API src

Found 77 results.

Other language confidence: 0.8683788518563034

Colored dissolved organic matter (CDOM) absorption coefficients in the sea-surface microlayer and the underlying water during a mesocosm phytoplankton bloom in 2023

The effects of a phytoplankton bloom and photobleaching on colored dissolved organic matter (CDOM) in the sea-surface microlayer (SML) and the underlying water (ULW) were studied in a month-long mesocosm study, in May and June of 2023, at the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany. The mesocosm study was conducted by the DFG research group BASS (Biogeochemical processes and Air–sea exchange in the Sea-Surface microlayer, Bibi et al., 2025) in the Sea Surface Facility (SURF) of the ICBM. The facility contains an 8 m × 1.5 m × 0.8 m large outdoor basin with a retractable roof, which was closed at night and during rain events. The basin was filled with North Sea water from the adjacent Jade Bay. Homogeneity of the ULW in the basin was achieved by constant mixing of the water column. The daily SML and ULW samples were collected alternating in the morning, about 1 h after sunrise, and in the afternoon, about 10 h after sunrise. The alternation of sampling times intended to capture a potential effect of sun-exposure duration on DOM transformations and elucidated the day and night variability of the layers. The SML was collected via glass plate sampling (Cunliffe and Wurl, 2014). The ULW was sampled via a submerged tube and a connected syringe suction system in 0.4 m depth. The removed sample volume was refilled with Jade Bay water every day. SML and ULW samples were filtered through pre-flushed 0.7 µm Whatman GF/F and 0.2 nucleopore filters into brown bottles and were stored dark and at 4 °C until measurement within weeks of the study. The brown bottles were previously combusted at 500 °C. CDOM was measured with three liquid waveguide capillary cells (LWCC, WPI, USA) of different pathlengths (10 cm, 50 cm, 250 cm) to increase the measurement sensitivity following the protocols of Röttgers et al. (2024) using a spectral detector (Avantes, Netherlands) for a total spectral range from 230 to 750 nm. A sodium chloride (NaCl) solution was used for the salinity correction. The blank-corrected absorbance spectra were then converted into Napierian absorption coefficients (Bricaud et al., 1981).

Salinity, temperature, pH, and fluorescent dissolved organic matter (fDOM) measurements in surface waters within DynaCom experimental islands and saltmarsh enclosed plots at different elevation levels, Spiekeroog, Germany, 2018-08 to 2022-01

Data were collected between August 2018 and January 2022 as part of the research unit DynaCom (Spatial community ecology in highly dynamic landscapes: From island biogeography to metaecosystems) of the Universities of Oldenburg, Göttingen, and Münster, the iDiv Leipzig and the Nationalpark Niedersächsisches Wattenmeer. Measurements were conducted almost bi-/monthly on experimental islands and salt marsh enclosed plots located in the back barrier tidal flat and salt marsh of the island of Spiekeroog (Germany). Field-based in situ measurements of salinity, temperature, and pH were conducted using portable hand-held instruments in groundwater (filter tubes within experimental plots) and in surface waters from a tidal channel (ITC) adjacent to the experimental islands and a tidal pond (STP) in the pioneer zone of the salt marsh. Measurements were performed and samples were taken during the day between 3 hours before and 3 hours after low tide. From August 2018 to September 2019 a HQ40D digital two-channel multi meter equipped with a pre-calibrated Intellical CDC401 field 4-pole graphite conductivity cell (Hach Lange GmbH, Germany) was used to measure temperature (°C) and salinity (psu). The same device was used for pH measurements with an Intellical PHC101 field low maintenance gel filled pH electrode (Hach Lange GmbH, Germany). The pH electrode was calibrated before each fieldwork using single-use pH buffer solutions (pH 4.01, 7.00, 10.01, Hach Lange GmbH, Germany). Since October 2019, salinity and temperature were measured using a Multi 3510 IDS SET 4 handheld device equipped with a TetraCon® 925/LV 4-Pol-IDS conductivity electrode with graphite cells (WTW, Xylem Analytics Germany GmbH, Germany). Fluorescent dissolved organic matter (FDOM, ppb QSE) was measured using an AquaFluor Modell 80000-010 for UV-420 (Turner Designs Inc., USA), pre-calibrated in the laboratory. For this, water samples were taken from the field to a nearby mobile central field unit and were filtered within 1-2 hours after sampling using 25 mm Nuclepore syringe filters (0.2 µm pore size) directly into sample-pre-rinsed measurement cuvettes. Data quality control (QC) was performed using MATLAB (R2024b). Outlier detection was conducted both visually and statistically using z-score analysis (|z| > 3) per sampling campaign and plot. Each data point was assigned a Quality Control Flag (QC).

Degradation of diatom-derived dissolved organic matter (DOM) in surface seawater

Stored surface seawater originally collected in the North Sea was amended with dissolved organic matter (DOM) obtained from the diatom Skeletonema marinoi by exposing the diatom culture to a hydrostatic pressure level of 40 MPa for 24 h. To this end, S. marinoi had been grown to stationary phase in L1 medium plus silicate (Guillard & Hargraves 1993) at 15°C under a light/dark regime of 14/10 h. Diatom-cell-free DOM was added to aliquoted seawater samples at initial concentrations of 250 µmol C/L. The microbial degradation of the added DOM and the microbial response to DOM-amendment at 15°C and in darkness was followed for 2 weeks. The seawater was subsampled at defined time intervals to analyze a number of variables.

Pressure-induced leakage of dissolved organic matter (DOM) from diatom-bacteria aggregates

Model diatom aggregates were produced from the diatom Skeletonema marinoi and the natural microbial community of seawater collected in Oeresund (Stief et al. 2023), Central Arctic Ocean, and Japan Trench. S. marinoi was grown to stationary phase in L1 medium plus silicate (Guillard & Hargraves 1993) at 15°C under a light/dark regime of 14/10 h. The diatom aggregates were individually incubated at either atmospheric pressure (0.1 MPa = control treatment) or at gradually increasing hydrostatic pressure (0.1-100 MPa = pressure treatment) throughout 20 days in darkness and at 3°C. The pressure treatment simulated the sinking of diatom-bacteria aggregates from the ocean surface down into a hadal trench of 10 km depth. Pressure-induced leakage of dissolved organic matter (DOM) was followed throughout the incubations. Ambient concentrations of different DOM components were measured: Dissolved organic carbon (DOC), total dissolved nitrogen (TDN), protein-like and humic-like DOM fluorescence.

PARAFAC components and fluorescent dissolved organic matter (FDOM) indices on organic matter transformation processes in the sea-surface microlayer and the underlying water during a mesocosm phytoplankton bloom in 2023

The effects of a phytoplankton bloom and photobleaching on colored dissolved organic matter (CDOM) in the sea-surface microlayer (SML) and the underlying water (ULW) were studied in a month-long mesocosm study, in May and June of 2023, at the Institute for Chemistry and Biology of the Marine Environment (ICBM) in Wilhelmshaven, Germany. The mesocosm study was conducted by the DFG research group BASS (Biogeochemical processes and Air–sea exchange in the Sea-Surface microlayer, Bibi et al., 2025) in the Sea Surface Facility (SURF) of the ICBM. The facility contains an 8 m × 1.5 m × 0.8 m large outdoor basin with a retractable roof, which was closed at night and during rain events. The basin was filled with North Sea water from the adjacent Jade Bay. Homogeneity of the ULW in the basin was achieved by constant mixing of the water column. The daily SML and ULW samples were collected alternating in the morning, about 1 h after sunrise, and in the afternoon, about 10 h after sunrise. The alternation of sampling times intended to capture a potential effect of sun-exposure duration on DOM transformations and elucidated the day and night variability of the layers. The SML was collected via glass plate sampling (Cunliffe and Wurl, 2014). The ULW was sampled via a submerged tube and a connected syringe suction system in 0.4 m depth. The removed sample volume was refilled with Jade Bay water every day. SML and ULW samples were filtered through pre-flushed 0.7 µm Whatman GF/F and 0.2 nucleopore filters into clear 40 ml SUPELCO bottles. These bottles were acid-washed twice and combusted at 500 °C for 5 h. The samples were stored dark and at 4 °C and measured within a few months of the study. FDOM was measured using a Aqualog fluorescence spectrometer (Horiba Scientific, Japan) with 10 seconds integration time and high gain of the CCD (charge-coupled device) sensor within an excitation range from 240 to 500 nm, and an emission range from 209.15 to 618.53 nm. The Aqualog measures fluorescence as well as absorption. The resulting data includes an excitation-emission-matrix (EEM) of the blank (MilliQ Starna cuvette), an EEM of the sample, and the absorption values of the sample. The raw exported Aqualog data was corrected for errors and lamp shifts. The corrected EEM data is then decomposed by PARAFAC (Murphy et al., 2013) for its underlying fluorophore components. Before running the PARAFAC routine, the corrected data needed to undergo a correction process by subtracting the blank from the sample EEM and canceling the influences of the inner-filter effect (IFE, Parker & Rees, 1962; Kothawala et al., 2013). The fluorescence intensity of the IFE-corrected EEM is calibrated by using the Raman scatter peak of water (Lawaetz & Stedmon, 2009). For PARAFAC the corrected data was processed using the drEEM and NWAY toolbox (version 0.6.5; Murphy et al., 2013) in MATLAB (R2020b). A 4-component model was validated with the validation style S4C6T3 for the split half analysis with nonnegativity constraints and 1-8e as the convergence criteria with 50 random starts and a maximum number of 2500 iterations. The resulting final model had a core consistency of 82.04 and the explained percentage was 99.54%. Furthermore, four fluorescence indices were calculated from the corrected EEM data (HIX – Humification index, Zsolnay et al., 1999; BIX – Biological index, Huguet et al., 2009; REPIX – Recently produced index, Parlanti et al., 2000, Drozdowska et al., 2015; ARIX, Murphy, 2025).

INSPIRE ST Höhenlage - Gitter-Coverage DOM1

INSPIRE-Datensatz zum Annex2-Thema Höhe für das Bundesland Sachsen-Anhalt. Der Datensatz wurde aus den Daten des Digitalen Oberflächenmodells mit Gitterweite 1m (DOM1) abgeleitet und INSPIRE-konform transformiert. -Dieser Datensatz steht ausschließlich bei online-Abruf kostenfrei zur Verfügung.-

3D-Messdaten NW

Die 3D-Messdaten (3DM) aus dem Laserscanning beschreiben das Gelände und die Oberfläche durch unregelmäßig verteilte georeferenzierte Höhenpunkte. Die Punktdichte liegt in NRW bei durchschnittlich 4 bis 10 Punkten pro Quadratmeter. Insbesondere in Waldgebieten kann die Punktdichte deutlich ansteigen. Als Erfassungsmethode kommt in Nordrhein-Westfalen das flugzeuggestützte Laserscanning (Airborne Laserscanning, ALS) zum Einsatz. Die 3DM enthalten sämtliche Reflexionen des ALS in einer klassifizierten Messpunktwolke. Als Datenformat wird der OGC Standard LAS in der Version 1.2 im Point Data Record Format 1 (PDRF 1) verwendet. Über das Downloadportal werden die Daten im komprimierten LAS-Format (LAZ) bereitgestellt. 2017 wurde in der Datenerfassung auf das sogenannte Full Wave Laserscanning umgestellt. Hier werden neben sämtlichen Reflexionen für jeden Laserimpuls zusätzliche Informationen erfasst. Da noch keine flächendeckende Erfassung mittels Full Wave Laserscanning erfolgt ist, unterscheiden sich Dateninhalte und die Anzahl der Punktklassen in NRW noch. Informationen über die Verfügbarkeit und Aktualität der 3D-Messdaten gibt der WMS-Viewer „DHM-Übersicht". Aus diesen Rohdaten, den 3D-Messdaten, werden Digitale Geländemodelle mit regelmäßiger Gitterweite berechnet. Geobasis NRW stellt im Rahmen ihres gesetzlichen Auftrags u.a. DGM1 bereit (siehe DGM1), wobei die Zahl in der Bezeichnung die Gitterweite angibt (beim DGM1 also eine Gitterweite von 1 m).

Temporales Digitales Oberflächenmodell 50 NW

Das temporale Digitale Oberflächenmodell (tDOM) entspricht der Differenz zweier Zeitschnitte von Digitalen Oberflächenmodellen (DOM). Der tDOM-Datenbestand ist flächendeckend und verwendet für die Kacheln, für die noch kein historisches bildbasiertes Digitales Oberflächenmodell (bDOM) vorliegt, ein DOM aus Lidar-Daten (Airborne Laserscanning, ALS). Zukünftig wird das tDOM ausschließlich die Differenz der letzten beiden Aufnahmezeitpunkte der bDOM visualisieren. Die dargestellten Veränderungshinweise gelten pro Kachel entweder für einen 2-Jahreszeitraum (bDOM-bDOM) oder für einen Jahreszeitraum von bis zu 4 Jahren (ALS-bDOM). Die entsprechenden Informationen können der Sachdatenabfrage entnommen werden.

Normalisiertes Digitales Oberflächenmodell 50 NW

Ein normalisiertes Digitales Oberflächenmodell (nDOM) ist ein Differenzmodell aus einem Digitalen Geländemodell (DGM) und einem Digitalen Oberflächenmodell (DOM) und erlaubt eine Ermittlung der relativen Objekthöhe über der als Ebene abgebildeten Geländeoberfläche. Die Bezirksregierung Köln, Geobasis NRW, stellt das Produkt nDOM50 im Rahmen ihres gesetzlichen Auftrags für Nordrhein-Westfalen flächendeckend zur Verfügung und führt dieses kontinuierlich fort. Zur Ableitung des nDOM50 wird ein Digitales Geländemodell mit einer Gitterweite von 0,5 m aus Laserscanning-Befliegungen sowie ein (ausschließlich aus Sommerbefliegungen abgeleitetes, also „belaubtes“) bildbasiertes Oberflächenmodell mit einer Bodenauflösung von 50 cm (bDOM50) verwendet. Das normalisierte Digitale Oberflächenmodell findet insbesondere Anwendung in der Forst- und Umweltverwaltung, z.B. für eine fernerkundungsbasierte Baumartenklassifikation, oder wird zur Ableitung der Landbedeckung verwendet.

Laserscanaufnahmen des Freistaates Sachsen ab 2005

Der Datensatz enthält die Grenzen der Laserscanaufnahmen seit 2005.

1 2 3 4 5 6 7 8