Chemische Reaktionen von Phenylarsinverbindungen

Diphenylarsenic chloride (CLARK I) and diphenylarsenic cyanide (CLARK II) react quickly and quantitatively with dimercaptanes at room temperature to yield diphenylarsine thiolthioether. The thiolthioethers could be identified using mass spectrometry. This reaction can be used for the gas-chromatographic detection of diphenylarsenic compounds.     

Chemische Reaktionen von Phenylarsinverbindungen

In an equilibrium reaction, phenylarsine dichloride (PFIFFIKUS) reacts rapidly with alcohols at room temperature to yield phenylarsine bisether and phenylarsine chloride ether. The reactions, however, are not quantitative. The derivatives were identified using mass spectrometry.     

Chemische Reaktionen von Chlorvinylarsinverbindungen (Lewisite)

2-Chlorovinylarsine dichloride (Lewisite I) react by room temperature quickly with alcohols in an equilibrium reaction to yield 2-Chlorovinylarsine chloride ether and 2-Chlorovinylarsine bisether. The reactions are not quantitative. The ethyl- and propylether are not stable. The ether were identified with mass spectrometry.     

Chemische Reaktionen von chlorvinylarsinverbindungen (Lewisite)

2-Chlorovinylarsine dichloride (Lewisite I) and 2,2′-dichlorodivinylarsine chloride (Lewisite II) react by room temperature rapidly and quantitatively with dithiols in a substitution reaction. The derivatives were identified with mass spectrometry. They can be detected with GC/ECD. This reactions can be used for the gas chromatographic detection of Lewisites in water and soil samples.     

Die Bedeutung der Zeit

Reflecting on time and its nature has a long tradition in such fields as philosophy, economy and the social sciences. In environmental sciences, however, time has not been taken into sufficient consideration to date, although many ecologists are indeed aware of its importance. Because of the importance of time for mankind, nature and the surrounding world, an outline incorporating time is possible and would lead to new insights in environmental sciences. Here, our idea of a balanced or “healthy” ecosystem, or the consequences of our actions such as depletion of the ozon layer, the greenhouse effect or floods are taken into consideration. A reflection on time its a basic requirement for our understanding of environmental science, its tools and our environmental and political actions. A consideration of time in environmental sciences means, among other things, to think of and to act in accordance with time scales and the rhythms of man and nature.     

Die Bedeutung der Zeit

The consideration of time in environmental research allows new insights into the fundamentals of environmental research and new pathways for perceiving and answering questions which might arise in environmental research. In order to take this all into account, one must realize that ecological systems have a history and that both the spatial aspects and the chronological expansion of these systems must be taken into consideration. Considering temporalities, rhythms and time scales as well as their interdependencies in environmental research and environmental protection enables us to obtain a better understanding. The significance of relationships and functions in ecological systems can be perceived better as well. The impact of pollutants as well as the outcome of human actions in ecology, and in economics and politics, is consequently mandatory for not only a spatial, but also for the involved temporal scales.     

Die Bedeckungsreaktion von Seeigeln. Neue Versuche und Deutungen

The conditions under which covering (“decorating”, “masking”) takes place have been studied in the sea urchins Paracentrotus lividus, Psammechinus miliaris and 2 other species. Covering occurs equally in darkness or light. It requires suitable objects and locomotion or searching activity of the tube feet. The covering reaction which may follow chemical, mechanical or optical stimuli may be purely the result of an increase in locomotory or general activity. Initial selection of different covering objects depends on the tube feet reflexes; size, form and weight of the object are important. Whether an object is accepted or not, depends on its surface and structure, the amount of water movement and the general activity level of the sea urchin. Transparency and colour of an object do not appear to be important. It is suggested that the covering process can be explained in terms of local tube feet and spine reflexes. The loading-up of objects may be understood as “relative walking”: the same reflexes which move the urchin on stable ground, draw loose particles towards the animal and then upwards.     

Die Umsetzung der FFH-Richtlinie in der Agrarlandschaft

The EU Habitats Directive (92/43/EEC) does include provisions for setting up the Natura 2000-network of protected areas based on listed species and habitats, and in addition specific regulations on species protection. Three Quarters of all designated sites (SCI’s) do not only include natural habitat types in a strict sense like forests or water-bodies, but also agricultural land. 18?% of the SCI’s even include between 25 and 50?% agricultural land and 24?% above 50?%. 48 species and three habitat types listed under the Habitats Directive have a clear focus in agriculture. Another eleven habitat types are dependant from a nature-friendly low intensity use or management. A large proportion of these habitats and species are actually in an unfavourable conservation status. The paper analyses the impact of EU nature conservation on agriculture based on the species and habitats falling under the Habitats Directive. On the other hand indirect negative influences of agriculture are discussed, that may have considerable impact on the future development of the conservation status of endangered habitats and species.     

Physiologische anpassungen eines marinen insekts. I. Die zeitliche steuerung der entwicklung

The Baltic populations of Clunio marinus (Chironomidae, Diptera) differ from their Atlantic counterparts in three ways: they neither pupate nor hatch in synchrony with a lunar rhythm; they live in a permanently submersed habitat; the structures of their gelatinous egg-masses are different. C. marinus produces two generations each year. The spring generation, which hibernates in the 4th larval stage, hatches in May; the summer generation hatches at the end of July or beginning of August; hatching periods last only a few days. In the laboratory, a permanent short-day period (8 h light, 16 h dark; LD 8:16) induces larval quiescence (oligopause), which can be terminated by long-day conditions (ca. LD 16:8). If larval populations are exposed to continuous light (LL) for 4 days every 30 days, particularly large numbers of imagos hatch about the time of the next LL-period. Increased illumination may influence the time of hatching. Raising the temperature for a few days does not affect hatching. The roles of photoperiod, illumination and temperature are discussed with regard to the temporal programming of development and the start of mass hatching in the natural habitat.

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Herrn Professor Dr. D. Neumann danke ich für die Anregung und Betreuung dieser Arbeit, die Teil einer Dissertation ist.

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Communicated by O. Kinne, Hamburg     

Die vertikale verteilung und tägliche migration der hydromedusen (Hydrozoa: Coelenterata) in der Bucht von Eilat (Rotes Meer)

During the summer of 1970, plankton samples were made in the Bay of Eilat (Red Sea) to study the vertical distribution and diurnal migration of zooplankton. During this project, three programs of 24 h were carried out with a closing net. The hauls were taken every 2 h in different depths, together with measurements of temperature and salinity. The vertical distribution of hydromedusae, especially of Aglaura hemistoma, Péron and Lesueur, 1809 and Liriope tetraphylla (Chamisso and Eysenhardt, 1821), between the surface and 300 m is described. The diurnal migration for these two species was studied. Presumably temperature and salinity had no direct influence on vertical distribution and diurnal migration, as there was a homogeneous water body. The results are discussed.     

Physiologische Anpassungen eines marinen insekts. II. Die Eigenschaften von schwimmenden und absinkenden Eigelegen

The gelatinous egg-masses of Clunio marinus (Diptera; Chironomidae) consist of a tube of jelly containing up to 175 eggs. The swimming egg-mass of the Atlantic populations (Race A) and the sinking egg-mass of the Baltic populations (Race B) have a higher density than the sea water, on which the female spawns; salinity is not important to the swimming or sinking of the egg-masses. Density and sinking velocity of gelatinous egg-masses from Atlantic midges are significantly higher than those from Baltic midges if the eggs are laid on water of the same salinity. The density of the eggs and the quantitative relation of eggs to jelly are the same in both races. The jelly of the egg-masses from the Baltic Sea race swells more than that from the Atlantic Sea race (increase of volume by absorption of water = 3-fold and 2.4-fold, respectively). During swelling the jelly alters from a trough-like shape into a tube-like from which closes around the eggs. If the surface tension of the spawning medium is lowered by use of detergents, the A-spawn will sink. A- and B-spawns occupy different positions at an oil-water interface. Interference contrast microscopy revealed that the A-jelly forms a well-defined outer line in relationship to the surrounding aqueous medium; this line is missing in the B-jelly. The morphological fine surface structures, as seen by the scanning electron microscope, do not explain the different properties of the A- and B-spawn. Extracts and hydrolysates of jelly material were separated by thin-layer chromatography. The results indicate that the spawn jelly of C. marinus consists of a polysaccharide-protein-complex, similar to the jellies of other invertebrates. It is rather probable that the chemical structure or the components of the jellies from A- and B-populations are not exactly the same; this would explain the different properties described. The ecological significance of swimming and sinking gelatinous egg-masses and the taxonomical position of both midge populations are discussed.     

Die Wirkung von Photooxidantien auf Sommerweizen (Triticum aestivum L. Star)

The effect of short-time fumigation with the peroxidic photooxidants ozone, peroxyacetyl nitrate (PAN), and hydrogen peroxide (H₂O₂) on the gas exchange of wheat leaves was investigated. Two types of experiments are to be distinguished:

1. Fumigation is carried out at atmospheric CO₂ partial pressure (350 μbar) and the assimilation and transpiration rates are followed simultaneously.
2. The alteration of CO₂-response curves by fumigation is determined; from this, characteristic photosynthetic parameters can be calculated.

With this method, statements about the reaction of both photosynthesis as a whole and specific reaction sites within the most important photosynthetic processes are possible. Ozone in concentrations of 260–280 ppb causes a primary perturbation of the photosynthetic apparatus, whereby the carboxylation rate is affected to nearly the same extent as the electron-transport rate.PAN (120 ppb) causes a reduction in the assimilation rate, primarily due to the closing of the stomata. H₂O₂ affects the gas exchange only in concentrations of above 1 ppm, whereby the reduction of the assimilation rate represents an almost pure stomatal effect. All three fumigants cause an increase in the respiration rate, which may point to an activation of detoxification and repair mechanisms.