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141.
Forests provide important ecosystem services, and protected areas around the world are intended to reduce human disturbance on forests. The question is how forest cover is changing in different parts of the world, why some areas are more frequently disturbed, and if protected areas are effective in limiting anthropogenic forest disturbance. The Carpathians are Eastern Europe's largest contiguous forest ecosystem and are a hotspot of biodiversity. Eastern Europe has undergone dramatic changes in political and socioeconomic structures since 1990, when socialistic state economies transitioned toward market economies. However, the effects of the political and economic transition on Carpathian forests remain largely unknown. Our goals were to compare post-socialist forest disturbance and to assess the effectiveness of protected areas in the border triangle of Poland, Slovakia, and Ukraine, to better understand the role of broadscale political and socioeconomic factors. Forest disturbances were assessed using the forest disturbance index derived from Landsat MSS/TM/ETM+ images from 1978 to 2000. Our results showed increased harvesting in all three countries (up to 1.8 times) in 1988-1994, right after the system change. Forest disturbance rates differed markedly among countries (disturbance rates in Ukraine were 4.5 times higher than in Poland, and those in Slovakia were 4.3 times higher than in Poland), and in Ukraine, harvests tended to occur at higher elevations. Forest fragmentation increased in all three countries but experienced a stronger increase in Slovakia and Ukraine (approximately 5% decrease in core forest) than in Poland. Protected areas were most effective in Poland and in Slovakia, where harvesting rates dropped markedly (by nearly an order of magnitude in Slovakia) after protected areas were designated. In Ukraine, harvesting rates inside and outside protected areas did not differ appreciably, and harvests were widespread immediately before the designation of protected areas. In summary, the socioeconomic changes in Eastern Europe that occurred since 1990 had strong effects on forest disturbance. Differences in disturbance rates among countries appear to be most closely related to broadscale socioeconomic conditions, forest management practices, forest policies, and the strength of institutions. We suggest that such factors may be equally important in other regions of the world.  相似文献   
142.
Bitterfeld (Germany) was a major site of chemical production in the former German Democratic Republic with chloralkali electrolysis as the basic process. Effluents were dumped via the creek Spittelwasser into the rivers Mulde and Elbe. Despite the fact that the chloralkali industry is known as a possible source of polychlorinated naphthalenes (PCNs), to date no data about PCN pollution in the region of Bitterfeld and downstream regions are available. Therefore, sediments of the creek Spittelwasser were isomer-specifically analysed for penta-, hexa- and heptachlorinated naphthalenes using GC/MS. Concentrations of 880, 543 and 1120 ng/g dry weight were found, respectively. The isomer pattern suggests chloralkali industry as the major source of PCN contamination. Because of their toxicological relevance we suggest to include PCNs into monitoring and risk assessment programs of the rivers Mulde and Elbe downstream of Bitterfeld.  相似文献   
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Understanding how long-term abiotic and biotic processes are linked at a landscape level is of major interest for analyzing future impact on humans and the environment from present-day societal planning. This article uses results derived from multidisciplinary work at a coastal site in Sweden, with the aim of describing future landscape development. First, based on current and historical data, we identified climate change, shoreline displacement, and accumulation/erosion processes as the main drivers of landscape development. Second, site-specific information was combined with data from the Scandinavian region to build models that describe how the identified processes may affect the site development through time. Finally, the process models were combined to describe a whole interglacial period. With this article, we show how the landscape and ecosystem boundaries are affected by changing permafrost conditions, peat formation, sedimentation, human land use, and shoreline displacement.  相似文献   
145.
The drastic socio-economic and political changes that occurred after the breakdown of socialism in Eastern Europe triggered widespread land use change, including cropland abandonment and forest cover changes. Yet the rates and spatial patterns of post-socialist land use change remain largely unclear. We used Landsat TM/ETM+ images to classify land cover maps and assess landscape pattern changes from 1990 to 2005 in Argeş County, Southern Romania. Cropland abandonment was the most widespread change (21.1% abandonment rate), likely due to declining returns from farming, tenure insecurity, and demographic developments during transition. Forest cover and forest fragmentation remained remarkably stable during transition, despite widespread ownership transfers. Cropland abandonment provides opportunities for increased carbon sequestration, but threatens cultural landscapes and biodiversity. Continued monitoring is important for assessing whether abandoned croplands will eventually reforest or be put back into production and to better understand the consequences of post-socialist land use change for ecosystems and biodiversity.  相似文献   
146.
Fe2O3-containing waste materials from the steel industry are proposed as oxygen carrier for chemical-looping combustion. Three such materials, red iron oxide, brown iron oxide and iron oxide scales, have been examined by oxidation and reduction experiments in a batch fluidized-bed reactor at temperatures between 800 and 950 °C. NiO-based particles have been used as additive, in order to examine if it is possible to utilize the catalytic properties of metallic Ni to facilitate decomposition of hydrocarbons into more reactive combustion intermediates such as CO and H2. The experiments indicated modest reactivity between the waste materials and CH4, which was used as reducing gas. Adding small amounts of NiO-based particles to the sample increased the yield of CO2 in a standard experiment, typically by a factor of 1.5–3.5. The fraction of unconverted fuel typically was reduced by 70–90%. The conversion of CH4 to CO2 was 94% at best, corresponding to a combustion efficiency of 96%. This was achieved using a bed mass corresponding to 57 kg oxygen carrier per MW fuel, of which only 5 wt% was NiO-based synthetic particles. The different materials fared differently well during the experiments. Red iron oxide was fairly stable, while brown iron oxide was soft and subject to considerable erosion. Iron oxide scales experienced increased reactivity and porosity as function of the numbers of reduction cycles.  相似文献   
147.
Results of a field experiment (please refer to Warrelmann et al. 2000a) document TNT-degradation and regeneration after the establishment of a phytoremediation. Various approaches are included in a complex monitoring system, which are conducted in the field (nitroaromatics in soil, seepage water, and plants; soil fauna; soil fungi; decomposition) as well as in the lab (a battery of 6 biotests). The data document a high heterogeneity of the TNT-contamination, a rapid initial decrease and a mediocre displacement of nitroaromatics in plants and seepage water. The initial rapid transformation of TNT to aminodinitrotoluenes ceases significantly after 3 months. Results of the biotest battery allow a sophisticated assessment of soil toxicity; the results from the soil ecological field investigations make the long-term effects of TNT-contamination likely. In a third part of the series of articles, a synopsis and judgement of the project will be delivered.  相似文献   
148.
This paper analyses the influence of climate change and land development on future flood risk for selected Austrian flood-prone municipalities. As part of an anticipatory micro-scale risk assessment we simulated four different inundation scenarios for current and future 100- and 300-year floods (which included a climate change allowance), developed scenarios of future settlement growth in floodplains and evaluated changes in flood damage potentials and flood risk until the year 2030. Findings show that both climate change and settlement development significantly increase future levels of flood risk. However, the respective impacts vary strongly across the different cases. The analysis indicates that local conditions, such as the topography of the floodplain, the spatial allocation of vulnerable land uses or the type of land development (e.g. residential, commercial or industrial) in the floodplain are the key determinants of the respective effects of climate change and land development on future levels of flood risk. The case study analysis highlights the general need for a more comprehensive consideration of the local determinants of flood risk in order to increase the effectiveness of an adaptive management of flood risk dynamics.  相似文献   
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150.
The capacity of a concentrating solar thermal power (CSP) plant can be considered flexible and firm, just like that of a conventional steam cycle power station. Periods without sunshine can be bridged by thermal energy storage or fuel, enabling a CSP plant to deliver power on demand at any time. To this technical quality is added the economic quality of electricity costs that will be stable for a lifetime because they are mainly composed of capital costs, spare parts and personnel. CSP is competitive with power from fuel oil and moving to break even in costs with natural gas by around 2020 and steam coal by around 2025. Carbon dioxide emissions of 10–40 tons/GWh, land use of 250–550 m²/GWh and water consumption of 250 m³/GWh (using dry cooling) compare favorably with other energy sources. Environmental benefits, the technical imperative of firm and at the same time flexible power supply, and the economic targets of affordability and cost stability are the main reasons for a significant role for CSP in a sustainable future electricity mix. Two case studies show the different roles CSP can play north and south of the Mediterranean Sea, in one case importing CSP to Germany for flexible power and in the second case using CSP in Jordan to provide firm and at the same time renewable power capacity for the quickly growing electricity demand.  相似文献   
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