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The Science of Nature - 相似文献
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Laturnus F Fahimi I Gryndler M Hartmann A Heal MR Matucha M Schöler HF Schroll R Svensson T 《Environmental science and pollution research international》2005,12(4):233-244
- DOI: http:/dx.doi.org/10.1065/espr2005.06.262
Goal, Scope and Background The anthropogenic environmental emissions of chloroacetic acids and volatile organochlorines have been under scrutiny in
recent years because the two compound groups are suspected to contribute to forest dieback and stratospheric ozone destruction,
respectively. The two organochlorine groups are linked because the atmospheric photochemical oxidation of some volatile organochlorine
compounds is one source of phytotoxic chloroacetic acids in the environment. Moreover, both groups are produced in higher
amounts by natural chlorination of organic matter, e.g. by soil microorganisms, marine macroalgae and salt lake bacteria,
and show similar metabolism pathways. Elucidating the origin and fate of these organohalogens is necessary to implement actions
to counteract environmental problems caused by these compounds.
Main Features While the anthropogenic sources of chloroacetic acids and volatile organochlorines are relatively well-known and within human
control, knowledge of relevant natural processes is scarce and fragmented. This article reviews current knowledge on natural
formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soils, with particular emphasis
on processes in the rhizosphere, and discusses future studies necessary to understand the role of forest soils in the formation
and degradation of these compounds.
Results and Discussion Reviewing the present knowledge of the natural formation and degradation processes of chloroacetic acids and volatile organochlorines
in forest soil has revealed gaps in knowledge regarding the actual mechanisms behind these processes. In particular, there
remains insufficient quantification of reliable budgets and rates of formation and degradation of chloroacetic acids and volatile
organochlorines in forest soil (both biotic and abiotic processes) to evaluate the strength of forest ecosystems regarding
the emission and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale.
Conclusion It is concluded that the overall role of forest soil as a source and/or sink for chloroacetic acids and volatile organochlorines
is still unclear; the available laboratory and field data reveal only bits of the puzzle. Detailed knowledge of the natural
degradation and formation processes in forest soil is important to evaluate the strength of forest ecosystems for the emission
and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale.
Recommendation and Perspective As the natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soil can
be influenced by human activities, evaluation of the extent of this influence will help to identify what future actions are
needed to reduce human influences and thus prevent further damage to the environment and to human health caused by these compounds. 相似文献
109.
Andrea M. Hofmaier Siegfried M. G. Schwirzer Friedrich J. Wiebel Karl-Werner Schramm Martin Wegenke und Antonius A. F. Kettrup 《Umweltwissenschaften und Schadstoff-Forschung》1999,11(1):2-8
Zusammenfassung Polychlorierte aromatische Kohlenwasserstoffe (PHAK), z.B. 2,3,7,8-Tetrachlordibenzo-p-dioxin (TCDD), weisen eine Vielzahl von toxischen Wirkungen und biologischen Effekten auf. Die Substanzklasse der PHAK besitzt
die Eigenschaft der Bindung an ein cytosolisches Rezeptor-Protein, gefolgt von der Synthese bestimmter Genprodukte, u.a. von
Cytochrom P450 1A1 (CYP 1A1). In dieser Arbeit wird ein Bioassay beschrieben, der erlaubt, die Induktion von CYP 1A1 als Summenparameter
für die biologische Wirksamkeit der kritischen, halogenierten Verbindungen in komplexen Umweltmatrizes zu bestimmen. Zur Abtrennung
von Substanzen aus den Extrakten von Umweltproben (z. B. Naturstoffe und polyzyklische aromatische Kohlenwasserstoffe), die
den Bioassay st?ren k?nnen, wurde ein Ein-S?ulen-Clean-up entwickelt. Die biologisch ermittelten TEQ-Werte stimmen gut mit
den Resultaten der chemischen Analytik überein. Der Bioassay in Kombination mit dem Clean-up bietet eine zeitsparende und
kostengünstige M?glichkeit zur Untersuchung von Umweltproben.
相似文献
110.
The interactions between moult phasing, growth and environmental cues in Northern krill (Meganyctiphanes norvegica) were examined through analysing populations at seasonal, weekly, and daily timescales. The analyses were carried out on resident populations of krill found in three different neritic locations that experience similar environmental signals (the Clyde Sea, Scotland; the Kattegat, Denmark; Gullmarsfjord, Sweden). Seasonal analyses were carried out on the Clyde Sea population and showed that moulting frequency increased significantly moving from winter to summer. The proportion of moulting females in summer samples was often more than double the proportion of moulting males, suggesting that females had a comparatively shorter intermoult period (IMP). Weekly samples taken from the Kattegat showed a similar pattern. However, although the difference between the proportion of female and male moulters was significant in one week, it was not another, mainly because of the variability in the proportion of female moulters. Such variability in females was equally evident in the daily samples taken at Gullmarsfjord. It suggests that females have a shorter IMP (12.5 days) than males (18.4 days) and are more likely to moult in synchrony. Nevertheless, the daily samples revealed that males are also capable of moult synchronisation, although less frequently than females. Shortened IMPs in females were not a result of the abbreviation of specific moult stages. Accordingly, reproductive activity did not alter the course of the normal moult cycle. There was no significant difference between the total body lengths of males and females indicating that females achieve the same levels of growth despite moulting more frequently and having to provision the energy-rich ovaries. This is in contrast to most other crustaceans where the energy costs of reproduction reduce female growth. The fact that females were less abundant than males, probably by suffering a greater level of mortality, suggests that different behavioural strategies, particularly vertical migration regimes, were adopted by each sex to maximise growth and reproduction. 相似文献