A. International Symposium on Applications of Geodesy to Engineering May 13–17, Stuttgart, Germany

InformationsIAG Scientific Meetings in 1991

A. International Symposium on Applications of Geodesy to Engineering May 13–17, Stuttgart, Germany     

Synthesis and Preliminary Characterisation of New Silicate, Phosphate and Titanite Reference Glasses

Eleven synthetic silicate and phosphate glasses were prepared to serve as reference materials for in situ microanalysis of clinopyroxenes, apatite and titanite, and other phosphate and titanite phases. Analytical results using different micro-analytical techniques showed that the glass fragments were homogeneous in major and trace elements down to the micrometre scale. Trace element determinations using inductively coupled plasma-mass spectrometry (ICP-MS), multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) and secondary ionisation mass spectrometry (SIMS) showed good agreement for most elements (Li, Be, B, Cs, Rb, Ba, Sr, Ga, Pb, U, Th, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Tm, Yb, Lu, Zr, Hf, Ta, Nb) studied and provide provisional recommended values.     

Dated Paleontological cave sites of Central Europe from Late Middle Pleistocene to early Upper Pleistocene (OIS 5 to OIS 8)

Caves are terrestrial depositories that preserve a large variety of organic and inorganic remains. These may contain important Quaternary climatic and ecological information. Most of the faunal remains, however, cannot be linked to any Interglacial or Glacial period exclusively. Reliable dating of such remains is therefore required. Experience has, however, shown that ESR dating of speleothems or ²³⁰Th/U dating of bones are of disputable value. Only TIMS-²³⁰Th/U dating of speleothems appears to yield reliable ages. Dating the bottom and top of speleothem layers permit assigning Pleistocene faunal remains to the OIS chronology if the deposition of the speleothems and the faunal remains are clearly correlated. Care must be taken to consider the depositional situation of each site before interpreting any age dates. In this paper we present an overview of all numerically dated paleontological cave sites in Central Europe between OIS 5 and OIS 8. A total of 25 strata were dated from 13 sites, most of them deposited during OIS 5; the rest belonging to OIS 6 and 7. Numerically dated paleontological sites older than OIS 8 are not known.     

Lithology‐controlled evolution of stream bed sediment and basin‐scale sediment yields in adjacent mountain watersheds,Idaho, USA

The composition, grain‐size, and flux of stream sediment evolve downstream in response to variations in basin‐scale sediment delivery, channel network structure, and diminution during transport. Here, we document downstream changes in lithology and grain size within two adjacent ~300 km² catchments in the northern Rocky Mountains, USA, which drain differing mixtures of soft and resistant rock types, and where measured sediment yields differ two‐fold. We use a simple erosion–abrasion mass balance model to predict the downstream evolution of sediment flux and composition using a Monte Carlo approach constrained by measured sediment flux. Results show that the downstream evolution of the bed sediment composition is predictably related to changes in underlying geology, influencing the proportion of sediment carried as bedload or suspended load. In the Big Wood basin, particle abrasion reduces the proportion of fine‐grained sedimentary and volcanic rocks, depressing bedload in favor of suspended load. Reduced bedload transport leads to stronger bed armoring, and coarse granitic rocks are concentrated in the stream bed. By contrast, in the North Fork Big Lost basin, bedload yields are three times higher, the stream bed is less armored, and bed sediment becomes dominated by durable quartzitic sandstones. For both basins, the geology‐based mass balance model can reproduce within ~5% root‐mean‐square error the composition of the bed substrate using realistic erosion and abrasion parameters. As bed sediment evolves downstream, bedload fluxes increase and decrease as a function of the abrasion parameter and the frequency and size of tributary junctions, while suspended load increases steadily. Variable erosion and abrasion rates produce conditions of variable bed‐material transport rates that are sensitive to the distribution of lithologies and channel network structure, and, provided sufficient diversity in bedrock geology, measurements of bed sediment composition allow for an assessment of sediment source areas and yield using a simple modeling approach. Copyright © 2016 John Wiley & Sons, Ltd.     

Analysis of Wellbore Skin Samples—Typology,Composition, and Hydraulic Properties

The presence of a wellbore skin layer, formed during the drilling process, is a major impediment for the energy‐efficient use of water wells. Many models exist that predict its potential impacts on well hydraulics, but so far its relevant hydraulic parameters were only estimates or, at best, model results. Here, we present data on the typology, thickness, composition, and hydraulic properties obtained from the sampling of excavated dewatering wells in lignite surface mines and from inclined core drilling into the annulus of an abandoned water well. Despite the limited number of samples, several types of skin were identified. Both surface cake filtration and particle straining in the aquifer occur. The presence of microcracks may be a determining feature for the hydraulic conductivity of skin layers. In the case of the well‐developed water supply well, no skin layer was detected. The observed types and properties of wellbore skin samples can be used to test the many mathematical skin models.     

Assessing the additive risks of PSII herbicide exposure to the Great Barrier Reef

Herbicide residues have been measured in the Great Barrier Reef lagoon at concentrations which have the potential to harm marine plant communities. Monitoring on the Great Barrier Reef lagoon following wet season discharge show that 80% of the time when herbicides are detected, more than one are present. These herbicides have been shown to act in an additive manner with regards to photosystem-II inhibition. In this study, the area of the Great Barrier Reef considered to be at risk from herbicides is compared when exposures are considered for each herbicide individually and also for herbicide mixtures. Two normalisation indices for herbicide mixtures were calculated based on current guidelines and PSII inhibition thresholds. The results show that the area of risk for most regions is greatly increased under the proposed additive PSII inhibition threshold and that the resilience of this important ecosystem could be reduced by exposure to these herbicides.     

Phytotoxicity induced in isolated zooxanthellae by herbicides extracted from Great Barrier Reef flood waters

To date there has been limited evidence anthropogenically sourced pollution from catchments reaching corals of the Great Barrier Reef (GBR). In this study, freshly isolated zooxanthellae were exposed to polar chemicals (chiefly herbicides) extracted from water samples collected in a flood plume in the GBR lagoon. Photosynthetic potential of the isolated zooxanthellae declined after exposure to concentrated extracts (10 times) from all but one of the sampling sites. Photosynthetic potential demonstrated a significant positive relationship with the concentration of diuron in the concentrated extracts and a significant inverse relationship with salinity measured at the sampling site. This study demonstrates that runoff from land based application of herbicides may reduce photosynthetic efficiency in corals of inshore reefs in the GBR. The ecological impacts of the chemicals in combination with other potential stressors on corals remain unclear.     

A unique aspect of ballast water management requirements - The same location concept

Under certain circumstances vessels do not need to meet ballast water management requirements as stated in the International Convention for the Management and Control of Ballast Water and Sediments (BWM Convention). Besides exceptions to ensure e.g., (a) the safety of a ship, (b) discharge of ballast water for the purpose of avoiding or minimizing pollution incidents, (c) uptake and discharge on high seas of the same ballast water, the same location concept comes into play as ballast water discharges from a ship at the same location where it was taken up is also excepted from BWM requirements. The term same location was not defined in this instrument, hence it is exposed to different interpretations (e.g., a terminal, a port, a larger area where two or more ports may be located). As the BWM Convention is an instrument with biological meaning, the authors recommend a biologically meaningful definition of the same location in this contribution.     

High-resolution coastal hazard assessment along the French Riviera from co-seismic tsunamis generated in the Ligurian fault system

Natural Hazards - The French Riviera is a densely populated and touristic coast. It is also one of the most seismically active areas of the Western Mediterranean. This is evidenced by the Mw...