Wolfgang Papesch

Deuterium excess in precipitation of Alpine regions – moisture recycling

The paper evaluates long-term seasonal variations of the deuterium excess (d-excess = δ2H − 8… δ18O) in precipitation of stations located north and south of the main ridge of the Austrian Alps. It demonstrates that sub-cloud evaporation during precipitation and continental moisture recycling are local, respectively, regional processes controlling these variations. In general, sub-cloud evaporation decreases and moisture recycling increases the d-excess. Therefore, evaluation of d-excess variations in terms of moisture recycling, the main aim of this paper, includes determination of the effect of sub-cloud evaporation. Since sub-cloud evaporation is governed by saturation deficit and distance between cloud base and the ground, its effect on the d-excess is expected to be lower at mountain than at lowland/valley stations. To determine quantitatively this difference, we examined long-term seasonal d-excess variations measured at three selected mountain and adjoining valley stations. The altitude differences between mountain and valley stations ranged from 470 to 1665 m. Adapting the ‘falling water drop’ model by Stewart [J. Geophys. Res., 80(9), 1133–1146 (1975).], we estimated that the long-term average of sub-cloud evaporation at the selected mountain stations (altitudes between about 1600 and 2250 m.a.s.l.) is less than 1 % of the precipitation and causes a decrease of the d-excess of less than 2 ‰. For the selected valley stations, the corresponding evaporated fraction is at maximum 7 % and the difference in d-excess ranges up to 8 ‰. The estimated d-excess differences have been used to correct the measured long-term d-excess values at the selected stations. Finally, the corresponding fraction of water vapour has been estimated that recycled by evaporation of surface water including soil water from the ground. For the two mountain stations Patscherkofel and Feuerkogel, which are located north of the main ridge of the Alps, the maximum seasonal change of the corrected d-excess (July/August) has been estimated to be between 5 and 6 ‰, and the corresponding recycled fraction between 2.5–3 % of the local precipitation. It has been found that the estimated recycled fractions are in good agreement with values derived from other approaches.

The application of isotope ratio mass spectrometry for discrimination and comparison of adhesive tapes

Forensic scientists are frequently requested to differentiate between, or compare, adhesive tapes from a suspect or a crime scene. The most common polymers used to back packaging tape are polypropylene and polyvinyl chloride. Much of the oriented polypropylene (OPP) needed to produce packaging tapes, regardless of the tape brand, is supplied by just a few polymer manufacturers. Consequently, the composition of the backing material varies little. Therefore, the discriminating power of classical methods (physical fit, tape dimensions, colour, morphology, FTIR, PyGC/MS, etc.) is limited. Analysis of stable isotopes using isotope ratio mass spectrometry (IRMS) has been applied in the broad area of forensics and it has been reported that isotope analysis is a valuable tool for the identification of adhesive tapes. We have tested the usefulness of this method by distinguishing different South Korean adhesive tapes produced by just a few manufacturers in the small South Korean market. Korean adhesive tapes were collected and analysed for their isotope signatures. The glue of the tapes was separated from the backing material and these sub-samples were analysed for their H- and C-isotope composition. The result shows the possibility for discriminating most tape samples, even from the same brand. Variations within single rolls have also been investigated, where no variations in H- and C-isotope composition significantly exceeding the standard deviation were found.

Forensic applications of stable isotope analysis: Case studies of the origins of water in mislabeled beer and contaminated diesel fuel

This paper describes the use of oxygen (18O) isotope analysis of water contained in two different materials--beer and diesel fuel--involved in the resolution of two separate cases. In the first case study, it was possible to demonstrate that a sample of beer labelled as premium brand in fact belonged to a cheap brand. The second case related to the contamination of diesel fuel from a service station. The diesel fuel contained visible amounts of water, which caused vehicles that had been filled up with it to become defective. For insurance purposes, it was necessary to determine the source of water. The delta18O values for the water of nearly all samples of diesel was close to the delta18O of local tap water at the filling station.

Hydrological and Biogeochemical Characterization of the Danube River System Using Isotopes

Meeting Danube Basin monitoring and management objectives such as those implied by the EU Water Framework Directive requires a comprehensive understanding about the hydrological and biogeochemical functioning of not only the river system but also the connections between groundwater and surface water across the basin. While hydraulic and geochemical measurements can provide some of this understanding, it is often difficult to obtain knowledge about some of the more critical aspects of basin functioning or it can take decades of intensive monitoring before adequate interpretations can be made. Isotope hydrology approaches can often provide critical insights on surface water/groundwater interactions and biogeochemical cycling with only moderate effort and cost. Such information can help clarify local behaviors as well as overall basin responses. Approaches using “environmental” stable and radioactive isotopes (i.e., isotopes that are already in the environment and not intentionally applied) have been used to understand sources and losses of water in the Danube, the importance of groundwater discharge, basin residence times, tributary mixing, and nitrate cycling using isotope methods. We review existing studies as well as present new isotope data that reveal important spatial and temporal dynamics occurring in the Danube River, tributaries, and across the basin.

Isotope Evidence to Link a Suspect with a Pipe Bomb Multimurder in Austria 1995

Abstract:  A bomb attempt in Oberwart, Austria, on February 4, 1995, was the culmination of several pipe and letter bomb attempts mainly in Austria. The pipe bomb had been mounted on a self‐made gypsum (plaster of Paris) pedestal and exploded when touched, killing four persons. With a level of 200 tritium units (TU), the water extracted from the gypsum pedestal was unusually enriched in tritium (3H) compared to an environmental level of about 20 TU at that time. Investigation of the 3H content of air moisture in the living room of an arrested suspect showed values of about 1000 TU (normally, 50 TU is not exceeded). Additionally, water used as sealing liquid in a glass with nitroglycerine found in the living room was also significantly enriched in 3H (>400 TU). The living room therefore offered the high 3H level environment necessary to lead to elevated 3H concentrations in the gypsum pedestal.