Search

As peatlands are a major terrestrial sink in the global carbon cycle, gaining an understanding of their development and changes throughout time is essential in order to predict their future carbon budget and potentially mitigate the adverse outcomes of climate change. With this aim to understand peat development, many studies have investigated the paleoecological dynamics by analyzing various proxies, including pollen, macrofossil, elemental, and biomarker analyses. However, as each of these proxies is known to have its own benefits and limitations, examining them in parallel allows for a deeper understanding of these paleoecological dynamics at the peatland and a systematic comparison of the power of these individual proxies. In this study, we therefore analyzed peat cores from a peatland in Germany (Beerberg, Thuringia) to (a) characterize the vegetation dynamics over the course of the peatland development during the late Holocene and (b) evaluate to what extent the inclusion of multiple proxies, specifically pollen, plant macrofossils, and biomarkers, contributes to a deeper understanding of those dynamics and interaction among factors. We found that, despite a major shift in the regional forest composition from primarily beech to spruce as well as many indicators of human impact in the region, the local plant population in the Beerberg area remained stable over time following the initial phase of peatland development up until the last couple of centuries. Therefore, little variation could be derived from the paleobotanical data alone. The combination of pollen and macrofossil analyses with the elemental and biomarker analyses enabled further understanding of the site development as these proxies added valuable additional information, including the occurrence of climatic variations, such as the Little Ice Age, and more recent disturbances, such as drainage.

A spatiotemporal reconstruction of slope movements on the edge of Lake Lucerne near the municipality of Horw, canton of Lucerne, is presented. The reconstruction was realized by analyzing growth reactions of beech (Fagus sylvatica L.) and fir (Abies alba Mill.) trees growing on this slope. Before dendrochronological sampling, a detailed geomorphological mapping of the landslide was conducted with the aim to determine the spatial extent of the sliding area. For tree-ring analyses, 124 increment cores from 62 trees were analyzed following standard techniques of dendrogeomorphology. In addition, long micro-sections were prepared from the entire cores to extend the common eccentricity analyses by microscopic determination of the onset of reaction wood in fir and beech. Results clearly show that the area is moving at least since 1948. A significant concentration of events was observed between the years 1990 and 2000 as well as after 2006. The definition of a threshold to define events using an eccentricity index alone is problematic and needs to be adapted to specific site conditions. For this reason, we recommend always combining the application of an eccentricity index with a detailed visual (anatomical) inspection to check for the occurrence of reaction wood.

Exposure dating has substantially improved our knowledge about glacier advances during the Younger Dryas (YD) and the early Holocene. The glacier development after the Last Glacial Maximum (LGM) and the timing of morphologically evidenced, earlier Lateglacial re-advances is, however, still widely unknown. In this study we used 10Be surface exposure and radiocarbon dating to address these phases and corresponding landforms in the catchment of the former Reussgletscher (central Swiss Alps). We obtained clear indication for moraine deposition prior to the YD. The oldest samples predate the Bølling–Allerød interstadial (>14.6 ka). Morphostratigraphically even older lateral moraines, probably corresponding to terminal positions in the Lake Lucerne, could not be dated conclusively. Due to the geomorphological constraints of the sampling environment, the establishment of a local pre-YD chronology remains a challenge: moraines with adequate numbers of datable boulders were rarely preserved, and age attributions based on few samples are complicated by outliers.

Due to the large size (e.g. sections of tree trunks) and highly heterogeneous spatial distribution of deadwood, the timescales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the chronosequence approach and the five-decay class system that is based on a macromorphological assessment. For the decay classes 1–3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) radiocarbon dating was used. In addition, density, cellulose, and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model, a regression approach, and the stage-based matrix model. In the decay classes 1–3, the ages of the CWD were similar and varied between 1 and 54 years for spruce and 3 and 40 years for larch, with no significant differences between the classes; classes 1–3 are therefore not indicative of deadwood age. This seems to be due to a time lag between the death of a standing tree and its contact with the soil. We found distinct tree-species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were estimated to be in the range 0.018 to 0.022 y−1 for spruce and to about 0.012 y−1 for larch. Snapshot sampling (chronosequences) may overestimate the age and mean residence time of CWD. No sampling bias was, however, detectable using the stage-based matrix model. Cellulose and lignin time trends could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 years for spruce and 50 years for larch. The half-life of lignin is considerably higher and may be more than 100 years in larch CWD. Consequently, the decay of Picea abies and Larix decidua is very low. Several uncertainties, however, remain: 14C dating of CWD from decay classes 4 and 5 and having a pre-bomb age is often difficult (large age range due to methodological constraints) and fall rates of both European larch and Norway spruce are missing.

Most glacier forefields of the European Alps are being progressively exposed since the glaciers reached their maximum expansion in the 1850s. Global warming and climate changes additionally promote the exposure of sediments in previously glaciated areas. In these proglacial areas, initial soils have started to develop so that they may offer a continuous chronosequence from 0 to 150-yr-old soils. The build-up of organic matter is an important factor of soil formation, and not only autochthonous but also distant sources might contribute to its accumulation in young soils and surfaces of glacier forefields. Only little is known about black carbon in soils that develop in glacier forefields, although charred organic matter could be an important component of organic carbon in Alpine soils. The aim of our study was to examine whether black carbon (BC) is present in the initial soils of a proglacial area, and to estimate its relative contribution to soil organic matter. We investigated soil samples from 35 sites distributed over the whole proglacial area of Morteratsch (Upper Engadine, Switzerland), covering a chronosequence from 0 to 150 yr. BC concentrations were determined in fine earth using the benzene polycarboxylic acid (BPCA) marker method. We found that charred organic matter occurred in the whole area, and that it was a main compound of soil organic matter in the youngest soils, where total Corg concentrations were very low. The absolute concentrations of BC in fine earth were generally low but increased in soils that had been exposed for more than 40 yr. Specific initial microbial communities may profit from this additional C source during the first years of soil evolution and potentially promote soil development in its early stage.

Chronosequenzen vermitteln einen Einblick in die im Boden ablaufenden Prozesse und ermöglichen zudem Aussagen über die Landschaftsgenese. Die Verbindung des Faktors Zeit mit festgestellten Änderungen im Boden geben Hinweise über die Geschwindigkeit der entsprechenden Prozesse. Die im Schmadri untersuchten Bodenprofile (ca. 3'500 und 11'500 Jahre) zeigen eindeutige Unterschiede hinsichtlich ihres Entwicklungsgrades. Eine gute zeitliche Einordnung der Böden lässt sich aufgrund des dithionit-exlrahierbaren Fe und AI bewerkstelligen. Auch die gespeicherte Menge an Stickstoff im Boden ist mit dem Bodcnalter eng verknüpft. Ganz deutliche Unterschiede lassen sich über die Bestimmung der Verwitterungsraten berechnen. Die Verwitterungsraten von AI widerspiegeln im wesentlichen den Verlauf der Podsolierung, währenddem Na sehr stark die Verwitterung von Plagioklasen reflektiert. Eine gute zeitliche Abfolge ist auch bei den Tonmineralien erkennbar. Die Verwitterung läuft im wesentlichen über die Umwandlung von Chloriten und Glimmern hin zur Bildung von Hydrobiotit oder HIS und schliesslich zu Smectiten oder einer Wechsellagerung zwischen Smectit und Mica.

Üblicherweise wird angenommen, daß die Bildung von Kaolinit in Böden, ausschließlich an das Vorherrschen warmfeuchter Klimabedingungen sowie einer intensiven Perkolation des Bodens gebunden sein muß. Die von uns durchgeführten Untersuchungen an ausgewählten Bodenprofilen im schweizerischen Mittelland, im Jura und in den Alpen belegen, daß Kaolinit in einigen Fällen nachgewiesen werden kann und dies auch unter temperierten bis subalpinen Klimabedingungen sowie in vergleichsweise jungen Böden. Entscheidend für eine rezente Kaolinitbildung scheint jeweils der Wasserhaushalt des Bodens zu sein: unsere Ergebnisse erlauben die Hypothese, daß eine gehemmte Perkolation oder der Einfluß des Grundwassers die Kristallisation von Kaolinit begünstigen.

Detaillierte Bodenkarten im schweizerischen Alpenraum existieren praktisch nicht. Die einzige Grundlage ist die Bodeneignungskarte im Massstab 1:200'000. Mit der GIS-Datenbasis des Kantons Graubünden wurde versucht, über eine räumliche Analyse einen Teil der Bodeninformationen nach der FAL-Nomenklatur zu modelieren. Die modellierten Grössen umfassen Bodentyp, Gründigkeit, Wasserhaushalt, Geländeform, pH-Wert, org. C-Gehalt, Skelettgehalt und die Körnung. Die Berechnungen basieren zu einem Teil auf der Bodentypenmodellierung, von welcher weitere Eigenschaften abgeleitet werden konnten. Die Modellierung stützt sich auf das prozess-orientierte entity relationship-Prinzip sowie auf Pedo-Transfer-Funktionen. Da die Rasterbeite des digitalen Höhenmodells von 20 Metern für die Modellierung der Bodeneigenschaften der Talebene nicht befriedigen konnte, wurden die Bodeneigenschaften in der Talebene mit einer Luftbildkartierung erfasst. Die erzielten Resultate stimmen zuversichtlich (die Übereinstimmung Feld – Modell liegt bei ca. 70%) und können in einem auch für die Praxis relevanten Massstab von ca. 1:50'000 dargestellt werden.

From 1967 to 2005, many astrophotos have been taken with the Baldone Schmidt telescope (80cmx120cmx240cm). These photos have being archived in theInstituteofAstronomyof theUniversityofLatvia(IAU code 069, longitude 24.4041 E, latitude 56.7734 N, altitude103 m). There are over 22000 direct and 2300 spectral photos of different regions of the sky in this archive. There are also information on the photo materials type as well as the types of color filters used for phographiing the sky fields and objects. The home page of theInstituteofAstronomy’s Baldone observatory (www.baldoneobservatory.lu.lv) has the archive’s description. Part of the description has also being published (Alksnis, et al., 1998).

TheUniversityofLatvia's Institute of astronomy possesses a collection of 22 thousand photographic plates taken by the1.2 mSchmidt telescope located at the Baldone observatory. Among others, there are 767 astronegatives in this collection obtained in 314 sky areas using the Johnson U-filter. The field of view of each negative covers 19 square degrees. The plate scale is 72”/mm. The digitizing of the UV-collection has started in June 2016 with EPSON EXPRESSION 10000XL flatbed scanner. The general aim of the digitizing is to obtain UV-magnitudes and positions of all objects registered on the plates. Up to date near a half of the UV-collection is digitized. 24 digitized MEGA program plates of the collection were used for the preliminary investigation of the quality of photographic material and scanner systematic behavior. The catalog of positions and UV-magnitudes of 68.784 stars and galaxies for 12 regions allows evaluating the expected accuracy of the whole observed material. The estimated accuracy for all objects is σαδ = ±0.28" and σU = ±0.20m for positions and brightness respectively. For the stars with U = 8m – 14m these errors are σαδ = ±0.11" and σU = ±0.09m. The convergence of coordinates with respect to the coordinates of the reference system Tycho2 is σαδ= ±0.06". The conformity with photoelectric Upe-magnitudes is ±0.13m.

Digital processing of photographic plates of star fields allows to determine with high accuracy the coordinates and stellar magnitudes for all registered objects on these plates. The processing results can be used for a broad search for images of small bodies of the Solar system and determination of their coordinates. From the observations of earlier epoch, we can extract information about the locations of these bodies well before discovering them. Modern approach to processing early photographic observations with new technologies can be an effective instrument for rediscovery of asteroids and correction their orbits. We analyzed the results of digital processing of observations of clusters in UBVR bands which were made on the 1.2-m Schmidt telescope of the Observatory of Institute of Astronomy ofUniversityofLatviain Baldone (code 069). As a result 87 images of minor planets from 9.8 to 17.1 stellar magnitude and 2 images of comets were identified on 152 plates for 1967-1996. The catalogue of positions and stellar magnitudes of the searching asteroids was compiled. Among them 12 observations of asteroids are the earliest of the world's known observations of these asteroids. All positions of asteroids were compared with the ephemeris JPL DE431. Analysis was carried out.

The Pleiades Star Cluster (M45) is one of the most studied star clusters in the galaxy. At the same time as part of the Pleiades are many long-period variable stars, including flashing that need further study. Recent work on the processing of photographic images of the Pleiades obtained at different observatory revealed a number of star clusters with large variations in coordinates, the reason you want to understand. Collection of UkrVO unified digital archive contains a number of plates with images of the stars of the Pleiades obtained on different instruments. Processing of this material allows to test out standard programs for digital astronomical images processing. Also we will add information about variable stars and will improve the coordinates and proper motions of cluster stars. Selected material covers the period 1909 – 1999 years. The plates have different margins, scale, number of stars on images and obtained limiting magnitude. Exactly this diverse set of options lets you to be sure of results.

The experience of calibrating Eglit’s avalanche model using data about the avalanche travel distance lengths and velocity data from the Zailiyskiy Alatau range (Kazakhstan) is discussed. Empirical equations are proposed that describe the dependence of the friction coefficients on the avalanche volume and type.

Method for estimating the accuracy of astrometric (rectangular coordinates) and photometric (diameters and magnitudes) characteristics of commercial scanners is proposed and applied. The method is demonstrated using an example of processing of sequential scans of plates, which were exposed with different telescopes and then digitized with resolution of 1200 dpi with several Epson scanners. Scanning operations were carried out in various observatories as part of development of the database of photographic observations for Virtual Observatories (Vavilova, 2012). Errors of studied scanners are equal to σx, y = ± 0.02-0.06px and σm = ± 0.015-0.024 mag for astrometry and photometry, respectively.

Harmful cyanobacterial blooms in freshwater ecosystems produce bioactive secondary metabolites including cyanopeptides that pose ecological and human health risks. Only adverse effects of one class of cyanopeptides, microcystins, have been studied extensively and have consequently been included in water quality assessments. Inhibition is a commonly observed effect for enzymes exposed to cyanopeptides and has mostly been investigated for human biologically relevant model enzymes. Here, we investigated the inhibition of ubiquitous aquatic enzymes by cyanobacterial metabolites. Hydrolytic enzymes are utilized in the metabolism of aquatic organisms and extracellularly by heterotrophic bacteria to obtain assimilable substrates. The ubiquitous occurrence of hydrolytic enzymes leads to the co-occurrence with cyanopeptides especially during cyanobacterial blooms. Bacterial leucine aminopeptidase and alkaline phosphatase were exposed to cyanopeptide extracts of different cyanobacterial strains ( Microcystis aeruginosa wild type and microcystin-free mutant, Planktothrix rubescens) and purified cyanopeptides. We observed inhibition of aminopeptidase and phosphatase upon exposure, especially to the apolar fractions of the cyanobacterial extracts. Exposure to the dominant cyanopeptides in these extracts confirmed that purified microcystins, aerucyclamide A and cyanopeptolin A inhibit the aminopeptidase in the low mg L–1 range while the phosphatase was less affected. Inhibition of aquatic enzymes can reduce the turnover of nutrients and carbon substrates and may also impair metabolic functions of grazing organisms.