Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Arsenic removal by iron based co-precipitation : Mechanisms in groundwater treatment
    Ahmad, Arslan - \ 2020
    Wageningen University. Promotor(en): A. van der Wal; P. Bhattacharya, co-promotor(en): H. Bruning. - Wageningen : Wageningen University - ISBN 9789463953740 - 194
    Mobility and redox transformation of arsenic during treatment of artificially recharged groundwater for drinking water production
    Ahmad, Arslan ; Heijnen, Leo ; Waal, Luuk de; Battaglia-Brunet, Fabienne ; Oorthuizen, Wim ; Pieterse, Brent ; Bhattacharya, Prosun ; Wal, Albert van der - \ 2020
    Water Research 178 (2020). - ISSN 0043-1354
    Arsenic - Co-precipitation - Drinking water - Fe(III)(oxyhydr)oxides - Rapid sand filtration

    In this study we investigate opportunities for reducing arsenic (As) to low levels, below 1 μg/L in produced drinking water from artificially infiltrated groundwater. We observe that rapid sand filtration is the most important treatment step for the oxidation and removal of As at water treatment plants which use artificially recharged groundwater as source. Removal of As is mainly due to As co-precipitation with Fe(III)(oxyhydr)oxides, which shows higher efficiency in rapid sand filter beds compared to aeration and supernatant storage. This is due to an accelerated oxidation of As(III) to As(V) in the filter bed which may be caused by the manganese oxides and/or As(III) oxidizing bacteria, as both are found in the coating of rapid sand filter media grains by chemical analysis and taxonomic profiling of the bacterial communities. Arsenic removal does not take place in treatment steps such as granular activated carbon filtration, ultrafiltration or slow sand filtration, due to a lack of hydrolyzing iron in their influent and a lack of adsorption affinity between As and the filtration surfaces. Further, we found that As reduction to below 1 μg/L can be effectively achieved at water treatment plants either by treating the influent of rapid sand filters by dosing potassium permanganate in combination with ferric chloride or by treating the effluent of rapid sand filters with ferric chloride dosing only. Finally, we observe that reducing the pH is an effective measure for increasing As co-precipitation with Fe(III)(oxyhydr)oxides, but only when the oxidized arsenic, As(V), is the predominant species in water.

    Heterogeneous anion exchange membranes with nitrate selectivity and low electrical resistance
    Mubita, T. ; Porada, S. ; Aerts, P. ; Wal, A. van der - \ 2020
    Journal of Membrane Science 607 (2020). - ISSN 0376-7388
    Multi-ionic solutions - Nitrate selectivity - Selective ion-exchange membranes

    Selective transport of specific ions across ion-exchange membranes can be enhanced by controlling membrane properties such as hydrophobicity. Previous studies have shown that hydrophobic membranes enhance transport of ions with low hydration energy, although such membranes often have increased electrical resistance. In the present work, we study the separation of monovalent ions, specifically nitrate and chloride, using newly-designed heterogeneous anion-exchange membranes. These membranes show high selectivity for nitrate over chloride and have low electrical resistance. We use a functionalized polymeric binder (ionomer) and three ion-exchange resins with different hydrophobic groups, i.e., resins with quaternary ammonium groups and methyl, ethyl, and propyl substituents, respectively. We find that in electrolyte solutions with nitrate and chloride, nitrate over chloride selectivity in our membranes increases with increasing length of the alkyl groups. The membrane with propyl groups, i.e., which has the highest selectivity for nitrate, was further tested in electrolyte solutions containing nitrate, chloride, sulfate, and nitrate, chloride, iodate. The transport of sulfate and iodate ions across the membrane with propyl groups was 6% and 2% of the total counterions transport, respectively. For monovalent ions with similar hydrated size it is possible to report selectivity trends based on the ion hydration energy. We find that the chemical structure of the membrane can either promote or hinder the transport of ionic species.

    Ontwerp Boerderij van de Toekomst
    Visser, Chris de; Sukkel, Wijnand ; Kempenaar, Corné ; Wal, Tamme van der; Wolf, Pieter de; Visser, Andries ; Smit, Bert ; Schoorlemmer, Herman ; Schoutsen, Maureen ; Klompe, Koen ; Veldhuisen, Bram ; Selin-Noren, Isabella ; Dijk, Chris van; Hol, Stefan ; Voort, Marcel van der; Janssens, Bas - \ 2020
    Wageningen : Stichting Wageningen Research, Wageningen Plant Research, Business unit Open Teelten (Rapport / Stichting Wageningen Research, Wageningen Plant Research, Business unit Open Teelten WPR-823) - 45
    On the merits and pitfalls of introducing a digital platform to aid conservation management : Volunteer data submission and the mediating role of volunteer coordinators
    Arts, Koen ; Melero, Yolanda ; Webster, Gemma ; Sharma, Nirwan ; Tintarev, Nava ; Tait, Elizabeth ; Mellish, Christopher ; Sripada, Somayajulu ; MacMaster, Ann Marie ; Sutherland, Hollie ; Horrill, Chris ; Lambin, Xavier ; Wal, René van der - \ 2020
    Journal of Environmental Management 265 (2020). - ISSN 0301-4797
    Environmental citizen science - Human-computer interaction - Invasive species control - Technological innovation - Volunteer coordination - Volunteer-based management

    Against a backdrop of accelerating digital innovation in nature conservation and environmental management, a real-world experiment was conducted with the research aims of assessing: 1) the effects of introducing a digital data-entry platform on volunteer data submission; and 2) the extent to which coordinators influence digital platform use by their volunteers. We focussed on a large-scale volunteer-based initiative aimed at eradicating the non-native American mink (Neovison vison) from northern Scotland. This geographically dispersed conservation initiative adopted a digital platform that allowed volunteers to submit records to a central database. We found that the platform had a direct and positive effect on volunteer data submission behaviour, increasing both the number and frequency of submissions. However, our analysis revealed striking differences in coordinator engagement with the platform, which in turn influenced the engagement of volunteers with this centrally introduced digital innovation. As a consequence, the intended organisation-wide rolling out of a digital platform translated into a diversely-implemented innovation, limiting the efficacy of the tool and revealing key challenges for digital innovation in geographically-dispersed conservation initiatives.

    Mechanisms of arsenate removal and membrane fouling in ferric based coprecipitation–low pressure membrane filtration systems
    Ahmad, Arslan ; Rutten, Sam ; Waal, Luuk de; Vollaard, Peter ; Genuchten, Case van; Bruning, Harry ; Cornelissen, Emile ; Wal, Albert van der - \ 2020
    Separation and Purification Technology 241 (2020). - ISSN 1383-5866
    Arsenic removal - Coprecipitation - Groundwater treatment - Iron chloride - Microfiltration - Ultrafiltration

    Ferric based coprecipitation–low pressure membrane filtration is a promising arsenic (As) removal method, however, membrane fouling mechanisms are not fully understood. In this study we investigated the effect of feed water composition and membrane pore size on arsenate [As(V)] removal and membrane fouling. We observed that As removal efficiency was independent of the membrane pore size because the size of the Fe(III) particles was larger than the pore size of the membranes, attributed to a high calcium concentration in the feed water. Arsenic coprecipitation with Fe(III) (oxyhydr)oxides rapidly reached equilibrium before membrane filtration, within 1 min. Therefore, As removal efficiency was not improved by increasing residence time before membrane filtration. The removal of As(V) was strongly dependent on feed water composition. A higher Fe(III) dose was required to reduce As(V) to sub-µg/L levels for feed water containing higher concentration of oxyanions such as phosphate and silicate, and lower concentration of cations such as calcium. Cake-layer formation was observed to be the predominant membrane fouling mechanism.

    Supplemental data for the paper: Biodegradation and adsorption of micropollutants by biological activated carbon from a drinking water production plant
    Piai, Laura ; Blokland, Marco ; Wal, Bert van der; Langenhoff, Alette - \ 2020
    Wageningen University & Research
    activated carbon bioregeneration - contaminants of emerging concern - micropollutants removal - temperature effect - water treatment
    The presence of micropollutants in surface water is a potential threat for the production of high quality and safe drinking water. Adsorption of micropollutants onto granular activated carbon (GAC) in fixed-bed filters is often applied as a polishing step in the production of drinking water. Activated carbon can act as a carrier material for biofilm, hence biodegradation can be an additional removal mechanism for micropollutants in GAC filters. To assess the potential of biofilm to biodegrade micropollutants, it is necessary to distinguish adsorption from biodegradation as a removal mechanism. We performed experiments at 5 °C and 20 °C with biologically active and autoclaved GAC to assess the biodegradation of micropollutants by the biofilm grown on the GAC surface. Ten micropollutants were selected as model compounds. Three of them, iopromide, iopamidol and metformin, were biodegraded by the GAC biofilm. Additionally, we observed that temperature can increase or decrease adsorption, depending on the micropollutant studied. Finally, we compared the adsorption capacity of GAC used for more than 100,000 bed volumes and fresh GAC. We demonstrated that used GAC shows a higher adsorption capacity for guanylurea, metformin and hexamethylenetetramine and only a limited reduction in adsorption capacity for diclofenac and benzotriazole compared to fresh GAC.
    Geschiktheid zeewindparken voor maricultuur en passieve visserij : een kwantitatieve beoordeling van de kansrijkheid van de gebieden voor de potentiële productiviteit van een selectie aan commercieel interessante soorten
    Bogaart, Lisanne van den; Wal, Jan Tjalling van der; Tonk, Linda ; Bos, Oscar ; Coolen, Joop ; Poelman, Marnix ; Vergouwen, Sophie ; Duren, Luca van; Janssen, Henrice ; Timmermans, Klaas - \ 2020
    Yerseke : Wageningen Marine Research (Wageningen Marine Research report C127/19A) - 111
    In de Nederlandse Exclusieve Economische Zone (EEZ) zijn windparken gepland op diverse locaties. Door de windparken ontstaan nieuwe kansen voor multifunctioneel gebruik zoals maricultuur en niet-bodemberoerende visserij met passieve vistuigen. Deze studie brengt de potentiële - kwantitatieve - productiviteit van het kweken of vissen (passief vistuig) binnen bestaande, geplande en mogelijke toekomstige windparklocaties op de Noordzee in kaart voor een aantal vormen van medegebruik; kweek van bepaalde soorten zeewier en schelpdieren en de niet-bodemberoerende vangst van bepaalde soorten vissen, schaaldieren en inktvissen. Dit project is een vervolg op een voorgaand project waarbij een kwalitatieve beoordeling gegeven is van de kansrijkheid van de gebieden. In de huidige studie is voor een selectie van kansrijke soorten een berekening voor oogst of productie uitgevoerd. Daarnaast is dit rapport bedoeld om op basis van de huidige stand van kennis een inschatting te geven van de orde van grootte van het ruimtebeslag van zeewierproductie binnen toekomstige windparken. Met een aantal berekeningen wordt inzicht gegeven in de orde van grootte van opbrengsten, beschikbare/benodigde oppervlakten en benodigde nutriënten in de Noordzee. Op basis van deze analyse lijkt een areaal van enkele honderden km2 zeewierproductie realistisch, hierbij is uitgegaan van een grove indicatieve berekening, met diverse aannames. Op basis van de beschikbare voedingsstoffen voor mosselen zou tussen ca. 50 en 100 ton drooggewicht mosselen per km2 per jaar kunnen worden geproduceerd, waarbij de bronnen van onzekerheid in acht genomen dienen te worden. Om een indruk te krijgen van het (relatieve) voorkomen van vissen, weekdieren en schaaldieren is gebruik gemaakt van VMS- en logboekgegevens samen met gegevens van twee jaarlijkse surveys (BTS en IBTS). Het is echter niet mogelijk gebleken om voor alle geselecteerde soorten een kwantitatieve inschatting te maken, aangezien er nog weinig bekend is over ruimtelijke verdeling van deze soorten. Daarom is voor deze soorten een overzicht gegeven van wat er in de literatuur over bekend is.
    Post-fire management treatment effects on soil properties and burned area restoration in a wildland-urban interface, Haifa Fire case study
    Wittenberg, Lea ; Wal, Hilde van der; Keesstra, Saskia ; Tessler, Naama - \ 2020
    Science of the Total Environment 716 (2020). - ISSN 0048-9697
    Ash - Post-fire management - Soil - Water repellency - Wildland-urban interface

    In November 2016, the urban dry streams (wadis) of the city of Haifa in Northern Israel were on fire. However, it was not just the fire that was threatening urban areas. Post-fire precipitation could turn into urban floods, further aggravating the fire damages. Several months after the fire a considerable restoration effort was initiated to restore the burned areas and mitigate future events. For urban forests the rehabilitation strategy was planned and implemented according to the topographic structure of the burned site and anticipated soil erosion. Accordingly, various post-fire management techniques were used: salvage-logging, afforestation, log erosion barriers and coconut fibre-webs. This study aimed to look at the effects of these methods on soil properties, namely, gravimetrical soil moisture, soil organic matter content, pH, electrical conductivity, hydraulic conductivity and soil water repellency. Results indicate that the control (burned, non-managed) site was the highest in soil moisture, organic matter and electrical conductivity compared to all other sites, however, the existence of ash cover made the response to precipitation unpredictable. The hydraulic conductivity (K) of the black ash (24.1 ± 8.6 mm/h), the white ash (19.0 ± 10.7 mm/h) and the disturbed (mixed) ash (11.7 ± 3.7 mm/h) were significantly higher than the underlying soil (3.3 ± 0.7 mm/h). As a result of these differences in K value, precipitation only infiltrates through the ash layers and then flows along the interface of the ash and the soil, triggering soil erosion. Most of the sites that were salvage logged showed signs of erosion. The log barriers were only effective for downstream areas. The afforestation could help to homogenise the soil, but the vegetation cover would be less dense and stable than after natural reforestation. Furthermore, the coconut fibre webs helped to improve the soil water retention and decreased the direct impact of rainfall.

    Biodegradation and adsorption of micropollutants by biological activated carbon from a drinking water production plant
    Piai, Laura ; Blokland, Marco ; Wal, Albert van der; Langenhoff, Alette - \ 2020
    Journal of Hazardous Materials 388 (2020). - ISSN 0304-3894
    Activated carbon bioregeneration - Contaminants of emerging concern - Micropollutants removal - Temperature effect - Water treatment

    The presence of micropollutants in surface water is a potential threat for the production of high quality and safe drinking water. Adsorption of micropollutants onto granular activated carbon (GAC) in fixed-bed filters is often applied as a polishing step in the production of drinking water. Activated carbon can act as a carrier material for biofilm, hence biodegradation can be an additional removal mechanism for micropollutants in GAC filters. To assess the potential of biofilm to biodegrade micropollutants, it is necessary to distinguish adsorption from biodegradation as a removal mechanism. We performed experiments at 5 °C and 20 °C with biologically active and autoclaved GAC to assess the biodegradation of micropollutants by the biofilm grown on the GAC surface. Ten micropollutants were selected as model compounds. Three of them, iopromide, iopamidol and metformin, were biodegraded by the GAC biofilm. Additionally, we observed that temperature can increase or decrease adsorption, depending on the micropollutant studied. Finally, we compared the adsorption capacity of GAC used for more than 100,000 bed volumes and fresh GAC. We demonstrated that used GAC shows a higher adsorption capacity for guanylurea, metformin and hexamethylenetetramine and only a limited reduction in adsorption capacity for diclofenac and benzotriazole compared to fresh GAC.

    Impact of phosphate, silicate and natural organic matter on the size of Fe(III) precipitates and arsenate co-precipitation efficiency in calcium containing water
    Ahmad, Arslan ; Rutten, Sam ; Eikelboom, Martijn ; Waal, Luuk de; Bruning, Harry ; Bhattacharya, Prosun ; Wal, Albert van der - \ 2020
    Separation and Purification Technology 235 (2020). - ISSN 1383-5866
    Arsenic removal - Drinking water - Ferric chloride (FeCl) - Groundwater treatment - Natural organic matter (NOM)

    Removal of arsenic (As) from water by co-precipitation with Fe(III) (oxyhydr)oxides is a widely used technique in water treatment. Nevertheless, As removal efficiency appears to be sensitive to the composition of the water matrix. The aim of this study was to gain a deeper understanding of the independent and combined effects of silicate (Si), phosphate (P), natural organic matter (NOM) and calcium (Ca) on arsenate [As(V)] co-precipitation efficiency and the size of Fe(III) precipitates. We found that, in complex solutions, containing multiple solutes and high levels of Ca, (variations in) Si and P concentrations reduce As(V) removal to some extent, mainly due to a decreased adsorption of As(V) onto Fe(III) precipitates. On the other hand, NOM concentrations reduced As(V) removal to a much greater extent, due to possible formation of mobile Fe(III)–NOM complexes that were difficult to remove by filtration. These findings have a great significance for predicting As(V) removal as a function of seasonal and process-related water quality changes at water treatment plants.

    The relationship between job demands, job resources and teachers’ professional learning: is it explained by self-determination theory?
    Jansen in de Wal, Joost ; Beemt, Antoine van den; Martens, Rob L. ; Brok, Perry J. den - \ 2020
    Studies in Continuing Education 42 (2020)1. - ISSN 0158-037X - p. 17 - 39.
    Job demands - job resources - motivation - self-determination theory - teacher professional learning

    Although teachers’ commitment to continuous professional learning is crucial for high quality education, research shows that this learning cannot be taken for granted. To better understand how teachers’ learning at work can be supported, this study investigates how effects of job demands (i.e. work pressure and emotional pressure) and job resources (i.e. task autonomy, transformational leadership, and collegial support) on teachers’ learning commitment (i.e. learning frequency and engagement) can be explained by basic psychological need satisfaction and autonomous motivation, as posited by self-determination theory. At two occasions, approximately one year apart, data was collected in a sample of 678 (T1) and 536 (T2) Dutch secondary school teachers. Structural equation models showed the consecutive positive longitudinal relationships between teachers’ experience of job resources, basic psychological need satisfaction, autonomous motivation, and commitment to professional learning. Job demands were not related to basic need satisfaction over and above the effects of job resources. Implications for how self-determination theory and the job demands resources model can mutually inform each other are discussed. In addition, implications for stimulating teachers’ professional learning in practice are provided.

    Reduction of low arsenic concentrations in drinking water to below 1 µg L−1 by adsorption onto granular iron (Hydr)oxides
    Jeworrek, A. ; Ahmad, A. ; Hofs, B. ; Mook, J. van; Wal, A. van der - \ 2019
    In: Environmental Arsenic in a ChangingWorld. - CRC Press/Balkema - ISBN 9781138486096 - p. 593 - 594.

    Arsenic in drinking water should be reduced as much as possible, because it is amongst carcinogenic substances. FerroSorp® Plus, Huijbergen and Spannenburg GIH could reduce As(V) levels in Ouddorp water below the desired 1 µg L−1. Particularly Huijbergen GIH had according to non-linear Freundlich modeling the higher KF value, translating into a potentially higher effective adsorption capacity. One of the characteristics that probably determines the success of a GIH is its physical properties. Since the effective adsorption capacity increases with higher initial As(V) concentrations, Huijbergen GIH is a promising adsorbent to reduce a wide range of arsenic concentrations from drinking water. Therefore, this affordable technology is not only reducing ultra-low arsenic concentrations to even lower concentrations in Ouddorp water but is also promising for developing countries that are seriously affected by high concentrations of arsenic in their drinking water.

    Ontwikkeling van enkele droogvallende mosselbanken in de Nederlandse Waddenzee, situatie 2018
    Glorius, S.T. ; Meijboom, A. ; Schop, J. ; Wal, J.T. van der - \ 2019
    Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-technical report 165) - 62
    Wageningen Marine Research is studying the long-term development of a number of individual intertidal mussel beds in the Dutch Wadden Sea to identify the characteristics that determine the survival of such beds. The study is being carried out as part of the WOT theme Nature Information Infrastructure. A large proportion of the mussel beds have been able to maintain themselves since the beginning of the study. About a year after new mussel beds are formed they gradually decline in area, coverage and population density, and the proportions of empty shells, macroalgae and barnacles increase. The decline in size and coverage is occasionally reversed by a good mussel spatfall, after which the process starts again. Japanese oysters have settled in most beds, leading to higher coverage of shellfish and a decline in mussel biomass.
    Effects of milk replacer composition on gut and lung health and performance in veal calves
    Greeff, A. de; Jansman, A.J.M. ; Ruuls-van Stalle, E.M.F. ; Vastenhouw, S.A. ; Schokker, D. ; Smits, M.C.J. ; Wal, E. van der; Mölder, P. ; Stockhofe, N. - \ 2019
    In: Proceedings of the 17th International Conference on Production Diseases in Farm Animals. - Bern, Switserland : University of Bern - ISBN 9783906813936 - p. 224 - 224.
    Negative energy balance (NEB) in dairy cows results from a fast increase in milk production post calving while feed intake is limited in this period. NEB is accompanied with an altered metabolic status, which triggers metabolic disorders. Metabolic status in early lactation is related with reproductive performance, e.g. reduced concentrations of insulin and IGF-I, which contributes to reduced follicular responsiveness to gonadotrophic stimulation, and thus prevents the dominant follicle to ovulate, resulting in a delay in the resumption of cyclicity. Omitting or shortening the dry period (DP), adjusting dietary energy level or feeding different dietary energy sources is of interest because that could minimize the risk of NEB, postpartum metabolic diseases and suboptimal fertility like delayed resumption of postpartum ovarian cyclicity. The aim of this study is to investigate the effect of DP length, dietary energy level, dietary energy source and interactions among these factors on fertility (resumption of ovarian cyclicity and days open) of dairy cows postpartum. Additionally, the relation between energy balance and metabolic status of dairy cows during early lactation and resumption of ovarian cyclicity and days open will be evaluated.
    Bodem- en waterkwaliteit in de Nederlandse landbouw : Relatie tussen bodemorganische stof en nitraatuitspoeling op melkveebedrijven op zandgrond
    Wal, A. van der; Hennen, W.H.G.J. ; Koeijer, T.J. de - \ 2019
    Bodem (2019)5. - ISSN 0925-1650 - p. 34 - 36.
    TMAP Kwelders (2019) : Tussenrapportage WOT-04-009-035.02
    Elschot, Kelly ; Puijenbroek, M.E.B. van; Wal, J.T. van der; Sonneveld, C. ; Lagendijk, D.D.G. - \ 2019
    Bats at the southern North Sea in 2017 & 2018
    Lagerveld, Sander ; Wal, Jan Tjalling van der; Vries, V. ; Verdaat, Hans ; Sonneveld, Cor ; Meer, Jaap van der; Brabant, Robin ; Noort, Bart - \ 2019
    Den Helder : Wageningen Marine Research (Wageningen Marine Research report ; C062/19 ) - 36
    Numerous land-based studies have shown that wind farms can have a significant negative effect on bat populations due to collisions and barotrauma. Since a few years it is also known that bats migrate regularly over the North Sea. In order to reduce uncertainties about possible impacts of the development of the offshore wind sector Rijkswaterstaat commissioned a follow-up offshore bat monitoring project as part of the WOZEP programme (Offshore Wind Ecological Programme). The monitoring will continue until at least 2019 and possibly throughout 2020. After that, the final report will be compiled, which will include a spatiotemporal analysis of the offshore occurrence of bats in all previous monitoring years. This report provides an overview of the monitoring effort and monitoring results in 2017 & 2018.Currently there are 14 monitoring locations where acoustic bat monitoring is executed, of which seven are oil & gas rigs, five are offshore high voltage stations of offshore wind farms and two are measurement platforms (Lichteiland Goeree and Europlatform). Since 2017 a new type of batdetector (Avisoft) is applied. In order to assess differences between the previously used batdetector (Batcorder) we monitored simultaneously with both detectors at three monitoring locations.The monitoring results in 2017 and 2018 show the same general pattern of occurrence as in previous years with Nathusius pipistrelle being the most common species, and Common pipistrelles and ‘Nyctaloids’ much more scarce.Furthermore the differences in performance are discussed between the currently used Avisoft detector and the previously used Batcorder. It appears that a correction should be applied in order to make measurements comparable between the two detectors, and the value of this correction factor depends on the time interval used in the analysis. At this moment the precision of the correction factor is estimated at 1.17 for 10 minute time intervals. In order to improve the precision to 1.1 simultaneous monitoring by both detectors should continue at least two monitoring years.Finally it is shown that there are obvious differences in occurrence amongst monitoring locations, between spring and autumn, as well as amongst years. However, a clear spatial pattern (e.g. from south to north or from east to west) does not emerge from this (preliminary) analysis. This should be investigated in a statistical model at the end of this project when all data of the entire monitoring period will be available as well.
    'Higher speeds at night not smart'
    Heusinkveld, Bert - \ 2019

    Om Nederland uit de stikstofcrisis te trekken, gaat de maximumsnelheid op de snelwegen terug naar 100. Alleen ’s nachts mag 130 nog rijden. Niet slim, vindt meteoroloog Bert Heusinkveld.

    Heusinkveld is onderzoeker bij de leerstoelgroep Meteorologie en Luchtkwaliteit. Zijn groep doet veel studie naar de gebeurtenissen in de zogeheten grenslaag, de laag lucht die wij ademen en waar ons weer zich afspeelt.

    Waarom is 130 's nachts niet slim?
    ‘De atmosfeer warmt overdag van onderaf op. Die warme lucht stijgt op en vormt de zogeheten grenslaag, de dunne laag lucht waarin wij leven en ademen. En waarin ook alle vervuiling terechtkomt. ’s Nachts koelt de lucht af, krimpt en vormt een dunne stabiele luchtlaag waarin door afnemende wind nauwelijks nog vermenging plaatsvindt. Een grenslaag die overdag een kilometer dik is, kan ’s nachts krimpen tot slechts honderd meter. Vervuilende stoffen uit het wegverkeer veroorzaken dan een hogere concentratie in die stabiele grenslaag.’

    Moet de maatregel dan andersom zijn: overdag 130 en ’s nachts 100?
    ‘Zo ver wil ik niet gaan. Maar 130 rijden is met het oog op luchtvervuiling overdag minder erg dan ’s nachts. Daar staat tegenover dat er overdag natuurlijk veel meer auto’s rijden dan ’s nachts.’

    Dus eigenlijk helemaal geen 130 km/uur?
    ‘Nee. Een limiet van 130 brengt onrustig rijgedrag met zich mee. Onderlinge snelheidsverschillen leiden sneller tot files en veroorzaken ongevallen. De grote milieuwinst van 100 rijden ontstaat door rustiger rijgedrag en minder files. Een auto in de file stoot per kilometer meer vervuilende stoffen uit dan eentje die kan doorrijden. Maar 130 rijden zorgt voor 30 procent meer vervuiling dan 100.’

    Zijn er nog andere meteorologische redenen om juist ’s nachts niet hard te rijden?
    ‘Ja, het geluid draagt ’s nachts veel verder. Doordat de grenslaag afkoelt, ontstaan flinke verschillen in de temperatuur in die laag. Bovenin kan het wel 10-15 graden warmer zijn dan onderin. In het warmere deel is de geluidsnelheid hoger. Geluid slaat daardoor makkelijker over geluidswallen heen. Het kan zelfs zo zijn dat het effect van zo’n wal daardoor volledig teniet wordt gedaan. Harder rijden in de nacht zorgt daardoor voor meer overlast dan overdag. In Duitsland mogen om die reden auto’s rond steden ’s nacht maar 80. En vrachtauto’s zelfs maar 60.’

    Diagnostiek Ontwikkeling en Toepassing voor het optimaliseren van uiergezondheid
    Griffioen, Karien ; Velthuis, A.G.J. ; Wal, F.J. van der; Mevius, D.J. ; Achterberg, R.P. ; Cornelissen, J.B.W.J. ; Dijkman, Remco ; Heuvelink, Annet E. ; Hop, G.E. ; Holstege, Manon M.C. ; Scherpenzeel, Christian ; Lam, Theo - \ 2019
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