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91.
Sabine Charmasson Pierre-Marie Sarradin Antoine Le Faouder Michèle Agarande Jeanne Loyen Daniel Desbruyères 《Journal of environmental radioactivity》2009
Hydrothermal deep-sea vent fauna is naturally exposed to a peculiar environment enriched in potentially toxic species such as sulphides, heavy metals and natural radionuclides. It is now well established that some of the organisms present in such an environment accumulate metals during their lifespan. Though only few radionuclide measurements are available, it seems likely that hydrothermal vent communities are exposed to high natural radiation doses. Various archived biological samples collected on the East Pacific Rise and the Mid-Atlantic Ridge in 1996, 2001 and 2002 were analysed by ICP-MS in order to determine their uranium contents (238U, 235U and 234U). In addition 210Po–Pb were determined in 2 samples collected in 2002. Vent organisms are characterized by high U, and Po–Pb levels compared to what is generally encountered in organisms from outside hydrothermal vent ecosystems. Though the number of data is low, the results reveal various trends in relation to the site, the location within the mixing zone and/or the organisms' trophic regime. 相似文献
92.
Sabine Douxchamps Mark T. Van Wijk Silvia Silvestri Abdoulaye S. Moussa Carlos Quiros Ndèye Yacine B. Ndour Saaka Buah Léopold Somé Mario Herrero Patricia Kristjanson Mathieu Ouedraogo Philip K. Thornton Piet Van Asten Robert Zougmoré Mariana C. Rufino 《Regional Environmental Change》2016,16(5):1305-1317
Adaptation strategies to reduce smallholder farmers’ vulnerability to climate variability and seasonality are needed given the frequency of extreme weather events predicted to increase during the next decades in sub-Saharan Africa, particularly in West Africa. We explored the linkages between selected agricultural adaptation strategies (crop diversity, soil and water conservation, trees on farm, small ruminants, improved crop varieties, fertilizers), food security, farm household characteristics and farm productivity in three contrasting agro-ecological sites in West Africa (Burkina Faso, Ghana and Senegal). Differences in land area per capita and land productivity largely explained the variation in food security across sites. Based on land size and market orientation, four household types were distinguished (subsistence, diversified, extensive, intensified), with contrasting levels of food security and agricultural adaptation strategies. Income increased steadily with land size, and both income and land productivity increased with degree of market orientation. The adoption of agricultural adaptation strategies was widespread, although the intensity of practice varied across household types. Adaptation strategies improve the food security status of some households, but not all. Some strategies had a significant positive impact on land productivity, while others reduced vulnerability resulting in a more stable cash flow throughout the year. Our results show that for different household types, different adaptation strategies may be ‘climate-smart’. The typology developed in this study gives a good entry point to analyse which practices should be targeted to which type of smallholder farmers, and quantifies the effect of adaptation options on household food security. Subsequently, it will be crucial to empower farmers to access, test and modify these adaptation options, if they were to achieve higher levels of food security. 相似文献
93.
Hannu Anttonen Juhani Niskanen Harriet Meinander Volkmar Bartels Kalev Kuklane Randi E Reinertsen Sabine Varieras Krzysztof So?tyński 《International journal of occupational safety and ergonomics》2004,10(3):291-300
According to the European prestandard ENV 342:1998, the thermal insulation of cold-protective clothing is measured with a thermal manikin. Systematic studies on the reproducibility of the values, measured with different types of clothing on the commonly used standing and walking manikins, have not been reported in the literature. Over 300 measurements were done in 8 different European laboratories. The reproducibility of the thermal insulation test results was good. The coefficient of variation was lower than 8%. The measured clothing should fit the manikin precisely, because poorly fitting clothing gave an error in the results. The correlation between parallel and serial insulation values was excellent and parallel values were about 20% lower than serial ones. The influence of ambient conditions was critical only in the case of air velocity. The reproducibility of thermal insulation test results in a single laboratory was good, and the variation was lower than 3%. 相似文献
94.
Tausz M Landmesser H Posch S Monschein S Grill D Wienhaus O 《Environmental monitoring and assessment》2007,128(1-3):75-82
In this work we measured a set of antioxidative and photoprotective compounds (chlorophylls, carotenoids, tocopherol, ascorbate
and glutathione), which were suggested previously as stress markers in conifer needles, at two spruce forest sites at different
elevation in Saxony, Germany. Most variables differed significantly between current and 1-year-old needles, but only the content
of the xanthophyll cycle per mg total chlorophyll and the oxidation state of glutathione were significantly different between
the sites. We applied principal component analysis (PCA) to address the question if underlying accumulated variables are similar
to the ones found in spruce needles across Alpine elevation profiles and/or for pines in Mediterranean ecosystems. Four principal
components (accumulated variables, PC) representing 68% of the total variance of the dataset were extracted. PC 1 encompassed
total chlorophyll, lutein, and β-carotene contents, PC 2 combined the epoxidation state of xanthophylls, ascorbate content
and redox state, and glutathione content, PC 3 represented the content of xanthophylls and the redox state of glutathione,
and PC 4 encompassed the content of α-carotene and the epoxidation state of xanthophylls. Only PC 3 was significantly different
between sites. The PCA structure shows many similarities to corresponding findings in studies on spruce in mountain forests
in the Alps and pines in Mediterranean systems. This corroborates the interpretation of PCs as indicative for underlying physiological
processes. However, separation of the two investigated sites by PCs was in the present case study not superior to the separation
by single input variables. 相似文献
95.
96.
97.
Mohammad I. Majdalawi Claudia Raedig Emad K. Al-Karablieh Sabine Schlueter Amer Salman Mohammad Tabieh 《国际发展与全球生态学杂志》2016,23(5):392-398
Many factors are aggravating desertification and degradation of forests such as urbanization, droughts, exploitation of natural resources and climate change. The study aims at estimating and assessing the degradation of forests in arid and semi-arid regions. This task however is complicated since the impact of the degradation will be in different forms such as loss of wood, soil erosion and lost recreational areas. Nevertheless the dynamic impact of the degradation is increasing the complexity of analysis since forest once lost is a reduction of value for all subsequent years. This study is considering the value of damages over time and it is using the concept of three environmental valuation methods to estimate the whole impact of the degradation: the habitat equivalency analysis (HEA), the productivity method and the benefit transfer method. The methods were applied to specific values of forests, depending on the best applicability, and the results combined to an overall value loss. The costs are calculated based on the year 2014 with two time horizons: 30 and 100 years. To apply the valuation approach, Jordan as an arid and semi-arid country is chosen. The result shows that the annual costs of environmental degradation of Jordanian forest areas equal about 0.14% of GDP in 2013, proving the enormous value lost to forest degradation or deforestation. The valuation approach can be transferred to other arid or semi-arid areas and stimulate forest conservation activities to prevent further degradation and to save the forest ecosystem services for the future. 相似文献
98.
Synchronized spike activity is discussed as a possible representational code for object integration and as a neuronal basis of attention, perception and awareness. As a byproduct of experiments in which monkeys were trained to detect simple figures composed of single Gabor patches in a noisy background of similar elements, we found in special cases increased spike synchrony above chance level specifically related to figure detection. The long latency of this effect is difficult to interpret. It may be a sign of the cognitive state of an animal when it perceives the figure. 相似文献
99.
The capacity of duckweed to treat wastewater: ecological considerations for a sound design 总被引:1,自引:0,他引:1
Duckweed species are promising macrophytes for use in sustainable wastewater treatment due to their rapid growth, ease of harvest, and feed potential as a protein source. This paper reviews growth rates of different duckweed species on wastewater and ammonia toxicity to duckweed and summarizes insights into the mechanism of organic matter and nutrient removal. Results were gained from laboratory experiments in small, shallow, duckweed-covered semicontinuous batch systems. Growth rates on different types of wastewater vary considerably among different species. Ammonia is toxic for duckweed in both the ionized and un-ionized forms. Duckweed, however, can be used to treat wastewater containing very high total ammonia concentrations as long as certain pH levels are not exceeded. The degradation of organic material is enhanced by duckweed through both additional oxygen supply and additional surface for bacterial growth. The duckweed mat with attached bacteria and algae is, independent of the loading rates, responsible for three-quarters of the total nitrogen (N) and phosphorus (P) loss in very shallow systems. Based on our results we suggest that full-scale pilot plants with duckweed should be shallower than the range encountered in the literature. A harvesting schedule that allows doubling times of 2 to 3.5 d, maintenance of a full coverage, and plug flow conditions are recommended. 相似文献
100.
Scott B. Franklin Thad Wasklewicz Jack W. Grubaugh Sabine Greulich 《Journal of the American Water Resources Association》2003,39(3):637-648
ABSTRACT: Periodic flood disturbance is a well known controlling factor of in channel and floodplain ecosystem function. However, channel manipulations during the last century have potentially altered hydrologic fluctuations, and thus ecosystem function. We examined temporal river stage hydrology, through autocorrelation analysis, at seven gauges along the Mississippi River to quantify flow periodicity and effects of systematic channel modifications on flow periodicity. Intraannual variation follows a strong one‐year cycle of six months higher flow and six months lower flow for the entire Mississippi River drainage, with precipitation as a driving force. Interannual hydrologic variation differs between the upper and lower river segments. A clear quasi‐biennial oscillation pattern was evident throughout the lower river section. The effect of channel alterations was a decreased magnitude of differences between lower and higher flows. The upper section, however, suggests a 12‐to 14‐year periodicity prior to alterations and a decreased duration of lower flow years following systematic modifications. Interannual variograms clearly depict very different temporal hydrology between the upper Mississippi River and the lower Mississippi River, suggesting the simple transfer of knowledge from one segment to the other oversimplifies the complexity of a large river system. 相似文献