Characterization of microbial communities in carbonate sediments

Microbial communities in carbonate sediments from the alkaline Lake Neusiedl and the Aldabra Atoll were characterized. The aim was to determine the microbial community composition and function in the context of their contribution to biogeochemical cycles and carbonate precipitation. Total DNA and RNA were extracted from sediment and water samples. 16S ribosomal RNA genes and transcripts were amplified and sequenced to determine the bacterial community composition. Metagenomes were assembled from selected sampling sites to determine the functional potential encoded within the microbial community. Detailed insights into bacterial genomes and metabolism were gained through isolation and characterisation of two novel bacterial species derived from Aldabra. The first sampling campaign represents the proof-of-concept study at Lake Neusiedl (Chapter C.1 & C.2). In this study the sampling procedure for the push-cores and water column was established. Bacterial 16S rRNA genes were amplified from the total DNA, sequenced, and analysed. The results showed that freshwater picoplanktonic Alphaproteobacteria and Actinobacteriota were abundant in the water column (Chapter C.1). Together with Synechococcales sheaths they may provide nucleation sites for carbonate precipitation in the water column. The sediment followed the standard biogeochemical succession and showed signs of diatom dissolution (Chapter C.2). This was linked to high abundance of heterotrophic Gammaproteobacteria and fermenting Chloroflexota, which likely contributed to maintaining the neutral pH and supported the dissolution process. The main sampling campaign to the Aldabra Atoll took place at the end of the dry season in November 2017. Sediment cores and water samples were taken at three sampling sites in the lagoon and one pool at the island rim (Chapter C.3). The bacterial community composition was identified using both 16S rRNA genes and transcripts, covering both present and past members of the community. The sampling sites Cinq Cases and Westpool D were selected for direct metagenome sequencing and analysis, as these were landlocked pools with a history of stromatolites (Chapter C.5). The sand sediment was oxic with low bacterial diversities and dominant Pseudomonas. The surface was covered by a slightly lithified crust, potentially linked to tidally induced carbonate oversaturation and precipitation driven by the activity of Gloeocapsopsis (Chapter C.3). In the mud and silt sediments bioturbation and tidal mixing led to a mixed surface and sulphate reduction zone. These were followed by atypical low bacterial phylogenetic diversity zones with high proportions of Gammaproteobacteria. Their onset was linked to changes in redox conditions, sediment age and available organic material (Chapter C.3). This was supported by results from the analysis of abundant metagenome-assembled genomes (MAGs) of the low-diversity zones at Cinq Cases. The MAGs harboured key genes for aerobic metabolism and denitrification (Chapter C.5). MAGs and 16S rRNA genes from Westpool D suggested that a biofilm comprising Gloeocapsa, Salinivibrio and Francisella is responsible for biologically induced carbonate precipitation of the local stromatolites. The unlithified microbial mat at the bottom of the pond harboured Cyanobium and Arthrospira, indicating that only specific Cyanobacteria support carbonate precipitation (Chapter C.5). To identify novel bacteria and provide information on the vast majority of uncultured taxa, we enriched halophilic members of the bacterial community. Two isolates were selected and characterized both physiologically and genomically (Chapter C.4). Pontibacillus sp. ALD_SL1 was isolated form the mudflat of the South Lagoon and exhibited a high relative abundance (30%) in the active bacterial community of the water column at Cinq Cases. Psychroflexus sp. ALD_RP9 was isolated from the bacterial bloom at Westpool D. Its ability to form extensive EPS to protect itself from salt and solar radiation may result in binding Ca2+-ions. Upon EPS degradation, local increase of Ca2+ and rearrangement of the EPS residues support the nucleation of carbonates. This study encompasses the first characterization of microbial communities from the Aldabra Atoll using amplicon, metagenome, and genome analyses. The study highlights the different modes of carbonate precipitation, which can occur in the lacustrine and lagoonal environments. It also provides a basis for in-depth analysis of individual members of the community and their involvement in sediment biogeochemical cycling.2021-12-0

Zur Grobabschätzung von Schwebstaubkonzentrationen ausSichtweitenbeobachtungen: Zur Grobabschätzung von Schwebstaubkonzentrationen ausSichtweitenbeobachtungen

Ein Weg zur Abschätzung von Schwebstaubkonzentrationen aus Sichtweitenbeobachtungen in einer belasteten Atmosphäre auf der Basis der Sichtweitentheorie nach Koschmieder, 1925 unter Berücksichtigung der Feuchtigkeit wird beschrieben.An approach for the estimation of concentrations of particulate matter in a polluted atmosphere has been described basing on the view range by the Koschmieder formula under consideration of the relative humidity

Essays on integrated maintenance and production scheduling with stochastic failures and non-resumable jobs

The dissertation is about the integration of the subject areas production scheduling and maintenance planning. In detail, the existence of a special kind of production tasks, which are called non-resumable jobs, is analysed. These jobs are not allowed to be interrupted, because otherwise the product in process would be destroyed and the whole production task has to be started from the beginning. Since the producing machines could be affected by failures, preventive maintenance activities are scheduled between the production tasks. The dissertation explains how to model the underlying problem and how to solve it

Retrieval of cloud spherical albedo from top-of-atmosphere reflectance measurements performed at a single observation angle

International audienceThe paper is devoted to the derivation of the simple analytical relationship between the cloud spherical albedo and the cloud reflection function. The relationship obtained can be used for the derivation of the spherical albedo from backscattered solar light measurements performed by radiometers on geostationary and polar orbiting satellites. The example of the application of the technique to MODIS data is shown

Estimating a relationship between aerosol optical thickness and surface wind speed over the ocean

International audienceRetrieved aerosol optical thickness (AOT) based on data obtained by the Sea viewing Wide Field Sensor (SeaWiFS) is combined with surface wind speed, obtained at the European Centre for Medium-Range Weather Forecasts (ECMWFs), over the North Pacific for September 2001. In this study a cloud screening approach is introduced in an attempt to exclude pixels partly or fully covered by clouds. The relatively broad swath width for which the nadir looking SeaWiFS instrument scanned over the North Pacific means that the AOT can be estimated according to relatively large range of wind speeds for each of the scenes analyzed. The sensitivity in AOT due to sea salt and hygroscopic growth of the marine aerosols has also been investigated. The validation of the results is based on previous parameterization in combination with the environmental quantities wind speed, RH and boundary layer height (BLH), estimated at the ECMWF. In this study a factor of 2 higher mean AOT is obtained for a wind speed up to about 13 m s?1 for September 2001 over remote ocean areas. Furthermore, a factor of 2 higher AOT is more or less supported by the validation of the results. Approximately, 50% of the enhancement seems to be due to hygroscopic growth of the marine aerosols and the remaining part due to increase in the sea salt particle mass concentrations, caused by a wind driven water vapor and sea salt flux, respectively. Reasonable agreement occurs also between satellites retrieved aerosol optical thickness and AOT observed at several AERONET (Aerosol Robotic NETwork) ground-based remote sensing stations. Finally, possible reasons why relatively large standard deviations occur around the mean values of AOT estimated for a single scene are discussed

Spektraler Extinktionsgang und Größenverteilung des Pinatubo-Aerosols

Spektralradiometermessungen (spektrale optische Dicke und Himmelshelligkeitsfunktion) unter Hochgebirgsbedingungen (Zugspitze, 2965 m) wurden zur Bestimmung der klirnarelevanten Aerosolparameter des stratosphärischen Vulkanaerosols (speziell des Pinatubo) verwendet. Die erhaltenen klirnarelevanten Aerosolparameter aus den Meßkampagnen werden mit Angaben der Aerosolklimatologien verglichen und zur Abschätzung des kurzwelligen Strahlungsforcings durch das Pinatubo-Aerosol verwendet.Spectral radiometer measurements (spectral optical thickness and sky brightness function) under high mountain conditions (Zugspitze, 2965 m) have been used for the determination of climate-relevant aerosol parameters of the stratospheric volcanic aerosol (columnar size distribution, refractive index, phase function and asymmetry parameter - especially of the aerosol of the Pinatubo volcano eruption in 1991). The climate-relevant aerosol parameters of the measurement campaigns and their temporal change have been compared with data of the aerosol climatologies and have been used for the estimation of the short wave radiative forcing of the Pinatubo event

Erfassung des atmosphärischen Trübungszustands und seiner zeitlichen Veränderung infolge von Emissionsabnahmen auf Grund sich vollziehender Strukturveränderungen in Mitteldeutschland

In the SANA project (Scientific Attandance Program for the Rehabilitation of the Atmospheric Environment in the German New Federal Lands) different kinds of turbidity measurements are used to characterize the change of the turbidity state of the atmospheric boundary layer produced by atmospheric aerosols within the time span between 1990 and 1995. For this characterization the following turbidity measurements are used: 1.) continuous measurements of the humidity corrected aerosol extinction coefficient obtained with a He-Ne-Lasertransmission path (length: 810 m, wavelength: 0.633 μm) within the urban boundary layer ofLeipzig, 2.) direct measurements ofthe particilate matter (PM10) concentration, 3.) combined measurements of spectral aerosol optical thickness (within the spectral range of0.35 - 1.1 μm) and sky brightness in the solar almucantar plane for cloud free situations, 4.) integrated radiation flux density measurement (Globalradiation). In all measurements a decrease of the atmospheric aerosol turbidity could be stated in the time span of 1990/91 to 1995: for the extinction coefficient and the particulate matter within the boundary layer of approximately 60 %, the turbidity coefficient derived from the spectral aerosol optical thickness ( corrected for the influence of the stratospheric volcanic aerosol by the Pinatobo) give a reduction of 57 %. The combined measurements of spectral aerosol optical thickness and the sky brightness are used for the determination of the main climate-relevant aerosol parameters: aerosol phase function, asymmetry parameter, columnar aerosol size distribution and apparent columnar refractive index. The largest change in the columnar aerosol size distribution could be stated in the size range of 0.2 - 0.8 μm (radius), also a reduction of approximately 60 %. Together with the measurements of the downwelling flux density an estimation of the aerosol absorption in kind of the imaginary part of the refractive index is made. The imaginary part is reduced in the same way: 1991: k = 0.021, 1994 and 1995 k = 0.008. A first estimation of the anthropogenic shortwave radiative forcing produced by the old East German air pollution of the on the basis of these data gives a change in the shortwave radiative balance of approximately -8 W/m2.Im Rahmen des SANA Projekts (Wissenschaftliches Begleitprogramm zur Sanierung der Atmosphärenumwelt) wurden verschiedene Trübungsmessungen verwendet, um die Veränderungen im Trübungszustand in der atmosphärischen Grundschicht, hervorgerufen durch Aerosole, im Zeitraum von 1990 bis 1995 charakterisieren zu können. Dazu wurden folgende Trübungsmessungen verwendet: 1.) kontinuierliche Messungen des feuchtekorrigierten Aerosolextinktionskoeffi.zienten mit Hilfe einer Laser- Transmissionsstrecke (Länge 810 m, He-Ne-Laser Wellenlänge: 0.633 μm) in der urbanen Grundschicht von Leipzig, 2.) direkte Messungen der Schwebstaubkonzentration, 3.) kombinierte Messungen von spektraler optischer Dicke des Aerosols (im Spektralbereich von 0.35 - 1.1 μm) und Himmelshelligkeitsfunktion im Almukantar unter wolkenfreien Bedingungen, 4.) integrale Strahlungsflußdichtemessungen (Globalstrahlung). In allen Messungen konnte im Zeitraum 1990/91 bis 1995 eine Abnahme der Aerosoltrübung festgestellt werden: Für den Extinktionskoeffi.zienten und die Schwebstaubkonzentration in der urbanen Grundschicht ungefähr 60 %, für den aus den spektralen optischen Dicken des Aerosols abgeleiteten Trübungskoeffizienten (korrigiert um den Beitrag des stratosphärischen Vulkanaerosols des Pinatubo) 57 %. Die kombinierten Messungen von spektraler optischer Dicke des Aerosols und der Himmelshelligkeitsfunktion dienten der Bestimmung der wesentlichen klimarelevanten Aerosolparameter: Aerosolphasenfunktion, Asymmetrieparameter, columnarer Aerosolgrößenverteilung und columnarer Brechungsindex des Aerosols. Die größte Änderung in der columnaren Aerosolgrößenverteilung ist im Radienbereich 0.2 - 0.8 μm festgestellt worden, ebenfalls eine Reduktion von ungefährt 60 %. Zusammen mit den Messungen der abwärtsgerichteten Strahlungsflußdichte wurde eine Abschätzung der Aerosolabsorption in Form des Imaginärteils des Brechungindex vorgenommen. Der Imaginärteil verringert sich in gleicher Weise: 1991: k = 0. 021, 1994 und 1995: k = 0. 008. Auf der Grundlage dieser Daten konnte der anthropogene Anteils des kurzwelligen Strahlungsforcings, das durch die Luftverunreinigung unter den alten Ostdeutschen Bedingungen hervorgerufen wird, mit ungefähr -8 W/m2 Änderung in der kurzwelligen Strahlungsbilanz abgeschätzt werden

Application of Generalized Likelihood Uncertainty Estimation (GLUE) at different temporal scales to reduce the uncertainty level in modelled river flows

In this study, the distributed catchment-scale model, DiCaSM, was applied on five catchments across the UK. Given its importance, river flow was selected to study the uncertainty in streamflow prediction using the Generalized Likelihood Uncertainty Estimation (GLUE) methodology at different timescales (daily, monthly, seasonal and annual). The uncertainty analysis showed that the observed river flows were within the predicted bounds/envelope of 5% and 95% percentiles. These predicted river flow bounds contained most of the observed river flows, as expressed by the high containment ratio, CR. In addition to CR, other uncertainty indices – bandwidth B, relative bandwidth RB, degrees of asymmetry S and T, deviation amplitude D, relative deviation amplitude RD and the R factor – also indicated that the predicted river flows have acceptable uncertainty levels. The results show lower uncertainty in predicted river flows when increasing the timescale from daily to monthly to seasonal, with the lowest uncertainty associated with annual flows

Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging

Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away