This study examines deforestation in a part of the Niger Delta region of Nigeria between 1987 and 2013 using remote sensing data and geographic information systems. The results indicate an increasing rate of deforestation, an increasing rate of water body loss and a decreasing rate of exposed surface/settlement increase. The results also show that the rate at which cropland/secondary vegetation is increasing is above average while sandbar is increasing below average. The implications of these changes include environmental degradation resulting from loss of biodiversity and loss of forest goods and services. These losses can also affect the social and economic conditions of local people. The study recommends that policies and strategies targeted at slowing down the rate of forest loss and degradation should be pursued. 相似文献
A 17-month research programme focused on development of an Education for Sustainability (EFS) Global Media Network at Ball State University Indiana was recently concluded. The study results include some surprising conclusions related to the contradictions between the benefits of education for global sustainability and the use of technology to facilitate that educational process in achieving a more sustainable world. This article provides an overview of the EFS Network research programme and a discussion of some of the key results and conclusions related to advantages and disadvantages of technology-based learning. The article then addresses the environmental impact of computer technology manufacturing, use, and after-use. Research findings are utilized to illustrate the ecological footprint of computer-based education. The article concludes with a discussion about achieving a balance between the need for global-to-local sustainable education and the environmental impact of technology use for sustainable education. 相似文献
While the concept of sustainable land management is now widely accepted, there remains considerable scope for developing location-specific land-use indicators for sustainability evaluation. A study was conducted to investigate the indicators of land-use sustainability in the context of tropical agro-ecosystems using the case of Sakaekrang watershed, Thailand. The biophysical data were generated from Geographic Information Systems (GIs) and the socioeconomic data were collected through a field survey. In the light of sustainable land management objectives, a total of 32 criteria were considered in the analysis to determine land-use sustainability and identify indicators that best explain the sustainability level. About one quarter of the agricultural area in the watershed meets the sustainability threshold, indicating a substantial unstable area in the watershed. Among 11 indicators that showed a significant relationship with the computed land-use sustainability, land quality, source of farm income, and evapo transpiration were the most important. 相似文献
Flood management policies in the United States rely on scientific information about the frequency and intensity of extreme precipitation and runoff. Yet, the available information is inherently uncertain because of the complexity of meteorological and hydrological processes. In mountainous areas, flood risk can vary greatly even within short distances depending on local climate, topography, soil characteristics, and land use. This paper describes two Colorado cases in which policy makers were presented with conflicting scientific estimates: revision of the Fort Collins floodplain map and modification of the Cherry Creek Dam. The case studies demonstrate that uncertainty can have substantial impacts on regulatory processes, public safety, and costs. The analysis considers the differing perspectives of various participants in the flood management processes, illustrating the interplay between uncertainties attributable to scientific issues and values issues. It suggests that attempts to provide a single “best” estimate do not necessarily meet the decision needs of all stakeholders. Conclusions indicate a need to improve communication about uncertainty when scientific estimates areprovided to decision makers. Furthermore, in highly controversial decisions, it may be necessary to reframe the discussion to consider the values issues raised by scientific uncertainty. 相似文献
The biochemical basis for resistance to metal ion toxicity is emerging though it is complicated by the different resistance mechanisms. Several strategies for resistance to toxic metal ions have been identified:
The development of energy driven efflux pumps which keep toxic element levels low in the interior of the cell. Such mechanisms have been described for Cd(II) and As(V).
Oxidation (e.g. AsO2‐ to AsO43‐) or reduction (e.g. Hg2+ to Hg0) can enzymatically and intracellularly convert a more toxic form of an element to a less toxic form.
The biosynthesis of intracellular polymers which serve as traps for the removal of metal ions from solution such as traps have been described for cadmium, calcium, nickel and copper.
The binding of metal ions to cell surfaces.
The precipitation of insoluble metal complexes (e.g. metal sulfides and metal oxides) at cell surfaces.
Biomethylation and transport through cell‐membranes by diffusion controlled processes.
In this short review I shall discuss the implications of biomethylation as a detoxification mechanism for microorganisms as well as for certain higher organisms. 相似文献
Abstract Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in ‘ring areas’ - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3–7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81–3.14 μmol cm?2 day?1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47–0.50 μmol cm?2 day?1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model. 相似文献
Floods have become increasingly alarming worldwide. Flood risk management in terms of assessing disaster risk properly is a great challenge that society faces today. Natural disaster risk analysis is typically beset with issues such as imprecision, uncertainty, and partial truth. There are two basic forms of uncertainty related to natural disaster risk assessment, namely, randomness caused by inherent stochastic variability and fuzziness due to macroscopic grad and incomplete knowledge sample. However, the traditional probability statistical method ignores the fuzziness of risk assessment with incomplete data sets and requires a large sample size of data. The fuzzy set methodology is introduced in the area of disaster risk assessment to improve probability estimation. The purpose of the current study is to establish a fuzzy model to evaluate flood risk with incomplete data sets. The present paper puts forward a composite method based on variable fuzzy sets and information diffusion method for disaster risk assessment. The results indicate that the methodology is effective and practical; thus, it has the potential to forecast the flood risk in flood risk management. We hope that by conducting such risk analysis, the impact of flood disasters can be mitigated in the future. 相似文献