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221.
The transfer of radiocaesium, one of the most important and widespread contaminants following a nuclear accident, to the fibre crops hemp (Cannabis sativa L.) and flax (Linum usitatissimum L.) as well as the distribution of radiocaesium during crop conversion were studied for sandy soil under greenhouse and lysimeters conditions. Soil parameters did not unequivoqually explain the transfer factors (TF) observed. TFs to flax stems ranged from 1.34 to 2.80x10(-3) m2 kg(-1). TFs to seeds are about a factor of 4 lower. During the retting process for separating the fibres from the straw, more than 95% of the activity was removed with the retting water. For hemp, the TF to the stem was about 0.6x10(-3) m2 kg(-1). For hemp, straw and fibres were mechanically separated and TF to straw was about 0.5x10(-3) m2 kg(-1) and to fibres 1.0x10(-3) m2 kg(-1). Generally, the TFs to the useable plant parts both for hemp and flax, are low enough to allow for the production of clean end-products (fibre, seed oil, biofuel) even on heavily contaminated land. Given the considerable decontamination during retting, contamination levels in flax fibres would only exceed the exemption limits for fibre use after production in extreme contamination scenarios (>12,300kBq m(-2)). Since hemp fibres are mechanically separated, use of hemp fibres is more restricted (contamination <740kBq m(-2)). Use of stems as biofuel is restricted to areas with contamination levels of <250 and 1050kBq m(-2) for flax and hemp, respectively. Use of seeds for edible oil production and flour is possible almost without restriction for flax but due to the high TFs to seed observed for hemp (up to 3x10(-3) m2 kg(-1)) consumption of hemp seed products should be considered with care. 相似文献
222.
223.
Action spectroscopy of light-induced hatching ofArtemia cysts (Branchiopoda: Crustacea) 总被引:2,自引:0,他引:2
The action spectrum for the hatching ofArtemia cysts and the results of illumination experiments with decapsulated cysts suggest that a haempigment may be involved in light-induced hatching. The screening role of haematin is proposed. Starting from the assumption that haematin and the photoreceptor are both haempigments, we can attribute a hatching delaying or photoreceptor protective function to haematin.This work is part of F.K.F.O. Project No. 2.0012.82 相似文献
224.
225.
Gino Van Begin 《Local Environment》2004,9(3):213-216
Since 1994, more than 2000 European local governments have adopted the principles of the Aalborg Charter as a basis for local sustainability action. Now, ten years later in June 2004, these local governments will gather once again in Aalborg, Denmark at the Fourth European Conference on Sustainable Cities and Towns in Europe, Inspiring Futures—Aalborg+10. The Aalborg+10 event will celebrate a decade of European local sustainability action, evaluate progress and stagnation, and, more importantly, will adopt new commitments to move from Agenda to Action. The conference will be crucial for accelerating local sustainability in Europe and to move towards Local Action. Here an overview is provided on the context against which this important conference is set and its expected outcomes. 相似文献
226.
This study focuses on the relationship between job stressors and mental strain in hospital work, adjusting for differences in personality traits. Questionnaires were obtained from 760 full-time employees. Fourteen scales of job stressors were clustered into four factors: professional latitude, clinical demands, workload problems and role difficulties. A mental strain index was derived from the addition of three sub-scales: depression, anxiety and irritation. Two personality traits were measured: Locus of Control (Rotter) and Striver-Achiever (Sales). The four job demand factors were dichotomized into high-low grouping variables. A 24 factorial analysis of covariance was conducted, using the two personality traits as covariates, in order to test and adjust for trait-related strain. Results show that Locus of Control adjusted differences in mental strain appear significantly related to work stressors. A direct relationship was found with role difficulties, professional latitude and workload problems. Moreover, high levels of role difficulties and low levels of professional latitude interact significantly with adjusted levels of mental strain. The Striver-Achiever trait, however, appears most strongly correlated with workload problems but not with mental strain. We believe that this exploratory analysis suggests that the stressor-strain relationship might be best conceived as a combination of direct and complex pathways, relating facets of both job demands and of personality with outcomes, under a cognitive and conditional paradigm. 相似文献
227.
W. Lissens M. Van Lierde J. Decaluwe W. Foulon P. Evrard F. van Hoof M. Freund I. Liebaers 《黑龙江环境通报》1988,8(1):59-62
The X-linked Hunter syndrome or mucopolysaccharidosis II was diagnosed in a male fetus by demonstrating a severe deficiency of iduronate 2-sulphate sulphatase activity in fetal plasma obtained by umbilical fetal blood sampling at 23 weeks of pregnancy. The diagnosis was confirmed after termination of pregnancy. 相似文献
228.
Initial ecological observations at Broken Spur in 1993 suggested a low biomass relative to other deep-water vent communities
known along the Mid-Atlantic Ridge. The persistence of a low shrimp biomass over 15 mo at Broken Spur vents appears to refute
the hypothesis that the community is expanding through reproduction and immigration to occupy habitat vacated during a recent
period of hydrothermal quiescence or catastrophe. Although the absence of “swarms” of shrimp similar to those found at the
hydrothermal mounds of TAG (26°N) and Snake Pit (23°N) is a visually striking feature of the majority of venting structures
known at Broken Spur, the biomass of fauna other than shrimp may not be significantly less than that of other Mid-Atlantic
sites. The discovery of “swarms” of shrimp at Bogdanov Site, visited for the first time in 1994, suggests that availability
of substratum exposed to the flow of hydrothermal fluids, which is a function of the topography of venting structures, may
be a prerequisite for the development of these dense aggregations. Two testable predictions arise from this hypothesis. Firstly,
dense aggregations of Rimicaris exoculata should occur at any other structures with a morphology similar to Bogdanov Site that may be discovered in the Broken Spur
vent field, and should not occur at other isolated chimney structures that may be found. Secondly, “swarms” of shrimp should
appear at any Broken Spur chimneys that develop into structures with a morphology more similar to that of Bogdanov Site in
future.
Received: 2 July 1997 / Accepted: 9 July 1997 相似文献
229.
Chitinolytic enzymes in the integument and midgut-gland of the shrimpPalaemon serratus during the moulting cycle 总被引:1,自引:0,他引:1
Chitinase andN-acetyl--D-glucosaminidase activity were quantified inPalaemon serratus (Pennant) integument and midgut gland during the moulting cycle. Studies were performed on specimens collected near Concarneau, France, in July 1989. The changes in specific activity are different in the two organs: in the midgut gland enzymatic activity is high throughout the whole moulting cycle with a weak peak at the early premoult Stage D1, whereas in the integument the activity of both enzymes is very low throughout post- and intermoult stages and rises only after premoult Stage D1. The highest specific activity is reached in D1 for chitinase and somewhat earlier (D1) forN-acetyl--D-glucosaminidase. The increase in specific chitinolytic activity coincides with an increase in ecdysteroids. 相似文献
230.