首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The integration of the social sciences into long-term ecological research is an urgent priority. To address this need, a group of social, earth, and life scientists associated with the National Science Foundations (NSF) Long-Term Ecological Research (LTER) Network have articulated a conceptual framework for understanding the human dimensions of ecological change for the LTER Network. This framework explicitly advocates that what is often divided into natural and human systems be considered a single, complex social-ecological system (SES). In this paper, we propose a list of core social science research areas, concepts, and questions; identify the need for multiscale investigatory frameworks crucial for implementing integrated research; and suggest practical approaches for integration. In sum, this paper is a general outline for empirical and cross-site research projects where investigators agree that bringing together social, biological, and earth scientists can lead to synthetic approaches and a unified understanding of the mechanisms regulating SES. Although the motivation for this goal is specific to the LTER Network and similar projects, we believe that the issues and ideas presented here are widely applicable to other interdisciplinary SES studies.  相似文献   

2.
Mass estimates of phytoaccumulated trace metal contaminants and transfers to soils are necessary to properly evaluate the impact of historic and continued anthropogenic metal deposition to northern forest ecosystems. An investigation of Cu, Ni, Pb, and Zn mass balances in plant communities subject to metal contamination from smelter emissions in Canada, found that accumulation of metals differed significantly among plant vegetation compartments (foliage, fine roots, bark, trunk, and branches). Analysis of plant community biological accumulation factors (BAFs), calculated using total soil metal and free soil metal ion (Me2+) found that free soil metal BAFs were more similar among locations than total soil metal BAFs, but that disparity still existed. Fine roots were found to dominate annual vegetation transfer of Cu, Ni, and Pb to soils, relative to foliage; fine root mortality played a smaller role than foliage for Zn plant-soil transfer. Plant-associated metal inputs were found to rival or exceed current estimates of atmospheric metal deposition, suggesting that potential benefits of future reductions in emissions to forests need to be evaluated within the context of phytocycling of metals already present.  相似文献   

3.
The Taurus Mountain range separates the central Anatolian steppe and the Eastern Mediterranean Region. The Amanos Mountains lie to the east, playing a significant role in forming this region which is strongly influenced by the Mediterranean Sea. Between the Taurus Mountains and the sea, there is a diversity of terrestrial, limnic and marine ecosystems. These contain a number of differing biotopes such as grassland above the timberline, evergreen and deciduous forests, scrubland, river beds, lagoons, coastal saltmarshes, coastal woodlands and sand dunes. Due to intensive land use, the ecological diversity is threatened, and so governmental and scientific bodies have combined resources to implement conservation measures. This paper emphasizes the importance of these conservation activities and discusses realistic proposals for conservation in the region.  相似文献   

4.
The belief that high density is stressful and unhealthy has contributed to a decline in urban density in many countries, particularly North America and Australia. Yet many physical planners are calling for an increase in urban density. Many human or individual-oriented studies (which involve ethological models, sociological models, and psychological models) have been used to suggest negative effects of urban density. This article raises questions about these conclusions and presents evidence from recent studies which suggests more positive human aspects of urban density. The physical or systems-oriented studies (which involve economic, ecological, historical, and engineering models) suggest advantages in costs, energy, environment, and transport from increasing urban density. The resolution of the conflict between populace and planner is suggested to include greater awareness of mutual benefits from increased density, better planning and design, and encouragement of the more positive human aspects of higher urban density.  相似文献   

5.
A healthy debate on the treatment of metals recycling in the life cycle assessment (LCA) community has persisted for more than a decade. While no clear consensus across stakeholder groups has emerged, the metals industry has endorsed a set of recycling “facts” that support a single approach, end‐of‐life recycling, for evaluating the environmental benefits of metals recycling. In this article we draw from research conducted in several disciplines and find that three key tenets of the metals industry capture the theoretical potential of metals recycling from a metallurgical standpoint rather than reflecting observed behavior. We then discuss the implications of these conclusions on environmental emissions from metals production and recycling. Evidence is provided that, contrary to the position of the metals industry, metals are not necessarily recycled at high rates, are recycled only a small number of times before final disposal, and are sometimes limited in recycling potential by the economics of contaminant removal. The analysis concludes that metal recycled from old scrap largely serves as an imperfect substitute for primary metal. As a result, large‐scale displacement of primary production and its associated environmental emissions is currently limited to a few specific instances.  相似文献   

6.
ABSTRACT

The aim of this paper is to present a joint vegetation data base and GIS application to produce a model to map the potential natural vegetation (PNV) of the Friuli-Venezia Giulia region (NE Italy) and to show how the map can be used to draw a biogeographic classification of the region. All the natural arboreal coenoses growing below the timber line, as well as the dwarf shrubs and prairies developing above this limit, were considered. Some cross sections, extracted from the potential vegetation map, were tested against transects of real vegetation distribution.  相似文献   

7.
China's remarkable economic growth in the last 3 decades has brought about big improvements in quality of life while simultaneously contributing to serious environmental problems. The aim of all economic activities is, ultimately, to provide the population with products and services. Analyzing environmental impacts of consumption can be valuable for illuminating underlying drivers for energy use and emissions in society. This study applies an environmentally extended input‐output analysis to estimate household environmental impact (HEI) of urban Beijing households at different levels of development. The analysis covers direct and indirect energy use and emissions of carbon dioxide (CO2), sulfur dioxide (SO2), and nitrogen oxide (NOx). On the basis of observations of how HEI varies across income groups, prospects for near‐future changes in HEI are discussed. Results indicate that in 2007, an urban resident in Beijing used, on average, 52 gigajoules of total primary energy supply. The corresponding annual emissions were 4.2 tonnes CO2, 27 kilograms SO2, and 17 kilograms NOx. Of this, only 18% to 34% was used or emitted by the households directly. While the overall expenditure elasticity of energy use is around 0.9, there is a higher elasticity of energy use associated with transport. The results suggest that significant growth in HEI can be expected in the near future, even with substantial energy efficiency improvements.  相似文献   

8.
31P-NMR is used to characterize the phase behavior of phosphonolipids in both model and biological membranes. (1′,2′-Dipalmitoyl-sn-glyceryl)-2-aminoethylphosphonate gives rise to static chemical shift tensor elements (?87, 5 and 63 ppm) which differ considerably from those reported for the analogous phospholipid, 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (?81, ?20 and 105 ppm). Phosphonolipid, as well as a mixture of phosphonolipid and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, in aqueous dispersion gives rise to 31P spectra which may be interpreted in terms of lamellar structures. A mixture of phosphonolipid and egg phosphatidylethanolamine exhibits a bilayer-to-hexagonal phase transition with a concomitant decrease by one-half in the value of the 31P chemical shift anisotropies of both the phosphonate and phosphate resonances. The chemical shift anisotropy associated with phosphonolipid has been found to be consistently smaller than that observed for the analogous phospholipid. 31P-NMR spectra of total lipid extracts of Tetrahymena sp. indicate that both phospho- and phosphonolipids have a bilayer organization between ?20 and 20°C.  相似文献   

9.
The Impacts of Household Consumption and Options for Change   总被引:1,自引:0,他引:1  
This introductory article situates the contributions that comprise this special issue within the field of sustainable consumption and production (SCP) studies. After a brief review of the policy history surrounding SCP, we organize our discussion and the subsequent collection of articles into two groups. The first suite of articles views the environmental impacts associated with household consumption from the perspectives of different consumer groups, income levels, and geographic areas. This work confirms and refines several insights that have been developing over the past several years, namely that food and beverages, mobility, housing, and energy-using products are the most critical consumption domains from the standpoint of environmental sustainability and that higher household income leads to greater (but less than proportional) impacts. The second subset of articles analyzes the potential for mitigating these impacts through behavioral changes and innovation strategies. Although the contributions to this special issue describe several noteworthy examples of information- and team-based initiatives to catalyze behavioral changes, the state of knowledge pertaining to this aspect of the consumption problem is much more inchoate. Research on the formulation and implementation of effective "change management for sustainable consumption" should be treated as an area of priority attention for industrial ecologists.  相似文献   

10.
11.
The tool for the reduction and assessment of chemical and other environmental impacts (TRACI) is a set of life-cycle impact assessment (LCIA) characterization methods that has been developed by a series of U.S. Environmental Protection Agency research projects. TRACI facilitates the characterization of stressors that may have potential effects, including ozone depletion, global warming, acidification, eutrophication, tropospheric ozone (smog) formation, eco-toxicity, human particulate effects, human carcinogenic effects, human non-carcinogenic effects, fossil fuel depletion, and land-use effects. This article describes the methodologies developed to address acidification, eutrophication, and smog. Each of these methods offers the ability to take account of differences in expected strength of impact as a function of pollution release location within North America. Specifically, the methods employ regionalized fate and transport modeling. The resulting factors differ regionally by up to more than an order of magnitude.  相似文献   

12.
T.S. Desai  V.G. Tatake  P.V. Sane 《BBA》1977,462(3):775-780
Out of the six thermoluminescence bands reported for a mature leaf, one band (Zv) appearing at the lowest temperatures is dependent on the temperature of illumination. The characteristics of this band in fresh leaf are compared with those in a leaf heated to 60°C for 5 min. It is concluded here that this band, following illumination at temperatures lower than 173 K, is part of Arnold and Azzi's Z band (Arnold, W. and Azzi, J.R. (1971) Photochem. Photobiol. 14, 233–240). However, it is a part of peak I when observed subsequent to illumination beyond 173 K. An explanation for the appearance of this band at different temperatures is proposed.  相似文献   

13.
Taking a published natural population life table of rice leaf roller, Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), as an example, we estimated the population trend index, I, via re‐sampling methods (jackknife and bootstrap), determined its statistical properties and illustrated the application of these methods in determining the control effectiveness of bio‐agents and chemical insecticides. Depending on the simulation outputs, the smoothed distribution pattern of the estimates of I by delete‐1 jackknife is visually distinguishable from the normal density, but the smoothed pattern produced by delete‐d jackknife, and logarithm‐transformed smoothed patterns produced by both empirical and parametric bootstraps, matched well the corresponding normal density. Thus, the estimates of I produced by delete‐1 jackknife were not used to determine the suppressive effect of wasps and insecticides. The 95% percent confidence intervals or the narrowest 95 percentiles and Z‐test criterion were employed to compare the effectiveness of Trichogramma japonicum Ashmead and insecticides (powder, 1.5% mevinphos + 3% alpha‐hexachloro cyclohexane) against the rice leaf roller based on the estimates of I produced by delete‐d jackknife and bootstrap techniques. At α= 0.05 level, there were statistical differences between wasp treatment and control, and between wasp and insecticide treatments, if the normality is ensured, or by the narrowest 95 percentiles. However, there is still no difference between insecticide treatment and control. By Z‐test criterion, wasp treatment is better than control and insecticide treatment with P‐value < 0.01. Insecticide treatment is similar to control with P‐value > 0.2 indicating that 95% confidence intervals procedure is more conservative. Although similar conclusions may be drawn by re‐sampling techniques, such as the delta method, about the suppressive effect of trichogramma and insecticides, the normality of the estimates can be checked and guaranteed, and the correlation among sequential life stages of rice leaf roller is also considered in the estimation. Judged by the P‐values from Z‐test, the delta method is more conservative.  相似文献   

14.
Iron plaque occurs on the roots of most wetland and submersed aquatic plant species and is a large pool of oxidized Fe(III) in some environments. Because plaque formation in wetlands with circumneutral pH has been largely assumed to be an abiotic process, no systematic effort has been made to describe plaque-associated microbial communities or their role in plaque deposition. We hypothesized that Fe(II)-oxidizing bacteria (FeOB) and Fe(III)-reducing bacteria (FeRB) are abundant in the rhizosphere of wetland plants across a wide range of biogeochemical environments. In a survey of 13 wetland and aquatic habitats in the Mid-Atlantic region, FeOB were present in the rhizosphere of 92% of the plant specimens collected (n = 37), representing 25 plant species. In a subsequent study at six of these sites, bacterial abundances were determined in the rhizosphere and bulk soil using the most probable number technique. The soil had significantly more total bacteria than the roots on a dry mass basis (1.4 × 109 cells/g soil vs. 8.6 × 107 cells/g root; p < 0.05). The absolute abundance of aerobic, lithotrophic FeOB was higher in the soil than in the rhizosphere (3.7 × 106/g soil vs. 5.9 × 105/g root; p < 0.05), but there was no statistical difference between these habitats in terms of relative abundance (1% of the total cell number). In the rhizosphere, FeRB accounted for an average of 12% of all bacterial cells while in the soil they accounted for < 1% of the total bacteria. We concluded that FeOB are ubiquitous and abundant in wetland ecosystems, and that FeRB are dominant members of the rhizosphere microbial community. These observations provide a strong rationale for quantifying the contribution of FeOB to rhizosphere Fe(II) oxidation rates, and investigating the combined role of FeOB and FeRB in a rhizosphere iron cycle.  相似文献   

15.
Abstract. Light, probably acting through the photo-receptor phytochrome, promotes germination of weed seeds when the soil is disturbed by tillage operations. A short period of burial is shown to induce an enormous ∼10000-fold increase in light sensitivity in the seeds of the arable weed Datura ferox which is interpreted as a natural transition to the 'very-low-fluence' mode of phytochrome action. Field experiments indicated that germination of buried seeds may be triggered by millisecond-exposures to sunlight and suggested a key role for the process of sensitization in the mechanisms whereby light requiring seeds detect the occurrence of soil cultivation events in arable lands.  相似文献   

16.
17.
18.
A simple and sensitive method for determining hypusine in proteins was developed. A greater part of amino acids in the acid hydrolysate of proteins was separated from hypusine by treatment with an ion-exchange resin. The sample containing partially purified hypusine was then analyzed by high-performance liquid chromatography using the post-column derivatization method with o-phthalaldehyde. The recovery rate of hypusine through the overall procedure was more than 95%. Using this method, the distribution and developmental changes of hypusine in proteins were determined. The amino acid was found in proteins of all examined organs of rat. Its concentration was 5–40 nmol/g protein. The subcellular distribution in rat liver was also determined. About 60% of total amount of hypusine was present in the proteins of cytoplasmic and microsomal fractions and its relative concentration was high in the proteins of microsome and lysosome and low in mitochondria. In developing rat, the concentration of hypusine in the brain proteins was relatively high during the first 2 or 3 weeks of postnatal life and then decreased until adulthood. Its concentration in the liver proteins was highest at birth and then decreased continuously to the adult level.  相似文献   

19.
In this contribution we investigate the applicability of different methods from the field of independent component analysis (ICA) for the examination of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data from breast cancer research. DCE-MRI has evolved in recent years as a powerful complement to X-ray based mammography for breast cancer diagnosis and monitoring. In DCE-MRI the time related development of the signal intensity after the administration of a contrast agent can provide valuable information about tissue states and characteristics. To this end, techniques related to ICA, offer promising options for data integration and feature extraction at voxel level. In order to evaluate the applicability of ICA, topographic ICA and tree-dependent component analysis (TCA), these methods are applied to twelve clinical cases from breast cancer research with a histopathologically confirmed diagnosis. For ICA these experiments are complemented by a reliability analysis of the estimated components. The outcome of all algorithms is quantitatively evaluated by means of receiver operating characteristics (ROC) statistics whereas the results for specific data sets are discussed exemplarily in terms of reification, score-plots and score images.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号