Dating problems with selected mining lakes and the adjacent groundwater body in Lusatia,Germany

This study presents selected results, applying environmental tracers to investigate lake water–groundwater interactions at two study sites located in Lusatia, Germany. The focus of the investigations were two meromictic pit lakes and their adjacent aquifers. In order to follow hydrodynamic processes between lake and groundwater, mixing patterns within the lakes as well as ages of lake and groundwater, water samples of ground- and lake water were collected at three occasions, representing summer and winter conditions in the aquatic systems. The water samples were analysed for stable isotopes (deuterium, oxygen-18) and tritium and sulphurhexafluoride (SF₆ concentration). Lake water profiles of conductivity and ¹⁸O could validate the permanent stratification pattern of both the lakes. Groundwater data sets showed a heterogeneous local distribution in stable isotope values between rain and lake water. A two-component mixing model had been adopted only from ¹⁸O data to determine lake water proportions in the surrounding groundwater wells in order to correct measured tritium and SF₆ concentrations in groundwater samples. This procedure had been hampered by upstream-located wells indicating strong ¹⁸O enrichment in groundwater samples. However, rough groundwater ages were estimated. For both study sites, Piston flow ages between 12.9 and 27.7 years were calculated. The investigations showed the good agreement between two different environmental dating tools, considering the marginal data sets.     

Messung des Reinigungsverlaufs von Milchtanks

Zur Verfolgung des zeitlichen Verlaufs von Reinigungsvorgängen in Milchtanks wurde Milch mit unstabilisiertem kolloidalem ¹⁹⁸Au markiert. Die Messung der “Schmutzmenge” erfolgte an der Innen- oder Auβenwand bzw. im ausflieβenden Schmutzwasser. Das Verfahren wurde wiederholt zur Prüfung bei der Entwicklung von Tankreinigungsgeräten angewendet.     

Estimation of N Absorption and Secretion by Digesta Exchange between 15N Labelled and Unlabelled Pigs

Abstract

Three female pigs (LW～30 kg) were fitted with re-entrant cannulas in the duodenum and the ileum and with bladder catheters. Animal No. 1 was labelled by continuous infusion of [¹⁵N]leucine via a catheter into the vena jugularis. After reaching a steady state in the level of endogenous N (4–5 d after beginning of the infusion) the digesta of the labelled animal No. 1 and the two unlabelled animals were exchanged in a 3 day experiment. During this time the course of transit rates of digesta, digesta N and ¹⁵N through duodenum and ileum as well as the proportion of endogenous N: exogenous N were estimated. Using these data it was possible to calculate the secretion and absorption rates of endogenous and exogenous N in the three segments of the digestive tract: mouth-duodenum, duodenum-ileum, ileum-anus and in addition the reabsorption (intestinal recycling) of the endogenous N during its passage through the gut could be computed.     

Zerstörungsfreie risstiefenbestimmung in Betonbauwerken mittels Radiotracerverfahren

At the Leipzig Technical University a method was developed, which allows to determine nondestructive the crack depth in concrete up to 15 cm. Based on a radiotracer technique the access to only one side of the object is required. The labelling of artificial-made cracks was carried out by use of a transport medium (not miscible with water) on the base of methyl isobutyl ketone (MIBK) and In- 113m as radionuclide. For the calculation of crack depth, measure-geometrical parameters were used. The improvement of the reliability of building-diagnostical interpretation using radio-physical parameters is described. A first application is provided for concrete structures below chemical equipments built as a barrier against ecologically harmful substances (petrol tanks). The intersectional aspect of further qualifications of the technique is emphasized.     

A new Technique for Measurement of Myocardial O2-Utilization

The coronary reserve of mammalian hearts is significantly heterogeneous. From this phenomenon we conclude on a heterogeneous energy-demand, i.e., ATP-demand and therefore on a nonuniform ischemic tolerance of cardiomyocytes.

Our aim was to establish a method for direct quantification of cardiomyocyte energy production. According to Langendorff, 10 isolated rabbit hearts were perfused with oxygen enriched Krebs-Henseleit solution. Using the stable oxygen isotope ¹⁸O₂, respiratory water of 7 hearts was labelled, and samples were taken from the coronary venous effluent. Defined cardiac tissue areas were lyophylized. Using the guanidine-hydrochloride technique, μl-water samples from the tissue and the coronary venous effluent were quantitatively converted to CO₂. With the help of mass-spectrometry the δ¹⁸O/¹⁶O-isotope ratios were determined and related to the SMOW-scale.

Compared to control hearts, a significant shift to higher SMOW-values within respiratory water from ¹⁸O-labelled hearts was detected (mean = 14.61%). Control hearts (maximal scatter = 1.42%) as well as ¹⁸O-labelled hearts (4.06%) showed high reproducibilit, of the method. With the employed experimental setup, significant regional differences were not detected. The kinetics of the coronary venous effluent showed a tendency toward saturation with H₂ ¹⁸O within 2 min after starting the ¹⁸O₂-perfusion. After 50 s perfusion increase in SMOW-values reached statistical significance.     

Seletivitätsbestimmung von Katalysatoren zur Toluolentalkylierung durch Einsatz von Toluol-14C-7

Die bei der katalytischen Toulolentalkylierung mögliche Konkurrenzreaktion der Spaltung des aromatischen Kernes führt zu unerwünschten Verlusten an Aromaten und kann infolge ihrer starken exothermen Wärmetönung bei der technischen Realisierung des Verfahrens Schwierigkeiten bei der thermischen Beherrschung des Reaktors bewirken. Bereits in der Entwicklungsphase des Katalysators ist man somit auf ein Verfahren angewiesen, das es erlaubt, diese Ringspaltung sicher nachzuweisen und quantitativ zu bestimmen.

In der vorliegenden Arbeit wird eine Tracermethode unter Einsatz von Toluol-¹⁴C-7 beschrieben, die diese Forderung weitgehendst erfüllt.     

15N-Labelled Ammonium and Nitrate Uptake by the Grass Calamagrostis villosa

Abstract

Calamagrostis villosa dominates the understory vegetation in declining spruce forests at higher elevations of the Central European mountain areas which show symptoms of needle yellowing and associated magnesium (Mg) deficiency. It was hypothesized that grasses would preferentially take up nitrate-nitrogen (NO₃-N) over ammonium-nitrogen (NH₄-N) which would support the cation balance in Mg deficient soils. In order to test this hypothesis, growth experiments were carried out in the greenhouse using plants which were cultivated in sand for nine weeks with full nutrient solution containing 0.2 or 2 mmol of N with different NH₄ ⁺ to NO₃ ^? ratios (1:0, 0.5:0.5, 0:1). In a short term experiment with labelled ¹⁵NH₄ ⁺ and ¹⁵NO₃ ^?, uptake of NH₄ ⁺ and NO₃ ^? was measured. When NO₃ ^? was the only N source it was taken up at similar rate per g dry mass as in the experiment in which NH₄ ⁺ was the only N source. However, at high supply pure NO₃ ^? nutrition resulted in higher biomass. In contrast, supply of only NH₄ ⁺ caused accumulation of N in the roots but growth remained restricted. If NH₄ ⁺ and NO₃ ^? were supplied at equal amounts, NH₄ ⁺ was the preferred form for N uptake. Biomass of the plants with mixed supply did not differ from the plants with pure NO₃ ^? nutrition.

The results point to an interesting interaction of carbon and nitrogen relation, but they do not support the initial hypothesis that grasses may prefer NO₃ ^? over NH₄ ⁺.     

The Influence of Ammonium on Nitrate Uptake and Assimilation in 2-Year-Old Ash and Oak Trees - A Tracer-Study with 15N

Abstract

Interactions between ammonium and nitrate as competitive N sources depend on various biotic and abiotic factors. The preference for one of these N sources and the influence of ammonium on nitrate uptake and nitrate reductase activity was investigated in a ¹⁵N labelling experiment using 2-year-old potted plants of ash (Fraxinus excelsior L.) and oak (Quercus robur L.) under greenhouse conditions.

Seedlings of both tree species use ammonium and nitrate in equal amounts when both N forms are supplied in a 1:1 ratio (1.5 mM NH₄ ⁺ + 1.5 mM NO₃ ^?), although there is a slight tendency that ammonium is preferred. In both species total N uptake is higher if ammonium and nitrate are supplied simultaneously when compared with uptake of nitrate alone (3 mM nitrate). If nitrate is the sole N source N uptake is only half as high as if ammonium and nitrate are supplied in a ratio of 1:1.

The distribution of nitrate reductase between shoot and roots is not influenced by the N-form: nitrate reductase activity is always highest in the roots of both species under the conditions of this experiment.

Xylem sap analyses showed that both species transport higher concentrations of amino acids than of nitrate from the roots to the shoot. The amino acid composition is independent of the type of N source. Furthermore, ash trees contain more nitrate in the xylem sap than oak trees, reflecting the higher N uptake and the higher nitrate reductase activity in the leaves of this species.     

An Attempt at the Identification of the Dynamic Properties of the Isomerization Column on the Basis of the Results of Radioisotope Measurements

The present paper makes an attempt of the interpretation of the tracer measurements by means of transfer function. Obtained data of residence time of catalyst in xylene isomerization column inserted in previous paper [1] were used to the identification of dynamic properties of individual sections of the column.     

Sauna,sweat and science II – do we sweat what we drink?

ABSTRACT

Inspired by a previous ‘Sauna, sweat and science’ study [Zech et al. Isot Environ Health Stud. 2015;51(3):439–447] and out of curiosity and enthusiasm for stable isotope and sauna research we aimed at answering the question ‘do we sweat (isotopically) what we drink’? We, therefore, pulse-labelled five test persons in a sauna experiment with beverages that were ²H-enriched at about +25,600?‰. Sweat samples were collected during six sauna rounds and the hydrogen isotope composition δ²H_sweat was determined using an isotope ratio mass spectrometer. Before pulse labelling, δ²H_sweat – reflecting by approximation body water – ranged from –32 to –22?‰. This is ～35?‰ enriched compared to usual mid-European drinking water and can be explained with hydrogen-bearing food as well as with the respiratory loss of ²H-depleted vapour. The absence of a clearly detectable ²H pulse in sweat after pulse labelling and δ²H_sweat results of ≤+250?‰ due to a fast ²H equilibration with body water are moreover a clearly negative answer to our research question also in a short-term consideration. Given that the recovery of the tracer based on an isotope mass balance calculation is clearly below 100?%, we finally answer the question ‘where did the rest of the tracer go?’