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871.
Experiments have been performed to evaluate the impact of weak permanent horizontal magnetic field of about 400 A/m on seed formation in the main magnetic orientation types of radish, the north-south (NS) and west-east (WE) types. The results show that external magnetic field exposure retards plant progression through all stages of ontogeny but does not alter the ratio of NS and WE types. Under its effect, the numbers of pods and seeds and seed weight decrease in the NS-type but increase in the WS-type plants. Therefore, external magnetic field acts as an ecological factor that differentiates the responses of radish plants depending on the type of their magnetic orientation. Differences in the sensitivity of plants to magnetic field exposure are explained by specific features of their physiological status.  相似文献   
872.
The structure of bumblebee communities has been studied in some ecosystems of Kunashir Island and Southern Sakhalin. The island taxocenes include five to eight bumblebee species. Bombus hypnorum is dominant in the majority of habitats. In geothermal areas near hot springs on Kunashir, the families of this species develop more rapidly than in areas without geothermal heating.  相似文献   
873.
Consideration is given to changes in the vegetation and climatic conditions on the eastern slope of the Northern Urals in the second half of the Holocene as reconstructed on the basis of integrated palynological, botanical, paleocarpological, and radiocarbon analysis of material from a peat bog section in the floodplain of the Loz’va River. The results show that the northern taiga zone of the study region in the period between approximately 5000 and 700 years BP was occupied by forests of southern taiga facies, as the climate was significantly warmer than it is today.  相似文献   
874.
Microcalorimetric, gasometric, and nuclear magnetic resonance (NMR) methods have been used to evaluate heat production, gas exchange, and root membrane permeability in dandelion of different morphological forms from populations exposed to different levels of air pollution. The results show that these forms differ in the level of energy metabolism and that the form with a higher metabolic level (T. off. f. dahlstedtii) is more tolerant of air pollution with motor vehicle exhausts.  相似文献   
875.
The food supply to a large metropolis such as Paris involves huge fluxes of goods, which considerably impact the surrounding rural territories. Here, we present an attempt to localise Paris food supply areas, over a period of two centuries (1786, 1886, 2006), based on the analysis of data from transportation and production statistics for cereals, animal products, and fruits and vegetables, all three categories being expressed in terms of their nitrogen (i.e. protein) content. The results show contrasting trends for the three types of agricultural products. As for cereals, the Paris supply area remained for the most part restricted to the central area of the Paris basin, a region which gradually became specialised in intensive cereal production. Conversely, as animal farming had been progressively excluded from this area, regions located west and north of Paris (Brittany, Normandy, Nord-Pas-de-Calais) gradually dominated the supply of animal products to the metropolis. In addition, imported feed from South America today contributes as much as one-third of the total ration of feed in the livestock raised in these regions. For fruits and vegetables, about one-half of the Paris supply currently comes from long-distance imports, the other half coming from areas less than 200 km from Paris. As a whole, the Paris food supply area, although it has obviously enlarged in recent periods, is still anchored to an unexpected extent (about 50%) in its traditional nearby hinterland roughly coinciding with the Seine watershed, and in the regions specialised in animal farming located west and north. On the other hand, the agricultural system of the main food supply areas has considerably opened to global markets.  相似文献   
876.
Urbanisation is increasing and today more than a half of the world’s population lives in urban areas. Cities, especially those where urbanisation is un-planned or poorly planned, are increasingly vulnerable to hydro-meteorological hazards such as heat waves and floods. Urban areas tend to degrade the environment, fragmenting and isolating ecosystems, compromising their capacity to provide services. The regulating role of ecosystems in buffering hydro-meteorological hazards and reducing urban vulnerability has not received adequate policy attention until now. Whereas there is a wide body of studies in the specialised biological and ecological literature about particular urban ecosystem features and the impacts of hazards upon people and infrastructures, there is no policy-driven overview looking holistically at the ways in which ecosystem features can be managed by cities to reduce their vulnerability to hazards. Using heat waves and floods as examples, this review article identifies the aggravating factors related to urbanisation, the various regulating ecosystem services that buffer cities from hydro-meteorological impacts as well as the impacts of the hazards on the ecosystem. The review also assesses how different cities have attempted to manage related ecosystem services and draws policy-relevant conclusions.  相似文献   
877.
Comparative analysis of the structure of small mammal communities has been performed in two European cities located in different biomes: Chisinau (2008?C2009) and Yaroslavl (1994?C2002). The parameters studied included abundance, species composition, similarity and difference of faunas, species diversity, and proportions of groups differing in predisposition to synanthropy. It has been found that the structure of small mammal communities in these cities depends on specific physiographic conditions of the surrounding areas and on the distinctive features of the cities themselves (their structure, age, etc.). The similarity between the faunas is accounted for by the common ecological patterns of fauna formation in the biota of urban cenoses.  相似文献   
878.
The results are presented that have been obtained during long-term studies (1991–2009) on the efficiency of natural reproduction of the beluga, Russian sturgeon, stellate sturgeon, and sterlet in different spawning zones of the Volga. The influence of major environmental factors on the formation of the offspring of these fishes is analyzed. It is shown that the productivity of Volga spawning grounds varies depending on the river flow volume during spring floods and the abundance of active spawners. Practical recommendations are proposed for enhancing sturgeon reproduction in the Volga.  相似文献   
879.
880.
The Pennsylvania Air Pollution Commission has developed a regulatory program based upon the control of local air pollution problems and reduction of pollutant levels in air basins. The geographical boundaries of 10 air basins have been established. The Commission’s air basin regulations will provide for the reduction of over-all pollutant levels and for emergency procedures in the event of adverse meteorological conditions. The paper discusses the format and objectives of the program.

In order to effectively enforce the air basin regulations and maintain the necessary surveillance of the state’s air quality, a "computerized real time on-line integrated air monitoring-data handling system" has been designed. The system will incorporate a network to constantly monitor the air in each air basin.The primary objectives of the system are: 1. Constant surveillance of air pollution in the air basins.

2. Provide information on air pollution potential alerts.

3. Aid in further development of air quality criteria and regulations.

The air monitoring network is estimated to include approximately 25 remote stations. Each remote will contain air pollution and meteorological sampling equipment and hardware to telemeter to a central station. The data will be transmitted over leased telephone lines. The central station in Harrisburg will contain the necessary hardware to receive and process data, calculate and display results and permit supervisory control of the network. Output options will include immediate display of edited data, command and alarm information, and presentation of statistical results.

Although the air monitoring system is one of the principle ingredients of the program, the air basin concept encompasses other component systems designed to knit together the entire air pollution control program in Pennsylvania.  相似文献   
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