estimates, but most PBPK models were developed for younger adults. A set of physiological parameters for ages 65, 75, and 85 of both genders were developed and were used with previously established human PBPK models of exposure to toluene and perchloroethylene (PERC) in order to investigate internal dose changes with increasing age. The predicted compartmental concentrations of toluene and PERC for aged adults were lower than predicted concentrations for younger adults, and this suggests that body composition changes with aging do not increase internal doses of inhaled toxicants alone after acute exposure. Hence, susceptibility to either toxicant was not expected to increase solely based on the physiological changes associated with aging. Predictions for a metabolite of PERC, however, were similar in magnitude across ages, which may lead to enhanced susceptibility if metabolic capacity changes with aging.     

Use of Life Cycle Assessment in Environmental Management

The aim of this paper is to demonstrate how life cycle assessment (LCA) can be used to develop strategic policies that can lead to a minimization of the environmental burden resulting from the provision of services or the manufacture, use, and disposal of products within the economy. We accomplish this aim by presenting a case study that evaluates the greenhouse gas contributions of each stage in the life cycle of containerboard packaging and the potential impact on emissions of various policy options available to decision-makers. Our analysis showed that, in general, the most useful strategy was to recycle the used packaging. However, our analysis also indicated that when measures are taken to eliminate sources of methane emissions, then recycling is no longer beneficial from a greenhouse perspective. This is because the process energy required in the form of gas and electricity is substantially greater for containerboard manufactured from recycled material than it is for virgin fiber.     

Future of forest gardens in the Uvan uplands of Sri Lanka

Forest gardens are traditional agroecosystems in the humid tropics that have evolved a forestlike structure and as such are commonly thought to be a good example of sustainable agriculture. While this may be true in the sense of soil protection and maintenance of biodiversity, they are not necessarily maintainable in the context of competing land use in the landscape. Such appears to be the case of forest gardens in the uplands of Uva Province of Sri Lanka. This paper reports an agroecological analysis of forest gardens and other forms of land use in Uva, and discusses how this understanding can be used to make use of the good properties of forest gardens. It shows that although they have very real environmental and social benefits, they are unable to satisfy the material needs of a rural population undergoing demographic and cultural changes. However, the alternative land-use systems, both private smallholder and state owned, have serious deficiencies with respect to long-term sustainability, and it is essential to develop appropriate alternatives. It should be possible to design a smallholder farming system that incorporates the high productivity of market gardens (i.e., the cultivation of seasonal crops such as vegetables) with, at least, the high stability and biophysical sustainability of the forest garden. Considerable work still needs to be done on the design of such a system as well as the agency for its development and promotion. The paper treats the forest gardens of Uva as a case study from which some general conclusions can be drawn with respect to the conscious development of forest garden systems elsewhere in the tropics.     

The changing pictures of the relationship between career and family

This paper discusses how male managers perceive the relationship between their careers and family lives. The authors suggest that a typology of perceptions is necessary to describe this relationship. The way individuals perceive the relationship is influenced by the emotional outcomes of work and the relative importance of work in the life of the person. While the former is mostly the consequence of the job-person fit, the latter is closely linked to the individual's life stage. Thus, work appears to be the more significant environment in an individual's early adult stages, while family and private life become the more salient environment later in life.