ÜBER DIE ROLLE DER PROGNOSTIZIERUNG DER WITTERUNGS- UND KLIMAVERHÄLTNISSE IM BA UPROZEß

The large stock of instruments und machines, their inherent performance und concomi- tant increase in efficiency require that the planning or programming of machines (resources) should take into account not only the machine power, but also natural (meteorological and climatic) conditions. The role and significance of natural factors differ in the various construction (technologi- cal) processes. This paper analyzes the possible utilization of domestic prognoses, their in- formation content und the time horizon und reliability of their validity

Sandstone caves on Venezuelan tepuis: return to pseudokarst?

Venezuelan table mountains (tepuis) host the largest arenite caves in the world. The most frequently used explanation of their origin so far was the “arenization” theory, involving dissolution of quartz cement around the sand grains and subsequent removing of the released grains by water. New research in the two largest arenite cave systems – Churi-Tepui System in Chimanta Massif and Ojos de Cristal System in Roraima Tepui showed that quartz dissolution plays only a minor role in their speleogenesis. Arenites forming the tepuis are not only quartzites but they display a wide range of lithification and breakdown, including also loose sands and sandstones. Speleogenetic processes are mostly concentrated on the beds of unlithified sands which escaped from diagenesis by being sealed by the surrounding perfectly lithified quartzites. Only the so-called “finger-flow” pillars testify to confined diagenetic fluids which flowed in narrow channels, leaving the surrounding arenite uncemented. Another factor which influenced the cave-forming processes by about 30% was lateritization. It affects beds formed of arkosic sandstones and greywackes which show strong dissolution of micas, feldspars and clay minerals, turning then to laterite (“Barro Rojo”). The main prerequisite to rank caves among karst phenomena is dissolution. As the dissolution of silicate minerals other than quartz appears to play not only a volumetrically important role but even a trigger role, these arenitic caves may be ranked as karst

Approaches and Frameworks for Managing Contaminated Sediments - A European Perspective

Sediment is an essential, integral and dynamic part of the hydrologic system. In natural and agricultural basins, sediment is derived from the weathering and erosion of minerals, organic material and soils in upstream areas and from the erosion of river banks and other in-stream sources. As surface-water flow rates decline in lowland areas, transported sediment settles along the river bed and banks by sedimentation. However, because sediments are the ultimate reservoir for the numerous potential chemical and biological contaminants that may be contained in effluents originating from urban, agricultural, and industrial lands and recreational activities, contaminated sediments in rivers and streams, lakes, coastal harbors, and estuaries have the potential to pose ecological and human health risks. The management of sediment quality and quantity in support of ecological and socioeconomic goals is a cause of extensive research, investment and regulatory and public scrutiny, both in Europe and internationally. This chapter examines the management of sediment from a European perspective. The first section discusses the role of sediment management in achieving European ecosystem objectives. Section two summarizes the findings of the EC-funded, demand driven European Sediment Research Network (SedNet). Section three describes a framework risk assessment and management in a major European region, the Venice Lagoon. The next three sections describe aspects of sediment management in an EC accession country, and the host country for this workshop - Slovakia. Section four describes river and lake sediment contamination and related legislation in Slovakia. Section five discusses the assessment and management of Persistent Organic Pollutants (POPs), a major risk driver in Slovakia. Section six discusses a specific class of POPs - PCBS in sediments of a specific region of Slovakia. Finally, Section seven discusses some barriers to successful sediment risk assessment and management, and lists science and infrastructure needs to address these barriers. Whilst all the authors of this chapter are living and/or working in Europe, and the focus is on European perspectives, much work has benefited from international collaborations and we feel that many of the observations and recommendations will have relevance to a broader audience

Morphological and mineralogical characterization of speleothems from the Chimalacatepec lava tube system, Central Mexico

Siliceous, opal-A speleothems of the Chimalacatepec lava tube system in central Mexico are characterized here for the first time. Morphologically, they can be classified into cylindrical and planar, and display a wide array of shapes, inner textures, and locations within the lava tube. All speleothems analyzed here are composed of opal-A, and their pores are filled with calcite and monohydrocalcite. Microscopic examination reveals a variety of microbial-looking, silicified filaments and cell casts embedded within the micro lamination of the structures. The abundance of biofilms in the Chimalacatepec lava tube may share similarities with other volcanic caves elsewhere. The direct presence of such bimorphs in the microstructure of the speleothems suggests the biological mediation of these structures. Potential mechanisms include nucleation and sorption of silica on extracellular polymeric substances in the biofilms that, along with the SiO2 saturation in the water film and evaporative effects, result in the formation of a speleothem. That said, the presence of microbes in these and other cave systems, or their inevitable interactions with the mineral phase of the speleothems, should not be surprising. In view of this, these structures can be most accurately described as biospeleothems. This study contributes to our understanding of the diversity of such structures in these types of cave systems and our ability to recognize the presence of microbes in these