Modeling the costs and benefits of dam construction from a multidisciplinary perspective

Although the benefits of dam construction are numerous, particularly in the context of climate change and growing global demand for electricity, recent experience has shown that many dams have serious negative environmental, human, and political consequences. Despite an extensive literature documenting the benefits and costs of dams from a single disciplinary perspective, few studies have simultaneously evaluated the distribution of biophysical, socio-economic, and geopolitical implications of dams. To meet the simultaneous demands for water, energy, and environmental protection well into the future, a broader view of dams is needed. We thus propose a new tool for evaluating the relative costs and benefits of dam construction based on multi-objective planning techniques. The Integrative Dam Assessment Modeling (IDAM) tool is designed to integrate biophysical, socio-economic, and geopolitical perspectives into a single cost/benefit analysis of dam construction. Each of 27 different impacts of dam construction is evaluated both objectively (e.g., flood protection, as measured by RYI years) and subjectively (i.e., the valuation of said flood protection) by a team of decision-makers. By providing a visual representation of the various costs and benefits associated with two or more dams, the IDAM tool allows decision-makers to evaluate alternatives and to articulate priorities associated with a dam project, making the decision process about dams more informed and more transparent. For all of these reasons, we believe that the IDAM tool represents an important evolutionary step in dam evaluation.     

Acid generation upon thermal concentration of natural water: The critical water content and the effects of ionic composition

Thermal evaporation of a variety of simulated pore waters from the region of Yucca Mountain, Nevada, produced acidic liquids and gases during the final stages of evaporation. Several simulated pore waters were prepared and then thermally distilled in order to collect and analyze fractions of the evolved vapor. In some cases, distillates collected towards the end of the distillation were highly acidic; in other cases the pH of the distillate remained comparatively unchanged during the course of the distillation. The results suggest that the pH values of the later fractions are determined by the initial composition of the water. Acid production stems from the hydrolysis of magnesium ions, especially at near dryness. Near the end of the distillation, magnesium nitrate and magnesium chloride begin to lose water of hydration, greatly accelerating their thermal decomposition to form acid. Acid formation is promoted further when precipitated calcium carbonate is removed. Specifically, calcium chloride-rich pore waters containing moderate (10–20 ppm) levels of magnesium and nitrate and low levels of bicarbonate produced mixtures of nitric and hydrochloric acid, resulting in a precipitous drop in pH to values of 1 or lower after about 95% of the original volume was distilled. Waters with either low or moderate magnesium content coupled with high levels of bicarbonate produced slightly basic fractions (pH 7–9). If calcium was present in excess of bicarbonate, waters containing moderate levels of magnesium produced acid even in the presence of bicarbonate, due to the precipitation of calcium carbonate. Other salts such as halite and anhydrite promote the segregation of acidic vapors from residual basic solids. The concomitant release of wet acid gas has implications for the integrity of the alloys under consideration for containers at the Yucca Mountain nuclear waste repository. Condensed acid gases at very low pH, especially mixtures of nitric and hydrochloric acid, are capable of corroding even alloys, such as nickel-based Alloy 22, which are considered to be corrosion-resistant under milder conditions.     

Beyond the Prevention of Harm: Animal Disease Policy as a Moral Question

European animal disease policy seems to find its justification in a “harm to other” principle. Limiting the freedom of animal keepers—e.g., by culling their animals—is justified by the aim to prevent harm, i.e., the spreading of the disease. The picture, however, is more complicated. Both during the control of outbreaks and in the prevention of notifiable, animal diseases the government is confronted with conflicting claims of stakeholders who anticipate running a risk to be harmed by each other, and who ask for government intervention. In this paper, we first argue that in a policy that aims to prevent animal diseases, the focus shifts from limiting “harm” to weighing conflicting claims with respect to “risks of harm.” Therefore, we claim that the harm principle is no longer a sufficient justification for governmental intervention in animal disease prevention. A policy that has to deal with and distribute conflicting risks of harm needs additional value assumptions that guide this process of assessment and distribution. We show that currently, policies are based on assumptions that are mainly economic considerations. In order to show the limitations of these considerations, we use the interests and position of keepers of backyard animals as an example. Based on the problems they faced during and after the recent outbreaks, we defend the thesis that in order to develop a sustainable animal disease policy other than economic assumptions need to be taken into account.     

Fundamental Moral Attitudes to Animals and Their Role in Judgment: An Empirical Model to Describe Fundamental Moral Attitudes to Animals and Their Role in Judgment on the Culling of Healthy Animals During an Animal Disease Epidemic

In this paper, we present and defend the theoretical framework of an empirical model to describe people’s fundamental moral attitudes (FMAs) to animals, the stratification of FMAs in society and the role of FMAs in judgment on the culling of healthy animals in an animal disease epidemic. We used philosophical animal ethics theories to understand the moral basis of FMA convictions. Moreover, these theories provide us with a moral language for communication between animal ethics, FMAs, and public debates. We defend that FMA is a two-layered concept. The first layer consists of deeply felt convictions about animals. The second layer consists of convictions derived from the first layer to serve as arguments in a debate on animal issues. In a debate, the latter convictions are variable, depending on the animal issue in a specific context, time, and place. This variability facilitates finding common ground in an animal issue between actors with opposing convictions.     

Mixed-Grass Prairie Canopy Structure and Spectral Reflectance Vary with Topographic Position

Managers of the nearly 0.5 million ha of public lands in North and South Dakota, USA rely heavily on manual measurements of canopy height in autumn to ensure conservation of grassland structure for wildlife and forage for livestock. However, more comprehensive assessment of vegetation structure could be achieved for mixed-grass prairie by integrating field survey, topographic position (summit, mid and toeslope) and spectral reflectance data. Thus, we examined the variation of mixed-grass prairie structural attributes (canopy leaf area, standing crop mass, canopy height, nitrogen, and water content) and spectral vegetation indices (VIs) with variation in topographic position at the Grand River National Grassland (GRNG), South Dakota. We conducted the study on a 36,000-ha herbaceous area within the GRNG, where randomly selected plots (1?km² in size) were geolocated and included summit, mid and toeslope positions. We tested for effects of topographic position on measured vegetation attributes and VIs calculated from Landsat TM and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data collected in July 2010. Leaf area, standing crop mass, canopy height, nitrogen, and water content were lower at summits than at toeslopes. The simple ratio of Landsat Band 7/Band 1 (SR71) was the VI most highly correlated with canopy standing crop and height at plot and landscape scales. Results suggest field and remote sensing-based grassland assessment techniques could more comprehensively target low structure areas at minimal expense by layering modeled imagery over a landscape stratified into topographic position groups.     

Monitoring Contrasting Land Management in the Savanna Landscapes of Northern Australia

We compared measures of ecosystem state across six adjacent land-tenure groups in the intact tropical savanna landscapes of northern Australia. Tenure groups include two managed by Aboriginal owners, two national parks, a cluster of pastoral leases, and a military training area. This information is of relevance to the debate about the role of indigenous lands in the Australian conservation estate. The timing and frequency of fire was determined by satellite imagery; the biomass and composition of the herb-layer and the abundance of large feral herbivores by field surveys; and weediness by analysis of a Herbarium database. European tenures varied greatly in fire frequencies but were consistently burnt earlier in the dry season than the two Aboriginal tenures, the latter having intermediate fire frequencies. Weeds were more frequent in the European tenures, whilst feral animals were most abundant in the Aboriginal tenures. This variation strongly implies a signature of current management and/or recent environmental history. We identify indices suitable for monitoring of management outcomes in an extensive and sparsely populated landscape. Aboriginal land offers a unique opportunity for the conservation of biodiversity through the maintenance of traditional fire regimes. However, without financial support, traditional practices may prove unsustainable both economically and because exotic weeds and feral animals will alter fire regimes. An additional return on investment in Aboriginal land management is likely to be improved livelihoods and health outcomes for these disadvantaged communities.     

Characterization of demethylation of methylmercury in cultured astrocytes

Mercury (Hg) is a well-known neurotoxicant but its toxicity depends on the species present. A steady emergence of inorganic Hg in the brain following chronic and accidental exposure to methylmercury (MeHg) has suggested that MeHg can undergo demethylation. The objective of this study is to develop an in vitro model to study factors affecting Hg demethylation in the central nervous system. Astrocytes obtained from neonatal rat pups were cultured for 24h with 1 microM MeHg in the presence of two pro-oxidants, buthionine sulphoximine (BSO) and rotenone. The BSO treatment produced a 21% increase in reactive oxygen species (ROS) content compared to the control (control vs. BSO; 100+/-1.35 vs. 121+/-1.52 relative fluorescence units (RFU)mg(-1) protein, p<0.001) but did not affect total Hg accumulation (control vs. BSO=86.5+/-4.14 ng mg(-1) vs. 95.7+/-9.26 ng mg(-1)). Rotenone increased ROS levels 107% (control vs. rotenone; 100%+/-1.35 vs. 207%+/-6.78RFU mg(-1)protein, p<0.001) and significantly increased the accumulation of total Hg (control vs. rotenone=86.5+/-4.14 ng mg(-1) vs. 124+/-3.80 ng mg(-1), p<0.001). There was no detectable demethylation in the control or BSO treated group, however, the rotenone treatment significantly increased the demethylation (control vs. rotenone=-1.86+/-5.57% vs. 16.3+/-2.68%, p<0.05). For the first time, we have demonstrated in an in vitro primary astrocyte culture model that MeHg can be converted to inorganic Hg and demethylation increases with oxidative stress. Our results provide a useful model to study demethylation of Hg in astrocytes and to explore potential ways to protect against Hg toxicity.     

Study of the toxicity of diuron and its metabolites formed in aqueous medium during application of the electrochemical advanced oxidation process "electro-Fenton"

Diuron (N'-[3,4-dichlorophenyl]-N,N-dimethylurea) is a herbicide belonging to the phenylurea family, widely used to destroy weeds on uncultivated surfaces. Because of its toxicity for aquatic organisms and suspicion of being carcinogenic for humans, diuron is the object of growing environmental concern. Therefore, we have developed the electro-Fenton method, an electrochemical advanced oxidation process (EAOP), to degrade diuron in aqueous medium, and we have studied the evolution of the toxicity of treated solution during the process. Indeed, the EAOPs catalytically generate hydroxyl radicals that oxidize the persistent organic pollutants, and can ultimately destroy and mineralize them. But, sometimes, relatively toxic organic metabolites are formed during the oxidation reaction. In this work, the evolution of toxicity of diuron aqueous solutions was studied at different initial concentrations, during treatment by the electro-Fenton method. Samples were collected at various electrolysis times and mineralization degrees during the treatment. The toxicity of the samples was measured using the bacteria Vibrio fischeri (Microtox) and the green alga Scenedesmus obliquus. Our results demonstrated that the toxicity of diuron aqueous solutions (concentrations=3.0-27.6 mg L(-1)) varied considerably with time. The formation and disappearance of several metabolites, having toxicity often stronger than that of the initial herbicide, were observed. To improve the efficiency of water decontamination, the electro-Fenton method should be applied during a time long enough (several hours) and at relatively high electrolysis current (I=250 mA) to reach a nearly complete mineralization of the herbicide in the aqueous medium.     

A design tool for planning emulsified oil‐injection systems

Emulsified oils have been used to stimulate anaerobic bioremediation at hundreds of sites contaminated with chlorinated solvents, perchlorate, heavy metals, and nitrate. A simple spreadsheet‐based tool has been developed to assist in the design of injection‐only systems for distributing emulsified oils in barriers and area treatments. This tool allows users to quickly compare the relative costs and performance of different injection alternatives and identify a design that is best suited to site‐specific conditions. Contact efficiency is estimated using results of prior numerical model simulations and dimensionless scaling factors that relate the volume of oil and water injected to treatment‐zone dimensions. Sensitivity analysis results indicate that maximum oil retention is one of the most important factors controlling system performance and cost. © 2008 Wiley Periodicals, Inc.