共查询到20条相似文献,搜索用时 31 毫秒
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This article identifies key questions and challenges for geomorphologists in investigating coupled feedbacks in human–landscape systems. While feedbacks occur in the absence of human influences, they are also altered by human activity. Feedbacks are a key element to understanding human-influenced geomorphic systems in ways that extend our traditional approach of considering humans as unidirectional drivers of change. Feedbacks have been increasingly identified in Earth-environmental systems, with studies of coupled human–natural systems emphasizing ecological phenomena in producing emerging concepts for social–ecological systems. Enormous gaps or uncertainties in knowledge remain with respect to understanding impact-feedback loops within geomorphic systems with significant human alterations, where the impacted geomorphic systems in turn affect humans. Geomorphology should play an important role in public policy by identifying the many diffuse and subtle feedbacks of both local- and global-scale processes. This role is urgent, while time may still be available to mitigate the impacts that limit the sustainability of human societies. Challenges for geomorphology include identification of the often weak feedbacks that occur over varied time and space scales ranging from geologic time to single isolated events and very short time periods, the lack of available data linking impact with response, the identification of multiple thresholds that trigger feedback mechanisms, the varied tools and metrics needed to represent both physical and human processes, and the need to collaborate with social scientists with expertise in the human causes of geomorphic change, as well as the human responses to such change. 相似文献
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Assessment of Eutrophication in Estuaries: Pressure–State–Response and Nitrogen Source Apportionment 总被引:1,自引:0,他引:1
Whitall D Bricker S Ferreira J Nobre AM Simas T Silva M 《Environmental management》2007,40(4):678-690
A eutrophication assessment method was developed as part of the National Estuarine Eutrophication Assessment (NEEA) Program.
The program is designed to improve monitoring and assessment of eutrophication in the estuaries and coastal bays of the United
States with the intent to guide management plans and develop analytical and research models and tools for managers. These
tools will help guide and improve management success for estuaries and coastal resources. The assessment method, a Pressure-State-Response
approach, uses a simple model to determine Pressure and statistical criteria for indicator variables (where applicable) to
determine State. The Response determination is mostly heuristic, although research models are being developed to improve that
component. The three components are determined individually and then combined into a single rating. Application to several
systems in the European Union (E.U.), specifically in Portugal, shows that the method is transferable, and thus is useful
for development of management measures in both the Unites States and E.U. This approach identifies and quantifies the key
anthropogenic nutrient input sources to estuaries so that management measures can target inputs for maximum effect. Because
nitrogen is often the limiting nutrient in estuarine systems, examples of source identification and quantification for nitrogen
have been developed for 11 coastal watersheds on the U.S. east coast using the WATERSN model. In general, estuaries in the
Northeastern United States receive most of their nitrogen from human sewage, followed by atmospheric deposition. This is in
contrast to some watersheds in the Mid-Atlantic (Chesapeake Bay) and South Atlantic (Pamlico Sound), which receive most of
their nitrogen from agricultural runoff. Source identification is important for implementing effective management measures
that should be monitored for success using assessment methods, as described herein. For instance, these results suggest that
Northeastern estuaries would likely benefit most from improved sewage treatment, where as the Mid and South Atlantic systems
would benefit most from agricultural runoff reductions. 相似文献
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The major purpose of this paper is to explore the potential value of benefit–cost evaluation for stormwater quality management
decisions at a local level. A preliminary benefit–cost analysis (BCA) screening method is used for maximum extent practicable
(MEP) analysis, identifying promising management practices, and identifying societal and economic tradeoffs for local stormwater
problems. Ballona Creek, a major urban storm drain in Los Angeles, California, USA, is used to illustrate the practicality
of the benefit–cost evaluation. The Ballona Creek example demonstrates the economic limits of stormwater management in an
urban region and attests to the value of coordinated basinwide management compared to uncoordinated management by individual
landowners. Evaluation results suggest that in urban areas, the benefit of stormwater quality improvements might be far greater
if accompanied by comprehensive redesign of drainage networks and neighboring land uses. In this case, benefit–cost analysis
is found to be useful for evaluating and understanding stormwater management alternatives despite the uncertainties in characterizing
stormwater quality and the effects of stormwater management on improving receiving water quality. 相似文献
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Mohamed Hanine Omar Boutkhoum Abderrafie El Maknissi Abdessadek Tikniouine Tarik Agouti 《The Environmentalist》2016,36(4):351-367
The location selection for landfill municipal solid waste is an important issue in waste management. Selection of the optimal location requires consideration of multiple alternative solutions and evaluation factors because of system complexity. Further, ranking of the alternative locations and selection of the most optimal and efficient locations for landfill waste are an important multi-criteria decision-making problem. In this study, the candidate locations for landfill are determined based on Political, Economical, Environmental and Social factors are assessed through decision-makers’ opinion and by the methodology that incorporates fuzzy analytic hierarchy process (fuzzy AHP) and fuzzy technique for order preference by similarity to ideal solution (fuzzy TOPSIS). Specifically, the fuzzy AHP technique is applied to determine the weights of selected criteria impacting the location selection process, and the fuzzy AHP is adapted to model the linguistic vagueness and ambiguity, which can also be expressed as triangular fuzzy numbers. Furthermore, fuzzy TOPSIS technique is employed to rank the alternative locations. The applicability of this methodology is demonstrated by a case study of landfill waste location selection in the region of Casablanca, Morocco, and the results are compared with other techniques. Finally, to complete the treatment, a sensitivity analysis is performed to examine the impact of the preferences given by decision-makers to choose the best location. 相似文献
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J. William Carey Robert Svec Reid Grigg Jinsuo Zhang Walter Crow 《International Journal of Greenhouse Gas Control》2010,4(2):272-282
Wellbore integrity is one of the key performance criteria in the geological storage of CO2. It is significant in any proposed storage site but may be critical to the suitability of depleted oil and gas reservoirs that may have 10’s to 1000’s of abandoned wells. Much previous work has focused on Portland cement which is the primary material used to seal wellbore systems. This work has emphasized the potential dissolution of Portland cement. However, an increasing number of field studies (e.g., Carey et al., 2007), experimental studies (e.g., Kutchko et al., 2006) and theoretical considerations indicate that the most significant leakage mechanism is likely to be flow of CO2 along the casing–cement microannulus, cement–cement fractures, or the cement–caprock interface.In this study, we investigate the casing–cement microannulus through core-flood experiments. The experiments were conducted on a synthetic wellbore system consisting of a 5-cm diameter sample of cement that was cured with an embedded rectangular length of steel casing that had grooves to accommodate fluid flow. The experiments were conducted at 40 C and 14 MPa pore pressure for 394 h. During the experiment, 6.2 l of a 50:50 mixture of supercritical CO2 and 30,000 ppm NaCl-rich brine flowed through 10-cm of limestone before flowing through the 6-cm length cement–casing wellbore system. Approximately 59,000 pore volumes of fluid moved through the casing–cement grooves. Scanning electron microscopy revealed that the CO2–brine mixture impacted both the casing and the cement. The Portland cement was carbonated to depths of 50–250 m by a diffusion-dominated process. There was very little evidence for mass loss or erosion of the Portland cement. By contrast, the steel casing reacted to form abundant precipitates of mixed calcium and iron carbonate that lined the channels and in one case almost completely filled a channel. The depth of steel corroded was estimated at 25– m and was similar in value to results obtained with a simplified corrosion model.The experimental results were applied to field observations of carbonated wellbore cement by Carey et al. (2007) and Crow et al. (2009) to show that carbonation of the field samples was not accompanied by significant CO2–brine flow at the casing–cement interface. The sensitivity of standard-grade steel casing to corrosion suggests that relatively straight-forward wireline logging of external casing corrosion could be used as a useful indicator of flow behind casing. These experiments also reinforce other studies that indicate rates of Portland cement deterioration are slow, even in the high-flux CO2–brine experiments reported here. 相似文献
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Andrea K. Gerlak 《Environmental management》2014,53(1):67-75
Given the heightened pace and extent of human interactions with landscapes, there is increasing recognition of the interdependence of hydrogeomorphological, ecological, and human systems in understanding human–landscape interactions. There is also widespread agreement for greater integration across disciplinary boundaries to generate new knowledge urgently needed for theory building to understand, predict, and respond to rapidly changing human–landscape systems. The development of new conceptual frameworks, methods, tools, and collaborations linking across the natural and social sciences are key elements to such integration. In an effort to contribute to a broader conceptual framework for human–landscape systems, this paper describes how environmental policy research has contributed to four integrative themes—thresholds and tipping points; spatial scales and boundaries; feedback loops; and time scales and lags—developed by participants in an NSF-sponsored interdisciplinary workshop. As a broad and heterogeneous body of literature, environmental policy research reflects a diversity of methodological and theoretical approaches around institutions, actors, processes, and ideas. We integrate across multiple subfields and research programs to help identify complementarities in research that may support future interdisciplinary collaborative work. We conclude with a discussion of future research questions to help advance greater interdisciplinary research around human–landscape systems. 相似文献
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《Journal of environmental psychology》1987,7(4):389-408
This paper describes events and interactions among scholars from the Geography and Psychology Departments at Clark University during the late 1960s. These events and interactions led to the establishment of a vigorous, informal program of training and research on the environment and behavior. The paper also describes an on-going, long-term organismic-developmental, systems-oriented research program which is an outgrowth of that activity. Paradigmatic research on critical person-in-environment transitions and open problems and issues are discussed. 相似文献
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We investigated differences in vegetation composition and dynamics for two globally rare ecosystems, bracken–grasslands and northern–dry forests of northern Wisconsin. These ecosystems commonly have been viewed as degraded pine barrens. Bracken–grasslands contained a high dominance of exotic species, low native richness, and no obvious prairie species, suggesting logging-era anthropogenic origins. Differences in cover for common plants among ecosystems were examined using Mann-Whitney U tests of equivalence. Cover of all 8 graminoid species, 4 of 5 Ericaceae and Myricaceae species, and 10 of 17 species of forbs were significantly different between ecosystems. Vegetation changes over a 4-year period were examined through detrended correspondence analysis (DCA) and analysis of variance (ANOVA) repeated measures. DCA analyses of community composition failed to detect significant temporal trends within individual management units, although differences were apparent between ecosystems, regardless of sample year. In addition, no apparent patterns could be detected between years when comparing dominant individual species to management history (prescribed fire). This is contrary to what would be expected for a degraded pine barrens and questions the efficacy of using repeated prescribed fire as a management tool in bracken–grasslands. Methods for conservation and restoration of xeric ecosystems of northern Wisconsin have historically relied heavily on single species (e.g., sharp-tailed grouse) wildlife models, without full consideration of other factors. We suggest that stakeholders involved in these restoration projects examine historic processes and reference conditions prior to formulating management goals. Greater attention to the differentiation and individual management needs of pine barrens, northern–dry forests, and bracken–grasslands is needed. 相似文献
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Tellurium is increasingly used in solar photovoltaics in the form of cadmium–telluride (CdTe) thin films. There are concerns regarding whether tellurium availability could be a constraint on large-scale deployment of CdTe photovoltaics. The present work brings a new perspective to the discussion of tellurium availability by providing the first extant global tellurium cycles constructed with material flow analysis principles. The tellurium cycles, for 1940–2010, present information on the production, fabrication and manufacturing, use, and resource management stages during this period. The results of the analysis show that during 1940–2010 approximately 11 Gg of refined tellurium was produced. This represents about 4.5% of the tellurium that was extracted from the ground during copper mining. Almost 80% of the refined tellurium, 8.5 Gg, was dissipated into end-uses such as metallurgical additives to iron, steel, and nonferrous metals, and thereby lost to potential reuse. As of 2010, the in-use tellurium stock is estimated at 1.1 Gg, which mainly accumulated after 1990s with the increasing tellurium use in electronics, specifically photovoltaic and thermoelectric devices. Because tellurium is a byproduct of copper ores, its supply can be enhanced by more attention to recovery during processing of the copper parent. Tellurium can also, in principle, be recovered from end-of-life electronics; the increasing in-use stock indicates the potential for significant end-of-life recycling in the coming decades. 相似文献
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Selenium plays an important role in emerging thin film solar energy technologies. As solar energy is expected to have a larger share in the world's future energy portfolio, the long-term availability of selenium becomes a potential concern, yet no global cycles have ever been generated. In this work, the global cycles, stocks, and flows of selenium are characterized for the entire time period 1940–2010 by using principles of material flow analysis (MFA). The cycles present information on the production, fabrication and manufacturing, use, and resource management stages during that period. The results of the analysis show that during 1940–2010 approximately 90 Gg of refined selenium was produced and entered into fabrication and manufacturing worldwide. 60 Gg of this amount (two-thirds!) was dissipated into the environment through end-uses such as chemicals, pigments, glass manufacturing, metallurgical additives, and fertilizer and feed additives. The in-use stock of selenium is estimated at 2.7 Gg as of 2010. Because of data limitations such as proprietary and withheld information, these figures represent informed estimates rather than exact values. Selenium can be recovered from end-of-life electrical and electronic equipment, while for other end-uses recycling is difficult or impossible. One of the ways to buttress supplies of selenium for future technologies would be to deploy recycling schemes for photovoltaics as well as other electronics applications. 相似文献
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Water supply and wastewater services incur a large amount of energy and GHG emissions. It is therefore imperative to understand the link between water and energy as their availability and demand are closely interrelated. This paper presents a literature review and assessment of knowledge gaps related to water–energy–greenhouse gas (GHG) nexus studies in an urban context from an ‘energy for water’ perspective. The review comprehensively surveyed various studies undertaken in various regions of the world and focusing on individual or multiple subsystems of an urban water system. The paper also analyses the energy intensity of decentralized water systems and various water end-uses together with the major tools and models used. A major gap identified from this review is the lack of a holistic and systematic framework to capture the dynamics of multiple water–energy–GHG linkages in an integrated urban water system where centralized and decentralized water systems are combined to meet increased water demand. Other knowledge gaps identified are the absence of studies, peer reviewed papers, data and information on water–energy interactions while adopting a ‘fit for purpose water strategy’ for water supply. Finally, based on this review, we propose a water–energy nexus framework to investigate ‘fit-for-purpose’ water strategy. 相似文献
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《International Journal of Green Energy》2013,10(3):301-312
Abstract Sustainable ecosystems can be designed to eliminate environmental toxins and reduce pathogen loads through the direct and indirect consequences of plant and microbial activities. We present an approach to the bioremediation of disturbed environments, focusing on petroleum hydrocarbon (PHC) contaminants. Treatment consists of incorporating a plant-based amendment to enhance ecosystem productivity and physiochemical degradation followed by the establishment of plants to serve as oxidizers and foundations for microbial communities. Promising amendments for widespread use are entire plants of the water fern Azolla and seed meal of Brassica napus (rapeseed). An inexpensive byproduct from the manufacture of biodiesel and lubricants, rapeseed meal is high in nitrogen (6% wt/wt), stimulates >100-fold increases in populations of resident Streptomyces species, and suppresses fungal infection of roots subsequently cultivated in the amended soil. Synergistic enzymatic and chemical activities of plant and microbial metabolism in root zones transform and degrade soil contaminants. Emphasis is given to mechanisms that enable PHC functionalization via reactive molecular species. 相似文献
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Land subsidence caused by extensive groundwater pumping has become a factor which cannot be ignored in the sustainable exploitation of groundwater resources. The Hangzhou–Jiaxing–Huzhou Plain is one of the locations with China’s most severe land subsidence problems; the region has experienced dramatic land subsidence since the 1960s. Historical records of groundwater extraction, hydraulic head, and land subsidence show the latter to be the result of continual and excessive extraction of groundwater from deep confined aquifers. This study reconstructs land subsidence using an integrated regional groundwater flow and land subsidence model. The model is calibrated using land subsidence and groundwater level measurements from 1996 to 2007. Simulation results reproduce the cones of depression for groundwater heads and nadirs of land subsidence reasonably well. The calibrated model is used to evaluate the efficacy of land subsidence prevention plans from 2008 to 2010, and to predict future land subsidence over the next decade considering several groundwater exploitation scenarios. The results show the main cause of land subsidence to be inelastic compaction of the aquifer system resulting from continuously declining water levels. The model reveals that while the area of land subsidence will continue to extend, the rate of this extension may be significantly decreased by reduction of groundwater extraction. If the current land subsidence prevention and reclamation plans are continued and surface water diversion projects implemented, though land subsidence cannot be halted, the rate at which it is occurring can be effectively reduced. 相似文献
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Peter J. Hancock 《Environmental management》2001,29(6):763-781
Active exchanges of water and dissolved material between the stream and groundwater in many porous sand- and gravel-bed rivers create a dynamic ecotone called the hyporheic zone. Because it lies between two heavily exploited freshwater resources—rivers and groundwater—the hyporheic zone is vulnerable to impacts coming to it through both of these habitats. This review focuses on the direct and indirect effects of human activity on ecosystem functions of the hyporheic zone. River regulation, mining, agriculture, urban, and industrial activities all have the potential to impair interstitial bacterial and invertebrate biota and disrupt the hydrological connections between the hyporheic zone and stream, groundwater, riparian, and floodplain ecosystems. Until recently, our scientific ignorance of hyporheic processes has perhaps excused the inclusion of this ecotone in river management policy. However, this no longer is the case as we become increasingly aware of the central role that the hyporheic zone plays in the maintenance of water quality and as a habitat and refuge for fauna. To fully understand the impacts of human activity on the hyporheic zone, river managers need to work with scientists to conduct long-term studies over large stretches of river. River rehabilitation and protection strategies need to prevent the degradation of linkages between the hyporheic zone and surrounding habitats while ensuring that it remains isolated from toxicants. Strategies that prevent anthropogenic restriction of exchanges may include the periodic release of environmental flows to flush silt and reoxygenate sediments, maintenance of riparian buffers, effective land use practices, and suitable groundwater and surface water extraction policies. 相似文献