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Conditional uncertainty analysis and implications for decision making: the case of WIPP.

Uncertainty analyses and the reporting of their results can be misinterpreted when these analyses are conditional on a set of assumptions generally intended to bring some conservatism in the decisions. In this paper, two cases of conditional uncertainty analysis are examined. The first case includes studies that result, for instance, in a family of risk curves representing percentiles of the probability distribution of the future frequency of exceeding specified consequence levels conditional on a set of hypotheses. The second case involves analyses that result in an interval of outcomes estimated on the basis of conservative assumptions. Both types of results are difficult to use because they are sometimes misinterpreted as if they represented the output of a full uncertainty analysis. In the first case, the percentiles shown on each risk curve may be taken at face value when in reality (in marginal terms) they are lower if the chosen hypotheses are conservative. In the second case, the fact that some segments of the resulting interval are highly unlikely--or that some more benign segments outside the range of results are quite possible--does not appear. Also, these results are difficult to compare to those of analyses of other risks, possibly competing for the same risk management resources, and the decision criteria have to be adapted to the conservatism of the hypotheses. In this paper, the focus is on the first type (conditional risk curves) more than on the second and the discussion is illustrated by the case of the performance assessment of the Waste Isolation Pilot Plant in New Mexico. For policy-making purposes, however, the problems of interpretation, comparison, and use of the results are similar.

Confidence Intervals↗

A model for optimal operation of land-treatment sites for oily wastes.

Land treatment as a disposal technology has been extensively used for the disposal of oily wastes. Effective management of land treatment sites require optimal operation of the system in order to achieve the fastest and most complete degradation of petroleum hydrocarbons without contamination of the environment. This paper describes a model that can be used for optimising the operation of land treatment sites for oily wastes. The model is composed of system simulator and optimisation submodels. Conceptually, the system simulation submodel is composed of a waste mixing zone, lower treatment zone and aquifer modules. The system simulation model allows for periodic waste applications and determines the spatial and temporal variation of the state variables such as phase summed (total) and aqueous phase contaminant concentrations and water content in the system. The optimisation submodel coupled with the system simulator determines the optimal values of system control variables, such as waste loading rate, infiltration rate, water content, frequency of waste application and the dimensions of the land treatment site. Optimisation of these system control variables is accomplished by maximising the hydrocarbon mass removal from the waste mixing zone under the constraint of satisfying a prespecified water quality criteria in the aquifer. Selected model applications are presented to demonstrate the applicability and utility of the model. Such model applications include determination of the optimal operating conditions for the land treatment of oily wastes under various different site and soil environmental conditions and practical waste disposal scenarios.

Environmental Pollution↗

Using sediment quality guidelines for dredged material management in commercial ports from Spain.

Dredged material contamination was assessed in different commercial ports from Spain: Port of Cádiz and Huelva, South West; Bilbao and Pasajes, North; Cartagena and Barcelona, East; Coruña, North West. Sediment from different locations of these ports was sampled and was characterized following the Spanish recommendations for dredged material management. This characterization included grain size distribution, organic matter content and concentration of the chemical compounds included in the list of pollutants and hazardous substances (As, Cd, Cu, Cr, Hg, Ni, Pb and Zn; PCB congeners IUPAC number 28, 52, 101, 118, 138, 153 and 180; PAHs were also analyzed). The results were compared to the limit values of Spanish Action Levels that define the different categories for assessment and management. A set of empirically derived sediment quality guidelines (SQG) was used to assess the possible toxicity of the dredged materials and to improve the use of the chemical approach to characterize dredged material for its management.

Engineering↗

Multicompartment ecosystem mass balances as a tool for understanding and managing the biogeochemical cycles of human ecosystems.

Nitrogen remains a ubiquitous pollutant in surface and groundwater throughout the United States, despite 30 years of pollution control efforts. A detailed multicompartment N balance for the Central Arizona-Phoenix ecosystem is used to illustrate how an ecosystem-level approach can be used to develop improved N management strategies. The N balance is used to demonstrate how nitrate in pumped groundwater used for crop irrigation could be used to reduce inputs of commercial fertilizer and decrease N leaching to aquifers. Effectively managing N pollution also will require an understanding of the complex factors that control the N balance, including targeted regulations, individual human behavior, land-use conversion, and other ecosystem management practices that affect the N balance. These sometimes countervailing factors are illustrated with several scenarios of wastewater treatment technology and population growth in the Phoenix area. Management of N eventually must be coupled to management of other elements, notably carbon, phosphorus, and salts. We postulate that an ecosystem framework for pollution management will result in strategies that are more effective, fairer, and less expensive than current approaches.

Arizona↗

Integrated, long term, sustainable, cost effective biosolids management at a large Canadian wastewater treatment facility.

The Greater Moncton Sewerage Commission's 115,000 m3/d advanced, chemically assisted primary wastewater treatment facility located in New Brunswick, Canada, has developed an integrated, long term, sustainable, cost effective programme for the management and beneficial utilization of biosolids from lime stabilized raw sludge. The paper overviews biosolids production, lime stabilization, conveyance, and odour control followed by an indepth discussion of the wastewater sludge as a resource programme, namely: composting, mine site reclamation, landfill cover, land application for agricultural use, tree farming, sod farm base as a soil enrichment, topsoil manufacturing. The paper also addresses the issues of metals, pathogens, organic compounds, the quality control program along with the regulatory requirements. Biosolids capital and operating costs are presented. Research results on removal of metals from primary sludge using a unique biological process known as BIOSOL as developed by the University of Toronto, Canada to remove metals and destroy pathogens are presented. The paper also discusses an ongoing cooperative research project with the Université de Moncton where various mixtures of plant biosolids are composted with low quality soil. Integration, approach to sustainability and "cumulative effects" as part of the overall biosolids management strategy are also discussed.

Calcium Compounds↗

Management and control of microbial populations' development in LSS of missions of different durations.

The problem of interaction between man and microorganisms in closed habitats is an inextricable part of the whole problem of co-existence between macro- and microorganisms. Concerning the support of human life in closed habitat, we can, conventionally, divide microorganisms, acting in life support system (LSS) into three groups: useful, neutral and harmful. The tasks, for human beings for optimal coexistence with microhabitants seem to be trivial: (1) to increase the activity of useful forms, (2) decrease the activity harmful forms, (3) not allow the neutral forms to become the harmful ones and even to help them to gain useful activity. The task of efficient management and control of microbial population's development in LSS highly depends on mission duration. As for short-term missions without recycling, the proper hygienic procedures are developed. For longer missions, the probability of transformation of the neutral forms into the harmful ones is becoming more dangerous. The LSS for long-term missions are to use cycling-recycling systems, including system with biological recycling. In these systems, microbial populations as regenerative link should be useful and active agents. Some problems of microbial populations control and management are discussed in the paper.

Aerospace Medicine↗

Regulating manure application discharges from concentrated animal feeding operations in the United States.

In the United States, reducing pollution from agriculture has received attention due to data suggesting that this is the leading source of impairment of many waterbodies. The federal government revised its regulations governing concentrated animal feeding operations (CAFOs) to enhance governmental oversight over sources of pollution. For the application of manure resulting in pollutant discharges, CAFOs need to implement nutrient management plans. A federal court affirmed the ability of the US federal government to oversee the application of manure from CAFOs that have discharges. Simultaneously, owners and operators of CAFOs who have implemented an appropriate nutrient management plan may forgo securing a permit if their discharges qualify under the agricultural stormwater discharge exemption.

Agriculture↗

Application of the analytic hierarchy process to compare alternatives for the long-term management of surplus mercury.

This paper describes a systematic method for comparing options for the long-term management of surplus elemental mercury in the US, using the analytic hierarchy process as embodied in commercially available Expert Choice software. A limited scope multi-criteria decision analysis was performed. Two (2) general types of treatment technologies were evaluated (stabilization/amalgamation and selenide), combined with four (4) disposal options: (a) hazardous waste landfill; (b) hazardous waste monofill; (c) engineered below-ground structure; and (d) mined cavity. In addition, three storage options for elemental mercury were considered: (a) aboveground structure; (b) hardened structure; and (c) mined cavity. Alternatives were evaluated against criteria that included costs, environmental performance, compliance with current regulations, implementation considerations, technology maturity, potential risks to the public and workers, and public perception. Considering non-cost criteria only, the three storage options rank most favorably. If both cost and other criteria are considered, then landfill options are preferred, because they are the least expensive ones. Storage options ranked unfavorably on cost because: (a) even relatively small per annum costs will add up over time; and (b) storage is a temporary solution and, sooner or later, a treatment and disposal technology will be adopted, which adds to the cost. However, the analysis supports continued storage for a short period (up to a few decades) followed by permanent retirement when treatment technologies have matured. Suggestions for future work include: (a) involving additional stakeholders in the process, (b) evaluating alternatives for mercury-containing wastes rather than for elemental mercury only, (c) revisiting the analysis periodically to determine if changes are required, (d) conducting uncertainty analyses utilizing Monte Carlo-based techniques.

Decision Making↗

Biological effects in the management of chemicals in the marine environment.

Coastal ecosystems are impacted by many stressors, of which chemicals are possibly not the most important. Chemicals differ from most other stressors such as eutrophication and hypersedimentation in the time scale-effects from the latter act on the scale of weeks or months, whereas effects from chemicals may take years to manifest themselves in population or community changes. There are four different approaches available to manage chemicals in marine ecosystems: target contaminant levels, target individual effects, target community impacts (biodiversity) and, finally, target processes. These four differ in the analytical methods available and the analyst's ability to separate effects from chemicals from other environmental factors and natural variation. There is furthermore, a need to develop a framework to integrate biological effects methods with risk assessment methodology. Such integration will improve the basis for risk-based assessment of chemicals. A problematic issue relevant to all aspects of environmental management are the interactions between chemicals, and between chemicals and eutrophication or sedimentation. There is a clear need for more knowledge about such interactions.

Animals↗

The plutonium problem: the Royal Society sits on the fence.

A recent Royal Society report, Management of Separated Plutonium, considers the production and disposal of plutonium from the spent fuel from civil and nuclear power reactors. It accepts the need for dealing with plutonium stocks because of the toxicity of the element and as it can be used to fabricate nuclear weapons, and expresses concern that it might be illicitly acquired by terrorists. It recommends an independent Government commission on the management of plutonium, and considers the various options for this. However, it does not analyse the arguments against plutonium as a reactor fuel, and underestimates the risks of diversion to nuclear weapons and nuclear terrorism. This paper reviews the options, and concludes that separated plutonium should be added to high-level waste, vitrified, and eventually buried in a deep geological repository.

Facility Regulation and Control↗

"Triple-bottom-line" assessment of urban stormwater projects.

New guidelines have been developed and trialled in Australia to assist urban stormwater managers to assess options for projects that aim to improve urban waterway health. These guidelines help users to examine the financial, ecological and social dimensions of projects (i.e., the so-called "triple-bottom-line"). Features of the assessment process described in the guidelines include use of multi criteria analysis, input from technical experts as well as non-technical stakeholders, and provision of three alternative levels of assessment to suit stormwater managers with differing needs and resources. This paper firstly provides a background to the new guidelines and triple-bottom-line assessment. The assessment methodology promoted in the new guidelines is then briefly summarised. This methodology is compared and contrasted with European guidelines from the "SWARD" project that have been primarily developed for assessing the relative sustainability of options involving urban water supply and sewerage assets. Finally, the paper discusses how assessment methodologies that evaluate the financial, ecological and social dimensions of projects can, under some circumstances, be used to evaluate the relative progress of options for urban water management on a journey towards the widely pursued, but vaguely defined goal of "sustainable development".

Australia↗

Management implications of metal transfer pathways from a refuse tip to mangrove sediments.

Mangroves have often been thought of as wasteland, and because of this attitude, many mangrove forests have been used as sites for refuse tips, sewage outfalls and as illegal dumping grounds. The transfer of metals from a refuse tip to mangrove sediments is investigated and four pathways of heavy metal migration are identified. These are direct seepage across the tip-cell floor to groundwater, tidal over-topping of the bund wall and capillary suction of leachates to groundwaters, direct seepage through the cell wall of leachates to surficial sediments, and surface runoff during rainfall events. Metal input by surficial runoff indicates that significant quantities of metals have been transferred to the mangroves via this mechanism. However, metal transfer via surface runoff is probably small in comparison to the other three mechanisms discussed. The variable nature of the transfer mechanisms operating, the variability in sediment texture both vertically and laterally, and the number of transfer pathways makes potential management of the site difficult. Any management plan for this site must consider both the feedback mechanisms that operate, and that the whole sediment column is involved in metal transfer.

Australia↗

Recovery of dairy manure nutrients by benthic freshwater algae.

Harnessing solar energy to grow algal biomass on wastewater nutrients could provide a holistic solution to nutrient management problems on dairy farms. The production of algae from a portion of manure nutrients to replace high-protein feed supplements which are often imported (along with considerable nutrients) onto the farm could potentially link consumption and supply of on-farm nutrients. The objective of this research was to assess the ability of benthic freshwater algae to recover nutrients from dairy manure and to evaluate nutrient uptake rates and dry matter/crude protein yields in comparison to a conventional cropping system. Benthic algae growth chambers were operated in semi-batch mode by continuously recycling wastewater and adding manure inputs daily. Using total nitrogen (TN) loading rates of 0.64-1.03 g m(-2) d(-1), the dried algal yields were 5.3-5.5 g m(-2) d(-1). The dried algae contained 1.5-2.1% P and 4.9-7.1% N. At a TN loading rate of 1.03 g m(-2) d(-1), algal biomass contained 7.1% N compared to only 4.9% N at a TN loading rate of 0.64 g m(-2) d(-1). In the best case, algal biomass had a crude protein content of 44%, compared to a typical corn silage protein content of 7%. At a dry matter yield of 5.5 g m(-2) d(-1), this is equivalent to an annual N uptake rate of 1,430 kg ha(-1) yr(-1). Compared to a conventional corn/rye rotation, such benthic algae production rates would require 26% of the land area requirements for equivalent N uptake rates and 23% of the land area requirements on a P uptake basis. Combining conventional cropping systems with an algal treatment system could facilitate more efficient crop production and farm nutrient management, allowing dairy operations to be environmentally sustainable on fewer acres.

Animals↗

Uncovering the historic environmental hazards of urban brownfields.

In Baltimore, over 1,000 vacant industrial sites persist across its urban landscape, yet little is known about the potential environmental health risks that may undermine future cleanup and redevelopment activities and the health of those in communities near these sites. This study examined the characteristics of urban brownfield properties in southeast Baltimore, Maryland, and screened sites for their potential environmental hazards. In addition, demographic and health data were evaluated to profile the social and health status of those in brownfield communities. The results show that brownfields in southeast Baltimore represent a range of historic operations, including metal smelting, oil refining, warehousing, and transportation, as well as paints, plastics, and metals manufacturing. The screening method identified a range of substances associated with these properties, including heavy metals, chlorinated hydrocarbons, and polycyclic aromatic hydrocarbons, all of which are suspected or recognized toxicants, and many of which are persistent in the environment. Spatially, these sites are concentrated in white, working class neighborhoods in which poverty levels exceed and educational attainment lags behind state and national averages. Moreover, these sites are concentrated in communities in which excess mortality rates due to respiratory disease, cancer, and heart disease exist when compared to the city, state, and national averages. This investigation demonstrated the usefulness of historic archives, real estate records, regulatory files, and national hazard-tracking systems based on standard industrial classification (SIC) to screen brownfield properties for their hazard potential. This analysis provides the foundation for further site monitoring and testing, cleanup and redevelopment priority setting, risk management strategies, and neighborhood planning, and it illustrates the need for increased health surveillance and disease prevention strategies in affected communities.

Adult↗

Development of Skylab medical equipment and flight preparations.

The purpose of this report is to provide an introduction and overview of the Skylab medical program. Some of the more important medical systems and equipment provided for crew sustenance are described. The major inflight medical experiments are reviewed, and the test programs are discussed. The medical operations procedures and the techniques used to monitor crew health are reviewed to provide an understanding of the medical management of this complex mission.

Aerospace Medicine↗

Identifying the source, transport path and sinks of sewage derived organic matter.

Since sewage discharges can significantly contribute to the contaminant loadings in coastal areas, it is important to identify sources, pathways and environmental sinks. Sterol and fatty alcohol biomarkers were quantified in source materials, suspended sediments and settling matter from the Ria Formosa Lagoon. Simple ratios between key biomarkers including 5beta-coprostanol, cholesterol and epi-coprostanol were able to identify the sewage sources and effected deposition sites. Multivariate methods (PCA) were used to identify co-varying sites. PLS analysis using the sewage discharge as the signature indicated approximately 25% of the variance in the sites could be predicted by the sewage signature. A new source of sewage derived organic matter was found with a high sewage predictable signature. The suspended sediments had relatively low sewage signatures as the material was diluted with other organic matter from in situ production. From a management viewpoint, PLS provides a useful tool in identifying the pathways and accumulation sites for such contaminants.

Environmental Monitoring↗