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601.
This two-part paper considers the complementarity between adaptation and mitigation in managing the risks associated with the enhanced greenhouse effect. Part one reviews the application of risk management methods to climate change assessments. Formal investigations of the enhanced greenhouse effect have produced three generations of risk assessment. The first led to the United Nations Intergovernmental Panel on Climate Change (IPCC), First Assessment Report and subsequent drafting of the United Nations Framework Convention on Climate Change. The second investigated the impacts of unmitigated climate change in the Second and Third IPCC Assessment Reports. The third generation, currently underway, is investigating how risk management options can be prioritised and implemented. Mitigation and adaptation have two main areas of complementarity. Firstly, they each manage different components of future climate-related risk. Mitigation reduces the number and magnitude of potential climate hazards, reducing the most severe changes first. Adaptation increases the ability to cope with climate hazards by reducing system sensitivity or by reducing the consequent level of harm. Secondly, they manage risks at different extremes of the potential range of future climate change. Adaptation works best with changes of lesser magnitude at the lower end of the potential range. Where there is sufficient adaptive capacity, adaptation improves the ability of a system to cope with increasingly larger changes over time. By moving from uncontrolled emissions towards stabilisation of greenhouse gases in the atmosphere, mitigation limits the upper part of the range. Different activities have various blends of adaptive and mitigative capacity. In some cases, high sensitivity and low adaptive capacity may lead to large residual climate risks; in other cases, a large adaptive capacity may mean that residual risks are small or non-existent. Mitigative and adaptive capacity do not share the same scale: adaptive capacity is expressed locally, whereas mitigative capacity is different for each activity and location but needs to be aggregated at the global scale to properly assess its potential benefits in reducing climate hazards. This can be seen as a demand for mitigation, which can be exercised at the local scale through exercising mitigative capacity. Part two of the paper deals with the situation where regional bodies aim to maximise the benefits of managing climate risks by integrating adaptation and mitigation measures at their various scales of operation. In north central Victoria, Australia, adaptation and mitigation are being jointly managed by a greenhouse consortium and a catchment management authority. Several related studies investigating large-scale revegetation are used to show how climate change impacts and sequestration measures affect soil, salt and carbon fluxes in the landscape. These studies show that trade-offs between these interactions will have to be carefully managed to maximise their relative benefits. The paper concludes that when managing climate change risks, there are many instances where adaptation and mitigation can be integrated at the operational level. However, significant gaps between our understanding of the benefits of adaptation and mitigation between local and global scales remain. Some of these may be addressed by matching demands for mitigation (for activities and locations where adaptive capacity will be exceeded) with the ability to supply that demand through localised mitigative capacity by means of globally integrated mechanisms.  相似文献   
602.
Seven cases of triploidy were encountered by the Prenatal Diagnosis Program at Dartmouth–Hitchcock Medical Center over an 8-year period through associated pregnancy complications. We describe the characteristic findings that facilitate prenatal diagnosis and management. Our experience includes fetuses with major central nervous system abnormalities (spina bifida aperta, holoprosencephaly) and anterior abdominal wall defects, which are detectable with routine prenatal diagnostic screening examinations (ultrasound and AFP). In addition, we stress the importance of recognizing obstetric complications and associated cystic placental changes, which are quite common among triploid conceptuses. Molar changes associated with triploidy have a more benign prognosis than that associated with diploid moles. Such molar changes may relate to the presence of a diploid paternal chromosome complement. The usefulness of cytofluorometric DNA determinations in helping to confirm a clinical suspicion of triploidy is emphasized. These cases are presented in an effort to facilitate prenatal recognition and management of this common cytogenetic condition and prevent unnecessary Caesarean section deliveries.  相似文献   
603.
A mathematical model was developed to estimate nitrate release from ocher pellets in benthic sediment. Ocher pellets, called “limnomedicine,” consisting of ocher and calcium nitrate were used to suppress phosphorus release from contaminated sediment under anaerobic conditions. The proposed model represents the fate and transport of nitrate released from the pellets, in both the water column and the sediment. Most of the nitrate (83.6%) released from the pellets was consumed in the degradation of organic matter and FeS in the sediment over a period of 12 days. While an increase in pellet dosage helps to accelerate the sediment treatment rate, it also has the effect of increasing the mass of nitrate that diffuses into the water column. Quantitative analysis of these effects using the proposed mathematical model makes it possible to determine the proper pellet dosage based on sediment conditions such as organic matter content.  相似文献   
604.
A highly sensitive sodium (Na+) transfer tissue biosensor (STTB) was designed using a frog bladder membrane to measure paralytic shellfish poisons (PSP). The STTB consists, of a Na+ electrode covered by the membrane, which was then integrated into a flow-through system for continuous measurements. In the absence of Na+ channel blocker, active transfer of Na+ occurred from inside to outside across the frog membrane. When the STTB was used to measure the Na+ -dependent dissociation of PSP, it was able to detect PSB at a level contained in a single cell. However, 5 fg or higher (100 cells or more) is needed for accurate and reproducible measurements. The toxicity obtained by the STTB was significantly correlated (r = 0.9449) to that determined by the HPLC. Therefore, the simple method of the STTB can be used not only to detect a low level PSP in toxic plankton populations, but also to monitor poisons in shellfish.  相似文献   
605.
The microbial leaching process was evaluated for the treatment of synthetic sediments contaminated with cadmium and nickel sulfides. A series of batch leaching experiments was conducted to compare metal solubilization in sediment inoculated with Acidithiobacillus ferrooxidans -inoculated sediments to that in sterile control sediment. The rate and extent of metal solubilization were significantly higher in A. ferrooxidans -inoculated reactors than in acidified sterile reactors. The efficiency of cadmium (Cd) solubilization (80) in the bioleaching process was higher than that of nickel (Ni) solubilization (60). The performance of leaching reactors containing only culture supernatants was comparable to that of A. ferrooxidans -inoculated reactors, indicating that indirect non-contact leaching by the products of microbial metabolism is the predominant mechanism for metal solubilization rather than direct microbial sulfide oxidation. Moreover, the similar (60–75%) extents of Cd2+ leaching with A. ferrooxidans , cell-free filtrate, and Fe3+ suggest that abiotic oxidation of CdS by Fe3+ controls the overall leaching rate, and the role of A.␣ferrooxidans is most likely not to oxidize CdS mineral directly but to regenerate Fe3+ as an oxidant.  相似文献   
606.
Two artificial neural networks (ANNs), unsupervised and supervised learning algorithms, were applied to suggest practical approaches for the analysis of ecological data. Four major aquatic insect orders (Ephemeroptera, Plecoptera, Trichoptera, and Coleoptera, i.e. EPTC), and four environmental variables (elevation, stream order, distance from the source, and water temperature) were used to implement the models. The data were collected and measured at 155 sampling sites on streams of the Adour–Garonne drainage basin (South-western France). The modelling procedure was carried out following two steps. First, a self-organizing map (SOM), an unsupervised ANN, was applied to classify sampling sites using EPTC richness. Second, a backpropagation algorithm (BP), a supervised ANN, was applied to predict EPTC richness using a set of four environmental variables. The trained SOM classified sampling sites according to a gradient of EPTC richness, and the groups obtained corresponded to geographic regions of the drainage basin and characteristics of their environmental variables. The SOM showed its convenience to analyze relationships among sampling sites, biological attributes, and environmental variables. After accounting for the relationships in data sets, the BP used to predict the EPTC richness with a set of four environmental variables showed a high accuracy (r=0.91 and r=0.61 for training and test data sets respectively). The prediction of EPTC richness is thus a valuable tool to assess disturbances in given areas: by knowing what the EPTC richness should be, we can determine the degree to which disturbances have altered it. The results suggested that methodologies successively using two different neural networks are helpful to understand ecological data through ordination first, and then to predict target variables.  相似文献   
607.
Heavy metal accumulation (Cu, Zn, Ni, and Pb) in common marine macroalga, Acrosorium uncinatum under nutrient (phosphate and nitrate) enriched (experiment 1) and starved (experiment 2) conditions over a short exposure period (12 h) were examined in this study. Control was maintained in seawater contained nutrient solution without addition of metals and in seawater alone for experiment 1 and 2, respectively. Among the four metals studied, the accumulation of Zn, Ni, and Pb was considerably lower than Cu. The accumulation factor for all metals varies greatly in different nutrient concentrations, but it increases as the exposure of metal concentration decreases in both the experiments. The results of the present findings established that this macroalga is an accumulator of metals Cu, Zn, Ni, and Pb and have the potential to accumulate these metals even in a short time exposure period (12 h). Even though metal accumulation by A. uncinatum largely depends on the available concentration in the medium, nutrients like phosphate and nitrate can affect the accumulation significantly.  相似文献   
608.
The stabilization potential of negatively charged sodium carboxymethyl cellulose (CMC) solution was assessed through investigation of its retention on clays under environmental conditions that promote soil desiccation. Sodium montmorillonite and kaolinite, commonly used in clayey soils, were mixed with aqueous CMC solutions in concentrations ranging from 0 to 10 g/L. These samples were dried in a specially-designed desiccation chamber which was operated at a temperature of 25°C and relative humidity of 30%. The results show an inverse proportionality between liquid loss and CMC concentration. Liquid loss from clayey soil follows the first-order reaction with a rate constant in the range of 4.6–6.7 mg/h. CMC half-lives on sodium montmorillonite during desiccation ranged from 103 to 181 h for an aqueous concentration range of 0.5–10 g/L compared to 108 h for distilled water. For kaolinite, more liquid was retained at 10 g/L CMC concentration than at other concentrations, but liquid retention was generally insignificant. These conclusions are valid for a desiccation duration of 890 h, a time that is reasonably simulative of the duration of exposures of bare ground surfaces to weather elements. The experimental results are explained in terms of the role of CMC molecular interactions with clay minerals in controlling fluid flow to desiccating clay surfaces.  相似文献   
609.
This paper investigates the challenges and opportunities of how firms and organizations can and will be able to strike a better balance between economic growth and environmental stewardship in the context of China’s emerging ‘circular economy’ policy paradigm and based on ecological modernization theoretic approaches.Based on three company case studies in the information technology and electronic industries in China, we identify and demonstrate how a blended business and environmental value can be created from adopting a sustainable supply chain management approach. The adoption of a sustainable supply chain management approach is rapidly becoming a key business challenge and opportunity in China and other large emerging economies around the world, where our greatest environmental management challenges currently reside and will continue to exist for many years to come. The value creation framework proposed in research focuses on evaluating three case study companies who appear in various stages of an electronic industry supply chain. Value creation within a supply chain can provide the impetus for organizations to adopt circular economy, sustainable supply chain practices, for competitive reasons.In addition, we describe how a value proposition can be evaluated at two levels of analysis, a more specific micro-level and a more general meso-level of analysis. The four major business value dimensions include cost reduction, revenue generation, resiliency, and legitimacy and image.The initial findings are that a variety of opportunities exist for electronic firms in emerging and developing countries, while results from this study provide an important scholarly foundation to develop and refine sustainable supply chain management practices in emerging and developing economies.  相似文献   
610.
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