4266 resultaten

  • Passive sampling and benchmarking to rank HOC levels in the aquatic environment

    Auteurs: Allan, I.J.; Weert, J.P.A. de (2021)
    Gepubliceerd in: Scientific reports : an open-access multidisciplinary journal, volume 11 (2021), pagina 1-12

    The identification and prioritisation of water bodies presenting elevated levels of anthropogenic chemicals is a key aspect of environmental monitoring programmes. Albeit this is challenging owing to geographical scales, choice of indicator aquatic species used for chemical monitoring, and inherent need for an understanding of contaminant fate and distribution in the environment. Here, we propose an innovative methodology for identifying and ranking water bodies according to their levels of hydrophobic organic contaminants (HOCs) in water. This is based on a unique passive sampling dataset acquired over a 10-year period with silicone rubber exposures in surface water bodies across Europe. We show with these data that, far from point sources of contamination, levels of hexachlorobenzene (HCB) and pentachlorobenzene (PeCB) in water approach equilibrium with atmospheric concentrations near the air/water surface. This results in a relatively constant ratio of their concentrations in the water phase. This, in turn, allows us to (i) identify sites of contamination with either of the two chemicals when the HCB/PeCB ratio deviates from theory and (ii) define benchmark levels of other HOCs in surface water against those of HCB and/or PeCB. For two polychlorinated biphenyls (congener 28 and 52) used as model chemicals, differences in contamination levels between the more contaminated and pristine sites are wider than differences in HCB and PeCB concentrations endorsing the benchmarking procedure.

  • Remote sensing-based automatic detection of shoreline position : a case study in Apulia Region

    Auteurs: Spinosa, A.; Ziemba, A.; Saponieri, A.; Damiani, L.; El Serafy, G.Y. (2021)
    Gepubliceerd in: Journal of marine science and engineering, volume 9 (2021) nummer 6, pagina 1-20

    Remote sensing and satellite imagery have become commonplace in efforts to monitor and model various biological and physical characteristics of the Earth. The land/water interface is a continually evolving landscape of high scientific and societal interest, making the mapping and monitoring thereof particularly important. This paper aims at describing a new automated method of shoreline position detection through the utilization of Synthetic Aperture Radar (SAR) images derived from European Space Agency satellites, specifically the operational SENTINEL Series. The resultant delineated shorelines are validated against those derived from video monitoring systems and in situ monitoring; a mean distance of 1 and a maximum of 3.5 pixels is found.

  • Are litter, plastic and microplastic quantities increasing in the ocean?

    Auteurs: Galgani, F.; Vethaak, A.D. (2021)

    Whilst both plastic production and inputs at sea have increased since the 1950s, several modelling studies predict a further increase in the coming years in these respective quantities. We compiled scientific literature on trends in marine litter, consisting largely of plastic and microplastics in the ocean, understanding that monitoring programs or assessments for these aspects are varied, frequently focusing on limited components of the marine environment in different locations, and covering a wide spectrum of marine litter types, with limited standardization. Here we discuss how trends in the amounts of litter in the marine environment can be compared with the information provided by models. Increasing amounts of plastic are found in some regions, especially in remote areas, but many repeated surveys and monitoring efforts have failed to demonstrate any consistent real temporal trend. An observed steady state situation of plastic quantities in many marine compartments and the fate and transport of plastic in the marine environment remain areas for much needed further research.

  • Toxicity characterization of surface sediments from a Mediterranean coastal lagoon

    Auteurs: Martinez-Gomez, C.; Valdehita, A.; Vethaak, A.D.; Navas, J.M.; Leon, V.M. (2020)
    Gepubliceerd in: Chemosphere, volume 253 (2020), pagina 1-12

    The occurrence of bioactive compounds and contaminant-associated effects was assessed by means of in vivo and in vitro assays using different extractable fractions of surface sediments from a contaminated coastal lagoon (Mar Menor, SE Spain). Sediment elutriates and clean seawater, previously exposed to whole sediment, were used for assessing the in vivo toxicity on embryo development of the sea urchin Paracentrotus lividus. Agonist and antagonist activities relating to estrogen and androgen receptors and agonist activities on aryl hydrocarbon receptor (expressed as ethoxyresorufin-O-deethylase (EROD) activities) were investigated in sediment extracts by using HER-Luc, AR-EcoScreenTM and fibroblast-like RTG-2 cell lines. Embryotoxicity effects were greater for sediment elutriates than those incubated in sediment-water interphase, implying that diffusion of bioactive chemicals can occur from sediments to sea water column, favoured by sediment disturbance events. In vitro results show the occurrence in extracts of compounds with estrogen antagonism, androgen antagonism and dioxin-like activities. Multidimensional scaling analysis classified the sampling sites into four sub-clusters according to their chemical-physical and biological similarities, relating in vitro bioactivity with the total organic carbon and known organic chemical load, with particular reference to total sum of PAHs, PCB 180, p,p-DDE and terbuthylazine. Overall, results pointed to the presence of unknown or unanalyzed biologically-active compounds in the sediments, mostly associated with the extracted polar fraction of the Mar Menor lagoon sediments. Our findings provide relevant information to be considered for the environmental management of contaminated coastal lagoons.

  • Modelling of thermal stratification and ice dynamics with application to Lake Teletskoye, Altai Republic, Russia

    Auteurs: Koshelev, K.; Goede, E.D. de; Zinoviev, A.; Graaff, R.F. de (2021)

    Numerical modelling of ice growth and transport of matter in lakes, estuaries, or coastal seas can provide crucial input for improving the environment. In this paper, the goal is to model the thermal stratification and ice dynamics in Lake Teletskoye, which is located in the Altai republic of Russia. Lake Teletskoye is a deep lake with a maximum depth of 325 m. The Delft3D modelling suite is applied for simulation of the temperature stratification and the ice formation in Lake Teletskoye, which is the first Delft3D application of ice melt and growth in a deep lake. Modelling deep lakes requires a special approach for the computation of the density. In Delft3D the UNESCO equation is applied, which is less suitable for deep lakes. Therefore, Delft3D has been extended with the TEOS-10 and the Chen-Millero density formulas, which yield accurate model results for Lake Teletskoye.

  • Towards network assessment of permanent railway track deformation

    Auteurs: Coelho, B.Z.; Varandas, J.N.; Hijma, M.P.; Zoeteman, A. (2021)

    The permanent railway track deformation caused by regular train traffic is important for infrastructure managers and railway contractors, as it determines the railway track quality. Although several successful approaches have been made to address the topic of the permanent railway track deformation, these have only been applied at specific locations, and have not yet been successfully applied at a network level. This paper presents a methodology that can be applied at the network level, by making use of a stochastic subsoil model to characterise the subsoil uncertainty and variability along the railway line, and by combining it with a dynamic train-track model and a cumulative cyclic deformation model. This methodology is illustrated by analysing a railway track section of 9 km in the Netherlands. The effects of the train service, such as train speed and axle loads, on the permanent deformation of the track are quantified. The proposed methodology has been partially validated against results of the dynamic stiffness obtained during the passage of a measurement train. The results illustrate the added value of this methodology for infrastructure managers and railway contractors as it allows for the quantification, at network level, of the consequences of train service changes for the future state of the railway network.

  • Understanding the impact of chemicals on marine fish populations : the need for an integrative approach involving population and disease ecology

    Auteurs: Martinez-Gomez, C.; Vethaak, A.D. (2019)

    The impact of acute and chronic marine pollution on the population changes of individual fish remains mostly unknown. In this paper, we share our study and review similar published work, emphasising fish health monitoring in European Seas and illustrating it using case studies. Arguably, an integrative approach is needed to assess the impact on population of chemical contaminants, beginning with field observations and complemented with experimental (laboratory and mesocosm) studies and modelling. Field surveys and monitoring using fish biomarkers should be intensified and ideally integrated with population statistics and fish ecology knowledge. Moreover, the indirect effects of chemicals -altering ecosystem functions- and the monitoring of immunological biomarkers and fatal diseases in wild fish populations should receive more attention.

  • An environmental dilemma for China during the COVID‑19 pandemic : the explosion of disposable plastic wastes

    Auteurs: Liu, J.; Vethaak, A.D.; An, L.; Liu, Q.; Yang, Y.; Ding, J. (2021)

    Plastic pollution control has been on top of the political agenda in China. In January 2020, China announced a phased ban on the production and usage of various types of single-use plastics as a solution to environmental pollution problems. However, the outbreak of COVID-19 seems to be a new obstacle to the ban on single-use plastic products. To basically satisfied the daily necessities and contain the spread of SARS-CoV-2 under the background of the regular epidemic prevention and control in China, online ordering, contactless delivery and wearing mask have become an important and feasible way of daily life. However, the unrestrained use of disposable plastic bags, lunch boxes and masks within the nationwide quarantine leads to hundreds of millions of plastics wastes every day. The potential environmental pollution caused by the use of disposable plastic products during the pandemic should arouse social concern. The Chinese government should manage environmental protection in parallel with anti-pandemic endeavors as the situation of the pandemic evolves.

  • Monitoring and characterising the solids loading dynamics to drainage systems via gully pots

    Auteurs: Rietveld, M.; Clemens, F.H.L.R.; Langeveld, J.G. (2021)
    Gepubliceerd in: Urban water journal, volume 18 (2021), pagina 1-12

    Runoff (re)mobilises solids and their associated pollutants from streets and transports them via gully pots to the drainage system. As the solids negatively impact the performance of the drainage systems, knowledge on the solids loading in terms of mass and composition is essential. However, monitoring data on the solids loading, in particular, covering all seasons and a number of sites, is scarce. This article presents the results of a monitoring campaign on the solids loading to a drainage system via 52 gully pots over a period of 2 years at a sampling rate of once per 3–4 weeks. The loading shows a maximum during the tree phases ‘leaf growth’ and ‘full capacity’ and is correlated with the rain intensity during these phases. The organic fraction and D50 of the solids are correlated with leaf abscission. The settling velocity of the particles <1800 μm is strongly correlated with their organic fraction.

  • Rheological analysis and rheological modelling of mud sediments : what is the best protocol for maintenance of ports and waterways?

    Auteurs: Shakeel, A.; Kirichek, A.; Talmon, A.M.; Chassagne, C. (2021)
    Gepubliceerd in: Estuarine, coastal and shelf science, volume 257 (2021), pagina 1-10

    Natural mud sediments display complex rheological behaviour like thixotropy, viscoelasticity and yield stress. These rheological characteristics can significantly vary over depth, from one mud layer to another, as each layer can have a different density and composition. Fast and reliable measurements of yield stresses of mud samples are important for maintenance operations in ports and waterways. These protocols, performed in the laboratory, should give a rheological fingerprint which is representative of the in-situ behaviour of the mud. In this article, we show that our recently developed stress ramp-up rheological protocol is a time-efficient and well-grounded protocol to determine the yield stresses of natural mud samples by comparing with other existing wellgrounded protocols. In this study, we also refine the stress ramp-up protocol such as to reduce the experimental time for different mud layers based on their densities. The protocol was tested on a large number of mud samples obtained from different locations/depths of the Port of Hamburg, Germany. An empirical model is proposed to fit the two-step yielding behaviour that the mud samples exhibit. The model captures the two-step yielding phenomenon in mud samples quite well, within the density range of 1050–1200 kg.m3. This two-step yielding is a feature of mud samples as found in various harbours and estuaries worldwide in rheometry.

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