Northern Black Forest Research Articles

Airborne C 1- and C 2-halocarbons at four representative sites in Europe

Air concentratiions of trichlorofluoromethane, trichloromethane, tetrachloromethane, 1,1,2-trichloro-1,2,2-trifluoroethane, 1,1,1-trichloroethane, trichloroethene and tetrachloroethene have been determined at four sites: a medium-sized (80, 000 inhabitants), moderately industrialized city in southwest Germany, a mountain forest site in the northern Black Forest, a suburb south of Lisbon at the Atlantic coast of Portugal, and a truly remote oceanic site, the island of Madeira. As expected, there are large differences in the concentrations of those halocarbons which find wide technical applications and have relatively short atmospheric lifetimes; moderate or small differences are found for those with small anthropogenic sources—chloroform and tetrachloromethane. Chloroform tends to be higher at the marine sites, suggesting that it arises from natural sources.

Detection of stress in coniferous forest trees with the VIRAF spectrometer

The Visible Infrared Reflectance Absorbance Fluorescence (VIRAF) spectrometer was applied in outdoor measurements to compare the needles of two spruce trees differently affected by the forest decline in the Northern Black Forest in Germany. Changes of the reflectance signatures due to loss of chlorophyll or other damage effects are interpreted with the help of other techniques currently used for the evaluation of physiological activity. The VIRAF spectrometer was used to examine the spectra of reflectance, absorption, and chlorophyll fluorescence. The measurements were carried out with the same sample without changing its position. By means of the two-wavelength chlorophyll fluorometer and pulse amplitude modulation fluorometer the fluorescence induction kinetics and several fluorescence parameters were determined as an indicator of vitality. In addition, the rate of photosynthetic CO/sub 2/ fixation and the stomatal closure were studied using a CO/sub 2/H/sub 2/O porometer. >

Radioaktivit�tsgehalte von 1987 und 1988 im Raum Karlsruhe gesammelten Pilzen

Radioactive contamination of wild-growing mushrooms collected in the Northern Black Forest and neighbouring Rhine Valley area has been monitored since the Chernobyl reactor accident. Cs-134, CS-137, Ag-100m and the natural nuclide K-40 were determined by gamma-spectrometry. Pooled data from all species and all locations showed a decrease in the radio-caesium levels from 1986 to 1988, both in mean values and maximum values. Samples of the same species collected at the same location exhibited large differences, although mixed samples rather than individual mushrooms were measured. Accumulation of caesium was observed particularly in Laccaria amethystina, Xerocomus badius, Xerocomus chrysenteron, Cantharellus tubaeformis, Laccaria laccata, and Russula ochroleuca, with maximum values of 3600 (1986), 2000 (1987), and 1200 (1988) Bq/kg of radiocaesium. A large number of species, among them Calocybe gambosa and Coprinus comatus, showed very small accumulations or no caesium. An accumulation of silver was found in Macrolepiota rhacodes and Agaricus arvensis, which contained a maximum of 11 Bq/kg Ag-110m.

Crustal structure of southern Germany from seismic refraction data

Seismic refraction data obtained along fifteen lines in southern Germany in the 60's and in 1982–1984 were used to derive a 3-D model of crustal structure below the “South-German Triangle” bounded by the Bohemian Massif in the east, the Alps in the south and the Rhinegraben in the west. Both the older and the more recent data were interpreted with the same techniques taking into account the results of published crustal information. Along three lines the observations could be interpreted as a reversed system and here both traveltime and amplitude information was used applying two-dimensional (2-D) raytrace modelling resulting in 2-D models controlled by traveltimes and amplitudes. These three crustal cross sections supplement an existing 3-D model for southwest Germany. The characteristic features of the crustal structure of the South-German Triangle can be summarized as follows: An intermediate boundary, identified by many authors as Conrad discontinuity, is found in its central part at depths between 16 and 18 km. Towards the northwest and south it descends to 20 and 22 km, respectively. In the region of the Black Forest it occurs at a rather shallow level at depths of only 14 km. The depth to the Moho reaches values between 27 and 28 km in the central part of the South-German Triangle. Beneath the Black Forest and the southwestern part of the Swabian Jura, the crustal thickness is reduced ranging from 25 to 26 km. To the northwest the Moho dips only slightly, but to the northeast under the Bohemian Massif it reaches depths up to 35 km. Beneath the northern foreland of the Alps the Moho descends gradually to about 40 km depth near the northern margin of the Alps. A low-velocity zone in the middle crust changes its characteristics throughout the area of investigation and is even absent in some areas. The velocity decrease is generally less than 0.3 km/s, except under the central and northern Black Forest, where the velocity decreases by as much as 0.5 km/s. The existence of a laminated lower crust, i.e. a crust which comprises layers of alternating high and low velocity as was found beneath the Black Forest, is also indicated in some of the data obtained in 1982–1984 and shown in this contribution.

Forms of metals in a sediment core of a severely acidified northern Black Forest lake

In a dated ( 137Cs, forest fire in the year 1800, industrial development) sediment core of the Huzenbachersee (northern Black Forest, Fed. Rep. of Germany) the chemical speciation of several metals (base cations: Mg, Ca; Al; heavy metals: Fe, Mn, Cu, Pb, Cr, Zn, and Cd) was evaluated applying sequential chemical extraction. In the sediment core, two distinct periods (2 nd half of both 19 th and 20 th century) of increased amounts of Pb, Zn, Cd, and Fe can be found, indicating phases of industrialization. Elevated contents particuliarly of Cr in lower sediment layers are thought to be caused by local glass factories. In the uppermost sediment layers the bonding strength of several metals shows decreasing tendency (increasing for exchangeable and easily reducible fractions). As a result, secondary contamination of the water column can occur through sediment release especially with Zn and Cd.

The fossil geothermal system of the Baden-Baden trough (northern Black Forest, F.R. Germany)

Limnic sediments of the Upper Carboniferous, Lower Permian and Triassic from the Baden-Baden trough were hydrothermally altered during the Jurassic. Concentric alteration halos, each having a characteristic mineral composition, were formed. From center to margin, zones of sericitization, albitization and weak alteration covering an area of > 100 km 2 are evident. These zones indicate decreasing hydrothermal influence, whereby the solutions must have risen in the center. The chemistry of mica, changing systematically from a muscovitic toward an illitic composition, also reflects this trend; the boron content increases from 75 to 205 ppm. The estimated maximum alteration temperature ranges between 240° and 290°C. These remarkable changes are obviously early manifestations of geothermal events related to the development of a continental rift (Rhine graben).

Intracellular infection by fungi in mycorrhizae of damaged spruce trees

AbstractIntracellular infection was found in the vascular tissue and meristem of mycorrhizae of a severely damaged stand of spruce and fir trees in the Northern Black Forest. Two fungal species could be isolated from surface sterilized mycorrhizae: Mycelium radicis atrovirens and Cryptosporiopsis cf. abietina. Infection tests with spruce seedlings revealed that mainly Cryptosporiopsis cf. abietina must be held responsible for infection of the vascular tissue. Less infectious was Mycelium radicis atrovirens, which infected only cortex cells.

Long core study on natural and anthropogenic acidification of Huzenbachersee, Black Forest, Federal Republic of Germany

The pH history of Huzenbachersee in the northern Black Forest has been studied by using diatom records of a long core and a short core. The results reveal that the pH of the lake has decreased by 1 unit since the end of the ice age until circa 1800, owing to natural long‐term acidification. The impact of man in the last 200 years, such as catchment afforestation and especially acid deposition, have caused additional dramatic pH declines in a very much shorter period of time.

Geothermal systems in the Upper Rhine graben and northern Black Forest: A chemical and stable isotope study

The reservoir temperatures of 22 hot spring waters from 9 localities in the Upper Rhine graben and the northern Black Forest have been determined using 4 different geothermometers (SiO 2, Na-K, Na-K-Ca and 18O-sulphate). The 18O-sulphate thermometer and the SiO 2 thermometer yield concordant temperatures in those thermal waters which have not been diluted by near-surface ground water components. Deviations of the SiO 2 thermometer from the 18O-sulphate thermometer can be applied to estimate the near-surface water components in hot spring waters. The alkali content of these waters can not be used for geothermometry. The highest reservoir temperatures have been calculated for the hot springs of Baden-Baden (156°C). All other hot springs have substantially lower reservoir temperatures (115 to 65°C). The ∂ 18O and ∂ D values of the hot water component are comparable with the mean of the ∂ 18O and ∂ D values of modern meteoric waters from higher elevations of the Black Forest; the cold components have stable isotope ratios of local precipitation.

Uran-Prospektion in der Bundesrepublik Deutschland

Two deposits that can be considered economically minable have been found during the last twenty years of prospecting for uranium in the Federal Republic of Germany. These deposits, Menzenschwand and Mullenbach, are situated in the northern and southern Black Forest, respectively. In addition, favorable indications have been found in Paleozoic granites of northeastern Bavaria, of the Black Forest, and Odenwald, as well as in Permian and Triassic sediments of Rheinland-Palatinate, Franconia, and Wurttemberg. The uranium resources that can be expected from all these deposits are insufficient to meet the domestic demand.

Exkursion durch den Nordschwarzwald am 10. September 1953

Exkursion durch den Nordschwarzwald am 10. September 1953