Frontiers of Engineering Reports on Leading-Edge Engineering from the 2003 NAE Symposium on Frontiers of Engineering (2004) / Chapter Skim
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Environmental Engineering
Environmental Engineering
Pages 1-24
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MINERAL RESPIRATION Respiratory metabolisms have impacted mineral formation and/or dissolution. The thought of respiring a mineral may seem suffocating, but bacteria have been doing it for billions of years (Figure 2~.
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Although we will never know the exact date when microbial life first developed, a variety of geochemical and geobiological indicators suggest that this happened several billion years ago. FIGURE 2 A scanning electron micrograph of the metal-reducing bacterium, Shewanella oneidensis strain MR-1, attached to a steel surface.
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For respiration to succeed, a terminal electron acceptor, such as oxygen, must be available to receive the electrons. Before the evolution of oxygen in the atmosphere, microorganisms had to respire with alternative electron acceptors.
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Although the addition of synthetic chelators has been shown to stimulate microbial electron transfer to iron minerals, no evidence has been found that bacteria use this mechanism in respiration. Another suggestion is that they may use soluble shuttles, such as organic compounds with quinone moieties, to transfer electrons from the cell to the mineral.
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generate energy. Microorganisms are extraordinarily versatile and can use a variety of compounds as electron donors or electron acceptors in these reactions.
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, oxidation of both organic and inorganic electron donors in the sediment supported power generation (Tender et al., 2002~. Although much work remains to be done before we can understand how microbial communities catalyze electron-transfer reactions to the anode, this process has the potential to sustain long-term power generation from marine sediments.
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It is possible that horizontal gene transfer has accelerated the distribution of this capability in both time and space; if so, this mechanism could be exploited in the future to deliver useful genetic material to targeted microbial populations. ACKNOWLEDGMENTS I would like to thank the Clare Boothe Luce Foundation, the Packard Foundation, and the Office of Naval Research for providing generous research support.
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2000. A role for excreted quinines in extracellular electron transfer.
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. Since the mid-1970s, concerns about improving water quality and meeting future demands have multiplied in scope and magnitude, prompting significant changes in public policy at the federal, state, and local levels (Cech, 2003~.
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Interdisciplinary analyses can integrate engineering and economic considerations into terms that policy makers can more readily incorporate into their decision-making process. The following case study involves a region in which restrictions were placed on aquifer access in response to environmental concerns about declining aquifer levels.
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These springs provide habitat for several endangered species, and a federal court has ruled that allowing spring flow to drop below specified levels constitutes a "taking" under the Endangered Species Act (Votteler, 1998~. As a result, the state of Texas has been instructed to take whatever actions are necessary to ensure that acceptable flow rates are maintained.
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In the case of the Edwards Aquifer, future shortfalls will be largely the result of the temporary pumping restrictions imposed when aquifer levels drop below specified levels, conditions that can be accurately predicted through hydrologic modeling (Durbin, 2002~.
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The information was then used to calculate spot-market prices as a basis for calculating the prices of the other transaction types. The monthly pumping restrictions imposed as a result of declining aquifer levels can considerably disrupt municipal water supplies, so the ability to assess the likelihood of restrictions can be valuable when formulating planning strategies.
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expected costs are lower, is not likely to appeal to municipal decision makers. They may, however, feel comfortable entering into annual leasing and option contracts, which provide much greater certainty about water availability and cost.
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1998. The little fish that roared: the Endangered Species Act, state groundwater law, and private property rights collide in the Texas Edwards Aquifer.
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In 2002, the leaders of many national governments converged, along with representatives from industry and civil society, in Johannesburg at the World Summit on Sustainable Development (WSSD)
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The interdisciplinary frontiers of this engineering-based methodology are constantly evolving in response to demands in the policy arena for sustainable development. ORIGINS The field of environmental LCA originated during a period of rising concern about disposable packaging.
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LIFE CYCLE DEVELOPMENT 21 The whole LCA enterprise can only be feasible over the long term with realworld budget constraints if studies contribute to ongoing, cumulative, reusable, modular, and "generic" databases about average or representative unit processes. These radically comprehensive LCA studies provided counterintuitive, nondefinitive results.
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SUSTAINABLE DEVELOPMENT The present application context of LCA is sustainable development, which is commonly considered to have three pillars: economic growth, ecological balance, and social progress (WBCSD, 2003~. Traditional LCA addressed only the environmental pillar.
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: 62-65. WBCSD (World Business Council for Sustainable Development)
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Johannesburg, South Africa: World Summit on Sustainable Development. Available online at: |
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