Auswirkungen einer Temperaturerhöhung in einem Freilandexperiment auf den Stickstoffaustrag aus Bodensäulen mit verschiedenartiger Humusform

Effects of a temperature increase in a field experiment on the nitrogen release from soil cores with different humus forms Global warming could have far-reaching consequences for the properties of soils. From the available knowledge it is postulated that an increase in temperature (all other climatic conditions unchanged) will decrease the nitrogen contents until a new equilibrium is reached. To test this hypothesis we established in the ‘Tegernsee Alps’ a field experiment. In spruce-dominated montane forests 60 undisturbed soil cores (= monoliths) were carefully digged out at 1250 and 1320 m asl and reestablished at 3 elevations (1250 m and 1010 m and at 740 m asl) corresponding to a warming of around 1 and 2°C. At each slope position we investigated a Dystric Cambisol with raw humus (RH) and another one with moder (MO). Each of these 6 trial-variants therefore was represented by 10 monoliths. From August 1992 to December 1995 seepage water was sampled by suction cups every 2 or 4 weeks and analyzed for the concentrations of important bioelements including aluminum, pH and electrical conductivity. After translocation to warmer climates additional nitrogen was released from both soil forms mainly as nitrate. The cambisol with the more active humus form moder reacted stronger than the one with raw humus (additional output > 40 vs. 34 kg ha^?1 a^?1; +2°C). In both soil forms the N release was accelerated in summer, in RH by 55 to 92 and in MO by 37 to 86 ppm. The Cambisol with moder showed higher nitrate leaching also in winter and thus was superior with regard to the total annual N output. In all cases Al was the most important associated cation to NO₃^? with 75% (RH) and 54% (MO) of the cation equivalent sum respectively. The experiment thus confirms a substantial increase of nitrification even by a temperature increase of only 1 and 2°C, which in permeable, well aerated soils should lead to increased nitrate leaching under conditions where no vegetation is interfering.     

Theoretical study of geometric phase effects in the hydrogen-exchange reaction

The crossing of two electronic potential surfaces (a conical intersection) should result in geometric phase effects even for molecular processes confined to the lower surface. However, recent quantum simulations of the hydrogen exchange reaction (H + H2 --> H2 + H) have predicted a cancellation in such effects when product distributions are integrated over all scattering angles. We used a simple topological argument to extract reaction paths with different senses from a nuclear wave function that encircles a conical intersection. In the hydrogen-exchange reaction, these senses correspond to paths that cross one or two transition states. These two sets of paths scatter their products into different regions of space, which causes the cancellation in geometric phase effects. The analysis should generalize to other direct reactions.     

Solar wind origin in coronal funnels

The origin of the solar wind in solar coronal holes has long been unclear. We establish that the solar wind starts flowing out of the corona at heights above the photosphere between 5 megameters and 20 megameters in magnetic funnels. This result is obtained by a correlation of the Doppler-velocity and radiance maps of spectral lines emitted by various ions with the force-free magnetic field as extrapolated from photospheric magnetograms to different altitudes. Specifically, we find that Ne7+ ions mostly radiate around 20 megameters, where they have outflow speeds of about 10 kilometers per second, whereas C3+ ions with no average flow speed mainly radiate around 5 megameters. Based on these results, a model for understanding the solar wind origin is suggested.     

We and our pets: allergic together?

The study of allergies in creatures living together without being relatives can help us understand the impact of environmental influences. We tested the association of allergies in humans and their pets. A nested unmatched case-control study was performed in a random sample of 4261 inhabitants, aged 25-74 years, of the City of Augsburg, Germany and two adjacent counties. Using standardised computer-assisted face-to-face interviews, we determined and compared the prevalence of doctor-diagnosed atopic diseases (hay fever, asthma, atopic dermatitis) in the study subjects and veterinarian-diagnosed allergies in their pets. Pets were kept in 48.0% of the households (cats 26.1%, dogs 20.1%, rodents 9.7%) and a veterinarian had diagnosed an allergy in 3.9% (cats 3.3%, dogs 4.7%, rodents 1.2%). Atopic diseases were diagnosed in 20.2% of the study subjects (asthma 6.1%, hay fever 13.7%, atopic dermatitis 5.1%). After adjustment for age, sex, parental predisposition and social status a significant association between hay fever in the study subjects and allergies in their pets was observed [odds ratio (OR) 1.74, 95% confidence interval (CI) 1.01-2.97]. This association was more pronounced when investigating dogs only (OR 2.76, 95% CI 1.32-5.77) where in addition an association with the overall prevalence of atopic diseases in the study subjects reached significance (OR 2.31, 95% CI 1.16-4.58). We conclude that there is indication for a concomitant occurrence of allergies in humans and their pets. Shared environmental factors are the most likely explanation.     

Die Bedutung der Kartoffel-Veredelung in Deutschland

Ohne Zusammenfassung Vortrag gehalten in der Sektion “Utilization” (Verwertung) auf der Ersten Dreijahrestagung der E.A.P.R., Braunschweig-V?lkenrode, September 1960.     

New cell lines for efficient propagation of koi herpesvirus and infectious salmon anaemia virus

The production of piscine viruses, in particular of koi herpesvirus (KHV, CyHV‐3) and infectious salmon anaemia virus (ISAV), is still challenging due to the limited susceptibility of available cell lines to these viruses. A number of cell lines from different fish species were compared to standard diagnostic cell lines for KHV and ISAV regarding their capability to exhibit a cytopathic effect (CPE) and to accumulate virus. Two cell lines, so far undescribed, appeared to be useful for diagnostic purposes. Fr994, a cell line derived from ovaries of rainbow trout (Oncorhynchus mykiss), produced constantly high ISA virus (ISAV) titres and developed a pronounced CPE even at high cell passage numbers, while standard cell lines are reported to gradually loose these properties upon propagation. Another cell line isolated from the head kidney of common carp (Cyprinus carpio), KoK, showed a KHV induced CPE earlier than the standard cell line used for diagnostics. A third cell line, named Fin‐4, established from the fin epithelium of rainbow trout did not promote efficient replication of tested viruses, but showed antigen sampling properties and might be useful as an in vitro model for virus uptake or phagocytosis.     

Die Stickstoffbilanz eines hochmontanen Bergwaldökosystems in den Tegernseer alpen in Abhängigkeit von der Jahreswitterung

The nitrogen budget of a montane forest ecosystem in the Bavarian Alps was investigated from summer 1993 to winter 1995/96 in dependence on seasonal weather in the project “The influence of climate change on the nitrogen budget of forest soils”. The N-budgets were calculated by the nitrogen input via throughfall and the nitrogen output by seepage water, that has been sampled using suction cups. The hypothesis of a more positiv nitrogen budget of the ecosystem in warmer summers — nitrogen input is greater than nitrogen output — could neither be confirmed nor rejected, because there were no two summers differing solely in temperature. Rather, the variable precipitation regime during the summer season predominates a potentially changed nitrogen uptake by vegetation. In the investigated ecosystem, the nitrogen budget is less positive if the precipitation is higher and/or the average temperature of the air is lower. Also, for winter periods with higher precipitation we calculated a lower rate of nitrogen accumulation or even a nitrogen loss. On the other hand, higher temperatures will cause accelerated nitrogen accumulation. This is explained by the importance of high nitrogen inputs via throughfall in winter. The sequestration of potentially mobile nitrate-N in organic matter, and thus its retention in the ecosystem, demands a certain degree of humus activity. This activity is diminished at low temperatures.