3645 results

  • 37th International International No-Dig conference and exhibition (Florence, Italy, 30th September - 2nd October 2019)

    Originally published in 2019

  • Assessment of exposure to estrogenic contaminants (PAHs and Alkylphenols) in bile extracts of red mullet from the Western Mediterranean Sea : an integrated chemical and biological approach

    Authors: Martinez-Gomez, C.; Lamoree, M.H.; Hamers, T.; Velzen, M. van; Kamstra, J.H.; Fernandez, B.; Leon, V.M.; Benedicto, J.M.; Vethaak, A.D. (2012)
    Published in: Securing a sustainable future: integrating science, policy and people : proceedings SETAC Europe 22nd annual meeting (Berlin, Germany, 20 - 24 May 2012) : abstracts (2012), page 1-2

    Many published studies link exposure of fish and other wildlife to environmental endocrine disrupting chemicals (EDCs) with adverse health consequences. Assessment of exposure to potentially estrogenic compounds such as polycyclic aromatic hydrocarbons (PAHs) or alkylphenols (APs) cannot be adequately done by measuring concentrations in fish tissue as these compounds are easily metabolized by fish. However, metabolites of these two groups of compounds can be chemically detected and quantified in fish bile. Interactions of estrogenic EDCs with estrogen receptors is believed to be an important mechanism of endocrine disruption in fish. Red mullet is being used as target species for pollution monitoring programmes in the Mediterranean Sea. In this work we have identified and measured the concentrations of major metabolites of PAHs and APs in field collected bile extracts of red mullet (Mullus barbatus) from Mediterranean Spanish waters. In addition we have applied the estrogen receptor-mediated, chemical-activated luciferase reporter gene-expression assay (ER-LUC) to measure total estrogenic activity in the same bile extracts of male fish. By integrating the results of both analytical chemical and bio-analytical approaches, we have attempted to explain the measured ER-LUC activity by the calculated potencies based on chemical analysis of hydroxylated PAH and AP metabolites.

  • Securing a sustainable future: integrating science, policy and people : proceedings SETAC Europe 22nd annual meeting (Berlin, Germany, 20 - 24 May 2012) : abstracts

    Originally published in 2012

  • Horizontal directional drilling, pipeline installation by pulling or pushing

    Authors: Kruse, H.M.G.; Stoelinga, J. (2019)
    Published in: 37th International International No-Dig conference and exhibition (Florence, Italy, 30th September - 2nd October 2019) (2019), page 1-9

    The success of a horizontal directional drilling is largely dependent on the success of the installation of the product pipe, which is installed in the created borehole. The costs of damaged pipelines and the costs for additional measures during and after the pipeline installation can be considerable. In order to reduce the unexpected costs related to problems during the pipeline installation, a detailed analysis of the installation forces should be carried out. Nowadays the pipeline installation can be performed by the normal pull back operation or by pushing the pipeline forward in the created borehole. Since the behavior of the pipeline, which is pushed forward by a thruster at the entry point, is different from the behavior during pulling, the right prediction model for the soilpipeline interaction during installation should be used. The prediction results of the installation forces using the available models for pushing and pulling the pipeline are in line with the measurements of pulling forces and thrust forces.

  • Benthic species distribution linked to morphological features of a barred coast

    Authors: Holzhauer, H.; Borsje, B.W.; Dalfsen, J.A. van; Wijnberg, K.M.; Hulscher, S.J.M.H.; Herman, P.M.J. (2020)
    Published in: Journal of marine science and engineering, volume 8 (2020) issue 1, page 1-23

    The composition of benthic species communities in the nearshore zone is closely related to the hydrodynamic and morphodynamic conditions. Sustainable management of the coastal ecosystem requires knowledge about the natural dynamics as well as human-induced changes on the ecosystem. To improve our knowledge of the benthic species distribution along a dissipative sandy shore with multiple breaker bars, an extensive dataset was collected in the nearshore zone of the barrier islands Ameland and Schiermonnikoog in the Dutch North Sea. From 2010 to 2014, every year, approximately 180 grab samples along 18 cross-shore transects were collected and analyzed for sediment characteristics and macrobenthic species composition. Mixed-eect-models and partial redundancy analysis were used to analyze the importance of morphological features (i.e., slopes, bar crests, and troughs) as an explanatory variable for the benthic species distribution. The results indicate that the morphological features in themselves explain three times more variation than the environmental parameters used. This demonstrates the importance of morphological features as a factor in explaining the distribution of benthic species communities in the nearshore. Detailed information on morphological features is easy to obtain from bathymetry maps or visual inspection. Incorporating morphological features in species distribution models will therefore help to improve sustainable management of our valuable sandy coastal systems.

  • The world is your oyster : low-dose, long-term microplastic exposure of juvenile oysters

    Authors: Maes, T.; Barry, J.; Stenton, C.; Roberts, E.; Hicks, R.; Bignell, J.; Vethaak, A.D.; Leslie, H.A.; Sanders, M. (2020)
    Published in: Heliyon, volume 6 (2020) issue 1, page 1-10

    Bivalve filter feeders, such as oysters, filter large volumes of water and are particularly exposed to microplastics (MP). Consequently, these animals digest and assimilate high levels of MP in their bodies that may likely impact their physiology, and potentially affect shellfish stocks, benthic habitats and, indirectly, the health status of the marine ecosystem and human consumers. In this study we exposed juvenile oysters, Crassostrea gigas, to 3 different MP concentrations, represented by 6μm Polystyrene (PS) microbeads, compared to a control treatment receiving no MP. The study ran for a period of 80 days to test for the impacts of MP on growth, Condition Index and Lysosomal Stability. From histological analysis, microbeads were detected in the intestines of exposed oysters and in the digestive tubules, but no cellular inflammatory features were observed over time. Weight and shell length remained comparable between the different treatments and control. We found that Condition Index in the highest concentration increased initially but significantly reduced over time. The oysters in the highest MP exposure also showed the lowest mean Lysosomal Stability score throughout the experiment. Lysosomes play a vital role in the cells defense mechanisms and breakdown of constituents, crucial for the oysters’ wellbeing. Most importantly, we detected an increased mortality in those oysters who were chronically exposed to the highest loads of MP.

  • Exploring protective decision-making in the context of impact-based flood warnings

    Authors: Meléndez-Landaverde, E.R.; Werner, M.; Verkade, J.S. (2019)
    Published in: Journal of flood risk management (2019), page 1-11

    Previous research has found that users fail to comprehend flood hazard warning messages as well as the possible impacts of the forecast events. A proposed way to improve understanding and uptake is the implementation of impact‐based warning services. However, even though extensive qualitative research has been done on the provision of these impact‐based warnings (IBWs) for different types of hazards and extreme events, there is still little scientific evidence that the additional information on impacts in flood warnings positively affects decisions made by the general public. The research reported here explores whether including messages of potential impacts increased the general public's likelihood of making a protective decision when provided with a flood warning. Nine hypothetical flood scenarios were presented to participants who were then asked to score their likelihood of making a specific protective decision. Participants were either presented IBWs or hazard flood warnings (HWs). Results show that IBWs indeed led to higher likelihoods of participants making a protective decision than HWs. Interestingly, we found that key factors identified in previous studies as influential elements in the decision‐making process had little impact on their decision. These factors include gender and previous experience with flood warnings.

  • Influence of monitoring on investment planning of flood defence systems

    Authors: Klerk, W.J.; Kanning, W.; Veen, N. van; Kok, M. (2019)
    Published in: Proceedings of the 7th International Symposium on Geotechnical Safety and Risk - ISGSR 2019 (Taipei, Taiwan, 12-13 December 2019) (2019), page 1-6

    Many flood defences in the Netherlands will have to be reinforced in the coming decades. Many dikes do not fulfill the safety standard due to geotechnical failure modes, largely due to epistemic, reducible uncertainties. The Value of Information is a measure to indicate beforehand whether an investment towards reducing epistemic uncertainty is economically attractive. This paper investigates how reduction of the epistemic uncertainty in aquifer permeability might influence the Total Cost of a dike reinforcement, and the choice of reinforcement method. From the case study it is shown that the Value of Information from measurements strongly depends on firstly, whether the overall prioritization of investment for a larger dike segment is influenced, and secondly, whether the local reinforcement decision is sensitive to the parameter for which uncertainty is reduced.

  • Groundwater extraction may drown mega-delta : projections of extraction-induced subsidence and elevation of the Mekong delta for the 21th century

    Authors: Minderhoud, P.S.J.; Middelkoop, H.; Erkens, G.; Stouthamer, E. (2019)
    Published in: Environmental Research Communications (2019), page 1-30

    The low-lying and populous Vietnamese Mekong delta is rapidly losing elevation due to accelerating subsidence rates, primarily caused by increasing groundwater extraction. This strongly increases the delta's vulnerability to flooding, salinization, coastal erosion and, ultimately, threatens its nearly 18 million inhabitants with permanent inundation. We present projections of extraction-induced subsidence and consequent delta elevation loss for this century following six mitigation and non-mitigation extraction scenarios using a 3D hydrogeological model with a coupled geotechnical module. Our results reveal the long-term physically response of the aquifer system following different groundwater extraction pathways and show the potential of the hydrogeological system to recover. When groundwater extraction is allowed to increase continuously, as it did over the past decades, extraction-induced subsidence has the potential to drown the Mekong delta single-handedly before the end of the century. Our quantifications also disclose the mitigation potential to reduce subsidence by limiting groundwater exploitation and hereby limiting future elevation loss. However, the window to mitigate is rapidly closing as large parts of the lowly elevated delta plain may already fall below sea level in the coming decades. Failure to mitigate groundwater extraction-induced subsidence may result in mass displacement of millions of people and could severely affect regional food security as the food producing capacity of the delta may collapse.

  • KPP Retourstroom REGIS : activiteiten 2019

    Authors: Bos-Burgering, L.; Zaadnoordijk, W.J.; Vernes, R.W.; Engel, W.; Roelofs, G.; Veen, R. van der; Kroon, T. (2019)

    Rijkswaterstaat en de waterschappen maken samen met andere partijen in het Nederlandse waterbeheer op verschillende manieren gebruik van REGIS II, het hydrogeologische model van Nederland van TNO Geologische Dienst Nederland (TNO-GDN). Een belangrijke vorm van gebruik is in grondwatermodellen, zoals NHI-LHM, MORIA (rivierengebied) en AMIGO (Gelderland Oost). In deze modellen wordt kennis opgedaan die aanvullende informatie oplevert voor REGIS 11. Voorliggende rapportage beschrijft de activiteiten in 2019 om ervaringen die in hydrologische modelleringen zijn opgedaan terug te koppelen aan TNO-GON voor eventuele verbetering van REGIS. Hiervoor zijn, in vervolg op de pilot in 2018, twee nieuwe pilots uitgevoerd waarbij de wijze van terugkoppeling is getoetst.

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