Showing papers by "Roland Psenner published in 2002"

Atmospheric deposition of organochlorine compounds to remote high mountain lakes of Europe

Abstract: Bulk deposition samples were taken near three mountain lakes located in the Pyrenees (Estany Redo), Alps (Gossenkollesee), and Caledonian Mountains (Ovre Neadalsvatn) for evaluation of the atmospheric deposition load of organochlorine compounds (OC), namely, polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and endosulfans, in the remote European high mountain areas. The compounds of present use in agriculture, namely, endosulfans and gamma-HCH, exhibit large differences in mean deposition fluxes between the three sites. They occur in large amounts in Estany Redo (340 and 430 ng m(-2) month(-1) for endosulfans and gamma-HCH, respectively), reflecting the impact of agricultural activities in southern Europe. This lake showed also the highest proportion of the more labile endosulfan isomers (alpha and beta = 82%) whereas only the most recalcitrant species, endosulfan sulfate, was found in Ovre Neadalsvatn. In contrast, the OC whose use is now banned exhibit a more uniform geographic distribution with deposition fluxes of 31-40, 30-100, and 1.4-15 ng m(-2) month(-1) for alpha-HCH, PCBs, and HCB. Both compounds of present and past use exhibit a clear seasonal pattern, with higher deposition in the warm periods, which is consistent with enhanced volatilization at higher temperatures. In the case of the agricultural pesticides it may also reflect higher use during application periods. The OC distributions in the atmospheric deposition of the three sites are rather uniform and highly enriched in compounds with volatilities larger than 0.0032 Pa. However, more than 90% of these compounds are not retained in the lake waters or sediments. Comparison of OC composition in atmospheric and sedimentary deposition evidences a selective trapping of the less volatile compounds. Trapping efficiencies increase at decreasing air temperatures of the lacustrine systems.

Environmental changes in an alpine lake (Gossenkollesee, austria) over the last two centuries- the influence of air temperature on biological parameters

Abstract: Changes in microfossils (diatoms, chrysophytes, chironomids and cladocera remains), geochemistry and deposition of atmospheric pollutants have been investigated in the sediment records of the alpine lake Gossenkollesee (Tyrol, Austria) spanning the last two centuries. The sediment records were compared with seasonal and annual air temperature trends calculated for the elevation (2417 m a.s.l.) and the geographical position (47° 13′46′′N, 11° 00′51′′E) of the lake, and with precipitation records available since 1866 from Innsbruck. Temperature trends followed a 20–30 year oscillation between cold and warm periods. Regarding long-term changes, temperature trends showed a U-shaped trend between 1780 and 1950, followed by a steep increase since 1975. Physical, geochemical, and organic parameters were not controlled by air temperature. Among the biological records only diatoms and chrysophytes reacted to air temperature changes: the relative abundance of planktonic diatoms increased during warm periods and changes in mean annual alpine air temperature explained 36.5% of their variation. The relation between abundance of seasonal stomatocyst types and air temperature varied on two different time scales: while summer stomatocysts were influenced by short term temperature fluctuations, the autumn stomatocysts were affected only by the long term changes. Other biological parameters exhibited a constant species composition (chironomids, pigments) or changes were small and independent of temperature (cladocera). Spheroidal carbonaceous fly-ash particles, and trends in Pb and Cr indicated increasing deposition of atmospheric pollutants but had no detectable effects on the biological parameters either. In respect to temperature variations over the last 200 years, this alpine lake is much less sensitive than expected and has thus to be regarded as a well buffered site. However, temperature alone is not sufficient to understand changes in species composition and other biogeochemical processes with unknown historical patterns might have affected species composition more strongly.

Trends in the water chemistry of high altitude lakes in europe

Abstract: Here we present the chemical trends of seven high altitude lakes, analysed within the AL:PE and MOLAR Projects of the EU (1999) and selected on the basis of the availability of complete and reliable data for the period 1984–1999. The lakes are representative of the Scandinavian Alps, the Cairngorm Mountains in Scotland, the Alps and the Pyrenees. Significant trends were identified for some indicators of acidification, for instance pH and alkalinity, but not all lakes reacted similarly to decreasing depositions of sulphate and base cations. Differences in lake response are discussed in relation to recent variations of atmospheric deposition chemistry and associated changes in climatic conditions. Beside individual variations of the studied lakes, depending, among other things, on altitude and morphology, catchment characteristics and climate trends play a major role for the reaction of high altitude lakes on changes in atmospheric depositions.

Impact of late glacial climate variations on stratification and trophic state of the meromictic lake Längsee (Austria): validation of a conceptual model by multi proxy studies

Abstract: Selected pigments, diatoms and diatom-inferred phosphorus (Di-TP) concentrations of a late glacial sediment core section of the meromictic Langsee, Austria, were compared with tephra- and varve-dated pollen stratigraphic and geochemical results. A conceptual model was adopted for Langsee and evaluated using multi proxy data. During the unforested late Pleniglacial, a holomictic lake stage with low primary productivity prevailed. Subsequent to the Lateglacial Betula expansion, at about 14,300 cal. y BP, okenone and isorenieratene, pigments from purple and green sulphur bacteria, indicate the onset of anoxic conditions in the hypolimnion. The formation of laminae coincides with this anoxic, meromictic period with high, though fluctuating, amounts of okenone that persisted throughout the Lateglacial interstadial. The occurrence of unlaminated sediment sections of allochthonous origin, and concurrent low concentrations of okenone, were related to cool and wet climate fluctuations during this period, probably coupled with a complete mixing of the water column. Two of these oscillations of the Lateglacial interstadial have been correlated tentatively with the Aegelsee and Gerzensee oscillations in the Alps. The latter climate fluctuation divides a period of enhanced anoxia and primary productivity, correlated with the Allerod chronozone. Continental climate conditions were assumed to be the main driving forces for meromictic stability during Allerod times. In addition, calcite dissolution due to severe hypolimnetic anoxia, appear to have supported meromictic stability. Increased pigment concentrations, which are in contrast to low diatom-inferred total phosphorus (Di- TP), indicate the formation of a productive metalimnion during this period, probably due to a clear-water phase (low catchment erosion), increased temperatures, and a steep gradient between the phosphorus enriched hypolimnion and the oligotrophic epilimnion. Meltwater impacts from an extended snow-cover and a summer temperature decline, together with climate instability, are assumed to be the main reasons for the lowering of the anoxic level during the following, climatically heterogeneous, Younger Dryas. Meromictic stability was re-established with the termination of the Younger Dryas. The sequence of key pigments, Di-TP, calcite, siliciclastics, and organic carbon, seem to be in accordance with the assumptions of the conceptual model.

Dynamics of Bacterial Abundance, Biomass, Activity, and Community Composition in the Oligotrophic Traunsee and the Traun River (Austria)

Abstract: The holomictic Traunsee is the deepest and second largest lakein Austria. The special characteristic of this ecosystem isthe fact that local salt and soda industries presumably alterthe lake by the discharge of waste materials. Since thebeginning of the 20th century salt and soda works areannually releasing up to 50,000 tons of solid wastes and up to150,000 tons of chloride into Traunsee. To assess potentialeffects of these anthropogenic impacts on the bacterioplanktonthree sampling sites, influenced as well as not influenced bythe industrial discharge, were chosen for comparison andsampled monthly from November 1997 to October 1998. Bacterialabundance ranged between 0.4 to 3.0 × 106 cells ml-1 with decreasing numbers along the depth profile. Theproportion of actively respiring bacteria, i.e. INT [2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride]reducing cells, never exceeded 10% of DAPI (4',6'-diamidino-2-phenylindole) stained cells. Fluorescence in situ hybridization (FISH) was used to examine the seasonal and spatial distribution of dominant phylogenetic groups of thebacterioplankton. Up to 84% of bacteria detected with DAPIcould be detected via FISH applying the universal bacterialprobe EUB338. Percentages of alpha- and beta-Proteobacteriaand members of the Cytophaga-Flavobacterium cluster did notexceed 60% of DAPI-stained cells.Beta-Proteobacteriaappeared to be the most abundant group, not only in Traunsee butalso in two reference lakes, Attersee and Hallstattersee. No significant differences in any of the bacterial parameters couldbe detected between the three sampling sites and all measurementswere found in the range reported for oligotrophic lakes. The highdischarge of the Traun River, resulting in a lake water renewaltime of only one year, may diminish possible effects of industrial waste discharge in the pelagic zone.

Protozooplankton in the deep oligotrophic traunsee (austria) influenced by discharges of soda and salt industries

Abstract: Traunsee is a deep oligotrophic lake in Austria characterised by an artificial enrichment of chloride in the hypolimnion (up to 170 mg L-1) caused by waste disposal of soda and salt industries. Protists were collected monthly over one year, observed alive and after Quantitative Protargol Staining (ciliates) or via epifluorescence microscopy (heterotrophic flagellates). Three sites within the lake (0–40 m depths) were compared to deeper water layers from 60–160 m depths where chloride concentrations and conductivity were increased. In addition, we observed the protozooplankton of two neighbouring lakes, i.e. reference systems, during one sampling occasion. In Traunsee the abundance of ciliates was low (200–36 600 cells L-1) in contrast to high species diversity (at least 60 different species; HS = 2.6) throughout the year. The main pelagic species in terms of abundance were small oligotrichs and prostomatids like Rimostrombidium brachykinetum/hyalinum, Balanion planctonicum and Urotricha spp. throughout the investigation period. Among free-living heterotrophic flagellates, which occurred at densities of 40–2800 cells mL-1, small morphotypes dominated in the pelagial. No differences at the community level between the three lakes could be observed and pelagic ciliates and flagellates seemed not to be affected by increased chloride concentrations or by enhanced conductivity.

Microbial communities in the winter cover and the water column of an alpine lake: system connectivity and uncoupling

Abstract: Active microbial communities formed by autotrophic and heterotrophic flagellates, ciliates and bacteria, inhabit slush layers of the ice and snow cover of high mountain lakes. Our study of the ice and snow cover of Gossenkollesee (Tyrolean Alps) during 2 complete winter periods, with special emphasis on the relationship between slush layers and the water column, confirms the hypothesis that the drastic changes in the physical and chemical structure of the cover determine biomass and composition of microbial assemblages. The temporal pattern previously described in the Pyrenees applies to the Alps, and we could distinguish 3 periods of winter cover: formation, growth and ablation. During the formation period (November to December), the ice sheet forms and slush layers start to develop. In the growth period (January to May), slush layer assemblages are mainly influenced by organisms deriving from lake plankton, predominantly flagellated chrysophytes, which peaked at different times and depths. During the ablation period (May to June/July), however, the cover assemblages are shaped by organisms and processes in the catchment. Microbial communities are characterized by the appearance of new species, such as Gymnodinium sp., red volvocales and large ciliates. The mutual influence between lake water and winter cover assemblages affects only the upper 1 to 2 m of the water column, while changes in the microbial composition of deeper water layers are slow and poorly related to slush layer assemblages. The appearance of '2 systems in 1 lake' is restricted to ca. 6 mo yr -1 and the reciprocal influence seems to be even more limited by space and time. During the ablation phase, i.e. when the influence of the catchment is much stronger than that of lake plankton, the slush microbial communities in the Alps and the Pyrenees are more similar to each other than during the growth phase of the cover. Over the whole winter period, the ice and snow cover appeared to be more dynamic, vertically variable and sporadically richer in biomass than the water column.

A hydrological tracer experiment with LiCl in a high mountain lake

Abstract: The water residence time of the high mountain seepage lake Gossenkollesee (2413 m, Tyrol, Austria) was determined by measuring the flushing rate of a tracer substance. During holomixis in July 1997, when circulation occurred throughout the entire water column, a dilute lithium chloride solution was injected into the lake causing the lithium concentration to rise from the background value of 0·06 to 3·1 μg L−1. The water residence time was derived from the exponential decline of the lithium mass in the lake between July and October holomixis. The water residence time was about 2 months, i.e. the lake volume was exchanged twice between the two periods of holomictic conditions. Copyright © 2002 John Wiley & Sons, Ltd.

Assessment of the ecological integrity of traunsee (austria) via analysis of sediments and benthic microbial communities

Abstract: Since nearly one hundred years Traunsee experiences the import of tons of liquid and solid waste originating from salt and soda production. Today, the lake exhibits chloride concentrations of up to 170 mg L-1 and 19% of the lake floor are directly or indirectly influenced by industrial deposits (ID). Based on the comparison of several microbial parameters in unaffected, directly affected and intermediate lake bottom sediments, the ecological integrity of the lake was evaluated. The highly alkaline ID, which were exclusively colonized by microorganisms, harbored a bacterial community reduced by a factor of 10 in abundance and biomass compared to undisturbed sediment areas within the lake. The bacterial community of ID was furthermore characterized by a reduced content of actively respiring cells (INT-formazan reduction), a lower frequency of dividing cells (FDC) and a significantly reduced cell and biomass production. A 80 to 90% reduction in carbon recycling is estimated for the area exclusively covered by ID. Protists, although occasionally absent from the industrial sediments, were in general found to be less sensitive to the contaminant stress. Differences in alkalinity and dissolved organic carbon (DOC) concentrations of sediment porewaters as well as the total organic content and C/N ratios of sediments partly explain the microbial pattern observed at the various sampling sites. Possible consequences of the continuous industrial tailings for the whole lake ecosystem and the validation of the ecological integrity are discussed.

Ecological Integrity: Concept, Assessment, Evaluation: The Traunsee Case

Abstract: Definitions and concepts relevant to the evaluation of theEcological Integrity of lakes are discussed herein. Theirapplication to Traunsee, a deep lake located in the AustrianAlps which is affected by wastes of salt- and soda-producingindustries, is evaluated, based on 13 contributions published inthis special issue of Water, Air, and Soil Pollution.: Focus.

The Application of Geographic Information Science (GIS) for Data Synthesis and Evaluation of Remote High Mountain Lakes in the Lake District Tyrol (Austria & Italy)

Abstract: In the EU-project EMERGE 5160 high alpine lakes are analysed for a pan-European regionalisation. In this study 465 Tyrolean lakes are selected to establish and test a method for this purpose. For an initial grouping of these lakes we created a GIS-dataset with 28 geomorphologic parameters (e.g. lake and catchment area, exposition, geology, soil, vegetation). Principal component analyses were used to identify the main gradients of variants within the large GIS-dataset. To assess the geomorphologic and chemical properties we undertook multivariate statistical analysis. The resulting variables, explaining variability in chemistry, were selected for grouping and regionalization. Combination of GIS and chemistry allowed an environmental evaluation over large areas. Major groups of lakes could be defined by geology, elevation and lake/catchment specific morphometry.

Clouds as habitat and seeders of active bacteria

Abstract: Transformation of organic and inorganic material in the atmosphere has been presumed to be caused by physical and chemical processes in the gas phase and in aerosol particles. Here we show that bacterial metabolism can play a measurable role in the production and transformation of organic carbon in cloud droplets collected at high altitudes, even at temperatures at or well below 0 degree(s)C. Although bacterial abundance and biomass in cloud water is low, compared to other oligotrophic aquatic environments, growth and carbon production rates per cell are approximately as high as in aquatic ecosystems. We hypothesize that microorganisms could play a crucial role in the transformation of airborne organic matter and the chemical composition of snow and rain. It has been recognized, the microbes can act as cloud condensation nuclei but we consider the impact on the global climate as low. With an increasing trend in cloudiness cloud systems can be seen as an ecosystem for active microbes with a seeding effort both for aquatic and terrestrial realms. Furthermore, air currents can distribute microbes over long distances to remote areas e.g. like ice caps and snow fields.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Bakterien der Lüfte: Vom Winde verweht

Abstract: Dass die Erdatmosphare Ubertrager von Bakterien, Algen, Pollen und auch Pilzen ist, ist schon seit langerem bekannt. Auch, dass jene Organismen als Eis- oder Wolkenkondensationskeime fungieren konnen. Nun jedoch konnte man das erste Mal nachweisen, dass Mikroben dort sogar bei Temperaturen um und weit unter dem Gefrierpunkt uberleben konnen [9, 10] und sich auch reproduzieren. Da die Erdoberflache zu rund 60 Prozent von Wolken bedeckt ist, konnte die Atmosphare als Lebenshabitat angesehen werden. Zudem werden Landschaften wie Schneeflachen oder Eiskappen, welche andererseits vollig von genetischem Austausch isoliert waren, durch diese Windverbreitung besiedelt und die dort ansassige mikrobielle Gemeinschaft wird durch den Transfer verandert.