How does landfill leachate affect the chemical processes in a lake system downgradient from a landfill site?

A field study on the geochemical properties of a chemically-stressed limnic environment was performed in Lake Silbersee, which receives leachate water of high inorganic loading from an upgradient landfill site. The highly concentrated sulfate ion in groundwater, when entering the pore water system of the lake, gives rise to an intensive microbial sulfate reduction. A diagenetic approach was used to explain the existence of a marine-like aqueous system within a geologically slightly acidic aquifer, consisting of a well-buffered lake water and an alkalinity producing, excess sulphide containing sediment pore water system.     

Effects of climate change on snow accumulation and melting in the Broye catchment (Switzerland)

The study used a daily step conceptual hydrological model to examine the effects of climate change on snowfall accumulation and on snow cover melting in the Broye catchment (moderate relief- altitude from 400 to 1500 m a.s.l.). Five elevation bands representing a range of climatic conditions were used together with three realistic climate change scenarios based loosely on GCM's predictions and which reflect feasible changes by extending time periods. For a very moderate climate change (rise in air temperature of ca 1 °C), possibly in a near future, the reduction of snow cover duration, mean water equivalent and monthly maximum water equivalent is the most sensitive in the lower part of the catchment and during the first and last months of the snow season. In the higher part of the basin and during the colder months January and February, similar reduction rates can be expected in case of larger climate changes. The floods due to the melting of snow cover are lower. Sometimes rainfall, considered as snow in the present day conditions, generates additional floods during the winter season. For winter sports resorts below 1500 m a.s.l., even the very moderate climatic change scenario (temperature rise around 1 °C) leads to economically very difficult conditions. Finally, a climatic change detection index based on snow cover duration is proposed.     

Eocene high pressure metamorphism in the Penninic units of the Tauern Window (Eastern Alps): evidence from40Ar−39Ar dating and petrological investigations

The⁴⁰Ar-³⁹Ar degassing spectra of white micas and amphiboles from three tectonic units of the central Tauern Window (Pennine basement and cover in the Eastern Alps) have been measured. White micas are classified as (1) pre-Alpine low-Si relic micas with an age value of 292 Ma, variously disturbed by the Alpine metamorphism; (2) Alpine phengitic micas of variable composition with an age between 32 and 36 Ma; (3) Alpine low-Si micas with a maximum age of 27 Ma. We attribute the higher Alpine ages to a blueschist facies event, whereas the lower age reflects the late cooling of the nappe pile. Blueschist facies phengites from the basement (Lower Schieferhülle) and the tectonic cover (Upper Schieferhülle) crystallized at a temperature below the closure temperature (T _c) for argon diffusion in white mica and record ages of 32 to 36 Ma. At the same time a thin, eclogite facies unit (Eclogite Zone) was thrust between the Lower and the Upper Schieferhülle and cooled from eclogite facies conditions at about 600°C at 20 kbar to blueschist facies conditions at 450°C or even 300°C at >10 kbar. Eclogite facies phengites closed for argon diffusion and record cooling ages, coinciding with the crystallization ages in the hanging and the footwall unit. Amphibole age spectra (actinolite, glaucophane, barroisite) are not interpretable in terms of geologically meaningful ages because of excess argon.     

Der Eiswinter 1983/84 im deutschen Küstengebiet zwischen Ems und Trave

Ohne Zusammenfassung     

Petrographische und Kalium-Argon-Untersuchungen an basischen tertiären Vulkaniten zwischen Westerwald und Vogelsberg

Between the upper tertiary volcanic areas of Westerwald and Vogelsberg (central Western Germany) occur more than 40 isolated tertiary volcanic dikes, eroded necks, plugs and domes. Twelve of these volcanic rocks have been investigated petrographically and chemically and classified by means of their modal and chemical composition. Additional modal analyses have been performed on seven other volcanics. On seventeen volcanic occurences K-Ar-whole rock age determinations have been made. The K-Ar age determinations yield- with the exception of an olivine-nephelinite — values between 27 and 15 Ma. Regarding the known intervals of volcanic activities of the Westerwald- and Voge1sberg-areas, most of the examined volcanics can be related genetically with one of the adjacent volcanic areas. There seems to be no geographical overlapping of volcanics showing Westerwaldages and Vogelsberg-ages. A possible influence of excess-Ar-bearing phases (e. g. mantle xenoliths) and an Ar-loss of constituent matter of the groundmass have been estimated by additional age determinations of enriched samples. These influences — partially compensating each other — may shift the K-Ar whole rock age to a maximum of 5 % and thus do not exceed the dimension of the standard deviations. A distinct NNE-SSW-striking fault in the region between Marburg and Gießen is situated parallel with the eastern border of the “Rheinisches Schiefergebirge”. Volcanics showing Westerwald-age and Vogelsberg-age respectively reach this fault, but obviously do not overlap it. Relations between rock-type an rock age, as it has been observed for the volcanics of the northern Hessian Depression (Kreuzer et al. 1973;Wedepohl 1982) cannot be proved certainly. On the other hand, similar to the basaltic rocks of the northern Hessian Depression, the youngest volcanic product is an olivine-nephelinite (9 Ma).