Gerd Schukraft

Growth rate of Usnea aurantiacoatra (Jacq.) Bory on Fildes Peninsula, Antarctica and its climatic background.

The ages of a fruticose lichen of Usnea aurantiacoatra (Jacq.) Bory, from Fildes Peninsula, King George Island, Southwest Antarctic, were determined by radiocarbon (14C), and it is 1993–1996 at bottom and 2006–2007 at top of the lichen branch. The growth rates of U. aurantiacoatra calculated are 4.3 to 5.5 mm year−1 based on its length and ages. The comparisons show that the growth rates of U. aurantiacoatra are higher than those of U. antarctica (0.4 to 1.1 mm year−1). The growth rates of fruticose lichens are always higher, usually >2 mm year−1, than those of crustose ones, usually <1 mm year−1, in polar areas. A warming trend on Fildes Peninsula is recorded in the period from 1969 to 2010 obviously: the mean annual temperature rose from −2.75 to −1.9°C and the average temperature of summer months from 0.95 to 1.4°C, as well as the average temperature of winter months from −6.75 to −5.5°C. The alteration of lichen growth rates in polar areas may respond to the climatic and environmental changes, and the lichens may act as bio-monitor of natural condition.

Built on Sand: Climatic Oscillation and Water Harvesting During the Late Intermediate Period

For the first time in South America, we found specific constructions for water harvesting from the Late Intermediate period. Their configuration allows the precise reconstruction of mean annual precipitation during that time. In that area, enhanced precipitation enabled the people to cultivate the desert. The remains of human occupation give evidence of a short climatic oscillation in the northern Atacama desert around ˜1300 AD.

Hochwasserdynamik und Sedimenttransport

Jede Messung in der Natur ist ein Eingriff in ein naturliches oder quasinaturliches System; das Ziel jeder dieser Messungen ist es, Daten zu erheben, mit deren Hilfe das untersuchte System ganz oder in bestimmten Aspekten beschrieben und erforscht werden kann. Dabei sind drei Dinge sicherzustellen: 1. Der Eingriff darf das System nicht so storen, das die Meswerte im besten Fall zwar reproduzierbar, zur Zustandserfassung aber unbrauchbar sind. 2. Die Messungen mussen sinnvoll im Hinblick auf die Fragestellung, d. h. auf die zu prufende Hypothese sein.; 3. Die Messungen durfen einen im Hinblick auf den Untersuchungsmasstab und das Ergebnis sinnvollen Aufwand nicht uberschreiten.

A Geoarchaeological Approach for the Localization of the Prehistoric Harbor of Akrotiri, Thera

The disastrous volcanic eruption of Thera in the Aegean that happened in late seventeenth century BC (Late Bronce Age, LBA) buried under a thick mantle of volcanic ash the thriving city harbor of Akrotiri, situated at the southern edge of the island. The archaeological excavations at the site have witnessed the city’s wealth and flourish; numerous, luxurious, and outlandish finds clearly indicate well-established maritime contacts between Akrotiri and eastern Mediterranean lands. Such maritime operations and overseas trade required, apparently, adequate harbor facilities. This paper deals with geoarchaeological and geophysical studies aiming at the localization of the buried harbor, a so far unrealized ambitious aim, in spite of the repeated intense attempts undertaken in the last decades. Preference for the relevant investigation was given to three small littoral valleys situated in small distances at both sides of the settlement, suggesting shallow bays before the Minoan eruption, hence probably having hosted the searched harbor(s). Prior to the fieldwork undertaken, all available geological and other related data were cartographically outlaid by means of GIS. Afterwards, in situ geomorphologic studies were conducted, followed by one littoral drilling and geophysical investigations including seismic refraction and electrical resistivity tomography (ERT). Both geophysics and drilling have shown that the hard pre-Minoan basement (consisting of dense andesitic lavas) is situated at depths of ca. 25 m in the Mavrorachidi valley.

Kohlendioxid-Messungen in einem Durchfluß-Meßsystem mit einem neu entwickelten CO2-Sensor am Beispiel eines Hartwassersees (Willersinnweiher, Ludwigshafen am Rhein)

Abstract The concentrations of free dissolved carbon dioxide in lake water were measured with a newly developed CO2 sensor, which was installed in a through-flow measurement system. The results of measurements demonstrate the CO2 dynamics in lake Willersinnweiher. The CO2 concentrations showed a correlation with the oxidation of CH4 in the metalimnion and caused shifts in the carbonate system, thus affecting the autochthonous precipitation and dissolution of calcite. From the results of measurement appears that the CO2 sensor is capable of very exact measurements of dissolved free CO2 in lake water. At the same time, the parameter is easily determined in the field without large expenditures.

Feststoff- und Sedimentdynamik von Elsenz und Neckar bei Hochwasserabfluß

“Im Bundesgebiet werden die Hochwasserschaden die Milliarden-Grenze deutlich uberschreiten”, war die erste Schatzung, als vor Weihnachten 1993 zahlreiche Flusse in der Bundesrepublik uber die Ufer getreten sind (Mannheimer Morgen, Weihnachtsausgabe 1993). Bei der Schadensabschatzung wird leider grundsatzlich nicht zwischen “Schaden durch Wasser” und “Schaden durch Schlamm” unterschieden. Der Schlamm, der vom Hochwasser zuruckgelassen wird, durfte bei der Abwagung zwischen beiden Schadensgruppen vielerorts das grosere Problem darstellen.