Remediation of Contaminated Sites — Case Histories

In this paper, two major remediation projects located in the German Ruhr District will be introduced. The key to an effective land re-utilization plan is a harmonized management of ground investigation, risk assessment and clean-up strategies. Geotechnical and hydrogeological techniques, as well as economical risks involved in the recycling of industrial wasteland will be discussed. Criteria which led to the acceptance of certain remediation techniques will be reflected and their validity will be examined. It will be analyzed whether the projected performance objectives have been met and the demands of both, the investors and the environmental protection agencies have been satisfied. Special attention will be paid to the cost-effectiveness of the remediation strategies proposed

Upwelling of melt-depleted mantle under Iceland

Seafloor anomalies along mid-ocean ridges with exceptionally thick and compositionally distinct basaltic crust, for example, at Iceland, suggest that the underlying mantle is hotter and chemically different from the adjacent subridge mantle. Here we present hafnium and neodymium isotope ratios of peridotites from the Charlie Gibbs Transform Zone, which is located at the southern end of the Reykjanes Ridge south-west of Iceland. These peridotites are strongly depleted in incompatible elements with extremely high hafnium isotope ratios, suggesting that they had already melted to a large extent before being incorporated into the plume, at least 1 billion years ago, and thereby also became less dense. We argue that seismic velocity anomalies, geodynamic models and geochemical affinities of ridge basalts connect the peridotites from the Charlie Gibbs Transform Zone to the 'Iceland plume'. The thermochemical buoyancy of the moderately hot Iceland plume, but also that of other plumes worldwide, may therefore be strongly influenced by composition. Variable peridotite depletion along the rising Iceland plume could also cause the transient, density-driven pulses in plume flux, which have formed the V-shaped Reykjanes Ridge south of Iceland. Overall, expansion of a ridge-centred plume along adjacent ridges and melting of heterogeneous plume material explains the topographic swell, the seismic anomaly and the formation of V-shaped ridges, as well as the regional distribution of basalts with Icelandic affinity.The upwelling mantle beneath Iceland underwent melt depletion at least 1 billion years ago and is therefore compositionally buoyant, according to a study of neodymium and hafnium isotope ratios in peridotites from the Charlie Gibbs Transform Zone

Ingenieurgeologische Erkundung und Beurteilung von Felsboeschungen im Rheinischen Schiefergebirge

SIGLETIB: in RO 1712 (3) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman