API src

Found 8 results.

Related terms

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).

Pollen counts from Kasten corer CON01-603-5, CONTINENT Ridge

Pollen counts from Kasten corer CON01-603-5 at CONTINENT Ridge.

Raw pollen data from kasten core CON01-605-5 (Vydrino)

Sediment slices of 0.5 cm thickness were obtained from gravity core segments and of 1 cm thickness from the Vydrino piston core. Volumetric subsamples of 5 cm3 (10 cm3 in case of the lowermost samples from Continent core) were prepared according to standard procedures, including 7-μm ultrasonic fine-sieving (Cwynar et al., 1979, Fægri et al., 1989 K. Fægri, P.E. Kaland and K. Krzywinski, Textbook of Pollen Analysis (4th edition), John Wiley & Sons, Chichester (1989) 328 pp..Fægri et al., 1989 and PALE Steering Committee, 1994). Two tablets of Lycopodium marker spores were added to each sample for calculating total pollen and spore concentrations (Stockmarr, 1971). Water-free glycerol was used for storage and preparation of microscopic slides. The palynological samples were counted at magnifications of 400–600×, applying 1000× for the identification of difficult pollen types, e.g., including Saxifragaceae, Crassulaceae, and Rosaceae.

Raw pollen data from piston core CON01-605-3 (Vydrino)

Sediment slices of 0.5 cm thickness were obtained from gravity core segments and of 1 cm thickness from the Vydrino piston core. Volumetric subsamples of 5 cm3 (10 cm3 in case of the lowermost samples from Continent core) were prepared according to standard procedures, including 7-μm ultrasonic fine-sieving (Cwynar et al., 1979, Fægri et al., 1989 K. Fægri, P.E. Kaland and K. Krzywinski, Textbook of Pollen Analysis (4th edition), John Wiley & Sons, Chichester (1989) 328 pp..Fægri et al., 1989 and PALE Steering Committee, 1994). Two tablets of Lycopodium marker spores were added to each sample for calculating total pollen and spore concentrations (Stockmarr, 1971). Water-free glycerol was used for storage and preparation of microscopic slides. The palynological samples were counted at magnifications of 400–600×, applying 1000× for the identification of difficult pollen types, e.g., including Saxifragaceae, Crassulaceae, and Rosaceae.

Raw pollen data from kasten core CON01-603-5 part1 (%)

Sediment slices of 0.5 cm thickness were obtained from gravity core segments and of 1 cm thickness from the Vydrino piston core. Volumetric subsamples of 5 cm3 (10 cm3 in case of the lowermost samples from Continent core) were prepared according to standard procedures, including 7-μm ultrasonic fine-sieving (Cwynar et al., 1979, Fægri et al., 1989 K. Fægri, P.E. Kaland and K. Krzywinski, Textbook of Pollen Analysis (4th edition), John Wiley & Sons, Chichester (1989) 328 pp..Fægri et al., 1989 and PALE Steering Committee, 1994). Two tablets of Lycopodium marker spores were added to each sample for calculating total pollen and spore concentrations (Stockmarr, 1971). Water-free glycerol was used for storage and preparation of microscopic slides. The palynological samples were counted at magnifications of 400–600×, applying 1000× for the identification of difficult pollen types, e.g., including Saxifragaceae, Crassulaceae, and Rosaceae.

Raw pollen data from kasten core CON01-603-5 part1 (counts)

Sediment slices of 0.5 cm thickness were obtained from gravity core segments and of 1 cm thickness from the Vydrino piston core. Volumetric subsamples of 5 cm3 (10 cm3 in case of the lowermost samples from Continent core) were prepared according to standard procedures, including 7-μm ultrasonic fine-sieving (Cwynar et al., 1979, Fægri et al., 1989 K. Fægri, P.E. Kaland and K. Krzywinski, Textbook of Pollen Analysis (4th edition), John Wiley & Sons, Chichester (1989) 328 pp..Fægri et al., 1989 and PALE Steering Committee, 1994). Two tablets of Lycopodium marker spores were added to each sample for calculating total pollen and spore concentrations (Stockmarr, 1971). Water-free glycerol was used for storage and preparation of microscopic slides. The palynological samples were counted at magnifications of 400–600×, applying 1000× for the identification of difficult pollen types, e.g., including Saxifragaceae, Crassulaceae, and Rosaceae.

Raw pollen data from the Eemian core CON01-603-2

The studied core CON01-603-2 was recovered from the Continent site, Northern Basin from a water depth of 386 m (Fig. 1) (see Charlet et al., 2005-this volume). The analysed sequence (725.5–608 cm) consists of mainly of biogenic, diatomaceous sediments, although the upper part of the sequence between ca. 611–608 cm contains more silt particles and less diatoms than the lower part of the sequence. From a depth of 690 cm upwards the sediments are finely and coarsely laminated.Based on a standard technique for processing palynological samples, silicates were removed from the sediment by treatment with 40% HF for 3 days and with 50% HF for 1 day. Following Erdtmans acetolysis (Faegri and Iversen, 1989) sediment samples were sieved through 7-µm meshes in an ultrasonic water bath (Cwynar et al., 1979).

Mechanismen der Interaktion im System Pflanze-Schaderreger-Nutzorganismen

Untersuchungen zum Einfluss von minierenden Phytophagen mit unterschiedlicher Angriffsstrategie an unterschiedlich integrierten Pflanzenorganen des Wirtsbaumes (Phloem, Blatt) zeigten die Ausbildung von grundsaetzlich aehnlich passiven und aktiven Resistenzmechanismen. Sie beeinflussen in Abhaengigkeit von Standort, Umweltbedingungen, Pflanzenalter und betroffenem Organ den Stoffwechsel des Wirtsbaumes mit unterschiedlicher Intensitaet. Von den geplanten Untersuchungen wird eine weitgehende Aufklaerung der durch den Phytophagenbefall induzierten Resistenzmechanismen der Laerche erwartet. Besondere Beachtung erfahren Befunde hinsichtlich des Abwehrstoffwechsels als Ausdruck unterschiedlicher Abwehrstrategien und im Hinblick auf die resultierende Beeinflussung des Primaerstoffwechsels des Baumes. Durch Zusammenfuehrung der Untersuchungen an unterschiedlich integrierten Organen (Nadel, Phloem) auf gleiche Freilandversuchsflaechen und durch den 1994/95 zu erwartendem Kahlfrass durch die Laerchenminiermotte werden Aussagen zur Disposition bzw. Konditionierung von im Kronenraum stark befressenen Baeumen fuer den Befall durch Borkenkaefer moeglich. Schwerpunkte der strukturchemischen Untersuchungen liegen bei der Analytik von Mono-, Sesqui- und Triterpenen und deren Glycosiden sowie bei Flavonoiden und Phenolkoerpern.

1