Publications

Cruise report RV SONNE 187 Vietnam

No abstract is provided for this article.

Mapping the plastic legacy: Geospatial predictions of a microplastic inventory in a complex estuarine system using machine learning

Sediments store the majority of the microplastic legacy in the aquatic environment. To predict microplastic distribution in sediments, models have been developed focussing on coarse ocean basin scales or suited to relatively simple geomorphological and hydrodynamic systems. However, such models reach their limits in more complex estuarine systems, leaving a significant lack of modelling capability for microplastic pollution in key ecosystems. We address this gap by employing machine learning techniques to predict spatial MP inventories deposited in the Schlei, Northern Germany. Notably, the complex hydrodynamic regime, influenced by narrowings and braided embayments, freshwater tributaries, wind-driven mixing, and brackish inflows, creates an interplay of fluvial and marine sedimentary processes, which poses non-trivial challenges for reliable modelling of sedimentary MP transportation. Our approach, termed NIXVEGS (Nested Iterative X-Validation-to-Ensemble-modelling through GridSearches), leverages machine learning, integrating model selection, rigorous validation, and ensemble techniques tailored for small datasets. We estimated 20 trillion MP particles or 14.5 tonnes (50-5000 µm) residing in upper sediments of the Schlei proper, representing the highest resolution picture of an MP inventory for an entire geomorphological region to date. Our modelling concept is founded on the idea of applying granulometric proxies to account for the hydrodynamic regime bias in observed MP concentrations. Estuarine sediments store some of the highest MP concentrations among all sediment types. As depositional systems at the terrestrial-aquatic and fluvial-marine interface, they are key indicator ecosystems for monitoring the evolution of (micro)plastic pollution. Optimising sampling strategies for sediment grain size coverage and spatio-temporal hydrodynamics, and using models such as NIXVEGS, will be important to understand the contribution of complex estuarine systems to the global microplastic budget. Also see: https://micro2024.sciencesconf.org/559755/document

Wochenbericht LI-18-06 [L18-06]

No abstract is provided for this article.

A. Herstellung von Lactonen : IV. Lactone durch Oxydationsreaktionen

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Über die Formaldehyd‐Kondensation. VI. Über die Formaldehyd‐Kondensation und über die Gewinnung von Polyalkoholen aus Formaldehydkondensaten

Die Formaldehyd‐Kondensation konnte durch Anwendung geeigneter organischer Katalysatoren so beeinflußt werden, daß die niederen Zucker, die sonst nur als Zwischenprodukte auftreten, angereichert wurden. Dadurch war es möglich, die Polyalkohole Glykol, Glycerin und Erythrit durch Hydrierung von Formaldehydkondensaten in guter Ausbeute zu gewinnen. Auf der Basis von Ionenaustauscher‐Harzen wurden heterogene organische Katalysatoren entwickelt, die die Formaldehyd‐Kondensation ausreichend beschleunigen und in der gewünschten Richtung lenken. Sie ließen sich leicht zurückgewinnen und zeigten bei wiederholtem Einsatz keinen Aktivitätsverlust. Bei der Hydrierung der Kondensate wurden verschiedene Nickel‐Katalysatoren, insbesondere Mischsalzkontakte, auf ihre Verwendbarkeit geprüft.

Geo-hydrodynamic forcing for mangrove cliff coast retreat in Southern Vietnam along the Saigon–Dong Nai River and the Mekong Delta

A Holocene relative sea-level database for the Baltic Sea

We present a compilation and analysis of 1099 Holocene relative shore-level (RSL) indicators located around the Baltic Sea including 867 relative sea-level data points and 232 data points from the Ancylus Lake and the following transitional phase. The spatial distribution covers the Baltic Sea and near-coastal areas fairly well, but some gaps remain mainly in Sweden. RSL data follow the standardized HOLSEA format and, thus, are ready for spatially comprehensive applications in, e.g., glacial isostatic adjustment (GIA) modelling. We apply a SQL database system to store the nationally provided data sets in their individual form and to map the different input into the HOLSEA format as the information content of the individual data sets from the Baltic Sea area differs. About 80% of the RSL data is related to the last marine stage in Baltic Sea history after 8.5 ka BP (thousand years before present). These samples are grouped according to their dominant RSL tendencies into three clusters: regions with negative, positive and complex (transitional) RSL tendencies. Overall, regions with isostatic uplift driven negative tendencies dominate and show regression in the Baltic Sea basin during the last marine stage. Shifts from positive to negative tendencies in RSL data from transitional regions show a mid-Holocene highstand around 7.5–6.5 ka BP which is consistent with the end of the final melting of the Laurentide Ice Sheet. Comparisons of RSL data with GIA predictions including global ICE-5G and ICE-6G_C ice histories show good fit with RSL data from the regions with negative tendencies, whereas in the transitional areas in the eastern Baltic, predictions for the mid-Holocene clearly overestimate the RSL and fail to recover the mid-Holocene RSL highstand derived from the proxy reconstructions. These results motivate improvements of ice-sheet and Earth-structure models and show the potential and benefits of the new compilation for future studies.

The Birth and Maintenance of Sorted Bedforms: Insights From Field Data, German Bight, South-Eastern North Sea

No abstract is provided for this article.

SEDIMENTARY FEATURES OF TSUNAMI BACKWASH DEPOSITS AS ASSESSED BY MICRO-BEAM SYNCHROTRON X-RAY FLUORESCENCE (μ-SXRF) AT THE SIAM PHOTON LABORATORY

Over the past few years, several attempts have been performed to find alternative “chemical proxies” in order to discriminate “tsunami backwash deposits” from “typical marine sediments”. A wide range of statistical tools has been selected in order to investigate the sediments and/or terrestrial soils transportation mechanism during the tsunami inundation period by using several types of chemical tracers. To relate the physical and chemical characteristics of Typical Marine Sediments (TMS), Tsunami Backwash Deposits (TBD), Onshore Tsunami Deposits (OTD) and Coastal Zone Soils (CZS) with their synchrotron radiation based micro-X-ray Fluorescence (μ-SXRF) spectra, the μ-SXRF spectra were built in the appropriate selected spectra range from 3,000 eV to 8,000 eV. Further challenges were considered by using the first-order derivative μ-SXRF spectra coupled with Probability Distribution Function (PDF), Hierarchical Cluster Analysis (HCA) and Principal Component Analysis (PCA) in order to investigate the elemental distribution characteristics in various types of terrestrial soils and marine sediments. Dendrographic classifications and multi-dimensional plots of principal components (i.e. bi-polar and three dimensional plots) could indicate the impacts of terrestrial soils and/or marine sediments transport on onshore and/or offshore during the tsunami inundation period. Obviously, these advanced statistical analyses are quite useful and provide valuable information and thus shed new light on the study of paleotsunami.

Thriving reefs in the Baltic? Diversity and small-scale variability of hard-bottom assemblages along natural and anthropogenic gradients in the German Baltic Sea

A. Herstellung von organischen Derivaten der Borsäuren : I. Herstellung von Orthoborsäurederivaten mit gleichartigen Gruppen am Bor (II)

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Insights on Germany's west coast shelf architecture imaged by closely spaced high-resolution 2D multi-channel reflection seismics in the German sector of the North Sea

No abstract is provided for this article.

Mapping the Plastic Legacy: Geospatial Predictions of a Microplastic Inventory in a Complex Estuarine System Using Machine Learning

The persistence of microplastics (MP) in aquatic environments presents a pressing concern, with sediments serving as substantial repositories for these anthropogenic particles. Estuarine depositional systems are sensitive indicator environments for MP monitoring as they: (1) represent aquatic-terrestrial interfaces acting as a bottleneck for MP accumulation coming from land (capable of capturing riverine run-off as well as the often highly populated coastal areas), (2) comprise a confined area, favourable for sampling initiatives as compared to other systems such as long river courses or disperse inland waters. Hence, understanding MP distribution in intricate estuarine systems is essential, yet current models often falter in capturing complexities to sufficiently describe the present pollution patterns for an entire geomorphological region.We address this gap by employing machine learning techniques to predict spatial MP inventories deposited in the Schlei, Northern Germany. Notably, the complex hydrodynamic regime, influenced by narrowings and braided embayments, freshwater tributaries, wind-driven mixing, and brackish inflows, creates an interplay of fluvial and marine sedimentary processes, which poses non-trivial challenges for reliable modelling of sedimentary MP transportation. Our approach, termed NIXVEGS (Nested Iterative X-Validation-to-Ensemble-modelling through Grid Searches), leverages machine learning, integrating model selection, rigorous validation, and ensemble techniques tailored for small datasets.We estimated ~20 trillion MP particles or ~14.5 tonnes (50-5000 µm) residing in upper sediments of the Schlei proper, emphasizing the pivotal role of sediments as primary MP reservoirs. Our modelling concept is founded on the idea of applying granulometric proxies to account for the hydrodynamic regime bias in observed MP concentrations. We found that the high complexity of the geomorphology and extreme input events – both are predominant conditions in our study system – produce major spatio-temporal discontinuities in MP data which are not alleviated by a granulometric normalisation. Here we use hydrodynamic tracer simulations to derive variables which incorporate these discontinuities in empirical predictive modelling, but discuss simpler possibilities to enable modelling studies in systems for which such simulation data might not be feasible to acquire.This study provides a novel framework for geospatial prediction of MP inventories in complex aquatic systems. The integration of granulometric proxies and hydrodynamic discontinuities elucidates MP distribution patterns, offering a pathway for robust predictions and informed mitigation strategies. Our findings underscore the critical role of sediments in storing and reflecting the contemporary plastic legacy, crucial for comprehensive environmental management.

A. Herstellung von organischen Derivaten der Kieselsäure

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Side scan sonar backscatter mosaic offshore Thailand, Andaman Sea

The attached mosaics of side scan sonar data were recorded during 3 field campaigns in 2007, 2008 and 2010. High backscatter values are represented by darker colours. The mosaic is georeferenced in EPSG:32647 - WGS 84 / UTM zone 47N. Please refer to Feldens, P.; Schwarzer, K.; Sakuna, D.; Szczuciński, W.; Sompongchaiyakul, P. Sediment distribution on the inner continental shelf off Khao Lak (Thailand) after the 2004 Indian Ocean tsunami. <em>Earth, Planets and Space,</em> 2012, 64, 875-887; DOI:10.5047/eps.2011.09.001 and Sakuna-Schwartz, D.; Feldens, P.; Schwarzer, K.; Khokiattiwong, S.; Stattegger, K. Internal structure of event layers preserved on the Andaman Sea continental shelf, Thailand: tsunami vs. storm and flash-flood deposits. <em>Natural Hazards and Earth System Sciences,</em> 2015, 15, 1181-1199; DOI:10.5194/nhess-15-1181-201 and Feldens, P., Schwarzer K., Sakuna-Schwartz, D., Khokiattiwong, S. (in prep) Offshore geomorphological evolution in Phang Nga province (Thailand) during the Holocene: An example for a sediment starving shelf and references therein for further information on the dataset. The research was funded by Deutsche Forschungsgemeinschaft (DFG) grant No. SCHW 572/11-1 and National Research Council of Thailand (NRCT)

Submarine hard-bottom substrates in the western Baltic Sea – human impact versus natural development

Schwarzer, K., Bohling, B., Heinrich, C., 2014. Submarine hard-bottom substrates in the western Baltic Sea–human impact versus natural development. In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium(Durban, South Africa),Journal of Coastal Research, Special Issue No. 70, pp. 145–150, ISSN 0749-0208.Large areas of the seafloor in the western Baltic Sea are covered by lag deposits of Pleistocene origin, consisting of gravel, stones and boulders. From about 1800–1974, commercial extraction of stones and boulders from these shallow submarine areas was carried out. These activities have fundamentally changed the sediment distribution patterns and ecological conditions of the seafloor. Based on comparisons between old analogue and modern digital sidescan sonar images and direct abrasion measurements on the seafloor by scuba divers, the development of this hard-bottom substrate was studied on a decadal to seasonal scale. We show that due to abrasion processes the amount of boulders has been increased over a 22 year period. Thus, natural regeneration of hard-bottom substrate and improvement of the ecological status of the shallow marine environment is possible. This needs to be considered in order to reestablish a "good ecological status" as demanded by administrative guidelines like the EU Water Framework Directive and the Marine Strategy Framework Directive.

Mapeamento por sonar de varredura lateral das formas de leito do Estuário Potengi

Side-scan sonar, combined with echo-sounding and sediment sampling, has been employed to examine and map the distribution of sediments, bedform types and bedform geometries in the Potengi Estuary. The Potengi river Estuary is located in the eastern coastline of the Rio Grande do Norte State, being inserted in the geological context for the coastal Pernambuco-Paraíba basin and spreading over 20 km with mesotidal regime. Much of this dynamic sector is characterized by mobile, fine to slightly gravelly sands. The most abundant bedforms are small to large dunes (wavelength 2.87 - 95.12m, height up to 4.3m) of varying sinuosity and superposition of asymmetries which are indicative of the dominance of flood currents and marine derivation of sands.