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1.
A hypothesis is considered that the establishment and maintenance of mass exchange processes in the Paramecium bursariasymbiotic complex (infusorian–alga) depends on the presence of the third component—bacteria—whose role is underestimated but essential for completing the exchange cycle. The role of this component in the symbiotic cycle of Paramecium bursariais possible to reveal using special bactericidal preparations specifically inhibiting the bacteria involved in the metabolic cycle but having no effect on the functions of the host cell and the zoochlorella population. Experiments with various preparations of this type were performed, and the response to treatment was estimated from growth rates of the symbiotic complex and its components. This allowed identification of an antibiotic (rifampicin) that had no adverse influence on free-living zoochlorella and chlorella-free paramecia (the basic components of the symbiotic cycle) but drastically inhibited the growth of the P. bursariasymbiotic complex, which could be interpreted as evidence in favor of the hypothesis concerning the existence of the third symbiotic component.  相似文献   

2.
Given the strategic situation of the José León de Carranza bridge, which spans the Bay of Cádiz (in the SW of Spain) and carries very heavy motor traffic, together with knowledge of the currents and tidal flows in the zone, we have used a technique of radioactive dating of sediments to study the temporal evolution presented by contamination from lead in the sediment column. This has allowed us to observe the environmental impact, in terms of the concentration of Pb in the sea bed sediments, that has been produced in the zone by the introduction of unleaded gasolines as substitutes for traditional automobile fuels that employ organic forms of tetra methyl lead as an antidetonant agent in the fuel.  相似文献   

3.
This article examines the Sarawak Corridor of Renewable Energy in Malaysia, or SCORE, a US $105 billion infrastructure development plan in Sarawak on the island of Borneo, from a sustainability standpoint. SCORE aims to build 20,000 megawatts of hydroelectric dams along a 320 km corridor comprising more than 70,000 km2 by 2030. The article begins by explaining social science methods utilized for its research interviews and site visits. It then argues that sustainability consists of seven principles articulated in international law: prudence, equity, responsibility, precaution, justice, governance, and compatibility. Next, the paper introduces readers to SCORE before assessing it according to these seven sustainability criteria. The paper finds that SCORE erodes environmental prudence by emitting millions of tons of carbon dioxide and feeding industries that will pollute the land and water. It worsens intergenerational equity by exacerbating poverty and consolidating wealth for corporations and politicians. It degrades responsibility by intensifying tropical deforestation and flaunts precaution by downplaying and ignoring risks to water quality and availability. It is unjust, imposing dams on communities and forcibly relocating thousands of indigenous people, mitigates good governance by condoning bribes and kickbacks along with the violent suppression of dissent, and is incompatible with Malaysia’s own energy policy targets and international standards.  相似文献   

4.
Metallothioneins (MTs), malonedialdehyde (MDA), and glycogen concentrations were determined in order to assess the health status of Ruditapes decussatus exposed to in situ contamination, showing the effects of time, site, and metal contamination on these three biomarkers.Metallothionein was positively correlated with Cd and Zn. If introduced in a multiple model, the factors site and time were shown to decrease significantly MT concentrations. MDA was inversely correlated with size of the animals and was affected by the factor time. Glycogen was inversely correlated with zinc and was affected by both site and time.This study constitutes a field-based validation of a multiparametric approach using specific and nonspecific biomarkers.  相似文献   

5.
Russian Journal of Ecology - This study has been carried out to determine water quality of Sang? Stream (West Anatolia, Turkey) and to compare the performance of indices used. Five biotic and...  相似文献   

6.
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7.
Research into landscape history makes it possible to follow landscape changes in the past and support landscape management, conservation and restoration programs. Floodplain habitats are lost, isolated and fragmented on account of land use. Nowadays, these habitats are threatened by modifications in the natural water regime, as well as agricultural and forestry practices. Floodplains have great importance because they provide a transition between aquatic habitats and terrestrial biotopes. Our analysis of aerial photographs and topographical maps revealed that the major predicted changes in the study area are related to agricultural abandonment and afforestation. The comparison of land cover maps from 1784 to 2005 showed intensification of agriculture with land cover conversions from arable land and orchards to grasslands, marshes and woodlands. The land use types that are mostly responsible for the fragmentation of the landscape are arable land, economic plantations and orchards. We found that fragmentation was greater after 1956. This was caused by socioeconomic changes and showed that the habitats of floodplains have changed intensively during the last 200 years. Knowledge of this last 200 years of history contributes to a more careful and wiser management of the region through biodiversity protection and environmental development.  相似文献   

8.
Minor and trace elements in the shell of Patella aspera (Röding 1798)   总被引:1,自引:0,他引:1  
Specimens of the limpet Patella aspera were collected from a clean, coastal marine site and a contaminated estuary on the south coast of Portugal. The shells were analysed individually for their minor (Mg, Sr) and trace element (Fe, Mn, Zn) content. Mean concentrations of these elements in the shell of P. aspera were 4651, 1318, 35.8, 29.9 and 5.5 microg g(-1), respectively. The elemental concentrations exhibited both a marked intra- and inter-population variability. Despite the variability within individual populations, significant differences in the trace element composition were apparent between the shells taken from the two sites. Small shells (< 2 g) provided the best resolution between sites for both manganese and iron. Differences in zinc were best resolved for larger shells. The shell of P. aspera has an extraordinarily high magnesium concentration, which is insensitive to gross salinity differences, and a trace metal assemblage that can be interpreted in terms of environmental exposure. On these grounds, it is recommended that the shell of P. aspera is a tissue for potential use in environmental trace metal monitoring.  相似文献   

9.
During 1998 regional surveys were conducted to evaluate natural radiation exposure of people in the vicinity of the six Spanish nuclear power stations. Indoor radon, external gamma dose rates outdoors and indoors and radioactivity in soil were measured in these surveys. The highest mean annual effective dose to the population was found in the surroundings of the Almaraz nuclear power plant in the province of Cáceres and was mainly due to the presence of high radon concentrations in homes. In order to make a more accurate assessment of the dose coming from the radon in this area, a new and more extensive surgery on indoor radon with a total of 380 measurements was carried out in 2000 in the Campo Ara?uelo region around the Almaraz nuclear power station. From the results obtained in this survey, a population-weighted mean annual effective dose from radon exposure of 1.7 mSv y(-1), 44% lower than that previously reported in 1998, was estimated for the whole Campo Ara?uelo region. The maximum dose value due to radon exposure, about 4 mSv y(-1), was reached in the so-called La Vera area located in the north of this region. The relationship between the indoor radon concentrates experimentally measured, the geological characteristics of this geographic area and the information provided by the radiation map of the Spanish MARNA Project is also analyzed, confirming that La Vera area should be considered as a high radon level area.  相似文献   

10.
Nowadays, the disparity of the basic pension in local regions of China can be described as follows: the low level of the unification of the basic pension systems, the large disparity of the level of the basic pension, and unfairness of the enterprises’ payment for the basic pension in different local regions in China. These have already brought many negative influences, which have greatly held back the development of the society and national economy. We should build the basic pension system in all local regions of China as a whole, which can cover all people and decrease the disparity in different local regions in China.  相似文献   

11.
The effect of long-term exposure to a stress factor on the pattern of variation and intrapopulation differentiation with respect to phenotypic plasticity was studied in Crepis tectorum L. by means of family analysis of various traits in seedlings. Trends in the changes of variation patterns in populations and the possible consequences of the decrease in the proportions of genotypes determining a low sensitivity to environmental changes and in genotypic diversity with respect to phenotypic plasticity are discussed.  相似文献   

12.
Relationships between abundance of basic net phytoplankton taxonomic groups (cyanobacteria, diatoms, and chlorophytes) and nutrient concentrations in water were studied on the Pas??ka River in years with varied water levels. In high water level conditions, large amounts of orthophosphates and total nitrogen from the catchment could favor development of cyanobacteria and chlorophytes. The species could be allochthonic. At low water levels, the factor stimulating phytoplankton development could be nutrients coming from mineralization of accumulated organic matter. The highest nutrient concentrations could favor diatom development. In such conditions, dominant taxa were autochthonic. In terms of numbers, F. capucina was dominant, and in terms of biomass—genus Spirogyra sp. It could come from plant periphyton inhabiting the concrete drops of the dam included in the river’s development in the vicinity of the hydroelectric power station.  相似文献   

13.
With the development of science and technology, the researches and application of water resources including the gas water have been constantly developed. Through an analysis on the flaws of the water right theory, and by executing reconstruction and renewal of the theory and system of water right in modem society, the water right position of the gas water will be established, leading to the maturity of the whole law effectiveness and substantial results of water right.  相似文献   

14.
Quantitative and qualitative characteristics of cones and seeds and the emergence and survival of seedlings in the Siberian spruce (Picea obovata Ledeb.) were studied in different parts of the timberline ecotone on the Iremel’ Massif, the Southern Urals, from 2003 to 2006. In the productive year 2003, a decrease in the number of cones (from 110000 to 3000 per hectare), the yield of seeds (from 13 × 106 to 0.09 × 106 per hectare), and their laboratory germination rate (from 34 to 14%) with an increase in elevation above sea level was recorded. In 2004, significant differences in the number of seedlings per hectare were revealed between the lower, middle, and upper parts of the ecotone (85 200, 19 800, and 0–400 ind., respectively). It has been shown that the greater part of seedlings (76–96%) perish during the first cold period. New generations of spruce trees are formed only after productive years. Seed production and seedling mortality in spruce apparently depend not only on air temperature and soil moistening but also on snow depth and soil temperature, which change more abruptly along the altitudinal gradient.  相似文献   

15.
Russian Journal of Ecology - Populations at the border of ranges are considered more vulnerable than those in the center. However, some recent reviews contradict this hypothesis. We have studied...  相似文献   

16.
The aim of this work was to make a comparison of indoor radon concentrations in dwellings and in soil air in the area of two geological formations in the Suwa?ki region (Poland). The mean arithmetic airborne concentration was found to be the highest (301 Bq m (-3)) in the basements of buildings in the gravel and sand areas, whereas in the boulder clay areas it reached 587 Bq m (-3). Out of 54 measurements of radon concentrations performed at the ground floor, in eight cases concentrations were found to exceed 200 Bq m (-3) - permissible radon level in new-built houses in Poland and in three cases these values were even higher than 400 Bq m (-3). The highest radon levels were noted in houses with earthen basement floors and with direct entrance from the basement to rooms or kitchens. The mean arithmetic radon concentration in the soil air in the sandy and gravel formations was 39.7 kBq m (-3) and in clay formation it was 26.5 kBq m (-3). Higher radon levels were also found in the water obtained from household wells reaching 8367 Bq m (-3) as compared with tap water (2690 Bqm (-3)). The mean indoor concentration for the whole area under study was found to be 169.4 Bq m (-3), which is higher than the mean value for Poland (49.1 Bq m (-3)) by a factor of 3.5.  相似文献   

17.
Snow cover in Spanish mountains is crucial for ensuring water availability in spring and summer months, for the success of winter tourism or for the maintenance of biodiversity in mountain ecosystems. A changing climate may affect the volume of snow cover even in high mountains, where weather conditions are usually favorable for snow accumulation. In this paper, we aim to investigate the evolution (1970–2007) of combined precipitation–temperature modes in the Spanish mountains, and the sensitivity of the snowpack to their occurrence. The climatic database “Spain02” and snow thickness data for Spanish mountains were used for this purpose. Results showed that the frequency of dry-warm and wet-warm days has increased over time in all mountain ranges, while the frequency of the “cold” modes has decreased. The thickness of the snowpack in the Pyrenees has also decreased and its evolution is negatively correlated with the frequency of dry-warm days, and positively correlated with the frequency of dry-cold and wet-cold days. This work constitutes the first approach that relates the evolution of climatic conditions favorable or unfavorable for snow accumulation and the evolution of the snowpack in Spanish mountains.  相似文献   

18.
The consideration of a possible enhanced vertical migration of radiocaesium with the application of ammonium-ferric-hexacyano-ferrate (AFCF) as countermeasure, due to the colloidal nature of AFCF, made us set up a series of migration experiments. For the study two soil types were considered, which were either left unplanted or cultivated with ryegrass. Two AFCF concentrations, 1 and 10 g m-2, and an untreated control were applied. A simple diffusion–convection model was fitted to the data.The application of AFCF did not enhance the downward migration of radiocaesium in the profile. Moreover, for an unplanted sandy soil the application of AFCF significantly retarded the migration: 10 g AFCF m-2 decreased the convection term, V, from 0·78 to 0·42 cm a-1 and the diffusion component, D, from 0·21 to 0·09 cm2 a-1. For all other experimental conditions (unplanted loamy soil, ryegrass cultivated sandy and loamy soil), the application of AFCF did not have any effect on radiocaesium migration. Since AFCF does not promote the vertical migration of radiocaesium, enhanced groundwater contamination is improbable.  相似文献   

19.
The forest ecosystem of the Orlovskoe Polese National Park has been studied in reference to the reintroduction of a rare species: the European bison (Bison bonasus L.). Preliminary data characterizing the state of forest resources and the populations of ungulates living in the forests, as well as the genetic problems associated with maintaining a viable population of the European bison, are considered.Translated from Ekologiya, No. 2, 2005, pp. 132–137.Original Russian Text Copyright © 2005 by Belousova, Smirnov, Kazmin, Kudrjavtsev.  相似文献   

20.
The third session of the Conference of the Parties to the UNFCCC was held in Kyoto, Japan, on 11 December 1997.  相似文献   

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