Comparison of Phytoscreening and Direct‐Push‐Based Site Investigation at a Rural Megasite Contaminated with Chlorinated Ethenes

The reliable characterization of subsurface contamination of spatially extended contaminated sites is a challenging task, especially with an unknown history of land use. Conventional technologies often fail due to temporal and financial constraints and thus hinder the redevelopment of abandoned areas in particular. Here we compare two site screening techniques that can be applied quickly at relatively low cost, namely Direct Push (DP)‐based groundwater sampling and tree core sampling. The effectiveness of both methods is compared for a rural megasite contaminated with chlorinated hydrocarbons. Unexpected pollution hot spots could be identified using both of these methods, while tree coring even enabled the delineation of the contaminant plume flowing into an adjacent wetland inaccessible for DP units. Both methods showed a good agreement in revealing the spatial pattern of the contamination. The correlation between groundwater concentrations and equivalent concentrations in wood was linear and highly significant for trichloroethene. Correlation was less obvious for its metabolite cis‐dichloroethene, but still significant. As outcome of our study we recommend tree coring and for initial screening in combination with a DP sampling to retrieve quantitative data on groundwater pollutants in order to assess the contamination situation of a non‐ or only partly investigated site. The subsequent placement of monitoring wells for long‐term monitoring of contamination levels is recommended. A combination of methods would achieve more relevant information at comparable or possibly even lower efforts in comparison to a conventional site investigation.     

Forensic hydrology: what function tells about structure in complex settings

Facing the challenges of the European Water Framework Directive and competing demands requires a sound knowledge of the hydrological system. This is a major challenge in regions like Northeast Germany. The landscape has been massively reshaped during repeated advances and retreats of glaciation during the Pleistocene. This resulted in a complex setting of unconsolidated sediments with high textural heterogeneity and with layered aquifer systems, partly confined, but usually of unknown number and extent of single aquifers. The Institute of Landscape Hydrology aims both at a better understanding of hydrological processes and at providing a basis for sustainable water resources management in this region. That would require sound information about the respective regions of interest that are rarely available at sufficient degree of detail. Thus, there is urgent need for alternative approaches. For example, time series of groundwater head, lake water level and stream runoff do not only depend on (unknown) geological structures, but in turn can reveal information about major geological features. To that end, different approaches have been developed and successfully applied at different scales, based both on advanced time series analysis and dimension reduction approaches and on well-known and rather simple methods. This approach has been coined “forensic hydrology”: Like in a crime story, numerous pieces of evidence are combined in a systematic way to end up with a consistent conceptual model about the prevailing cause–effect relationships. An example is given for the Quillow catchment in Northeast Germany in a rather complex geological setting.     

Multiplier hysteresis and image motion errors in limb darkening scans obtained in April 1981 (and later)

In response to the comment of P. Foukal (1989) we show that in our limb darkening observations multiplier hysteresis and image motion (seeing) can be ruled out as major sources of error.     

Bjørn Helland-Hansen †

Ohne Zusammenfassung

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Bjørn Helland-Hansen

     

Geochemistry of basaltic and gabbroic rocks from the West Mariana basin and the Mariana trench

This paper describes the chemistry of 33 basaltic rocks dredged from the West Mariana basin and from the Mariana trench during the R/V “Dmitry Mendeleev” 1976 cruise in the western Pacific.The shipboard investigations were carried out by an international working group of 66 earth scientists under the IGCP Project “Ophiolites” and sponsored by the U.S.S.R. Academy of Sciences, Moscow. The purpose of the expedition was to investigate the structure and composition of the oceanic crust of marginal basins, remnant island arcs and deep-sea trenches. Tholeiitic basalts and gabbros as well as ultramafic rocks in various stages of alteration were dredged from the central part of the West Mariana basin demonstrating the presence of oceanic crust.The Pacific slope of the Mariana trench yielded altered basaltic rocks of tholeiitic and alkalic (? trachybasaltic to shoshonitic) composition. The lower part of the island arc slope contains typical tholeiitic basalts, dolerites and gabbros as well as ultramafics associated with flysch-type sediments. This is strong evidence for the formation of an “ophiolite-schuppenzone”, probably due to subduction of Pacific oceanic crust.Associated with these rocks are amygdaloidal, highly magnesian lavas (similar to boninites), which have not been recognized previously in oceanic ridge basalts.These rocks (together with the dolerites) are interpreted as parts of the Mariana island arc and are thought to be the first stage of island arc development (an immature island arc).     

Der Tektonische Stil der Rocky Mountains in Alberta,Canada

Zusammenfassung Die Canadian Rockies bestehen aus westfallenden, relativ über das Prärie-Becken nach E transportierten Abscher-Decken, deren Gefüge an 3 Beispielen aus Süd-Alberta beschrieben wird. In der Tiefe herrscht Transport, Plättung und a-Längung, nahe der ursprünglichen Oberfläche Einengung und b-Längung. Da das transportierte Material die Grenze zwischen beiden Gefüge-Typen überschreitet, entsteht in der oberen Zone ein Überlagerungs-Gefüge, dessen Erklärung als zweiphasige Verformung bestritten und das als ortskonstanter stoffvariabler Formungsraum (Sander) bezeichnet wird.     

Krokodile als Klimazeugen

Zusammenfassung Aus den wenigen bekannten Daten über Lebensweise und Verbreitung rezenter Krokodile wird versucht, Mindesttemperaturen für das Biotop fossiler Krokodile zu ermitteln. Die gefundenen Werte (+10 C und mehr für die Durchschnittstemperatur des kältesten Monats) sind im Vergleich mit bekannten PaläoTemperaturen durchaus wahrscheinlich.

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Summary Recent crocodiles are distributed up to the 10 or 15 C isothermal line of January/ N. Hemisphere or July/S. Hemisphere, see fig. 1. The analysis of the distribution of tertiary crocodiles in Europe indicates that probably recent and fossil crocodiles are restricted in their geographical range by the same temperature limits.

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Résumé Une analyse de la distribution des crocodiles tertiaires en Europe montre que probablement cettes formes fossiles de mÊme que les récents vivaient en régions oÚ les temperatures étaient au mois le plus froid au-dessus de 10 ou 15 degrés (v. Fig. 1).

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Erweiterte Fassung eines auf Anregung von Herrn Prof. Dr. H.Tobien auf der Jahrestagung der Geol. Ver. in Köln 1964 gehaltenen Vortrags.

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Zu danken habe ich Herrn Prof.Brinkmann, Bonn, und Herrn Prof. v.Gaertner, Hannover, für Diskussionshinweise (bezüglich des Biotops von Krokodilen und lokaler Temperaturverhältnisse), die in obigen Ausführungen berücksichtigt wurden; ferner danke ich Herrn Dipl.-Biol.Hemmer, Mainz, für kollegiale Beratung in zoologischen Fragen.     

Absetzbecken

Ohne Zusammenfassung