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51.
长江中下游浅水湖泊群具有十分重要的生态服务功能。然而,该湖群正面临江湖阻隔和富营养化等严重威胁。近年来,湖泊生态环境的保护和修复越来越受到重视,但治理效果不甚明显。其根本原因是:对由流域诸多胁迫导致的湖泊问题缺乏系统全面的认识,导致头痛医头、脚痛医脚。为此,本文提出应对长江湖群实施环境-水文-生态-经济协同管理战略,即在湖泊及其流域实施环境工程以控制入湖污染,实施生态水文工程以恢复自然水文体制,实施生态修复工程以增强生物自净能力,制定水环境经济制度以建立湖泊保护修复的激励和约束机制,构建生态健康评价体系以实施适应性管理,前提是责任主体明确。  相似文献   
52.

The release of carbon dioxide from the burning of fossil fuels is believed to be responsible for climate change. In the UK, road transport emits 22% of the total output of carbon dioxide. This study applies the ecological footprint to Merseyside to ascertain the global environmental impact of passenger transport (expressed in hectares). Results show that car travel has a footprint of 704 000 hectares, which is 87% of the total footprint. It is demonstrated in scenarios that Policy initiatives involving the Local Transport Plan will cause the footprint to increase. It is also shown that individual behaviour could be influenced when highlighting the impacts of different modes of transport along the same route. By using the ecological footprint in educational programmes, the effect can be shown of carbon emissions and land appropriation on the 'school run'; these issues could be promoted alongside others such as health, safety, congestion, global equity and fairness.  相似文献   
53.
This article presents the results of an analysis of annoyance caused by low-frequency noise (including infrasonic noise) that occurs at work stations located in offices. The tests covered measurements of acoustic parameters specific for this type of noise and a survey conducted in the working environment and in laboratory conditions at a model of a work station.  相似文献   
54.
Tamarisk and river-channel management   总被引:1,自引:0,他引:1  
Tamarisk (Tamarix chinensis, Lour.) an artificially introduced tree, has become a most common species in many riparian vegetation communities along the rivers of the western United States. On the Salt and Gila rivers of central Arizona, the plant first appeared in the early 1890s, and by 1940 it grew in dense thickets that posed serious flood-control problems by substantially reducing the capacities of major channels. Since 1940 its distribution and density in central Arizona have fluctuated in response to combined natural processes and human management. Groundwater levels, channel waters, floods, irrigation return waters, sewage effluent, and sedimentation behind retention and diversion works are major control mechanisms on the growth of tamarisk; on a regional scale of analysis, groundwater levels are the most significant under present conditions.  相似文献   
55.
This article describes three applications of the Universal Soil Loss Equation for further defining differences between natural environments in terms of their suitabilities for recreation use. Physical capacity limits based upon vulnerability to erosion and loss of soil productivity are discussed. Examples include: (a) applications to site planning and comparison of existing campsites; (b) use of the methodology for setting limits of acceptable change; and (c) characterization of third-order or larger watersheds that compare ecological land type interpretations with those based upon application of the equation.  相似文献   
56.
The objective of this study was to determine the concentrations of trace elements in sediment samples taken from impermeable urban areas of a city with predominantly agroindustrial development characteristics. For this, samples were taken every month from paved streets in the city of Toledo, Paraná State (PR), Brazil. Thus, trace element levels were obtained through analysis performed by optical emission spectrometry with inductively coupled plasma. Levels of total organic carbon were also obtained through the dry combustion method. When compared to local background levels, the trace element levels were shown to be enriched in the following percentage proportions: barium (Ba) (45.4%), copper (Cu) (48.6%), chromium (Cr) (37.2%), manganese (Mn) (81.6%), nickel (Ni) (0%), lead (Pb) (40%), zinc (Zn) (283.7%), magnesium (Mg) (34.3%), and sodium (Na) (250.2%), whereas the carbon (C) percentages were around 1%. The most significant enrichment factors occurred for Ba, Cr, Pb, Zn, Mg, and Na. The highest rates occurred in geoaccumulation where the sediments were enriched by zinc. According to the principal guidelines, the concentrations obtained for cadmium (Cd), Cr, Cu, Ni, and Zn can cause adverse environmental impacts.  相似文献   
57.
Volcanic eruptions originated the Canary Islands (Spain), and today, different landscapes clearly show that active volcanism. The microbial communities present in these volcanic environments, both at high (above 70 degrees C) and moderate (25-35 degrees C) temperatures, were analyzed. Rock samples were processed using molecular techniques based on both DNA and RNA and complemented with the culture of microorganisms at a wide range of temperatures. Microorganisms detected through RNA-based molecular surveys were mostly related to mesophilic microorganisms, while representatives of hyperthermophiles were not detected. RNA decay curves at 80 degrees C resulted in half-life estimates of less than 2 min for mesophilic microorganisms, supporting a recent and continuous arrival of microorganisms to the high temperature sampled sites. This study constitutes a unique experimental approach showing a great natural potential of microorganisms to spread out to different natural environments. The implications are of great interest for the biogeography, dispersal, and potential distribution of microorganisms, and their genetic information, in natural environments.  相似文献   
58.
用实验室模拟的方法着重研究硅藻的角刺藻(Chaetocerosgracilis)和乳游甲菏的前沟藻(Amphidimiumhoeflier)生长过程中DMS的生产及不同氮营养条件下对前沟藻DMS生产的影响。结果表明(1)前沟藻和角刺激都可以生产二甲基硫(DMS),但2者DMS生产能力有很大差别,前沟藻DMS平均生产率大约是角刺激藻的100倍。(2)不同生理阶段的DMS产量不同。对数增生匠前沟藻细胞  相似文献   
59.
At work, people may experience fatigue and a depletion of mental resources. The subsequent need for recovery is generally assessed employing subjective reports on evaluative statements. In this paper, we explore whether it is possible to assess employees’ recovery needs with a systematic inspection of behaviors. The idea is based on Campbell’s paradigm (Kaiser, Byrka, & Hartig, 2010), which holds that individuals will perform more, and more difficult behaviors to recover from fatigue when their need for recovery is higher.  相似文献   
60.
Sediments from Polish coastal environments were classified by a quality assessment approach that took into account trace metal and organic micropollutant concentrations, grain-size distribution, and organic carbon content. Generally, no benthic organisms were found at sites where sediments were classified as heavily polluted. However, areas characterized by a moderate contamination showed a variable composition of the benthic community and changing bioaccumulation patterns; therefore, no single species found in the Gulf of Gdańsk could be considered representative of the whole benthic environment. Although sediment monitoring must be considered a suitable tool to detect hot-spot pollution areas in coastal and inland waters, it should be complemented by bioaccumulation measurements to evaluate the actual risk posed by contaminants to benthic organisms. This “biological information” allows a better appreciation of the real benthic infaunal community exposure to chemicals and can usefully complement the existing sediment quality guidelines.  相似文献   
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