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While geological models traditionally focus on the natural status of the underground, the shallow subsurface has been significantly altered by human activities over centuries. Particularly in urban contexts, ground has been raised, reworked, filled-in or disturbed in other ways. The rationale behind these alterations is as varied as the characteristics of the associated anthropogenic deposits: large-scale structures such as residential and industrial areas built on extensive sheets of filling materials or reclaimed lands are intertwined with smaller-scale features related, for example, to road and railway infrastructures, dikes or landfills. Their composition is equally diverse, ranging from displaced natural materials, such as crushed rocks, gravel, sand or clay, to artificial substances like recycled steel slags, concrete or rubble, or mixtures of these. Gaining knowledge on the presence and characteristics of such deposits is highly relevant, as their physical and chemical behaviour may differ significantly from those of natural deposits. The significance of anthropogenic deposits is increasingly recognized in urban geology. Resolving the geometry and properties of the urban shallow subsurface is essential for anticipating associated risks, for example dealing with pollution, ground stability or distorted water infiltration patterns. Anthropogenic deposits are, however, often scantily archived in permit documentation or represented on (geological) maps. Within the GSEU (Geological Service for Europe) project, the GSB is contributing to the task to develop a common, international vocabulary to describe all aspects of anthropogenic deposits, allowing standardised representation and characterisation in geological models. In parallel, VITO is developing shallow subsurface urban models for the Flemish government (VPO) within the VLAKO-framework, such as the published model of the Antwerp harbour and city. As the anthropogene inherently is part of these models, we are always aiming to better incorporate these deposits into the models. However, modelling the anthropogene presents unique challenges due to its high-resolution variability, scarcity of input data, and dynamic nature. It requires an approach that differs radically from traditional geological modelling techniques, in which depositional concepts related to the sedimentational or structural environment can be incorporated. In this presentation we will outline how we integrate various 1D, 2D and 3D sources to identify and characterize anthropogenic deposits and incorporate these insights in a 3D geological model of the anthropogene. This methodology is applied to the urban periphery of Brussels, where a new 3D geological model is being developed to support infrastructure projects and urban planning with special focus on the ring road (R0) of Brussels. Secondly, we will evaluate current lithological standards, vocabulary and stratigraphic approaches to characterize anthropogenic deposits. We will discuss their applicability in Flanders with practical examples from the periphery of Brussels. Ultimately, improving the representation of the anthropogene in geological models will significantly enhance their utility for urban planning, environmental management, and the sustainable utilization of the subsurface in urban areas.

Nearly every geological subdiscipline relies to some degree on regional geological knowledge. In the introductory section of most geological papers it is standard practice to provide regional geological background information. Stratigraphic terminology is often well defined while other disciplinary concepts rely, at least to some degree, on generally agreed definitions or hierarchical schemes, such as paleontological, structural or magmatic terminology. This, however, is much less the case for the regional geological building blocks. Their names are usually composed of a combination of a geographical locality and a geological term. A few examples from Belgium are Brabant Massif, Campine Basin, Stavelot-Venn Inlier, and Malmedy Graben. Most of these have in common that, although their importance is well recognised, their definitions are vague and sometimes even conflicting, in that their meaning may differ between contexts and authors. Even if their meaning has drifted or become less exact, as a result of their frequent historical use, they commonly remain in use today. This issue is not exclusive to Belgium, but seems to be an altogether historic and worldwide phenomenon. Recently within Europe there is a growing awareness of this issue, resulting in important but rather isolated efforts to better structure and define regional information (Hintersberger et al. 2017; Németh 2021; Le Bayon et al. 2022) which have been brought together through pan-European cooperation (GSEU – Horizon Europe 101075609). The central element that seems to encompass most geologic features, is the lithotectonic unit (a distinct unit based on its partly separate geological history; URI: http://inspire.ec.europa.eu/codelist/GeologicUnitTypeValue/lithotectonicUnit). Grabens, basins and inliers are examples of lithotectonic units. In order to define and describe these units more accurately, lithotectonic limits are introduced. These are planar features, such as faults and unconformities, that correspond to the geologic events that formed the lithotectonic unit (Piessens et al. 2024). All information is organised and linked in vocabularies (thesauri) that together not only adequately define each concept, but also determine the relations between them, placing them in space and geological time (Plašienka 1999). This outlines the core methodology, around which 2D and 3D multi-scale visualisations are built, annotations can be added, existing ontologies can be linked (such as the ICS Geological Time Scale Ontology; Cox and Richard, 2005) and newly developed extensions such as the Modified Wilson Cycle (Németh 2021). As such, the work at Belgian level is closely linked to the ongoing international developments. Making use of the ongoing developments at European level, Belgium was the first country to set up a lithotectonic working group that became operational in 2023. Its first goal is to provide a lithotectonic framework that describes a starting set of main geological units and limits in Belgium, according to emerging European standards (the work at European level is linked to the implementation of INSPIRE and 195 is in communication with the GeoSciML community), by the end of 2024. The working group meets approximately every 2 months, and organisationally resides under the National Commission for Stratigraphy in Belgium. The working group will soon be looking for additional experts (junior and senior) in its continuing effort to identify and define broad superstructures, detail the regional geology to the more local level, to tackle new types of lithotectonic elements, or better address parts of geological history. Potential candidates are encouraged to contact one of the authors or the NCS secretariat. Cox SJD, Richard SM (2005) A formal model for the geologic time scale and global stratotype section and point, compatible with geospatial information transfer standards. Geosphere 1:119. https://doi.org/10.1130/GES00022.1 Hintersberger E, Iglseder C, Schuster R, Huet B (2017) The new database “Tectonic Boundaries” at the Geological Survey of Austria. Jahrbuch der geologischen Bundesanstalt 157:195–207 Le Bayon B, Padel M, Baudin T, et al (2022) The geological-event reference system, a step towards geological data harmonization. BSGF - Earth Sci Bull 193:18. https://doi.org/10.1051/bsgf/2022017 Németh Z (2021) Lithotectonic units of the Western Carpathians: Suggestion of simple methodology for lithotectonic units defining, applicable for orogenic belts world-wide. Mineralia Slovaca 2:81–90 Piessens K, Walstra J, Willems A, Barros R (2024) Old concepts in a new semantic perspective: introducing a geotemporal approach to conceptual definitions in geology. Life Sciences Plašienka D (1999) Definition and correlation of tectonic units with a special reference to some Central Western Carpathian examples. Mineralia Slovaca 31:3–16

Geological units are the fundamental building blocks that help understand regional geological history and architecture. Classifying these correctly is therefore crucial, as is acknowledging how they relate to each other. This is where traditional definitions fall short, which is increasingly becoming evident with the ongoing effort of setting up advanced knowledge systems that rely on semantic grounding. In exploring the way forward for fundamental improvements, we use the foreland basin and related concepts to introduce a geotemporal conceptual approach of defining geological units with relative limits in time and space. This approach closes the semantic gap between definitions in thesauri and formal instantiation in ontologies.

To enhance the climate resilience of coastlines, measures are being implemented to protect and restore coastal ecosystems, such as biogenic reefs and dunes. These measures, known as Nature-based Solutions (NbS), provide protection against storms, coastal erosion, and flooding. They are also recognised for increasing biodiversity and delivering a range of ecosystem services (ES). This study investigated the ES provided by biogenic reefs composed of two reef-building species (Mytilus edulis and Lanice conchilega) under distinct hydrodynamic conditions. Three ES were assessed at two sites in the Belgian part of the North Sea: (1) coastal protection, (2) carbon sequestration, and (3) water quality regulation. The two sites have different hydrodynamic conditions due to their relative locations in relation to local sandbanks, making one site more exposed and the other more sheltered. The ES were quantified and monetised using in-situ measurements and literature data based on the SUstainable Marine Ecosystem Services (SUMES) model. The results suggest that the provision of ES in biogenic reefs is determined by multiple factors, including environmental conditions (e.g. hydrodynamics) and reefbuilding species. (1) Sediment accumulation was only observed under low hydrodynamic conditions, due to the higher settlement success of M. edulis and the presence of L. conchilega. (2) M. edulis “produces” carbon under both low and high hydrodynamic conditions, due to high respiration and biocalcification rates. However, low hydrodynamic conditions are more conducive to carbon burial, thus enhancing carbon sequestration. (3) M. edulis patches exhibited higher denitrification rates under low hydrodynamic conditions than under high hydrodynamic conditions or in L. conchilega patches, due to divergent macrobenthic functional diversity. In conclusion, the level of ES provision is determined by location and associated environmental conditions, as well as temporal and spatial variation in biogenic reefs and the physiological characteristics of reef builders. Therefore, both aspects need to be carefully considered when planning coastal protection measures and determining the provision of ES. Finally, when implementing NbS along high-energy coastlines, sheltered sites should be prioritised.

The global expansion in offshore renewable energy, primarily through offshore wind, is associated with the proliferation of subsea power cables (SPCs) throughout marine and coastal benthic environments. The transmission of electrical power through these SPCs will introduce electromagnetic fields (EMFs) into the seabed and the adjacent water column, which raises questions regarding the potential impact on benthic fauna, particularly during critical developmental early-life stages for which research considering the effects of both the electric and magnetic components of SPC EMFs is lacking. We conducted an experiment on three benthic egg-laying species, – the elasmobranch Scyliorhinus canicula, the cephalopod Loligo vulgaris, and the cephalopod Sepia officinalis – found in areas under consideration for the routing of SPCs. We exposed the embryos to realistic EMF levels (magnetic field 4–6 μT) recreated in the laboratory using an AC power cable set-up that simulated the EMF conditions, and examined the morphological, physiological, and behavioural responses. Our findings indicate subtle responses to EMF exposure in S. canicula and L. vulgaris with faster growth rates and morphometric differences, but no responses in S. officinalis. Our results highlight the value of a multiple end point approach to determine the potential influence of chronic exposure to EMFs on embryogenesis in benthic fauna and provide a baseline for future studies to build upon. Although our study cannot extrapolate the consequences of individuallevel effects to population-level impacts, it does underscore the necessity of realistic and longer-term studies to assess the potential consequences of EMFs to marine fauna.

Based on a thorough literature review and expert consultation, this study provides an inventory of all introduced non-indigenous species (iNIS) reported for Belgian marine and brackish waters. The data indicate a strong increase in iNIS in the study area from the 1990s onward, averaging 2.2 newly detected species per year, with a cumulative total of 108 iNIS between 1800 and 2024. The majority of these iNIS have the Northwestern Pacific or Northwestern Atlantic as their native region and are primarily introduced in Western Europe via shipping or aquaculture. In addition to compiling the inventory, the context in which the iNIS are detected is examined, distinguishing between official monitoring programs, project-based data collection efforts, and citizen science initiatives. Our findings indicate that while the EU aims to promote coordination between its Marine Strategy Framework Directive (MSFD) and Water Framework Directive (WFD), a misalignment occurs in the practical implementation of iNIS monitoring at the Belgian level. For example, a coherent and integrated monitoring framework across marine, brackish, and freshwater systems is still lacking. Furthermore, despite the EU’s ambition to ensure comprehensive iNIS monitoring, no legal framework currently mandates targeted monitoring in coastal ports, despite their well-documented role as hotspots for new marine introductions. After all, iNIS monitoring is only mandatory under the MSFD, which in essence applies only seaward from the coastal baseline and therefore does not cover waters within these ports. In addition, while the EU’s IAS Regulation has recently incorporated a few marine species on the Union list, its monitoring requirements remain primarily focused on terrestrial and freshwater species. As a result, observations published by citizens with significant expertise in the field represent the primary source of marine iNIS data in coastal port areas in recent decades in Belgium. The fragmentary nature of iNIS data complicates the efficient flow of information to international or European iNIS reference databases that support policy and decision-making. Yet, even species officially reported by Member States under MSFD Descriptor 2 are not always included in these reference databases. Nonetheless, accurate data on iNIS presence and distribution are essential for effectively targeting and managing iNIS.