Limnological situations in two shallow Greek Lakes (Kastoria and Mikri Prespa lakes)

The shallow Kastoria lake supports an important fishery but the effluent discharges from the local town renders the lake polluted and eutrophic. From a limnological point of view, its water exhibits unstable thermal stratification, dimictic as well as meromictic situations, low concentrations of dissolved oxygen close to its bottom sediments and rather high nutrient concentrations. The internationally important wetland of Mikri Prespa lake belongs to the dimictic lacustrine type. The lake is directly influenced by runoff from nearby agricultural land as well as by the organic matter produced mainly in the luxuriant bank vegetation of reeds.     

Parametric studies on ozone photochemistry

Summary A numerical experiment was made in order to investigate whether it is possible to obtain agreement between photochemical theory and observation of ozone in a pure oxygen (i.e. a dry) atmosphere at levels where near-equilibrium can be expected. Considerable but not completely unreasonable adjustment of some of the uncertain photochemical parameters (reaction rates and their temperature dependence, solar spectral energy distribution) from their presently most probable value is found to be needed.

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Zusammefassung Mit einem numerischen Experiment wurde untersucht, ob es möglich ist, Übereinstimmung zwischen photochemischer Theorie und Beobachtung in einer reinen Sauerstoff-(d.h. wasserdampffreien) Atmosphäre zu erreichen. Es zeigt sich, dass eine im Vergleich zu den gegenwärtigen Annahmen beträchtliche, aber nicht völlig unvernünftige Anpassung einiger noch unsicheren photochemischen Parameter notwendig ist. (Reaktionskonstanten und ihre Temperaturabhängigkeit, spektrale Energieverteilung in der extraterrestrischen Sonnenstrahlung.)

     

Organochlorines and metals in harbour seals (Dutch Wadden Sea)

Maximum concentrations of PCB and members of the DDT family in liver, brains, kidney, spleen and heart and Cu, Pb, Zn and Cd in brains of harbour seals found dead in the Dutch Wadden Sea are higher than those reported for specimens from the German Wadden Sea, where the population is stable in contrast to the strong reduction observed for the population in the former part. Results are also compared with data from the east coast of England.     

A fossiliferous resin from the Cenomanian of the Paris and Aquitanian basins of northwestern France

The discovery of a Cenomanian fossiliferous resin at different localities in the Paris and Aquitanian basins of northwestern France is described. The abiotic peculiarities and methodological difficulties are mentioned and evidence for the following arachnid and insect orders given: Phalangiida, Araneae; Blattariae, Isoptera, Psocoptera (?), Heteroptera, Planipennia, Coleoptera, Hymenoptera, Lepidoptera and Diptera. Biostratonomic and palaeoecological implications are discussed.     

Chemical control of Al-solubility in orthopyroxene and its implications on pyroxene geothermometry

Two suites of spinel peridotites of the Westeifel/West Germany were found to have equilibrated in a narrow temperature interval each. Temperatures calculated from the CaO-solubility in orthopyroxene using experimental data of Lindsley and Dixon (1976) are 945° C to 980° C for the amphibole bearing Ia-suite and 1,150° C to 1,165° C for the Ib-suite. From the study of phase equilibria in both series it appears that Al-solubility in orthopyroxene is controlled by the composition of the coexisting spinel. Temperatures calculated from Al-solubility in orthopyroxene using an equation of Fujii (1976) derived from the univariant reaction en+spfo+Al-en in the MgO-Al₂O₃-SiO₂ system show a clear dependence on the FeCr₂O₄ component in the spinel phase, although ideal solution correction allowing for additional components was made. Temperatures obtained for the most chromite rich spinel — orthopyroxene pairs are 1,370° C and 1,240° C, respectively. These temperatures are by 220° C higher than those from Cr-poor pairs and those obtained from Ca solution in orthopyroxene.For practical purposes of geothermometry in spinel peridotites, an empirical equation allowing for the mole fraction of FeCr₂O₄ in spinel has been derived by a linear least squares fit to the orthopyroxene — spinel compositional data and temperatures calculated from the CaO-solubility of orthopyroxene in the present paper.     

Dating the events of metamorphism and granitic magmatism in the Alpine orogen of Naxos (Cyclades,Greece)

An isotopic dating investigation (66 K-Ar and 34 Rb-Sr analyses) provided the geochronological framework for the Alpine events of metamorphism and granitic magmatism on Naxos. The oldest phase of high-pressure/medium-temperature metamorphism, M1, was dated by Rb-Sr and K-Ar analyses of paragonites, phengitic muscovites and muscovites at 45±5 Ma (Middle Eocene). Most of the record of the M1 phase has been eraded by a second phase of medium-pressure/high-temperature metamorphism, M2, which induced a metamorphic zonation with anatectic melting in the highest-grade part, the migmatite dome. Most K-Ar dates of M2 hornblendes, muscovites, biotites and tourmalines range from about 21 Ma in the lower-grade part (biotite-chloritoid zone) to about 11 Ma in the migmatite dome. From the pattern of K-Ar mineral dates it is concluded that the M2 phase took place 25±5 Ma ago (Late Oligocene/Early Miocene) and was followed by a prolonged cooling history until about 11 Ma ago (Late Miocene), when the ambient temperature in the migmatite dome had decreased to below 400–360 °C. A Rb-Sr whole-rock isochron analysis of a granodioritic mass dated the intrusion (and the associated M3 phase of contact-metamorphism) at 11.1±0.7 Ma (Late Miocene), with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.7112 ±0.0001. A local phase of low-grade retrograde metamorphism, M4, probably related to Late Alpine overthrusting, was dated at about 10 Ma (Late Miocene).     

On the reconstruction of temperature records from proxy data in mid Europe

Summary The problem of the reconstruction of mean summer temperatures from proxy data on a rigorous statistical basis is addressed: Cross spectral analysis is used for evaluating the suitability of linear transfer models between proxy data and temperature, the linear model is estimated from the data of a calibration period and it is verified using the data of a different period. Strict statistical tests are applied at every step of the analysis. Three examples using the proposed method are given: the reconstruction of mean April–July temperatures at Basel from grape harvest data in NE France (1484–1768), mean April–September temperatures at Basel from late wood density of trees from the Swiss Prealps (1270‐1768), and mean April–September temperatures at Great St. Bernhard from the late wood proxy too (1270–1850). The grape harvest data give a very good reconstruction, the resulting temperatures from 1500–1768 are documented. The late wood data fails to give a good reconstruction.

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Die Rekonstruktion von Temperaturreihen aus Proxydaten in Mitteleuropa

Zusammenfassung Es wird das Problem der Rekonstruktion von mittleren Sommertemperaturen aus sogenannten Proxydaten untersucht. Sehr viel Wert wird auf die statistische Signifikanz der Rekonstruktion gelegt. Kreuzspektralanalyse wird benutzt, um die Verwendungsf?higkeit eines linearen Modells als Transfermodell zwischen Temperatur und Proxydaten zu ermitteln. Die Parameter des linearen Transfermodells werden aus den Daten der sogenannten Eichperiode abgesch?tzt und die damit für eine unabh?ngige Periode rekonstruierten Temperaturen werden mit gemessenen verglichen. In jedem Schritt der Analyse werden strikte statistische Tests durchgeführt, um die Ergebnisse zu untermauern. Die Methode wird an drei Beispielen erprobt: die mittlere April–Juli Temperatur in Basel wird mit Hilfe von Weinlesedaten von NE-Frankreich für die Zeit (1484–1768) rekonstruiert, die mittlere April–September Temperatur in Basel und am Gro?en Bernhard wird mit Sp?tholzdichtewerten der Schweizer Voralpen verglichen. Die Weinlesedaten ergeben eine sehr gute Rekonstruktion und die Temperaturreihe für den Zeitraum 1500–1768 wird dokumentiert. Die Sp?tholzdichten liefern keine gute Temperaturrrekonstruktion.

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With 11 Figures